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ANTHRACENE AND ANTHRAQUINONE
J^*
ANTHRACENE AND ANTHRAQUINONE
^t
.V
BY
E BARRY BARNETT, B.Sc.(Lond.), F.I.C.
LECTURER IN ORGANIC CHEMISTRY AT THE SIR JOHN CAbS TECHNICAL INSTITUTE;
FORMERLY RESEARCH CHEMIST TO LEVINSTEIN, LTD. ; AND WORKS
MANAGER OF THE STOCKTON-ON-TEBS CHEMICAL WORKS, LVD.
NEW YORK D. VAN NOSTRAND COMPANY
EIGHT WARREN STREET 1921
PRINTED IN GREAT BRITAIN
^;Vs
2qs
PREFACE
It is now over forty years since Auerbach published his "Das Anthracen und seine Derivate,"* and during this period, and more particularly during the last fifteen years, enormous advances have been made in our knowledge of the chemistry of the anthracene derivatives. Much of the research which has been carried out has appeared only in the form of patent specifications, and for that reason has escaped the attention which it merits. It seemed, therefore, that a short account of the anthracene derivatives would not be without value, more especiall}^ as many of the most valuable fast dyes belong to this class of compound. At the urgent request of several friends the author has there- fore arranged his own private notes on the subject in book form, and trusts that the appearance of this volume will lead to greater attention being paid to anthraquinone chemistr}' in this country than has been the case up to the present. Many of the claims made in the patent literature require elaborating and confirming (or contradicting), and as several anthraquinone derivatives are now manufactured in this country, work of this nature would be suitable for senior students in universities. Such research would be of the utmost value at the present time, when serious attempts are being made to manufacture the very valuable anthra- quinonoid dyes in this country.
In the following pages wiU be found a fairly complete account of the work which has been published up to November, 1920, on the derivatives of anthracene and
* Second German edition, 1880. English translation by Sir William Crookes of first German edition, 1877.
V
vi PREFACE
anthraquinone ; but an account of naturall}- occurring anthracene derivatives, such as chrysarobin, etc., has purposely been omitted, as an up-to-date account of these substances has recently appeared elsewhere.* References have been given liberally, although it is not claimed that those cited form a complete bibliography of the subject. All references given have been read by the author in the original with the exception of a few German patents which have been granted during or siftce the war, and which at the time of going to press are not available in the Patent Office librar5\ For such patents the author has been compelled to rely on the very inadequate abstracts pub- lished in j ournals such as the Chemisches Zentralhlatt, Chemi- ker Zeitung, and Journal of the Society of Chemical Industry. The introduction of new systems of notation is not to be encouraged as a rule, but after mature consideration the author decided to make use of his own modification of Pfaff 's system. The best excuse he can offer for this is the very considerable saving in the cost of composing which it has effected. In cases where the straight line notation is not suitable, the formulae have been reproduced by means of blocks.
The author wishes to take this opportunity of expressing his thanks to Mr. J. W. Cook, B.Sc, for much valuable help while the book was passing through the press.
E. DE BARRY BARNETT.
Sir John Cass Technical Institute, Jewry Street, Aldgate, E.C. 3, yannary, 192 1.
* Perkin and Everest, "Natural Organic Colouring Matters."
CONTENTS
CHAPTER I.— INTRODUCTION
Historical sketch, i. Dyeing, 5. Commercial names, 7. Colour and con- stitution, 8. Nomenclature, lO.
CHAPTER II.— ANTHRACENE AND ITS HOMOLOGUES
Anthracene, 14. Structure, 18. Oxidation, 19. Paranthrene, dianthrene, 24. Homologous anthracenes, 26.
CHAPTER III.— SIMPLE DERIVATIVES OF ANTHRACENE
Hydroanthracenes, 39. Halogen compounds, 41. Action of nitric acid on anthracene, 50, Sulphonic acids, 61. Hydroxyanthracenes, 64. Amino- anthracenes, 67. Nitriles and carboxylic acids, 69. Aldehydes and ketones, 70.
CHAPTER IV.— THE ANTHRAQUINONES AND DIANTHRAQUINONYLS
i.2-Anthraquinone, 73. 1.4-Anthraquinone, 73. 9.10-Anthraquinone, 73. Homologous anthraquinones, 79. Reduction products, 80. Action of Grignard's solution, 85. Dianthraquinonyls, 90. Anthradiquinones, 92. Anthraflavones, 94.
CHAPTER v.— ANTHRONE, ANTHRANOL AND ALLIED PRODUCTS
Anthrone and anthranol, 96. Hydroxyanthrone and anthraquinol, 108. Dianthryl and its derivatives, 114. Tautomerism, 118.
vii
VUl
CONTENTS
CHAPTER VI.— ANTHRAQUINOxNE RING SYNTHESES
I. From aromatic monocarboxylic acids .....
II. From phthalic acid by the direct method ....
III. Phthalic acid synthesis .......
PACK
125 127 130
CHAPTER VII.— THE BENzAnTHRAQUINONES
I.
II.
III.
IV.
V.
(7«^.-Benzanthraquinone (Naphthanthraquinone) //«.-Benzanthraquinone (Naphthacenquinone) //«.-Benzanthradiquinone (Xaphthacendiquinone) irafis-disaMg-.-Dihenza.uihraqumone (Dinaphthanthraquinoue) /j«.-Dibenzanthraquinone (Dinaphthanthraquinone)
143 145 152 154 156
CHAPTER VIII.— THE ALDEHYDES, KETONES, AND CARBOXYLIC ACIDS
I. Aldehydes IS9
II. Ketones 160
III. Carboxylic acids 162
CH.\PTER IX.— THE NITRO, NITROSO, AND HALOGEN ANTHRAQUI NONES
I. Nitro compounds ......... 167
II. Nitroso compounds ......... 169
III. Halogen compounds . . . . • • • .170
CHAPTER X.— THE SULPHONIC ACIDS, MERCAPTANS AND SULPHIDES
I. II. III. |
Sulphonic acids Sulphinic acids Sulphenic (Sulphoxylic) acids . |
||||
IV. V. VI. VII. VIII. |
Mercaptans Selenophenols . Sulphides Bisulphides Diselenides |
||||
IX. |
Thianthrenes . |
176 180 181 182
185
186
187
188 188
CONTENTS ix
CHAPTER XL— THE AMINOANTHRAQUINONES AND DIANTHRAQUINONYLAMINES
Reduction of nitre groups, 192. Replacement of negative groups, 195. Replacement of halogen atoms, 196- Replacement of nitro groups, 198. Replacement of hydroxyl groups, 200. Replacement of sulphonic acid groups, 205. Hofmann's reaction, 206. Alkylation and arylation, 207. Tinctorial properties, 210. Acylaminoanthraquinones, 212. Ureas and thioureas, 219. Addendum, 223. Nitration, 223. Nitra- mines, 226. Halogenation, 227. Dianthraquinonylamines, 231.
CHAPTER XII.— THE HYDROXY AND AMINO- HYDROXY ANTHRAQUINONES AND ETHERS
I. The hydroxy compounds ........ 236
Replacement of sulphonic acid groups, 239. Replacement of nitro groups, 241. Replacement of halogen atoms, 247. Replacement of amino groups, 249. Direct oxidation in alkaline solution, 252. Direct oxidation in acid .solution by concentrated sulphuric acid or oleum, 256 ; by nitrosyl sulphuric acid, 260 ; by various oxidising agents, 263. Reduction of polyhydroxy compounds, 264. Miscel- laneous methods, 266. Properties and reactions, 267. Tinctorial properties, 271. Halogenation, 273. Sulphonation, 276. Nitra- tion, 279. II. The aminohydroxy compounds ....... 282
III. The ethers 285
CHAPTER XIII.— PYRIDINE AND QUINOLINE
DERIVATIVES
I. Pyridanthrones ......... 290
II. Anthraquinone quinolines ........ 293
III. Anthraquinone phenanthridones ...... 297
IV, Pyranthridones ......... 297
V. Flavanthrones ......... 300
CHAPTER XIV.— THE ACRIDONES, XANTHONES, AND THIOXANTHONES
I. The Acridones . 305
II. The Xanthones . . . . . . . . • 3»5
III. The Thioxanthones 317
CONTEXTS
CHAPTER XV.— THE BENZANTHRONES
I. Simple benramh^one^ .... II. Complex beiizamhrones ....
Violan thrones, 329. ;>tf-Violamhrones, 331. Helianthrones, 333. Pyranthrones, 335.
Cyanthrones, 332.
320 327
1. II.
CHAPTER XVI.— THE CVCLIC AZINES AND HYDROAZINpS
Mixed amines and hydroazines ......
Simple axines and hydroazines ......
340 342
CHAPTER XVII.— MISCELLANEOUS HETERO- CYCLIC COMPOUNDS
1. The Pjtidazineanthrones
II. The Pyrimidoneanthrones
III. The Ox.vzines
IV. The Thi.izines V. The Carbazols
VI. The ?\Trolanthrones
VII. The Pyrrazols
VIII. The Ind.izols
IX. The Imidiuols
X. The Oxazols
XI. The Isoxazols
XII. The Thiophenes
XI II. The Thiazols
XIV. The ut'-Thiazolanthrones XV. The Cffroxene derivatives
XVI. The Ccerthiene deri%-atives
XVII. The Coeraniidine derivatives
XVIII. Miscellaneous compounds
353 354
355 358 360 362
363 364 36s 368
369 370 371
374 37S 379 380
CHAPTER XVIII.— MISCELLANEOUS COMPOUNDS
1. Arsenic compounds .....
II. .\ceanthrenequinones .....
III. Diazonium salts ......
IV. Azo, azimino, and azoxy compounds
V. Hvviroxylamines, hydrazines and hydrazo compounds
Addenda
Index to German Patents Index to Authors . Index to Subjects
382
383
3S5 3S7 3^
393 401 419 424
\
ABBREVIATIONS
Literature.
A. Annalen der Chemie.
A. ch. Annales de Chimie et de Physique.
A. P. United States of America Patent. Am. American Chemical Journal.
Am. Soc. Journal of the American Chemical Society.
B. Berichte der Deutschen Chemischen Gesellschaft. Bl. Bulletin de la Societe Chimique de Paris.
C. Chemisches-Zentralblatt.
C. r. Comptes rendus de I'Academie des Sciences.
Ch. Z. Chemiker-Zeitung (Cothen).
D.R.P. Patentschrift des Deutschen Reiches.
E.P. English Patent Specification.
P.P. French Patent Specification.
F.T. Zeitschrift f. Farben- u. Textil-Industrie.
F.Z. Farbe-Zeitung.
G. Gazetta chimica itaUana.
J. Jahresbericht der Chemie.
J. pr. Journal fiir praktische Chemie.
M. Monatshefte der Chemie.
Mon. Sci. Moniteur Scientifique.
Pat. Anm. Patent Anmeldung.
Proc. Proceedings of the Chemical Society.
R. Receuil des travaux chimiques des Pays-Bas.
R.G.M.C. Revue General des Matidres Colorantes.
Soc. Journal of the Chemical Society.
Z. Zeitschrift fiir Chemie.
Z. ang. Zeitschrift fur angewandte Chemie.
Firms.
Agfa. Aktien-Gesellschaft fiir Anihn Fabrikation, Berlin-Treptow. B.A.S.F. Badische Anihn- u. Soda-Fabrik, Ludwigshafen a/Rh. By. Farbenfabriken vorm. Friedr. Bayer u. Co. Elberfeld u. Leverkusen. Cas. Leopold Cassella u. Co., G.m.b.H. Frankfurt a/lVL G.E. Chemische Fabrik Griesheim-Elektron, Frankfurt a/M. K. Kalle u. Co. Aktien Gesellschaft, Biebrich a/Rh. M.L.B. Farbwerke vorm. Meister Lucius u. Briining, Hochst a/M. Wed. Wedekind u. Co. G.m.b.H., Uerdingen. W.t.M. Chemische Fabrik vorm. Weiler-ter-Meir, Uerdingen.
xi
ANTHRACENE AND ANTHRAQUINONE
CHAPTER I INTRODUCTION
HiSTORICAI. vSkETCH
Anthracene was first discovered in 1832 by Dumas and Laurent, who obtained it from the higher boihng fractions of coal tar and named it " paranaphthalene," although Laurent, who investigated the substance more closely a few years later, changed the name to anthracene. In 1857 I'ritzsche also obtained anthracene from coal tar, and seems to have prepared it in a purer state than Dumas and Laurent ; and a few years later, in 1862, Anderson also described its isolation and the preparation from it of several derivatives. In 1866 the first synthesis of anthracene was published, as in this year Limpricht obtained it by heating benzyl chloride with water at 180'', and Bert helot showed that anthracene is obtained by the pyrogenic de- com]josition of many simpler hydrocarbons.
About this period some doubt was thrown on the belief that anthracene was really a single chemical compound, and Fritzsche regarded it as a mixture of two substances, which he named photene and phosene. That anthracene should be regarded as a mixture is hardly surprising in view of the fact that it is not a particularly easy compound to obtain in a state of purity, and at the period in question ver>' little was known of, the constituents of coal tar.
I I
I
ANTHR/CEXE AND ANTHI'AQLIXONK
CHAFFFl I INTRODrTIOX
Historic AL SKETCH
Anthracp:n'e was first disco\'i -d in 1832 b>' T)xuna» mad Laurent, who obtained it from he hicher b<nlinK fractiom ot cool tar and named it " aran. altboagb
ibstanoe more cloady a
th* name to antfancmr. la
raorae from ooaJ tar. aad
i It tn* portr than
Laurent, who in^
r. ch
to have pr
I a iew
^n.
■m i v»«f aot
St «l
^
>
INTODUCTION
in a remarkably short sace of time, as in the same year synthetic alizarin was pipared in Gennany by Graebe and Liebermann, and in the y]lowiag year the technical process for its manniactare fror anthraqninone solphonic add was patented independently - Caro, Graebe and Uebermann,^ and by Perkin.'
The soccessfal mantECtare of alizarin natuially led to the investigation of othf polyhydroxyanthraquinones, and dming the following yers several of these were described, bnt although some of t^rm were found to be of value as dyes, their importance from a technical standpoint was relatively smalL llie ivestigation of alizarin and its de- rivatives led to the prearaticni of its quinoline. Alizarin Blue X, by PmdTiomie in 1877, and ten years later Peter Bohn discovered hat fresh hydroxyl groi^ could be introduced into the lolecule by direct oxidaticni. The immediate result of thisdiscovery was the technical manu- facture of Alizarin Gree X and Alizarin Indigo Blue, but simultaneously, ahhouii independently, R. £. Schmidt discovered that the readon was a ven- general one in the anthraqninone series, ad that by it many hydrox3>-anthra- quinones could be prepred. It is difficult to overestimate the in^Hntance of this liscovery, as it rendered available ccmqKnmds which have- roved to be of the utmost value as starting-out substares. Among other valuable ^es which were discovered ? a direct result of hydroxyanthra- qninones being made esily available may be mentioned Alizarin Cyanine Greet and Alizarin SaphiroL Both of these discoveries were ne to K. E. Schmidt, the former being obtained in 1S4 and the latter in 1897. To R- E. Schmidt is also dc the credit of the discoveiy in 1903 that the presence of r^rcury during the suJ^honation of anthraqninone leads aiiost esdusively to the formation of a-sulphonic adds, bt Iljinsky seems to have made the same discovery indepenently and almost simuhaneonsly. In a patent applied or in 1894 an insoluble product is
* Paleni apjr
* Patent apj:.
:- -r. J-jine 25, 1S69. :- en j-ane 26, 1869.
2 ANTHRACENE AND ANTHRAQUINONE
The first ^ructural formula which was proposed for anthracene was diie to Graebe and Liebermann, who pro- posed both the forniida now assigned to phenanthrene and also what is now known to be the correct formula. They discussed the merits of both of these, but regarded the phenanthrene formula as being more in accordance with the then known facts. Shortly after, however, the discovery of phenanthrene rendered tlie second alternative almost certain, final confirmation being obtained by the synthesis of anthracene derivatives from phthalic acid and phenols, and of anthraquinone itself from benzoyl benzoic acid. Further proof of the presence of two benzene rings lies in the fact that whereas nitroanthraquinone on oxidation gives nitrophthalic acid, the corresponding aminoanthra- quinone gives phthalic acid itself. The oxidation of anthra- cene to anthraquinone was first described by Laurent, who named the product " paranaphthalose," or, at a later date, " anthracene." Anderson also prepared anthraquinone and named it " oxanthracene," the modern name, " anthra- quinone," being introduced by Graebe and Liebermann.
Up to the year 1868 anthracene was regarded merely as a chemical curiosity, but in that year Graebe and Liebermann made the discovery that alizarin 3delds anthracene when distilled over zinc dust, and hence that alizarin was to be regarded as a derivative of anthracene. 1 This epoch- making discovery came at an opportune moment, as in 1856 Perkin had started making Mauveine on a commercial scale, and other synthetic dyes such as Magenta, Nichol- son's Blue, Methyl Violet, Saffranine, and Bismarck Brown had rapidly rewarded the labours of those investigating the possibility of obtaining dyewares from coal products. The verj' great success that had recently attended other researches made with a view to obtaming synthetic d3'es, naturally led to hopes that alizarin might also be made by an artificial process, and these expectations were fulfilled
^ The formula of alizarin had been previously determined by Strecker, who, however, had not published his results in any journal, although he mentioned the matter in his text-book of inorganic chemistry, published in 1866.
INTRODUCTION 3
in a remarkably short space of time, as in the same year synthetic aUzarin was prepared m Germany by Graebe and lyiebermann, and in the following year the technical process for its manufacture from anthraquinone sulphonic acid was patented independently by Caro, Graebe and lyiebermann, ^ and by Perkin.^
The successful manufacture of alizarin naturally led to the investigation of other polyhydroxyanthraquinones, and during the following years several of these were described, but although some of them were found to be of value as dyes, their importance from a technical standpoint was relatively small. The investigation of alizarin and its de- rivatives led to the preparation of its quinoline, Alizarin Blue X, by Prud'homme in 1877, and ten years later Peter Bohn discovered that fresh hj^droxyl groups could be introduced into the molecule by direct oxidation. The immediate result of this discover}^ was the technical manu- facture of Alizarin Green X and Alizarin Indigo Blue, but simultaneously, although independently, R. E. vSchmidt discovered that the reaction was a very general one in the anthraquinone series, and that by it many hydroxyanthra- quinones could be prepared. It is difficult to overestimate the importance of this discovery, as it rendered available compounds which have proved to be of the utmost value as starting-out substances. Among other valuable dj-es which were discovered as a direct result of hydrox3-anthra- quinones being made easily available may be mentioned Alizarin Cyanine Green and Alizarin Saphirol. Both of these discoveries were due to R. E. vSchmidt, the former being obtained in 1894 and the latter in 1897. To R. E. Schmidt is also due the credit of the discovery in 1903 that the presence of mercury during the sulphonation of anthraquinone leads almost exclusivel)' to the formation of o-sulphonic acids, but Iljinsky seems to have made the same discover}- independently and almost simultaneously. In a patent applied for in 1894 an insoluble product is
' Patent applied for on June 25, 1S69. * Patent applied for on June 26, 1869.
4 ANTHRACENE AND ANTHRAQUINONE
described as being obtained by heating anthrachr3-sazin with concentrated aqueous ammonia for fifteen hours at 150-200°, and it is claimed that this substance acts as a brownish black vat d3-e. ^ This seems to be the first occasion on which the possibility of vat dyeing with anthraquinone derivatives was taken into consideration, and it is truly remarkable that the discovery- should have been delayed so long. At that period, of course, vat dyeing was not a common method of applying a colouring matter, but it was well known that the indophenols could be applied in this way, and in the case of indigo, vat d^-eing had been carried out since almost prehistoric times. The d^-estuff described in the patent proved to be of no technical value, and no further interest seems to have been taken in the matter for some seven 5'ears. In 1901, however, Bohn discovered Indanthrene and Flavanthrene, and the great value of these d^-estuffs led to an immediate search for other vat d5'es containing the anthraquinone ring S3'stem. Success was soon achieved, as Anthraflavene was discovered by Isler in 1905, and P3'ranthrene b3^ Scholl in the same 3'ear, whereas the next 3-ear saw the discover3^ of Violanthrene b3' Ball3\ Since that time the discovers' of new anthra- quinonoid vat d3'es has been continuous, although during the last tw-o or three 3-ears there has been a ver3' remarkable falling ofi' in the number of patents taken out. This falling off in the patent claims is not, however, confined to the anthraquinone series, but is ver3' noticeable throughout the whole of the chemical industr3^ It does not denote an3' slackening of research, nor does it point to exhaustion of the subject, but is to be attributed to the formation of the " Interessengemeinschaft " among the leading German firms having removed practicall3' all competition, with the result that the firms interested prefer to preserv^e their dis- coveries as trade secrets, and thus avoid furnishing rival concerns in other coimtries with information. The de- preciated value of the mark rendering protection in foreign countries somewhat costh- is also, no doubt, to some extent
1 M. L. B., D. R. p. 83,068.
INTRODUCTION 5
responsible for the policy of secrecy. Up to the present the British firms which are now interested in the manufacture of vat d^-es have applied for ver}^ few patents. This, how- ever, is not at all surprising, as they have naturally been full}- engaged in reducing " known " processes to a workable form. The chief workers on anthraquinone have been Lieber- manu, R. E. Schmidt, Bally, Bohn, Ullniann, and vScholl. Liebermann worked almost continuously on the subject from 1868 right up to the time of his death in igi6. Ullmann has been responsible for much very useful synthetic work, but in recent years the beautiful work of Scholl must be regarded as taking first place. The names of R. E. vSchmidt, Ball}^ and Bohn are found comparatively little in the literature, as their discoveries are usually patented by the firms with which they are associated. The same remark also applies to Isler, Iljinsky, and others.
Dyeing
Any detailed description of either the theory or practice of dyemg would be completeh- out of place in a volume of this description, but a few ver\- brief notes concerning the more important types of dyestuffs may prove useful to the reader who has not studied tinctorial chemistry.
An acid dye is usually a sulphonic acid, and is applied to the fibre from an acid or neutral bath. In the anthraqui- uone series the most important acid dyes are Alizarin Cj-anine Green and Alizarin Irisol, although several others are used. They are almost exclusively used for colourmg wool and have Httle or no affinit}- for vegetable fibres.
A basic dye is a salt of an amine. In the anthraquinone series the basic dyes which have been described are of no importance. Basic dyes are used for dyeing silk and wool, and often give extremeh- bright shades.
A mordant dye is a dye which can only be fixed on the fibre by means of a metallic oxide, usually the oxide of aluminium, chromium, tin, or iron, although nickel and magnesium are also sometimes used. In this case the colour
6 ANTHRACENE AND ANTHRAQUINONE
developed is due to salt formation taking place between the metallic oxide and the dyestuff, although exactly how the salt or " lake " becomes fixed to the fibre is not known. All mordant dyes contain h3^droxyl groups and, as wall be seen later, the positions occupied b}^ these groups is of great importance. Mordant dyes usually give different shades according to the mordant used, alizarin being a t^'pical dye of this type.
Sometimes when a fibre is dyed* with an acid dye, after- treatment with a solution of sodium bichromate or chromium fluoride alters the shade and renders it much faster. The change is brought about by salt formation, so that such dyes can be regarded as mordant dyes in the widest sense. In their case it should be noted that the " mordant " is applied after the dyestuff itself, w^hereas in the case of the true mordant dyes the mordant is applied first and then the colouring matter. Mordant dyes can be applied to both animal and vegetable fibres.
A vat dve is an insohible coloured substance which, however, is readily reduced to a soluble substance which has affinity for the fibre and which is readily reoxidised on exposure to the air. The soluble reduction product or " vat, " may either be colourless, as is the case with indigo, or it may be highly coloured, as is almost always the case where anthraquinone derivatives are concerned. The colour of the " vat," however, has no relation to the colour of the dye itself, as the finished shade is only developed by sub- sequent oxidation by exposing the dyed fibre to the air. All anthraquinone derivatives in which there are two cyclic carbonyl groups in suitable positions, not necessarily form- ing part of the same ring, give easily oxidised reduction products when reduced in alkaline solution. Not all anthra- quinone derivatives, however, are vat dyes, as a vat dye is only obtained when the reduction product has affinity for the fibre.
Vat dyes can be applied either to animal or vegetable fibres, but the use of the anthraquinonoid vat dyes is almost completely confined to cotton dyeing, as the vats are usually
INTRODUCTION y
too strongly alkaline to be used for wool. Vat dyeing is almost always carried out with the yarn, as \\ilh piece goods penetration is not sufficienth- good to allow satis- factory results to be obtained. Vat dyes, however, are largely used in printing, and are often well adapted for obtain- ing discharge effects, i.e. where a white pattern is obtained by dicliarging the d}'e.
Vat dyeing is somewhat expensive, but the shades ob- tained are usually ver>^ fast. Vat dyeing is largely used in the preparation of the best quality shirtings and upholstery materials.
The commercial tiames given to dyes were formerly purely fancy names, and names containing works like anthracene were not given with a view to representing chemical con- stitution— Anthracene Red, for example, being a disazo dye in no waj- connected with anthracene. Now, however, a much more sensible system is adopted, as the various manufacturing firms have registered trade names for different types of dyes, the individual d}-es being distinguished by a word and initials denoting the shade given. This method of nomenclature has been carried out most systematically in the case of the antliraquinone vat dyes, the following being a list of the chief registered names applyhig to this class of dye, together with the name of the firm registering. 1
REGISTERED NAME. FIRM.
Algol 2 Bayer & Co.
Caledon Scottish Dyes, Ltd.
Chloranthrene 3 British Dyestuffs Corporation, Ltd.
Helindon Meister Lucius and Briinning.
Hydranthrene L. B. Holliday & Co., Ltd.
Indanthrene Badische Anilin u. Soda Fabrik.
' Some Cibanon colours (G.C.I.B.) are anthraquinonoid vat dyes con- taining sulphur.
- Also Leucol.
3 Duranthrene was used by Levinstein, Ltd., before their amalgamation with British Dyes, Ltd.
8 ANTHRACENE AND ANTHKAQUINONE
Colour and Constitution
Tlie relation of colour to constitution will be treated in detail, so far as our present knowledge permits, in connection with the different classes of anthraquinone derivatives, but at this point attention may be drawn to a few generalities which have been found to apply to the simple derivatives in which only one anthraquinone residue is present. The colour referred to is in every casQ the colour of the finely divided substance, or the colour of its solution in some indifferent solvent, and is not the colour obtained by dye trials. The usual conventional method of considering the shade to " deepen " when it passes successively from yellow to orange, red, violet, blue, and green is employed, the reverse charge being a " lightening " of the shade,
Anthraquinone itself is practically colourless, and the entrance of nitro groups and halogen atoms has but a vei}^ slight effect, although bromine atoms deepen the colour rather more than chlorine atoms. The entrance of a hydroxyl group, however, has a ver}- considerable influence, although the auxochromic effect is almost completely destroj'Cd by replacing the hydroxyl hydrogen atom by an alkyl, aryl, or acyl group. As would be expected, the sulphydrate group has a similar but more marked influence than the h^^droxyl group.
The influence of a primarj^ amino group is much greater than that of a hydroxyl group, and in this case replacement of one aminohydrogen atom by an alkyl or ar^^l group increases its auxochromic character, the influence of an aryl group in this direction being considerabty greater than that of an alkyl group. On the other hand, replacing one amino hydrogen by an acyl group decreases its auxo- chromic character, although by no means destroying it, and at the same time confers powerful tinctorial properties, so that the acyl amino anthraquinones can be used as vat dyes.
The above facts are well illustrated by the following compounds : —
INTRODUCTION
OH
NH.,
NHCH3 NHPh NHCOCHj
1 |
1 |
1 |
1 |
1 |
Yellow. Brick red. Bluish red. Violet red. Yellow.
The influence of a group is always much greater when in the a-position than when in the j3-position.
When two or more groups are present their effect is more or less additive, but when they are in the para- position to one another they seem to reinforce one another, a property which has been made use of to a considerable extent. The following formulae represent the reinforcing effect of a second substituent in the para- position : —
NHCOPh NHCOrh
NH,
NH,
1 |
1 |
1 |
Brick red. NH,
OH
Bluish red. NHCH.
Yellow. NHPh
NHCOPh Red.
NHPh NHPh
NH2 NH2
Violet. Bluish violet.
NH2 NHCH3 NHPh
Blue. Greenish blue. Green.
The above rules are very general in their application and render it possible to predict the colour of a simple anthra- quinone derivative with considerable accuracy. Where the more complicated compounds are concerned, however, the state of our knowledge at present hardly justifies the drawing of conclusions, although, as will be seen in the sequel, regularities can often be detected.
10 ANTHRACENE AND ANTHRAQUINONE
Nomenclature
The ten positions in the anthracene ring are numbered as shown, although when dealing with monosubstitution products it is often more convenient to denote the i, 4, 5, and 8 positions by the Greek letter a, the 2, 3, 6, and 7 positions by the Greek letter j3, and the 9 and 10 positions b)^ the prefix meso- or ms- :
8orc< dorms lorc< 5oro( lOorms 4orc(,
In the case of the more complex condensed derivatives this system is insufficient, and the following notation has been proposed by Scholl.i
Compounds which when written in the ordinary waj^ contain a straight line of rings are called linear {lin.), whereas those which when written in this wa}- do not contain a straight line of rings are denoted as angular [ang). When the Hue of rings is twice bent the terms cis-bisangrdar and /mws-bisangular are employed. The following examples will make this clear : —
Linear. Angular.
cis -Bisangular . ^ra;; s-Bisangulax .
For greater accuracy- condensed systems are regarded as anthracene derivatives and the fused-on rings as sub- stituents. The anthracene ring is numbered as usual, beginning with that a-carbon atom which takes part in the
^ B. 44, 1235 ; 1662.
INTRODUCTION
II
formation of a fused-on (" aufgepropfte ") ring, or is nearest such a ring. The following examples illustrate this system.
7( Y ] y
5 CO ^ 1.9-Benzanthronc. 2.9 Naphthaiithronc.
2.3-Pyridiuoantlira- quinone.
3 (N) . 4 Pyridino- 1 2-benzanthra- quinone.
If two or more independent fused-on rings are present the simplest takes the lowest numbers, isocj-clic rings having preference over heterocyclic ones.
The positions in the fused-on ring are numbered by beginning with the carbon atom nearest the lowest numbered carbon atom of the anthraquinone ring, the rings being specified by the usual prefixes such as Bz., Py, Nt, etc. When the rings are heterocyclic it is often more convenient to denote the positions of substituents by Greek letters.
8-Nitro[5.61Bz.-i-chlor- Bz.-i-chlor-Py-a-hydroxy- 2.9-Naphthanthrone-
1.2.5.6-dibenzanthra- 3(N)-4-pyridino-i,9-benz- Nt-2-sulphonic acid,
quinone [1.2] BZ..3- anthrone - 6 - sulphomc
sulphonic acid. acid.
If two independent anthraquinone rings are present the above system is applied, but the positions in one anthra- quinone ring and its attached groups are denoted by plain
12 ANTHRACENE AND ANTHRAQUINONE
figures, and the positions in the other anthraquinone ring and its groups b}- dashed figures :
With more highly condensed sj-stems any system of numbering becomes ver}^ cumbersome, and it is best to use the formula.
For denoting the position of substituents in simple derivatives of anthracene and anthraquinone the author has for man}- years employed an adaptation of Pfaff's system. In this anthracene is denoted by three vertical lines of equal length and anthraquinone by two lines of equal length with a shorter line between them :
8 9
8
6 o
5 10 4
Anthracene.
6 3
5 4
Anthraquinone.
The same system is adopted when dealing with more complex linear bodies, such as naphthacenquinone, naphtha- cendiquinone, dinaphthanthraquinone, etc., a short line always representing a ^am-quinone ring :
1.4.9.10-Anthradi-
quinone.
2.3-Benzanthraquinone. /i/;-Benzanthraquinone
/i;/-Dibenz-i.4.5.8 anthradiqiiinone.
INTRODUCTION 13
This sjstem has its limitations as it is not well adapted for denoting benzanthrones and other derivatives in which an ws-carbon atom forms part of a fused-on ring. It, how- ever, is easily and rapidly written and is perfectly satis- factory in cases where the simpler derivatives of anthracene and anthraquinone are concerned. Its use when making notes will be found a great saving of time.
CHAPTER II ANTHRACENE AND ITS HOMOLOGUES
Anthracene. — Coal tar is, of course, the only source of anthracene which is of an}' practical importance, the hydro- carbon being first isolated by Dumas i in 1832. Dumas named it " paranaphthalene," and obser\^ed that it was oxidised by nitric acid to a yellow crj-stalline substance. Xo synthesis of anthracene that is of any practical im- portance as a method of obtaining the h5'drocarbon has yet been de\'ised, but numerous syntheses have been de- scribed which have considerable interest from a theoretical standpoint, and the chief of these will be briefl}- mentioned.
Anthracene has been obtained by several pyrogenic methods, and these throw some light on the probable mechanism of formation of the hydrocarbon during the distillation of coal. Schultz 2 found that anthracene is formed when turpentine vapour is passed through a red-hot tube, and imder somewhat similar conditions it was obtained by Letny 3 from Caucasian petroleum, by Liebermann and Burg 4 from lignite tar oil, and by Atterberg 5 from wood tar oil. o-Benz3d toluene also gives it when passed through a red-hot tube,^ or, in better yield, when passed over lead oxide below a red heat.'^
Toluene, benzene, or styrene, when mixed with ethylene and passed through a red hot tube, give anthracene, ^ and in connection with this it is interesting to notice that Kraemer and Spilker ^ have foimd that meth\lated benzenes \\'ill
» A. 5, 10. 2 B. 7, 113. cy. Staudinger, B. 46, 2466.
3 B. 10, 1112 ; 11. 1210. « B. 11, 723.
« B. 11, 1222. 6 Dorp, A. 169, 216.
' Behr and Dorp, B. 6, 75-1 . « Berthelot, A. 142, 254.
9 B. 23, 3160; 3269.
14
ANTHRACENE AND ITS HOMOLOGUES 15
combiue quite readih' with styrene in the presence of sulphuric acid to form phen}^ aryl propanes, which when passed through a red-hot tube yield anthracene hydrocarbons, the 3'ields being in some cases as high as 63 per cent. It is not impossible that the anthracene derivatives found in coal tar have been formed by very similar reactions.*
Numerous syntheses of anthracene and its homologues by means of aluminium chloride have been recorded. Thus toluene when heated in a sealed tube with anh}-drous aluminium chloride gives anthracene, and X3-lene gives dimethyl anthracene, 1 but in all cases the yields are minute. By condensing an aromatic hydrocarbon in the presence of aluminium chloride with acetylene tetrabroniide,^ ethylidene bromide or cliloride,^ vinyl bromide,"* perchloreth3'lene,5 meth}-lene chloride 6 or chloroform,'^ anthracene hydro- carbons are obtained. In these syntheses it is probable that a ^/zs-dih3'droanthracene is liist formed, which is then oxidised at the expense of part of the halogen compound, or that an ?«s-dichlordihydroanthracene is the first product, this then splitting off two atoms of chlorine. These are not evolved as such, but clilorinate part of the hydrocarbon or react with the carbon bisulphide which is usually used as a dilutant.
Perkin and Hodgkinson ^ and Schramm ^ have shown that benzj-l chloride itself gives anthracene under the influence of aluminium chloride, and Limpricht 10 and Zincke 1 ^ have found that benzyl chloride, when heated under pressure with water at 160°, gives a mixture of benz}-! alcohol, benzyl ether and co-chlortolyl phenyl methane, this latter yielding anthracene on distillation.
Jackson and White 12 have applied the method of Wurtz, and by treating o-brombenzyl bromide with metallic sodium
* But compare R. Mej^er, B. 45, 1609 ; 46, 3183, who has obtained anthracene by condensing naphthalene with acetylene.
1 Anschiitz, A. 235, 137. ^ A. 235, 157.
» A. 235, 299 ; B. 17, 165. * A. 235, 323.
5 Bl. [3] 19. 554- ' A- Ch. [6] 11, 264 ; Bl. 41, 323.
■ B. 18, 348. 8 soc. 37, 726.
9 B. 26, 1706. *- 1" A. 139, 308.
" B. 7, 276. >* B. 12, 1965.
i6 ANTHRACENE AND ANTHRAQUINONE
obtained a mixture of anthracene and dihj'droanthracene. They state that the reaction is very slow when benzene is used as a solvent, but becomes rapid in absolute ethereal solution. Anthracene in 60 per cent, yield can be obtained by the action of aluminium chloride on benzyl trichloracetate, 1 but in spite of the good 34eld this method does not seem to have been applied to the study of other anthracene derivatives. In the distillation of coal tar the anthracene passes over with the fraction which boils between 280-400°. This fraction has a specific gravity of about iioo and is known as " anthracene oil " or " green oil " on account of its green colour, although after standing in the air for some time the colour usually changes to brown. The crude oil contains only 5-10 per cent, of anthracene, and on cooling this is deposited together with phenanthrene, carbazol, acridine, and other impurities. The crude solid thus obtained con- tains 15-25 per cent, of anthracene, but can be brought up to 40-50 per cent, strength by hot or cold pressing and by washing with solvent naphtha or creosote oil. It is in this state that it is usually sold, sales always being effected on a percentage basis, and the price at present (1920) being quoted at gd. per unit per cwt., an increase of about 500 per cent, over the pre-war price. Anthracene in this state is quite suitable for conversion into anthraquinone, as if it is reduced to a state of fine subdivision by distillation with superheated steam and condensation of the vapours with fine jets of water, oxidation with the calculated amount of chromic acid converts the anthracene into anthraquinone without to any great extent affecting the impurities. The presence of any considerable quantity of methyl anthracene, however, spoils the shade of the alizarin obtained, and the presence of paraffins gives endless trouble by choking the filters. It is for this latter reason that the crude anthracene obtained by the distillation of mixtures of hard coal with cannel-coal is not popular with dye-makers, and, of course, low-temperature carbonisation also increases the content of paraffins.
1 Delacre, C. r. 120, 155 ; Bl. [3] 13, 302.
ANTHRACENE AND ITS HOMOLOGUES 17
Numerous methods have been proposed for purifying crude anthracene. For example, it can be recrystalHsed from fatty acids such as oleic acid,^ or it can be washed with acetone,- or liquid ammonia,-^ or sulphur dioxide. * By far the best method, however, is washing with pyridine or quinoline bases, ^ as this leaves a product containing 90-98 per cent, of anthracene. Graebe ^ obtained anthra- cene free from carbazol by fusing with caustic potash, the carbazol forming its potassium salt and the anthracene bemg distilled off. This process has been the subject of several patents'^ but does not seem to have been a com- mercial success. Wirth ^ attacked the problem in a rather different way, and claims that if crude anthracene is treated with nitrous acid the anthracene is unaffected, whereas the carbazol is converted into a nitroso compound which is soluble in benzene and can therefore be removed b}' washhig with this solvent.
When pure, anthracene is a colourless crystalline solid which melts at 2i6"5° and boils at 351°. It has an intense violet fluorescence, but this is complete!}- masked by small quantities of impurities. This fluorescence is shown by all anthracene derivatives in which each w^so-carbon atom is in combination with only one monovalent element or group, and may be due to double symmetrical tautomerism (see p. 19).
Molinari 9 has prepared an ozonide of anthracene but does not seem to have examined its decomposition products.
Schlenk, Appenrodt, and Thai 10 have found that when ethereal suspensions of anthracene are shaken with sodium powder a disodium addition compound is formed. In this
1 Renev and Erhart, D.R.P. 38,417.
- By., b.R.P. 78,861.
3 Welton, D.R.P. 113,291.
* By., D.R.P. 68,474.
* Chemische Fabriks-Actiengesellschaft in Hamburg, D.R.P. 42,053. Clark, J. Ind. Eng. Chem. 1919, 204.
* A. 202, 22.
' A. G. fiir Teer- u. Erd-oUndustric, D.R.P. 111,359; By., D.R.P. 157,123 ; Agfa, D.R.P. 178,764. 8 D.R.P. 122,852. » B. 40, 4160. " B. 47, 473.
i8 ANTHRACENE AND ANTHRAQUINONE
the sodium atoms must be attached to the ms-carboii atoms, as treatment with carbon dioxide leads to the forma- tion of the sodium salt of dihydroanthracene dicarboxjdic acid :
H Na H COONa
c |
C |
|
^6^4.^0611.1 |
CO., |
CoH4<()>C6H4 |
c |
c |
|
/\ |
/\ |
|
H Na |
H COONa |
Anthracene forms a well-cr3-stallised picrate with one molecule of picric acid when treated with alcoholic solutions of picric acid.i
Structure. — There is some doubt as to the disposition of the fourth valency of the ;«esc>-carbon atoms in the anthracene molecule, and the formula of anthracene can be written either as a bridged ring or as a quinonoid compound :
CH CH
C6H4<' 5^)06114 C6H4^^C6H4
CH CH
Against the ortho-qmnonoid formula it ma}- be urged that this would represent a coloured compound, whereas anthra- cene is colourless. 2 Our present knowledge of the relation- ship between molecular structure and the absorption of light, however, is not sufhcienth- wide to allow much weight to be given to arguments of this nature. On the other hand, the formation of a disodium addition compound is much more in accordance with the quinonoid structure, asSchlenk, Appenrodt, and Thai 3 have found that in the case of other hydrocarbons the formation of such compounds is closely allied with unsaturation. Auwers,^ from a study of the optical anomality of ;HS-amylanthracene and ms-amyl- 9.10-dihydro-anthracene, also concludes in favour of the
1 B. 7. 34; A. 139, 309
- Absorption spectrum. Baly Soc. 93, 162. 3 B. 47. 473. * B. 53, 941-
ANTHRACENE AND ITS HOMOLOGUES 19
quinonoid structure. The quinonoid structure, however, indicates a type of isomerism among anthracene derivatives which is totally unknown, as a monosubstitution product, for example, should exist in two forms :
CH CH
C6H4^)>C6H3C1 and C6H3C1^)>C6H4
CH CH
The powerful iluorcscence of anthracene and of all its derivatives in which the " bridge " remains intact points to double symmetrical tautomerism, so that on the whole Ihc dynamic formula :
CH CH CH
C6H//;>CcH, ^ CeH^^^CoH, ^ CeH4<;^J:CeH, CH CH CH
is the best representation. In the following pages the " bridge " formula is used as a matter of convenience ; but its use is without prejudice, and it must be understood that it probably merely represents the middle point of the vibration.
It should be noted that anthracene compounds show a marked capacit}- for forming addition compounds, e.g. with picric acid. This capacity for forming addition compounds apparently lies in the arrangement of the valencies of the central ring, as destruction of the " bridge," e.g. by reduction, is accompanied by complete loss of capacity to form a picrate. Destruction of the bridge also leads to the dis- appearance of fluorescence.
Oxidation. — The oxidation of anthracene and its de- rivatives leads usually to anthraquinone or an anthraquinone derivative ; but if one of the benzene rings is weakened by the presence of hydroxy-1 or amino groups, this ring is usually ruptured. Sulphonic acid groups, halogen atoms, alkyl groups, carboxylic acid groups, etc., do not weaken the ring, so that such derivatives of anthracene on oxidation pass into the corresponding anthraquinone derivative, and
20 ANTHRACENE AND ANTHKAQUINONE
in many cases advantage has been taken of this for deter- mining the position of substituents.
On the other hand, groups attached to the ms- carbon atoms are usually eliminated on oxidation, so that ms- substituted derivatives of anthracene give anthraquinone on oxidation ; but Simonis and Remmert ^ have shown that 9-io-diphen3danthracene on oxidation does not give anthra- quinone, the chief oxidation product being o-dibenzoyl- benzene :
C«H
6^^i
CfiH
6^^i
CfiH
6X14N
.COCfiH
6^^5
^COC«Hr,
6^^5
and, curiousl}- enough, i.2-dimethoxy-9-io-diphenylanthra- cene on oxidation gives dibenzo}^! veratrol :
I C
(MeO)2C6H2
.COCfiH
>CfiH
e^^i
(MeO)2C6Ho<
6-»^-^5
^COCeHs
CeHs
Anthraquinone is a verj- stable substance and resists the action to oxidising agents to a ver^" marked extent. Hence although it is possible in some cases to rupture the centre ring with the production of an o-benzo^-l benzoic acid or a phthalic acid, the method is of no importance, as such violent means have to be used that the phthalic acid is usualh^ almost completely destro3'ed. Of course, if only one of the benzene rings is weakened b}^ the presence of hydroxyl or amino groups, it will be possible to obtain phthalic acid from the substance, and this in many cases gives useful information as to the position of substituents.
' ]}. 48, 2o8.
ANTHRACENE AND ITS HOMOLOGUES 21
Although anthraqiiinone is the final stable stage in the oxidation of anthracene, by moderated oxidation it is some- times possible to isolate lower oxidation products. Thus, Schulze 1 oxidised anthracene with lead dioxide m boiling glacial acetic acid solution and obtained anthraquinol, and Kurt Meyer 2 has shown that under these circum- stances the first product formed is acetoxj- anthrone, which passes into anthraquinol by hydrolysis and subsequent isomerisation :
H OCOCH., H OH OH
/
c c
'Z
c c c
II II I
O O OH
From ms-alk3'l dihydroanthracenes lyiebermann ^ was able to obtain alkylh^'droxyanthrones by careful oxidation with chromic acid :
H R |
HO R |
|
C |
C |
|
C6H4<(' ^C6H4 CHo |
-> |
C6H40C C |
^Hj
O
and Bae^-er * obtained ;;?s-phenyl h3'drox}^anthrone b}' the careful oxidation of ?«s-phenyl anthracene. In both cases more vigorous oxidation leads to anthraquinone. lyiebermann ^ also found that the moderated oxidation of the ?«s-alkyl hydroxj^dihydroanthracenes led to «?s-alkyl hydrox>'anthrones :
^ B. 18, 3036.
3 A. 212,' 67'; B. 13, 1596 ; 15. 452. 455. 462. « A. 202, 54. ^ A. 212, roi.
22 ANTHRACENE AND ANTHRAQUINONE
HO R |
HO R |
|
C |
C |
|
CcH^. ^C6H4 CH2 |
-> |
C6H4<^ /C6H4 CO |
As will be seen later, the moderated oxidation of the anthranols readily leads to dianthrdnes :
OH
! I 1
C C6H4 C6H4
C6H4<^,\C6H4 -> CO<^\c=C<^^^CO C C6H4 LeH4
I H
Kurt Mej^er,^ by Oxidising anthracene with one molecule of lead dioxide in boiling glacial acetic acid, obtained a mixture of anthranol acetate and hydrox3'anthrone acetate, this latter substance being the main product when two molecules of lead dioxide are used. 2 Similar results were obtained by using
CeH. |
OCOCH3 1 c /V6H4 |
<- |
CeH |
CH 4<^,^C6H4 |
~> |
H OCOCH3 \/ C C6H4<(' yCeBi |
|
CH |
CH |
C |
O
manganese dioxide, eerie acetate, and vanadic acid, all in boiling glacial acetic acid solution. With other solvents, however, the course of the reaction is different, dianthrone often being formed :
I A. 397, 73. 2 Cf. Schulze. B. 18, 3036.
ANTHRACENE AND ITS HOMOLOGUES 23 C6H4 C6H4 H H C6H4
HC^CH ^ 0=C<^^C-C<;^^C=0 CqH.4, C6H4 CgHi
The fact that Schiilze 1 obtained aiithraquinol by oxi- dising anthracene in glacial acetic acid with lead dioxide is obviously due to the fact that he treated his product with alkali without first examining it, the effect of the alkali being to split off the acetyl group from the acetox>'- anthrone and then to enolise the hydroxyanthrone formed (p. 108).
Kurt Meyer 2 has also found that halogens in aqueous solvents below^ 25° oxidise anthracene very smoothly. In this case oxidation probably takes place by alternate addition and hydrolysis :
OH
I C
H. -> C^-Ry^C^K^
H Br |
H OH |
C |
C |
C6H4<(' ^C6H4 c |
c |
c
I
H
O
II
c c c
C6H4<^V6H4 -> C6H4<^^C6H4 "> C6H4<^^C6H4
c c c
H Br H OH H OH
The further action of halogen brings about substitution of the ;ns-hydrogen atom in the h>-droxyanthrone, subse- quent hydrolysis leading to anthraquinone :
1 Loc. cit. ' A. 379, 73, 166.
c CeH/^CeH^ |
C /\ Br OH |
24 ANTHRACENE AND ANTHRAQUINONE
000
II 11 II
C C
c c
/\ II
HO OH O
The action of nitric acid on anl^racene is discussed on p. 50, but Dimroth,! b}'^ treating anthracene with nitric acid in glacial acetic acid solution, obtained dianthrone :
CeH^ CeH^ H H C6H4
2CH<^^CH ~> OC/^C— C<^Vo
CeH^ C6H4 C6H4
Paranthrene, Dianthrene. — When solutions of anthra- cene are exposed to direct sunlight or ultraviolet light, polymerisation takes place, and an almost insoluble bimole- cular 2 polymer is precipitated. This is known as paranthrene or dianthrene, and as it readily reverts to the monomolecular form when heated, its formation has been employed in the laboratory' as a means of obtaining ver}^ pure anthracene. The process, however, is a very inconvenient one to carr}^ out owing to the very slight solubility of anthracene itself.
The polymerisation of anthracene under the influence of sunlight has been known almost since the discovery of hj'drocarbon,^ and, in fact, gave rise to the old name " photene," In more recent j-ears the reaction has formed the subject of several investigations. Linebarger, Orndorff, and Cameron * found that the polymerisation takes place best in xylene solution,'and can also be effected in benzene, toluene, alcohol, chloroform, and acetic acid, but will not take place in carbon bisulphide or in ethylene dibromide.
' B. 34, 219. 2 Klbs, J. pr. [2] 44, 267.
2 Fritsche, Z. 1867, 290; Ernst Schmidt, J pr. [2] 9, 248; Graebe and Liebermann, A., Suppl. VII., 264. * Am. 14, 599.
ANTHRACENE AND ITS HOMOLOGUES 25
Weigert 1 and his students, and Byk 2 have examined the reaction from a physico-chemical and thermodynamic point of view, and have found that the amount of change is directly proportional to the light energy absorbed.
The formation of bimolecular polymers by anthracene derivatives has been studied b}" Fischer and Ziegler 3 and by Weigert and Kummerer.* The former investigators showed that a-methyl anthracene is much more rapidly polymerised than either anthracene itself or j3-methylanthra- cene. They also found that 1-4-methylchloranthracene, a-chloranthracene, ms-monobromanthracene and a-chlor- ;«s-monobromanthracene all polymerise, whereas dihydro- anthracene, dihydromethylanthracene and ws-dibromanthra- cene do not. Weigert and Kummerer studied the action of light on the anthracene monocarboxjlic acids and found that all three acids are polymerised, but the a-acid is only poly- merised slowly, whereas in the case of the ^-acid the action is rapid. The ms-acid is also polymerised both in glacial acetic acid solution and in alkaline solution. In the latter case the action of light also causes rapid oxidation b}- atmospheric oxygen, so that it is necessary' to work in evacuated vessels.
The bimolecular polymers are all colourless solids which melt at fairly high temperatures, and either at the melting point or at a slightly higher temperature revert to the monomolecular form. They are not fluorescent, do not form picrates, and on oxidation give the same products as the monomolecular hj'drocarbons. In all probability their structure is represented bv the formula :
C6H/V6H4 CeH/^CaH,
Dianthrene itself melts at 244*^ and is depolymerised at 272°.
1 B. 42, 850 ; 1783 ; Ann. der Phys., 24, 55, 243 ; Z. f. Elektrochemie, 14, 591 ; Z. f .physikal, Chemie, 51, 297 ; 53.' 385 ; '63, 458. * B. 42, 1 145 ; Z. f. physikai. Chemie, 62, 454. 3 J. pr. [2] 86, 289. * B. 47. 898.
26 ANTHRACENE AND ANTHRAQUINONE
Homologous Anthracenes
i-Methylanthracene. — Ve^ little information is avail- able with reference to this substance, although it has been described by two investigators. Birukoff i obtained it by condensing phthalic acid with ^-cresol and then distilling the resulting i-methyl-4-h5^droxyanthraquinone with zinc dust. He describes it as melting at 199-200° and giving a quinone which melts at i66-i67°.« O. Fischer 2 repeated Birukoff's work and obtained a hydrocarbon which melted at about 200°, but which on oxidation gave anthraquinone itself, and which he therefore concluded consisted chiefly of anthracene, the methyl group having been split off as methane during the distillation with zinc dust. Fischer also observed that the mother liquor from the recr^-staUisation of the hydrocarbon contained a substance of very low melting point which on oxidation gave a quinone melting at about 170°, but he did not investigate it further. He, how- ever, prepared i-meth^^anthracene by distilling i-metltyl- 4-chloranthraquinone, obtained from phthalic acid and ^^-chlortoluene, with zinc dust and described it as melting at 85-86°, and giving a quinone which melted at 170-171°. At first sight the melting-point seems extremely low, and reminds one of the compounds of uncertain composition which have been obtained by Elbs ^ by the alkaline reduc- tion of methylanthraquinones in which a meth}^ group is in the a-position to one of the carbonyl groups ; but Lavaux ^ has obtained what he describes as i.8-dimethylanthracene, m.p. 86°, although the composition of this substance cannot be said to be proved. The low melting point of the a-deriva- tive is also to be expected from analog}' with the correspond- ing naphthalene h5^drocarbons. Thus naphthalene itself melts at 79° and j3-methylnaphthalene at 32-5°, whereas a-methylnaphthalene melts at — 20°, and i.6-dimethyl- naphthalene is also liquid at the ordinary temperature. The bimolecular form of a-methyl anthracene melts at 246°.
1 B. 20, 206S. 2 j_ pr. [-2] 83, 201.
=> B. 20, 1365 ; J. pr. [2] 41, 12.
* C. r. 139, 976 ; 140. 44 ; 150, 1400 ; Bl. [4] 7, 539-
I
ANTHRACENE AND ITS HOMOLOGUES 27
2-Methyi.anthracene. — This is a much more important compound than the isomeric i-methjdanthracene and, as it is much more readily obtained, it has been much more carefully investigated. It seems to be the parent hydro- carbon of many naturally occurring anthracene derivatives, and is obtained from them by distillation with zinc dust. Thus Ciamician ^ obtained it from colophonium, and lyiebermann 2 and Jowett and Pother ^ from chrysarobin and emodin. It is present in coal tar and has been isolated from this source b}^ Schulz ^ and Bornstein, •'' and Waschen- dorff 6 has obtained it from the pitch left from the distillation of commercial aniline oil. Its formation by the pyrogenic decomposition of h3'drocarbons seems to be quite common, as Schulz '^ has obtained it by passing turpentine vapour through a red-hot tube, and O. Fischer,^ Schulz, ^ and Weiler 10 have obtained it b}" similar means from ditolyl- methane and ditolylethane.
Elbs 11 has obtained it by the prolonged boiling of the phenyl X3dyl ketone obtained by condensing benzoyl chloride with p-xylene, and Gresley ^^ has obtained it by condensing phthalic anhydride with toluene and then distilling the ketonic acid over zinc dust.
A rather interesting synthesis has been carried out by Kraemer and Spilker,i3 who find that methyl benzenes, in this case w-xylene, condense with styrene in the presence of sulphuric acid to form diaryl propanes :
CgHqCH : CHo+CcH4(CH3)2 -» CgHoC— CH2C6H.1CH3
I
CH3
and these when passed through a red-hot tube apparently split off a carbon atom and yield an anthracene derivative.
1 B. 11, 269. * A. 183, 162 ; 212, ^4. s Soc. 81, 15S1.
* B. 10, 1049, 5 B. 15, 1821.
" B. 10, 1481. It must be remembered that this observation was pub- lished in 1S77. It is highly improbable that any anthracene derivatives could be obtained from modern commercial anihne oil.
' B. 10, 118. 3 B. 7, 1195 ; J. pr. [2] 79, 555-
9 B. 10. 118. 10 B. 7. 1185.
'1 J. pr. [2] 35. 471 ; 41, 1,1 ; B. 17. 2848. "* A. 234, 238. " 12 B. 23, 3169 ; 3269.
28 ANTHRACENE AND ANTHRAQUINONE
lu the case in question a 63 per cent, yield of 2-methyl- anthracene was obtained. This reaction suggests a possible explanation of the presence of meth3^1 anthracene in coal tar.
2-Methylanthracene can, of course, be obtained by the distillation of methylhydrox^-anthraquinones over zinc dust,i but this method is of theoretical rather than of practical importance. It is most readily obtained b}^ the reduction of the coi responding qumone,^ and as this is readily obtained from phthalic anhydride and toluene, the h3'drocarbon is easily available.
The melting point of 2-methylanthracene given in the literature is ver}' variable, most investigators giving it as 198-204°. Probably the figures given by O. Fischer, ^ viz, 203° (uncor.) and 207*^ (cor.), are the most reliable. The latter figure is also given b)^ Limpricht and Wiegand,"* Kraemer and Spilker,^ and Scholl.^
Orndorff and Megraw"^ find that when its solutions are exposed to sunlight 2-methyl anthracene passes into a non- fluorescent bimolecular form which melts at 228-230° with simultaneous reversion to the monomolecular form.
Methanthrene. — In addition to a- and jS-methyl- anthracene a third isomer has been described by Oudemas,^ who states that he obtained a hydrocarbon with the formiila C15H12 by distilling podocarpinic acid with zinc dust. He gives the melting point of the h5^drocarbon as 117°, and states that on oxidation it gives a quinone, C15H10O2, which melts at 187°, and which is slowly reduced by sulphurous acid. It seems improbable that Oudemas's compound was an anthracene derivative at all.
Dimethyl Anthracenes. — The chemistry of the dimethyl anthracenes is far more complicated than would seem to be the case at first sight, and in spite of numerous investigations comparatively little really reliable data is
1 Nietzki, B. 10, 2013 ; Niementowski, B. 33, 1633.
2 Limpricht and Wiegand, A. 311, i8i ; Scholl, M. 39, 237.
3 J. pr. [2] 79, 555. * A. 311, iSi. 6 B. 23, 3169 ; 3269. 6 M. 39, 237.
' Am. Soc, 22, 154. « A. 170, 243 ; J. pr. [2] 9, 416.
ANTHRACENE AND ITS HOMOLOGUES 29
forthcoming. As Ivavaux ^ has pointed out, nearly all the reactions which lead to dimethyl derivatives are capable of yielding more than one isomer, and nearly all these re- actions have to be carried out under conditions under which there is considerable danger of methyl groups wandering. In addition the isomers have a great tendency to form eutectic mixtures which are extremel}- difficult to recognise as such, and which can only be separated into their con- stituents by special means.
Several uivestigators have described a dimethyl anthra- cene melting at 225°, and givmg on oxidation a quinone melting at 156-160°. Thus Waschendorff and Zincke 2 obtained it from the heavy fractions of connnercial aniline oil ; Aiischiitz 3 obtained it by treating toluene with sym- tetrabrom-ethane and aluminium chloride, and also by treating toluene with aluminium chloride. '^ P'riedel and Crafts 5 obtained it b}- the action of methylene chloride and aluminium chloride on toluene, and by the action of aluminium chloride on toluene also obtained a dimetli>-l anthracene. The melting point of this latter substance thc}^ give as 231°, but find that it gives a quinone melting at 160°. Elbs and Wittich ^ from toluene, chloroform, and aluminium chloride obtained a dimethyl anthracene melting at 215-216° and giving a quinone melting at 161-162° ; but Lavaux has shown that the melting point of their compound was too low owing to the presence of a little monometh}l anthracene.
Lavaux '^ has shown that all these so-called dimethyl anthracenes are really eutectic mixtures, and from them he has isolated two distinct dimethyl anthracenes, one melting at 244*5° and the other melting at 240°. In addition, from the product of Friedel and Crafts reaction he has isolated a third ver^- soluble isomer which melts at 86°. This last he seems to assume to be i.8-dimethylanthracene, but does not appear to have investigated in detail.
1 C. r. 146. 137. 2 B. 10. 1481.
3 A. 235, 171 ; B. 17, 2816. * A. 235, 181.
B A. Ch. [r.] 11. 265 ; Bl. 41. 323. 6 B. 18, 348.
' C. r. 139, 976 ; 1*0, 44 ; 152, 1400 ; Bl. [4] 7, 539.
30 ANTHRACENE AND ANTHRAQUINONE
The compound melting at 244-5° seems to be identical with the dimeth}^ anthracene obtained by Anschiitz and Roniig 1 by distilling the condensation pioduct of toluene and ethylidene bromide over zinc dust. On oxidation it gives a quinone melting at 236-5°, and also a methyl anthra- quinone carboxylic acid and an anthraquinone dicarboxylic acid. The nieth}^ anthraquinone carbox3dic acid was reduced by zinc dust and ammonia to methylanthracene carboxylic acid, and from this it can be concluded that the methyl group is in the ^-position, as Elbs ^ has shown that a-methyl anthraquinones do not give the corresponding anthracene derivative by reduction in alkaline solution. Further, Lavaux showed that the meth}^ anthracene carbox3dic acid, by loss of carbon dioxide, gave ^-methyl- anthracene.
Lavaux ^ fomid that his anthraquinone dicarboxylic acid on fusion with caustic potash * gave a mixture of isophthalic acid and terephthalic acid, but no phthalic acid. The only anthraquinone carboxylic acids which could give this are the 2.6- and the 2.7-acids, and Lavaux con- cluded that his acid was anthraquinone-2. 7 -dicarboxylic acid, and consequently that the dimeth^d anthracene which melted at 244-5° was 2.7-dimethyl anthracene.
Seer ^ by heating ;»-methyl benzojd chloride with aluminium chloride to 140° obtained a mixture of three dimeth}-l anthraquinones, of which the main product melted at 235-236°. By the action of ;«-methylbenzoyl chloride on m-:xylene in the presence of aluminium chloride he obtained a tolyl xylyl ketone which ' when boiled (b.p. 315-320°) for five days & gave a dimethyl anthracene which melted at 243°, and which on oxidation gave a quinone melting at 235-236°. Seer's products are presumably
1 A. 235, S17; B. 18, 662.
2 J. pr. [2] 15, 121 ; B. 20, 1365. » C. r. 141, 354 ; 14.3, 687.
* In the anthraquinone series these fusions are often ver^- troubles ome to carry out. In the case in question, for example, it was necessary to maintain a temperature of 260° for 300 consecutive hours.
* M. 32, 143.
» C/. Elbs, J. pr. [2] 33, 1S5.
ANTHRACENE AND ITS HOMOLOGUES 31
identical with the products obtained by Lavaux. The fact that the tolyl x^-lyl ketone gave an anthracene derivative is proof that one nieth>l group is in the ortho- position to the carbonyl group, and if it is assumed that nieth}! groups have not wandered there are only two alternatives for the structure of the ketone and the dinieth>-l anthracene derived from it :
CO
CH3 CH3 ^•' ^ CH3
CH,
i
CH3 r T Y >CH:
1.7-Dimethylanthracene. 26 Dimcthylanthraceue.
Lavaux, however, has proved conclusively that it is either the 2.6- or the 2.7- compound, and hence Seer con- cludes that it must be 2.6-dimeth3-l anthracene.
Lavaux has also investigated the second isomer of his eutectic mixture. This on oxidation gives a methyl anthra- quinone carboxylic acid which can be reduced to a meth\l- anthracene carboxylic, this latter by loss of carbon dioxide passing into j3-methyl anthracene. By further oxidation an anthraquinone dicarbox\lic acid is formed and this by fusion with caustic potash gives a mixture of phthalic, isophthalic, and terephthalic acids, and consequently must be either the 1.6- or the 1.7- dicarboxylic acid. Lavaux considers the former alternative the more probable, and consequently designates the dimethyl anthracene which melts at 240° as i.6-dimethyl anthracene. The corre- sponding quinone melts at 169°.
The production of an anthracene derivative by means of methylene chloride is obviously preceded by the pro- duction of a dihydroanthracene, subsequent oxidation being brought about at the expense of part of the methylene chloride. In the case of chloroform a dichlordihydroanthra- ceue is the intermediate product, this passing into the
32 ANTHRACENE AND ANTHRAQUINONE
anthracene by loss of two atoms of chlorine. This chlorine is not evolved as such during the reaction but chlorinates part of the toluene or reacts with the carbon disulphide used as a dilutant.
The structure of the dimethyl anthracene described b}' Dewar and Jones ^ as being obtained by heating toluene with nickel carbonyl and aluminium chloride is very doubt- ful. They describe it as 2.6-dimeth5d anthracene and state that it melts at 215-216° and give* a quinone which melts at 159-160°. Seer 2 suggests that it may be 2.7-dimethyl anthracene, but it seems much more probable that it is a rather impure eutectic mixture.
Other heteronuclear dimethyl anthracenes have also been described. For example, van Dorp ^ by heating X34yl chloride with water to 210° obtained a dimethyl anthracene which melted at 200°, and on oxidation gave a quinone melting at 153°. van Dorp's products were probably complex mixtures, as he states that he made his xylyl chloride from xjdene which boiled at 136-139°, and which on oxidation gave a mixture of isophthalic and terephthalic acids, the former " in prepondering amount." The chloride itself he describes as boiling at 190-200° and " consisting chiefly of the desired chloride."
Of the four possible homonuclear dimethylanthracenes neither the 1.2- nor the 1.4- isomers have been described, although Gresly * and Heller ^ prepared 1.4-dimethyl anthraquinone from /)-xylene and phthalic acid thc}^ do not seem to have reduced it to the anthracene com- pound.
Klbs and Eurich 6 condensed phthalic anhydride with o-x>'lene and obtained 3-4-dimethylbenzoylbenzoic acid, the position of the methyl groups being proved b}^ F. Me3^er,'' who, by fusion with caustic potash, obtamed a mixture of benzoic acid and 2. 3-dimethyl-i -benzoic acid. The ketonic acid by loss of water passed into a dimethylanthraquinone
1 Soc. 85, 216. 2 M. 33, 143. 3 A. 169, 207.
« A. 240, 240. 6 ]3, 43^ 2892.
« B. 20. 1361 ; J. pr. [2] 41, 5. ' B. 15. 637.
ANTHRACENE AND ITS HOMOLOGUES 33
which melted at 183°.* This might be either i.2-dimcth3-l- anthraquinone or 2-3-dimethylanthraquinone ; but since toluene jaelds exclusively j3-methylanthraquinone one is j ustilied in assuming that the reaction takes a similar course in the case of o-xylene, the product in this case being 2.3-dimethyl anthraquinone. That this is correct has been proved by the fact that the dicarboxylic acid obtained from it b}^ Elbs b}^ oxidation melts at 340°, whereas the di- carboxylic acid obtained by Scholl ^ by the oxidation of i.2-benzanthraquinone (naphthanthraquinone) melts at 267-268°. As Scholl's acid must be anthraquinone 1.2-dicar- boxylic acid, it follows that Elb's acid nmst be the 2.3-dicar- boxylic acid. Both acids readily yield cyclic anh3"drides, which shows that no wandering of the methyl groups can have taken place. Elbs and Enrich reduced the dimethyl- anthraquinone by zinc dust and ammonia and obtained 2.3-dimethylanthracene, m.p. 246°.
vSeveral investigators have prepared 1.3-dimetliyl- anthracene, but their descriptions are so conflicting that it is very doubtful if the substance has ever been obtained pure.
Elbs 2 found that benzoyl mesitylene on heating does not pass into a dimethyl anthracene : but Louise, 3 by passing benzyl mesitylene through a red-hot tube obtained two dimethylanthracenes, viz. one which melted at 218-219° and gave a quinone which melted at 170°, and one which melted at 71° and gave a quinone which melted at 157-158°. It is rather difficult to see how two dimethylanthracenes could be produced from benzyl mesit3'lene unless an impure sample of mesitylene were used, or unless a wandering of the methyl groups takes place either during the passage of the benzyl mesitylene through the red-hot tube, or, more probably, during the preparation of the benzyl compound. Louise's quinone, which melts at 170°, is not identical with Lavaux's i.6-dimethylanthraquiuone (m.p. 169°), as the
* Limpricht, A. 312, 99, gives the melting point as 200", and Heller, B. 43, 2891, as 205-206°.
* B. 44, 2002 ; O.R.P. 2.(1,624.
« J. pr. [2] 35, 487 : 41, 12. => A. ch. [6] 187.
3
34 ANTHRACENE AND ANTHRAQUINONE
latter investigator has done a mixed melting point deter- mination. Tlie very low melting point of the second isomer would be in agreement with the assumption that it was the dihydro compound, but Louise's analysis is not in agreement with this explanation. The low melting point might, of course, also be explained by the presence of the methyl group in the a-position (cf. a-meth34anthracene, p. 26), and at first sight it would seem possible that the compound was the unknown ' i .4-dimethylanthracene. This, however, can hardly be the case, as i .4-dimethylanthra- quinone 1 melts at 118°. Louise considers that the hydro- carbon which melts at 71° is really 1.3-dimethylanthracene, as he has prepared 2 1.3-dimethylanthraquinone from benzoyl mesitylenic acid, and finds that it melts at 157- 158°.*
Totally different results have been described by other investigators. Gresly ^ distilled xyloylbenzoic acid with zinc dust and obtained what he described as 1.3-dimethyl- anthracene melting at 202-203°, but did not oxidise it to the quinone. He obtained the corresponding quinone, however, by loss of water from the xyloylbenzoic acid, and gives its melting point as 180°. Birukoff * condensed 2.4-dimethyl benzoic acid with gallic acid in the presence of sulphuric acid and obtained i.3-dimeth3d-6.7.8-trihydroxy- anthraquinone. This by distillation with zinc dust gave a dimethylanthracene which melted at 220-226°, and which on oxidation gave a quinone melting at 112°. Birukoff obtained his dimethyl benzoic acid from commercial xylidine, and as the condensation with gallic acid gave a yield of only two per cent, it is not improbable that the reaction was taking a different course to that intended.
Kraemer and Spilker ■'"' condensed st3'rene with un- symmetrical trimethyl benzene (pseudocumene ?), and by
1 Gresly. A. 234, 240.
2 A. ch. [6] 6, 233.
* Elbs, J. pr. [2] 33, 319, obtained 1.3-dimethylanthraquinone from m-xylene and phthalic anhydride, and gives the m.p. as 162°. B. A. S. F. in D.R.P. 200,335 refer to 1.3-dimethylanthraquinone, m.p. 159-163°.
« A. 234, 246.
* B. 20, 870. » B. 23, 3169 ; 3260.
ANTHRACENE AND ITS HOMOLOGUES 35
passing the product through a red-hot tube obtained a dimethylanthracene. This, unfortunately, cannot be com- pared with the dimethylanthracenes described by other in- vestigators, as, owing to a misprint, Kraemer and wSpHker give the melting point of their product as 298 uncor. = 235° cor.
Tremethylanthracenes. — Excluding ms - compounds there are sixteen possible trimethylanthracenes. Of these very few have been prepared, and in view of the very con- tradictor}^ results obtained in the case of the dimethyl compounds the structures allotted to the trimethyl com- pounds can only be accepted with some reserve pending further investigation. As the trimethylanthracenes are of very little interest they will be treated very briefly.
Gresly 1 by distilling 2.4.5-trimetli3dbenzoyl benzoic acid with zinc dust obtained 1.2.4-trimethylanthracene, m.p. 243°, the quinone melting at 161° ; and Elbs - has repeated this work with almost exactly similar results, his melting points being 244° and 162°. The same compounds have also been obtained by Wende ^ by condensing durylic acid with gallic acid by means of sulphuric acid and then dis- tilling the trimeth3'ltrihydroxy anthraquinone with zinc dust. By this means he obtained 1.2.4-trimethylanthracene and from it the quinone by oxidation. He gives the melting points as 236° and 157-160°.
Elbs 4 has obtained 1.3.6- and i.4.7-trimeth3danthracenes by heating 2.^.2'.^'- and 2.5.2'.5'-tetrameth3'lbenzophenone. He finds that the}^ melt at 222° and 227°, the corresponding quinones melting at 190° and 184°.
In the case of the trimethylanthracenes it is noticeable that methyl groups in the a-position do not seem to cause any fall in the melting point. This phenomenon cannot at present be compared with the behaviour of the corresponding naphthalene derivatives, as very few trimethylnaphthalenes have been described, but 1.4-dimethylnaphthalene is a liquid and melts at —18°.
Tetramethylanthracenes. — Friedel and Crafts ^ by
I a. 234, 2^8. 2 J.,pr. [2] 41, 121. ^ B. 20, 867.
* J. pr. [2] 35, 482 ; 41, 141 ; B. 19, 408. » a. ch. [6] 11, 2O7.
36 ANTHRACENE AND ANTHRAQUINONE
treating w-xylene with methylene chloride and aluminium chloride obtained a tetramethylanthracene which melted at 162-163°, and which on oxidation gave a quinone which melted at 204-206°. From pseudocumene and methylene chloride they obtained the same substance and also a tetramethylanthracene melting at 290°, and a hexamethyl- anthracene melting at 220°. Friedel and Craft's first com- pound (m.p. 162-163°) is probably identical with the 1.3.5.7- tetramethylanthracene obtained by Seer 1 by the action of aluminium chloride on the cliloride of mesitylenic acid :
COCl
cioc
and subsequent reduction by distillation with zinc dust. Seer also obtained the same tetramethyl compound directly from xylyl mesityl ketone by the action of heat. He agrees with Friedel and Crafts as regards the melting point of the hydrocarbon (163-164°), but gives the melting point of the quinone as 235°.
Anschiitz,2 by heating w-xylene with acetylene tetra- bromide and aluminium chloride, or by heating xylene in a sealed tube with aluminium chloride, obtained a tetramethyl compound which melted rather indefinitely at 280°, and gave a quinone melting at 228-230°. Dewar and Jones ^ by heating m-xylene with nickel carbonyl obtained a tetramethyl anthracene which melted at 280°, and gave a quinone melting at 228-230°. This they conclude is i.3.5.7-tetrameth3danthracene, on the ground that the action of nickel carbonyl in the cold leads to 2.4-dimethyl- benzaldehyde. On their own showing, however, it is very improbable that the aldehyde is formed as an intermediate product when anthracene compounds are produced, as although benzene and nickel carbonyl gives anthracene, they were unable to obtain anthracene from benzaldehyde.
Seer * has repeated the work of Friedel and Crafts, and
1 M. 33, 33. 2 A. 235, 173. » Soc. 85, 21G. * M. 33, 33.
ANTHRACENE AND ITS HOMOLOGUES 37
by a slight variation in the experimental conditions lias obtained a very small quantity of a tetramethylanthracene which melted at 281°. He concludes that the product obtained by Friedel and Crafts consisted mainly of 1.3.5.7- tetramethylanthracene (m.p. 162-163°) with a little 1.3.6.8- tetramethylanthracene (m.p. 281°). The products obtained by Dewar and Jones and by Anschiitz are probably also 1 .3.6,8-tetrametliylanthracene.
Other Anthracene Homoi^ogues. — There seem to be no records of attempts to prepare homologous anthracenes by the Friedel and Crafts' reaction, but Lippmann, Pollok, and Fritsch,! by the prolonged boiling of anthracene with benzyl cliloride in carbon bisulphide solution in the presence of zinc dust, claim to have obtained mono- and di-benzyl anthracenes. The former of these was also obtained by Bach 2 by benzylating anthraquinol. The monobenzyl compound melts at 119° and the dibenzyl compound at 239-240°. Both on oxidation give anthraquinone, so that the benz^d groups must be attached to the w^s-carbon atoms. The dibenz5'l compound gives a monobrom substitution product, which when treated with basic substances such as potassium acetate, potassium carbonate, pyridine, or quinoline, loses hydrobromic acid and passes into two new compounds. These Lippmann regards as dibenzalanthracene and 6ts-dibenzalanthracene and assigns them the formula? :
C CIiC6H5 C — CHCgH5 — CHCgH.5 — C
CfiHZ >C6H4 and CgHZ | >C6H4 CgHZ 1 >C6H4
C CHCgHs C — CHCgHg — CHCgHg — C
Dibenzalanthracene, 6Js-Dibenzalanthracene,
m.p. 236°. m.p. 184°.
It is surprising that the bimolecular compound should melt at such a much lower temperature than the mono- molecular form, and in any case the formulae can only be accepted with some reserve pending further confirmation.
Other ;«s-homologues of anthracene have also been described, but they are invariably obtained by indirect 1 M. 23. 672 ; 25, 793'. » B. 23, 1570.
38 ANTHRACENE AND ANTHRAQUINONE
methods. Thus, Jiingermann i obtained wis-diamyl anthra- cene by reducing the product obtained by the action of amyl-magnesium bromide on amylh3^droxy anthrone :
HO CgHn CgHn
CO C c
C6H4< >C6H4 -^ CeH/ >C6H4 -» CeH/NCeH^
C C C
HO CsHn HO Crjlu CgHn
It melts at 132-137°. Other homologous anthracenes have been obtained by similar methods, and will be referred to elsewhere. Wis-Diphen3dantliracene has been obtained by Simonis and Remmert 2 by treating o-brombenzyltriphenyl carbinol with concentrated sulphuric acid :
Ph Ph
H^l^/Br •.
C6H4<( CgHs -> C6H4<(|y^6H4
nOH V
Ph Ph
and by a similar reaction the same investigators have pre- pared i.2-dimethoxy-w/s-diplienylanthracene.
1 B. 38, 2868. - B. 48, 208.
CHAPTER III
SIMPLE DERIVATIVES OF ANTHRA- CENE
Hydroanthracenes
A CONSIDERABLE uumber of hydroaiitliraceiics have been described, although none of them are of any particular interest. They arc almost invariably obtained by the reduction of the anthracenes, although some of the lower members can be conveniently obtained by the partial dehydrogenation of the higher members, a method chiefly developed by Godchot.i
The reduction of anthracene and its derivatives can be effected by various reducing agents. Liebermann 2 and his co-workers made extensive use of hydriodic acid and red phosphorus, and by varying the concentration of the acid and the temperature and time of heating were able to obtain di-, tetra- and hexahydroanthracenes. More recently O. Fischer and Ziegler 3 have found that i-methyl-4-chlor- anthracene can be reduced to a dihydro compound by simply passing a stream of hydriodic acid gas through its boiling solution in glacial acetic acid. The ease with which this reduction takes place is probably exceptional, as O. Fischer and Reinkober * have found that ^-method- anthracene is quite unaffected by treatment in this wa3^ Sodium amalgam ^ in conjunction with ethjd or amyl alcohol has been used by several investigators, and, like
1 A. ch. [8] 12, 468 ; Bl. [4] 1, 701 ; C. r. 139, 605 ; 141. 1029 ; 142, 1202.
* A. Suppl. VII., 257 ; 212, 5 ; B. 1, 187 ; 9, 1202, ' J.pr. [2]86, 289.
* J. pr. [2] 92, 51.
5 Bamberger and Lodter, B. 20, 3076 ; Padova, C. r. 148, 290 ; Wie'and, B. 45, 492.
39
40 ANTHRACENE AND ANTHRAQUINONE
hydriodic acid, seems to produce hydroantliracenes in which the ws-carbon atoms are affected, as the reduction products are non-fluorescent, do not form picrates, and, so far as an}' information is available, do not polymerise to bimolecular compounds when their solutions are exposed to direct sunlight.
Catalytic reduction of anthracene by hydrogen in the presence of finely divided nickel at 200-250° has been studied by Godchot 1 and by Ipatjew, Jacowlew and Rakitin,^ and often leads to products which differ from those obtained by hydriodic acid or by sodium amalgam. Thus the tetra- hydroanthracene obtained by means of h^'-driodic acid melts at 101-103°, is not fluorescent, and gives no picrate, whereas that obtained by reduction by h3^drogenation in the presence of nickel melts at 89°, shows a blue fluorescence, and gives a picrate.
The hydroanthracenes as a rule are colourless soHds which melt below 100°, and which are more or less fully dehydrogenated by passing through a red-hot tube. They reduce sulphuric acid to sulphur dioxide, although Godchot 3 states that octahydroanthracene gives a sulphonic acid in which sulphonic acid group is attached to one of the />/s-carbon atoms.
Of the individual members, only one dihydroanthracene, C14H12, is known. This melts at 108-5°, and is dehydro- genated when shaken in benzene solution with finely divided palladium. 4 Two tetrahydroanthracenes, C14H14, are known, which melt at 101-103° and at 89°. The former is obtained by means of hydriodic acid, and the latter by catah^tic reduction. As the latter is fluorescent and gives a picrate the ?HS-carbon atoms are probably intact. Two hexahydro compounds, C14H16, have been described. One is obtained by reduction with hydriodic acid and melts at 63°, and boils at 290°. The other is obtained by loss of water from octahydroanthranol ^ and melts at 66*5°, and
1 A. ch. [8] 12, 468 ; Bl. [4] 1, 701 ; C. r. 139, 605 ; 141, 1029 ; 142, 1 202.
2 B. 40. 1289 ; 41, 997. 3 Bl. [4] 1, 701. * Wieland, B. 45 492. 5 Godchot, C. r. 142, 1203 ; A. Ch. [S] 12, 468.
SIMPLE DERIVATIVES OF ANTHRACENE 41
boils at 303-306°. The method of formation renders it almost certain that the ;«s-carbon atoms are intact, and this is supported by the blue fluorescence of the compound. An octahydroanthracene, C14H18, has been prepared by catalytic reduction. It melts at 71°, gives a picrate, and shows a green fluorescence. Hence, in all probability the wzs-carbon atoms are intact, although Godchot 1 brings forward some arguments to the contrary, e.g. it gives hexa- hydroanthrone on oxidation Nvith chromic acid. Deka- hydroanthracene, C14H20, melts at y;^° ; dodekahydro- anthracene, C14H22, boils at 140-150° at 15 mm. ; and perhydroanthracene, C14H24, melts at 88° and boils at 270°. None of them form picrates, and none of them are fluorescent.
Halogen Compounds
The action of chlorine and bromine on anthracene has been studied by many investigators, but often with contra- dictory results. The reactions which take place are some- what compUcated, as their course is very largely dependent on the solvent used and on the temperature at which the experiment is carried out, but as a rule the first compound formed is an addition compound which readily splits out halogen acid to give halogen anthracenes, in which one or both of the nieso- hydrogen atoms have been substituted. The resulting halogen anthracenes then again form addition compounds with more halogen atoms, and these again lose halogen acid, substitution now taking place in the benzene rings. The case is complicated by the fact that in addition to place isomerism the addition compounds also exliibit geometrical isomerism of the cis-trans type.
Diel ~ by passing chlorine gas over anthracene, first at the ordinary temperature and then at 230°, obtained a dichloranthracene tetrachloride, C14H8CI2.CI4. This melted with decomposition at 141-145°, and when treated with alcoholic caustic soda passed into a tetrachlor anthracene, m.p. 220°. By treating anthracene at 200° with chlorine
1 Bl. f4] 1, 121. * B. 11, 173.
42 ANTHRACENE AND ANTHRAQUINONE
in the presence of antimony pentachloride, he obtained hexa-, hepta-, and octa-chlor anthracene, the former passing into tetrachloranthraquinone on oxidation. The passage of a hexachlor anthracene into a tetrachloranthraquinone shows that two of the chlorine atoms are attached to the wis-carbon atoms, and, as the tetrachloranthraquinone is quite different from that sj^nthesised from tetrachlor phthalic acid, the remaining four chlorine atoms must be heteronuclear. Their exact positions have not beea determined, but Diel's hexachloranthracene was probably a mixture, as he gives the melting point as 320-330°. Meyer and Zahn 1 have shown that ;»s-dichloranthracene tetrachloride when heated de- composes into 2.3.9. lo-tetracliloranthracene, so that the chief constituent of Diel's hexachlor compound was pro- bably 2.3.6.7.9. lo-hexachloranthracene.
Diel also studied the action of bromine on anthracene and found that when heated to 120° in the presence of a trace of iodine a hexabromanthracene was formed, whereas at 200° he obtained a mixture of heptabrom- and octabrom- anthracene. The hexabrom- and the heptabrom- compounds on oxidation gave respectively tetra- and penta-brom- anthraquinone. Anderson 2 also studied the action of bromine vapour on anthracene, and working at the ordinary tempe- rature he obtained what he thought was an addition product (anthracene hexabromide, Ci4HioBr6) ; but Graebe and Liebermann ^ have proved it to be dibromanthracene tetrabromide. When heated alone it gives tribromanthra- cene, and when treated with alcoholic potash tetrabrom- anthracene. Hammerschlag ^ found that the final product of the action of bromine vapour on anthracene at the ordinar}- temperature was tetrabromanthracene tetrabromide. This on heating alone to 180° lost one molecule of hydrobromic acid and two atoms of bromine, and yielded a penta- brom anthracene giving a tribromanthraquinone on oxida- tion. On treatment with alcoholic caustic soda, on the other hand, it lost tv/o molecules of hydrobromic acid and
1 Page 44. 2 A. 122, 304.
» A. Suppl. VII, 304. * B. 10, 1212.
SIMPLE DERIVATIVES OF ANTHRACENE 43
passed into hexabromanthracene, from which tetrabrom- anthraquinone was obtained by oxidation.
Very similar reactions take place when wis-dichloranthra- cene is treated with bromine vapour, 1 addition and substitu- tion products being formed, which when heated alone lose both bromine and hj-drobromic acid, whereas only hydro- broniic acid is lost by treatment with alcoholic caustic alkali.
More definite information as to the positions of the bromine atoms has been obtained by Kauffler and Imhoff.2 They treated w/s-dibromanthracene with bromine vapour and obtained a dibromanthracene tetrabromide. From this they obtained a tribromanthracene, m.p. 171°, which on oxidation gave 2-bromanthraquinone, and a tetrabrom- anthraccne, m.p. 20)8-300°, which on oxidation gave a di- bromanthraquinone (m.p. 289-290°), which was identical with the 2.6-dibromanthraquinone obtained from the corresponding diaminoanthraquinone by the diazo reaction.
When anthracene is treated with chlorine or bromine in carbon bisulphide solution ^ the first action is the formation of a very unstable addition compound, anthracene dilialide, wliich then splits off halogen acid and yields ;;is-halogen anthracene, the second wzs-hydrogen atom being replaced in the same way.^ The action of chlorine on anthracene in chloroform and benzene solution was first studied by Schwazer,^ who obtained first ;;is-dichloranthracene, which by the further action of chlorine passed into dichloranthra- cene dichloride. This on heating did not split off free halogen, but at 170° lost one molecule of hydrocliloric acid and gave trichloranthracene. ]\Iore recently Meister Lucius and Briining 6 have re-examined the action of chlorine on anthracene in chloroform and in benzene solution. They state that Schwazer's dicliloranthracene dichloride is really
1 Schwazer, B. 10, 376; Hammerschlag, B. 19, 1106.
* B. 37, 4708.
' Perkin, Bl. [i] 27, 464 ; Chem. News, 34, 145 ; Graebe and Lieber- mann, A. Suppl. VII. 257; B. 1, 186; Anderson, A. 122, 306; O. Fischer, and Ziegler, J. pr. [2] 86, 291.
* Meyer and Zahn, A. 396, 166.
5 B. 10, 376. Cf. Radulescu, C. 190S (2), 1032. « D.R.P. 283,106.
44 ANTHRACENE AND ANTHRAQUINONE
a mixture of anthraquinone tetracliloride (m.p. i8o°) and dichloranthracene dichloride (m.p. 139-140°) :
CI CI \/ CI
c c
C6H4<(' ^C6H4 C6H4<' ^C6H4Cl2
C C
CI
CI CI
Thej' find that low temperatures and the use of cliloro- form as a solvent favours the formation of the former; whereas higher temperatures, certain carriers, such as phosphorus pentachloride, and the use of benzene as a solvent, favour the formation of the latter. By chlori- nating anthracene or ws-dichloranthracene in chloroform suspension at 2°, or in tetrachlorethane at —10° to —15°, they obtain pure anthraquinone tetrachloride, whereas almost pure dichloranthracene dichloride is obtained by clilori- nating in benzene at 60°. In a later patent 1 they claim that clilorination in chloroform in the presence of iodine or in sulphuryl chloride leads to dichloranthracene hexa- chloride and dichloranthracene octachloride.
Hammerschlag,2 by treating anthracene in benzene solution with chlorine, obtained a dichloranthracene tetra- chloride which yielded a tetrachloranthracene when treated with alcoholic potash. This latter on oxidation gave a dichloranthraquinone which melted at 205°.
Meyer and Zahn ^ have repeated Hammerschlag's work, and state that Hammersclilag's tetrachloride was impure. They were unable to obtain any isomeric forms of dichlor- anthracene tetrachloride, and state that their product is identical with that obtained by Liebermann and lyinden- baum 4 by treating " nitrosoanthrone " with phosphorus pentachloride. On heating it does not split off free halogen like the corresponding bromo- compound (see below), but parts with two molecules of hydrochloric acid, and forms
1 D.R.P. 284,790. 2 B. 19, 1106. 3 A. 396. 166. « B. 13, 158S.
SIMPLE DERIVATIVES OF ANTHRACENE 45
tetracliloranthracene. An isomeric tetrachloranthracene is also formed by treatment with alcoholic caustic potash. The tetrachloranthracene formed by the action of heat must be 2.3.9.10-tetrachloranthracene, as on oxidation it yields 2.3-dichloranthraquinone, the structure of which is known by its synthesis from 3.4-diclilorphthalic acid.i The iso- meric tetrachloranthracene obtained by the action of alcoholic caustic potash must be 1.3.9.10-tetrachloranthra- cene, as on oxidation it gives a dicliloranthraquinone which is not identical with 1.2-dicliloranthraquinone obtained from 3.4-dichlorphtlialic acid, nor with 1.4-dichloranthra- quinone obtained from 3.6-dichlorphthalic acid. 2
CI CI ^^ 01
KOH >r Heat
<■ CcHK >C6H4Cl4
—CI
CI (il CI
I— CI
-CI
B}^ heating anthracene or ^HS-dibromanthracene in cliloroform solution with bromine, Meyer and Zahn 3 obtained a dibromanthracene tetrabromide. This when heated and when treated with alcoholic caustic potash gives the same tribrom- and tetrabrom-anthracene as Graebe and Lieber- mann * obtained from their tetrabromide, but Meyer and Zahn's bromide (a-compound) differs widely in its physical properties from Graebe and Liebermann's product (j3- compound). Thus Meyer and Zahn's tetrabromide melts at 134°. whereas Graebe and Liebermann's product melts at 182°. The substances differ also in their crystalline form and solubility. The most marked difference, however, is in their behaviour towards light, for whereas Graebe and Liebermann's compound is unaffected, Meyer and Zahn's compound loses four atoms of bromine and passes into ms- dibromanthracene. The reaction, however, takes place only in benzene solution or, ver^' slowly, in chloroform solution.
1 Ullmann, A. 381, 27. " Ullmann, A., 381. n, 26.
« A. 398, t60. « A. Suppl. VII., 304.
46 ANTHRACENE AND ANTHRAQUINONE
Me^'er and Zahn have also obtained a dichloranthracene tetrabromide which is sensitive to light and which is iso- meric with the compound obtained by Schwazer i and by Hammerschlag.2 The isomerism is probably geometrical, Meyer and Zahn's compounds being the cis- form and Graebe and Liebermann's, Schwazer's and Hammerschlag's being trans- forms. This is in agreement with the great ease with which a- compounds lose bromine, and also with the general rule that the trans- isomer has the higher melting point. 3
In connection with the above it is interesting to notice that Radulescu,^ by heating anthraquinone with a large excess of phosphorus pentachloride, has obtained a hexachlor compound to which he ascribes the formula :
CI CI
.H
CI
,H
^Cl
CI CI
He states that it exists in two stereoisomeric forms, one melting with decomposition at 185°, and one melting with decomposition at 149°. Both on heating give the same trichloranthracene.
Kurt Me^-er and Zahn ^ have also studied the chlorina- tion of anthracene in other solvents. They find that in water or dilute acetic acid the action of chlorine at tempe- ratures below 25° is chiefly an oxidising action, hydroxy- anthrone (anthraquinol) and anthraquinone being formed, whereas at higher temperatures ws-dicliloranthracene is produced. In alcoholic solution the action is very similar, alkox3^antlirone and anthraquinone being produced in dilute solutions, whereas from concentrated solutions ms-
1 B. 10, 376. 2 B. 19 1 106.
' Stewart, " Stereochemistrv " (1919), p. 107.
* Bull. Soc. Stii. Buciiresci, 17, 29; C. 1908 (2), 1032.
'- A. 396, 166.
SIMPLE DERIVATIVES OF ANTHRACENE 47
dicliloranthracene can be obtained. Ether has much the same effect as carbon bisulphide, anthracene dichloride and mono- and di-cliloranthracene being produced. When glacial acetic acid is used as a solvent they find that the chief products are anthraquinone and dichloranthracene tetra- chloride.
Liebermann 1 and Schilling 2 have prepared numerous chloranthracenes by reducing the corresponding chloranthra- quinones with zinc dust and ammonia. ^ They firid that, as in the case of the cliloranthraquinones the a-chloranthra- cenes melt at considerabh' lower temperatures than the corresponding ^- compounds.
Liebermann finds that the a-chloranthracenes readily give addition products with chlorine, whereas the j3- com- pounds only give them with difficulty, as the chlorine atom in the j3-position seems to facilitate the substitution of the ;«s-hydrogen atoms. The ease with which a-chlor- com- pounds form addition products is borne out by O. Fischer and Ziegler,4 who obtained a dibromide from i-chlor-4-methyl anthracene by treating it with bromine in carbon bisulphide
solution :
H Br
C
Y ^ci
H Br
According to a patent ^ by Meister, Lucius, and Briining, although the ;;is-dicliloranthracene polyhalides lose halogen acid when treated with alcoholic caustic potash, they do not do so when treated with aqueous alkali unless benzyl sulphanilic acid is present. By means of this re- agent they obtain pentachlor- and hexachloranthracene, and suggest their use as yellow pigments.
» B. 47. loii. * B. 46, 1066.
' Cf. Fischer and Zieeler, J. pr. [2] 86, 291.
* J- pr- [2] 86, 291. "^ * D.R.P. 282,818.
48 ANTHRACENE AND ANTHRAQUINONE
The clilorination of anthracene and of 9.10-dichlor- anthracene by the action of sulphuryl chloride in the presence of an inert solvent, e.g. nitrobenzene at 100°, has been in- vestigated and it is claimed 1 that in both cases the product is 2.9.10-trichloranthracene.
Very little work has been done on the halogenation of the homologous anthracenes, but O. Fischer and Reinkober - have studied the action of bromine and chlorine on j8-methyl- anthracene. With bromine they claim to have obtained a pentabrom substitution product, but with chlorine they obtained impure substances which seemed to be mixtures of compounds containing five, six, nine, and ten chlorine atoms.
I/ippmann and PoUok 3 endeavoured to chlorinate anthracene by treating it with sulphur chloride in petroleum ether solution. They claim that prolonged action leads to ws-dichloranthracene, but that an intermediate com- pound, Ci4Hc,S2Cl, is first formed. This, they state, on oxidation yields anthraquinone and on reduction takes up two atoms of hydrogen. To the addition compound and its reduction product they assign the formulae :
CI— S : S CI— SH— SH
I I
c c
^6^4^ /C6H4 »^ C6H4<(' |^C6H4 j
CH CH
but as they state themselves that the addition compound is iinaffected by boiling alcoholic potash, these formulae can hardly be accepted pending some independent confirmation.
In addition to methods depending on the direct chlorina- tion of anthracene, chloroanthracenes can be obtained by other methods. Graebe and Liebermann * heated anthra- cene to 200° with a mixture of phosphorus pentachloride and oxychloride and obtained what appeared to be a mixture of trichlor- and tetrachloranthracene. More recently this reaction has been examined by Radulescu,^ who finds that
1 M.L.B., D.R.P. 292,356. 2 J. pr. [2] 92, 49.
' B. 34. 276S. * A. 160, 126.
■• Bull. Soc. Stii. Fincuresci, 17, 29. C. 1908 (2), 1032.
SIMPLE DERIVATIVES OF ANTHRACENE 4(3
the first product is anthraquiiione tetrachloride (red needles, m.p. 139°, with decomposition), and that this on heating then passes into dichloranthracene dicliloride and tricliloranthra- cene :■
CI CI 01 CI
I I
c c
C6H4<^j>C6H, -> CoH^^I^CeH^Cl^ C^Ki<^^C^ll,Cl
C C C
I I
CI CI CI CI
As stated on p. 46, he finds that the use of larger quantities of phosphorus pentacliloride leads to the forma- tion of two stereoisomeric licxachlor compounds.
As alread}^ stated (p. 47), lyiebermann, Schilling, and O. Fischer and Ziegler have prepared cliloroanthracenes by reducing the corresponding chloroanthraquinones with zinc dust and ammonia. Kircher 1 endeavoured to obtain 1,2.3.4-tetrachloranthracene in the same way from tetra- cliloranthraquinone, but during reduction two chlorine atoms were lost, so that the product was a dichloranthracene. This, Kircher states, gave a dichloranthraquinone on oxida- tion which gave alizarin on fusing with caustic potash. From this he concluded that his reduction product was 1.2- dicliloranthracene ; but Ullmann and Billig 2 have since proved it to be 2.3-dicliloranthracene, as its oxidation product is identical with the dicliloranthraquinone obtained from 4.5-dichlorphthalic acid. Although Kircher was unable to obtain tetrachloranthracene by the reduction of tetrachlor- anthraquinone, he succeeded in obtaining it by heating tetrachlor-o-benzoyl benzoic acid with hydriodic acid to 220°. Very little is known of the chloranthracene sulphonic acids, but ;ns-dichlorantliracene-^-suiphonic acid is said to be obtained by sulphonating ;»s-dichloranthracene with chlorsulphonic acid, preferably in the presence of some neutral solvent such as chloroform,^ or with oleum. *
1 A. 238. 346. ^ » A. 381 26.
» B.A S.F.. D.R.P. 260,562. * M.L.B.. D.R.P. 292,590.
4
50 ANTHRACENE AND ANTHRAQVINONE
It has recently been found that 9.10-dichloranthracene, when treated in the cold with nitric acid and an inert solvent, forms an addition compound with one molecule of the acid.i This addition compound apparently has the formula :
HO CI
C
CfiH4< yC^H.^^
NO2 CI
and on heating to 90-95° is decomposed into antiiraquinonc. The formation of such addition compounds seems to be connnon to nearly all derivatives of 9.10-dichloranthracene.
Action of Nitric Acid on Anthrackne
The action of nitrous and nitric acids on anthracene was first studied by Liebermann and his co-workers 2 and by A. G. Perkin,3 and also at a later date by Dimroth * and others. The somewhat complicated reactions which take place have more recently been fully investigated by Meisen- heimer,5 who has established the constitution of the various products formed, and also the mechanism of the reactions which lead to them. He has to a large extent confirmed the experimental results obtained by Liebennann and A. G. Perkin, but has shown that their interpretations of the reactions involved were usualh^ quite erroneous.
Although the exhaustive action of nitrous or nitric acid on anthracene leads, as would be expected, to anthraquinone, the moderated action leads to several interesting compounds, including a mono- and a dinitro- compound in which the nitro groups are attached to the ins- carbon atoms. Nitro derivatives of anthracene in which the nitro groups are attached to benzene nuclei are as yet unknown.
1 M.L.B., D.R.P. 296,019. 2 B. 13, 1584 ; 14, 467.
8 Soc. 59, 644; 61, 866.
• B. 20, 974 : 33, 3548 ; 34, 221. D.R.P. 127,399. » A. 323,205; 330, 133.
SIMPLE DERIVATIVES OF ANTHRACENE 51
If anthracene is suspended in acetic acid and then treated with exactly one molecule of nitric acid, the lirst action is one of addition, g-hydroxy-io-nitro-g.io-dihydro- anthraccne being obtained (dihydro-nitro-anthranol) :
H OH
C
c
H NO2 ♦ L/ieberniann and Lindemann 1 described this com- pound as being obtained by the action of nitrous oxides of anthracene, and named it " salpetersaiireanthracen ; " but Meiscnheimer failed to obtain it, and pointed out the pro- bable cause of the error on the part of Liebermann (see p. 52). The hydrox3'l group in this compound is excessively reactive, so that in the presence of acetic acid it is at once acetylated, the acetyl derivative being formed :
H OCOCH,
C
CgHix /C6H4
C
y
H NO2
If this compound is treated with hydrochloric acid the corresponding cliloride is obtained, whereas with nitrous acid it yields the nitrite, a somewhat unstable substance which, like the other esters, yields the methoxy compound very readily when treated with methyl alcohol.
H ONO H OCH;i
c |
C |
||
C6H40C6H, |
-> |
C6H4<^yC6H4 |
|
C |
c |
||
/\ |
- |
/\ |
|
H NOo |
H NO2 |
||
1 U. 13. |
15S4. |
52 ANTHRACENE AND ANTHRAQUINONE
It was probably this nitrite that Liebermann and Linde- mann obtained, as it corresponds very closely in its properties with their " salpetersaiireanthracen," although differing con- siderably in composition. Liebermann, however, states in his paper that the sample aualj-sed was recrystallised from benzene, and Meisenheimer has pointed out that under these conditions the nitrite is decomposed into nitroanthrone, which differs but slightly in composition from the substance analysed. The formation of the nitrite was no doubt due to Liebermann having generated his oxides of nitrogen from arsenious acid and* nitric acid (D=i'33), as under these conditions it is very difficult to prevent nitric acid being carried over. If this were the case the nitric acid would cause the formation of Meisenheimer's acetate, which would then be precipitated as the nitrite by the nitrous acid.
The formation of dihydronitroanthranol as the primary product of the action of nitric acid on anthracene is con- firmed by the study of the action of nitric acid on ethyl dihydroanthracene, and Meisenheimer has shown that in this case the first action of the nitric acid is to oxidise the dihydro- compound to ms-ethy\ anthracene :
H C2H5 C2H5
LfiH,
C«H
6^-»-4
CfiH,
CfiH
Q^^i
H H H
This then adds on nitric acid to form «iS-ethyl-nitro- anthranol, but the influence of the etlijd group has been to render the hydroxyl group much less reactive, so that the free hydroxy- compound is stable and can be isolated.
HO C2H5
C,;H.
CfiHi
H NO2
1
SIMPLE DERIVATIVES OF ANTHRACENE 53
If nitric acid is added to nitroantliranol acetate the nitrate is not obtained, as the action of an excess of nitric acid causes a different reaction to take place ; but Meisenheimer was able to prepare the nitrate by nitrating anthracene in chloroform solution. If any attempts are made to hydrolyse these esters, loss of water takes place at once with the formation of ;«s-nitroanthracene :
H OH H
C C
C C
H NO2 NO2
a perfectly stable substance which melts at 145-146°, and which distils in vacuo at over 300° without decomposi- tion. On reduction it gives the corresponding amino com- pound. 1 The nitro- compound can also be obtained directly by the nitration of anthracene in acetic acid solution in the presence of acetic anhydride, but it is more easily obtained by the hydrolysis of the acetate.
Perkin 2 nitrated anthracene in the presence of methyl alcohol, and obtained a compound which he named anthra- cene methyl nitrate. Other alcohols, such as ethyl alcohol, propyl alcohol, and iso-butyl alcohol, gave similar products, and these are luidoubtedly formed by the action of the alcohol on the nitroanthranol nitrate or nitrite first formed : H 0X0 H OCH3
\/ \/
C C
^e^K /C6H4 -> CeHiv /CeH^i
H NOo H XO2
They are very readil}^ hydrolysed by alkali and simulta- neously lose water, the product being ;»s-nitroanthracene. If anthracene in glacial acetic acid is treated with zh >■ D.R.P. 127,390. - - Soc. 59, 648 ; 61, S<.r..
54 ANTHRACENE AND ANTHRAQUINONE
molecules of nitric acid instead of with one molecule, the reaction takes a somewhat different course and two unstable substances are formed. One of these is soluble in hot alkali, and Meisenheimer has identified it as nitroanthrone ; a compound first obtained by Perkin i by the action of nitric acid on anthracene in the presence of iso-hntyl alcohol under certain conditions, and more lately and in good yield by Kurt Meyer 2 by nitrating anthrone in acetic acid :
O
II
c
C
H NO2 The other substance is insoluble in alkali, but is left behind as a decomposition product. Meisenheimer obtained it in the pure state by fractional precipitation from chloroform by the addition of petroleum ether, and identified it as trinitro- dihydroanthracene :
H NO2
C
c
NOo NOo
It might be argued that this compound was a nitrous ester and not a true trinitro- compound. If it were an ester one would expect it to react with methyl alcohol in the same way as nitroanthranol nitrite (p. 51) ; but methyl alcohol has no effect on it. With alkali it splits off one.nitro group and at the same time loses a molecule of water, the product being wjs-dinitroanthracene. This is a stable compound melting at 294°, which has also been obtained by Perkin, ^ together with the mononitro compound, by nitrating anthra- cene in nitrobenzene solution. He did not recognise it,
1 Soc. 61, 868. 2 A. 396, 150. ^ goc. 59, 637.
SIMPLE DERIVATIVES OF ANTHRACENE 55
however, as dinitroanthracene, and appears to have satisfied
himself with identifying it as being identical with the
" nitrosonitroanthracene " previously obtained by Lieber-
mann and Landshoff.i
The composition of the above trinitro- compound
receives support from the investigation of the action of nitric
acid on ethyl-dih^'droanthracene carried out by Meisen-
heimer. As stated previously, the first product formed is
ethyl nitroanthranol :
HO C2H5
\/ C
C
H NO2 This forms stable alkali salts from which it is reprecipitated as such by acetic acid, although mineral acids cause an im- mediate loss of water and formation of ethyl nitroanthracene :
C2H5
I C
C6H4<( j /C6H4
N02
a stable compound melting at 135°.
The further action of nitric acid on ethyl anthracene takes two directions. In the first, oxidation takes place with the production of ethyl nitroanthrone :
O
II
c
C6H4<^^CcH,
C
/\ C2H5 NO2
1 B. 14, 470.
56 ANTHRACENE AND ANTHRAQUINONE
while in the second place the nitrous acid thus generated combines with the ethyl nitroanthracene formed simultane- ously to produce trinitrodihydroethylanthracene :
C2H5 NO2
Cc^4\ /CfiH
NO2 NO2
This corresponds exactl}^ to the trinitro compound obtained from anthracene. It cannot be a nitrous ester as it is stable towards alkali, and can in fact be warmed with 30 per cent, methyl alcoholic caustic potash without undergoing decompo- sition.
Liebermann and LandshofE 1 nitrated dih5^droanthracene and obtained a substance which the}' named h^-droanthracene nitrite, and to which the}' ascribed the formula :
H H H H
C
C6H4< >C6H4 or CeH^/^CeH,
C C
ONO ONO ONO NO2
It seemed ver}^ improbable that dih^-droanthracene would react differently towards nitric acid than anthracene itself, especially as ethyl dih3'droanthracene reacts in the same way as anthracene, and Meisenheimer therefore re-examined the point and found that Liebermann's and Landshoff's " hydro- anthracene nitrite" is really nothing but a mixture of nitroanthrone and trinitrodih3-droanthracene.
It was mentioned on p. 51 that lyiebermann and Lindemann - studied the action of nitrous acid on anthracene and obtained a substance which they named " salpetersaure- anthracen." Under somewhat different conditions and by
i^B. 14, 467. ^ B. 13. 1585 ; 14, 4S4 ; 33, 3547-
SIMPLE DERIVATIVES OE ANTHRACENE 57
using nitrous oxides carefully freed from nitric acid, they obtained a different compound, which they named " unter- salpetersaureanthracen." This has also been re-investigated by Meisenheimer, who confirms Liebermann and Linde- mann's results, but finds the compound is most readily obtained if the nitrogen dioxide is generated by heating lead nitrate. He considers that the compound is sj/m-dinitro- diliydroanthracene, and that it is formed by the addition of two (single) molecules of nitrogen dioxide :
H NO2
C
C6H4\ yC6H4
c
H NO2 With reference to this it should be noted that a similar reaction takes place between stilbene and nitrogen dioxide : 1
H H
CgHsCH^CHCeHs -> CgHsC CCeH,,
I I
NO2 NO2
The action of alkali on the various nitration products of anthracene is very interesting.
As stated on p. 53, the esters and ethers of nitro- anthranol when treated with alkali pass into ws-nitro- anthracene. This, by the further action of alkali, passes into anthraquinone-monoxime,2 a compound which was obtained by Perkin b3^ this method, but which, curiously enough, he did not identify, although he prepared an acetj'l derivative : ^ H OH O
I I II
c c c
C6H4<(!^C6H4 -> CcH4<(^\c6H4 or C6H4<^\CoH4
C C C
I I II
NO2 .^ NO NOH
i B. 34, 3540. « A. 328, 232. » sqc. 59, 644 ; B. 16, 2179.
58 ANTHRACENE AND ANTHRAQUINONE
The change is obviously due to the wandering of an oxygen atom, and although it seems curious at first sight, it is by no means unique. Thus i-nitro-naphthalene- 3.8-disulphonic acid when boiled with aqueous caustic soda passes into i.4-nitrosonaphthol-3.8-disulphonic acid : 1
S NO.
S NO
— S
OH
and dinitro-, trinitro-, and tetranitronaphthalene also give nitronitroso- compounds under the influence of alkali. 2 sjym-Trinitrobenzene and sywi-trinitrotoluene behave in a somewhat similar manner.
Meisenheimer ^ has made a very careful study of the action of potassium methoxide on ws-nitroanthracene. He finds that the first action is one of addition, the product being :
H OCH3
C6H4<^^C6H4
C
N^^ \0K
By the action of potassium hypobromite on this compound
he obtained :
H OCH3
CcH^^^^^CeH^ C
» B. 28, 1535-
Br NO2
2 B. 32, 2S76, 3528 ; D.R.P. 127.295.
8 A. 323, 205.
SIMPLE DERIVATIVES OF ANTHRACENE 50
which by loss of hydrobromic acid gave methoxynitro- anthracene. By treating this with potassium methoxidc and then with sodium hypobromite he got :
CHoO OCH,
CH3O OCH3
c
C
and
11^0
N
\o
K
c
Br NO2
This last compound he oxidised to dimethoxyanthrone. On treating it with mineral acids, however, it was instan- taneously h3'drolysed to anthraquinone oxime.
Trinitrodihydroanthracene under the influence of alkali loses a nitro group and passes quantitatively into dinitro- anthracene :
H NO2
C CeH^^CeH., -> C
NO2 NO2
H NO2
\/ C
C6H4<r y>C6H4
c
HO NO2
-> C6H4<^
NO2 I
c
C6H4
c
I
N02
and dinitrodihj'droanthracene by a very similar reaction gives mononitroanthracene :
r H OH 1
H NO2
\/ C
C6H4<^CcH4
C
/\ H NO2
<-'6H4'C '>C6H4
c
H NOo
H
I C
-^ C6H4<;^;>C6H4 c
I
N02
Nitroanthrone dissolves in alkali to form a coloured solution from which it is reprecipitated by acetic acid in
6o ANTHRACENE AND ANTHRAQUINONE
the original colourless form. If, however, a mineral acid is used to liberate it from its salts it can be obtained in a less stable red form. This can be preserved in a vacuum in the dark for some months, but under the action of light slowly reverts to the colourless form. These Meisenheimer con- sidered corresponded to the normal and aci- forms :
O O
c |
c |
C |
C |
H NO2 |
11^0 |
Colourless. |
Red. |
and Hantzsch 1 claims to have isolated a third, yellow, variety which is very unstable and rapidly passes into the red form. He ascribes to it the formula :
OH
\^4\ i /C6H4
NO2
This compound was described by Perkin,^ but Meisen- heimer 3 has shown that Perkin's substance was really pure nitroanthrone (colourless variety) .
Kurt Meyer 4 has re-examined the subject, but has failed to obtain the labile compound described by Hantzsch. He has, however, confirmed the existence of the two isomerides described by Meisenheimer, and although he agrees with the anthrone formula for the colourless variety, he considers that Meisenheimer' s red unstable substance is not the aci- (nitrolic) form, but is nitroanthranol :
1 B. 42. 121C. - See. 61, 868.
8 A. 330, 153. * A. 396, 137.
SIMPLE DERIVATIVES OF ANTHRACENE 6i
O OH
II I
c c
C6H4<^NC6H4 C6h/J^CoH4
c c
H NO2 NO2
Colourless. Red.
The latter compound should give an acetyl derivative, and although Meisenheimer failed to obtain one, Meyer has been able to do so by treating it with acetyl chloride in pyridine solution. He has also obtained a benzoyl derivative by the same means.
It might be argued that the latter anthranol formula represents a fluorescent compound, whereas nitroanthranol shows no fluorescence. The nitro- group, however, has a great influence in hindering fluorescence, so that this objec- tion does not hold good, and it is fairly certain that Meyer's interpretation of the isomerism is the correct one.
The question of anthrone-anthranol isomerism will be found more fully discussed on p. 119.
SuLPHONic Acids
The anthracene sulphonic acids can be obtained either by sulphonating anthracene or by the reduction of the corresponding anthraquinone sulphonic acid.
As regards the sulphonation of anthracene, the literature is very confusing, and even now it is not at all clear exactly what takes place. Linke,i by sulphonating anthracene claimed to have obtained two dift'erent monosulphonic acids, each of which gave a difterent hydroxyanthracene when fused with caustic potash. Ivieberniann,2 however, repeated lyinke's work and failed to obtain any monosulphonic acid the conditions specified by Linke always leading to disul- plionic acids. Graebe and Liebermann,2 and Liebermann and Rath, 3 however, obtained a monosulphonic acid by
» J. pr. [2] 11, 227. * A. 212, 43 ; B. 11, 1C13. ^ B. 8, 246.
62 ANTHRACENE AND ANTHRAQUINONE
sulphouation. These latter observers distilled the sodium salt of their acid with potassium ferrocyanide and saponified the resulting nitrile. They thus obtained an anthracene carboxylic acid which gave a soluble barium salt and which melted rather indefinitely at 260°. On oxidation it gave the corresponding anthraquinone carboxylic acid, m.p. 282-284". There can be but little doubt that the sulphonic acid they obtained was anthracene-i -sulphonic acid. Thc}^ give no details of the sulphonation process except to state that it was carried out at as low a temperature as possible.
On the other hand, the Societe Anon^ane des Matieres Colorantes 1 sulphonate anthracene at a tem^jerature of 120-135°, with an acid of 67 per cent, strength (53° Be.), and obtain yields of 60 per cent, of anthracene- 1 -sulphonic acid. They state that the same product is formed when tlie sulphonation is carried out at 140-150° with sodium bi- sulphate or nitre-cake instead of with sulphuric acid. 2 They also state that a certain quantity of three different disulphonic acids is formed at the same time, and that one of these, by heating with hydrochloric acid under pressure, is hydrolysed and converted into anthracene or anthracene monosul- phonic acid. None of these acids seem to have been in- vestigated, but the one that is hydrolysed is probably an a-sulphonic acid, as sidphonic acid groups in the a- position are much more readily removed than those in the j8- position. More recently Bayer and Co. 3 have described the sulphona- tion of anthracene by chlorsulphonic acid in glacial acetic solution at 95°, and claim to obtain a yield of 50 per cent, of anthracene- 1 -sulphonic acid and 30 per cent, of anthracene- 2-sulphonic acid. Helf ter ^ has carried out some in- vestigations with the monosulphonic acid made by the French process and has prepared the sulphochloride. This is remarkably stable for a sulphocliloride and can be boiled with water for a few minutes without it undergoing decom- position. In order to convert it into the sulphamide he apparently found it necessary to heat it in a sealed tube for
1 D.R.P. 72,226 ; 7^.961; 76,280. 2 D.R.P. 77,^1 r.
3 D.R.P. 251,695. ' ^ B. 28, 2256.
SIMPLE DERIVATIVES OF ANTHRACENE 63
four hours at 150° with alcohoHc ammonia. By reduction with zinc and ammonia or with sodium sulphite he obtained the sulphinic acid.
Liebermann 1 by sulphonating anthracene obtained two disulphonic acids which he separated by taking advantage of the different sohibilities of their lead and sodium salts. These on fusion with caustic alkali gave two different liydroxyanthracenes, the acetyl derivatives of which Lieber- niann oxidised and then hydrol3^sed, and thus obtained anthrarufin and chrj^sazin. He therefore concluded that the two sulphonic acids were the 1.5 and the 1.8 isomers, and states that a high temperature during sulphonation favours the formation of the former.^ This deduction, however, is hardly justified, as caustic fusion is notoriously unreliable as a method of determining constitution, and at high temperatures hydroxyl groups have a great tendency to wander to the a- position. It is true that Lampe ^ has obtained the two disulphonic acids by the reduction of the corresponding anthraquinone sulphonic acids, and states that they are the same as those obtained by Liebermann ; but the description he gives of the acids is not full enough to justify this statement, and it must therefore be accepted with some reserve until further information is forthcoming.
It seems reasonably certain that under some conditions anthracene is sulphonated in the a- position, while it is equally certain that under other conditions it is the /3- position that is attacked. In the naphthalene series exactly the same phenomenon is encountered, as when sulphonated below 80° the a-sulphonic acid is almost the sole product, whereas above 80° the ^- isomer predominates, and on heating with sulphuric acid the a- acid is converted into the ^- acid by the wandering of the sulphonic acid group. Tliis wander- ing must be regarded as hydrolysis and subsequent sulpho- nation, and the conditions specified in the patented process for the manufacture of anthracene-i -sulphonic acid would favour hydrolysis. It is, of course, quite possible that sulphonation first takes place at the ms- carbon atoms, but
1 A. 212, 43 ; B. 11, 1C13. « B. 12, 182. » B. 42, 1413.
64 ANTHRACENE AND ANTHRAQUINONE
no anthracene ws-sulphonic acids seem to have been described.
The reduction of the anthraquinone sulphonic acids can be carried out with hydriodic acid and phosphorus, i or with zinc and ammonia. 2 Reduction must, however, not be more vigorous than is necessary, as otherwise the sulphonic acid group may be spUt off. This is particularly likely to happen in the case of the a-sulphonic acid, Liebermann and Hormann,^ by reducing anthraquinone sulphonic acid, obtained an anthracene sulphonic acid which on fusion with caustic potash gave an hydroxyl compound the acetyl derivative of which melted at 139°, i.e. was probably i-acetoxy anthra- cene. It is improbable that I^iebermann and Hermann were using anthraquinone-i -sulphonic acid, as it is only in recent years that this has been available, and it must therefore be concluded that the production of i-hydroxy- anthracene was due to a wandering of the hydroxyl group during the alkali fusion. This receives confirmation from the fact that Liebermann and Bischoff * reduced com- mercial anthraquinone sulphonic acid with hydriodic acid and then distilled the sodium salt of the resulting anthracene sulphonic acid with potassium ferrocyanide. On hydro- lysing the resulting nitrile they obtained an acid which melted rather indefinitely at over 280° and which gave an insoluble barium salt and was undoubtedly anthracene- 2-carboxyUc acid. It was accompanied by a small quantity of an isomeric acid which gave a soluble barium salt and which Liebermann ^ has since recognised as anthracene- a-carboxyhc acid, and which, as he has proved, was derived from the small amount of anthraquinone-a-sulphonic acid always present in commercial samples of the ^- acid.
Hydroxyanthracenes
Hydroxyanthracenes, in which the hydroxyl groups are attached to the ;»s-carbon atoms, the anthranols and anthra-
1 A. 212, 43 ; B. 12, 589. 2 B. 13, 47.
3 B. 15, 1807 ; 37. 70 ; 38, 2863. D.R.P. 21,178 (Agfa).
* B. 13, 47. * B. 37, 646.
SIMPLE DERIVATIVES OF ANTHRACENE 65
quinols, differ very considerably in their properties from those in which the hydroxyl groups are attached to the benzene rings. These wzs-compoimds are almost invariably obtained by the reduction of the corresponding anthra- quinone, and will be described in Chapter IV.
The hydroxyanthracenes, in which the hydroxyl groups are situated in the benzene rings, are known as anthrols to distinguish them from the anthranols, in which the hydrox>d group is attached to one of the 7«s-carbon atoms. They can be obtained by the reduction of the corresponding hydroxyanthraquinones, e.g. with zinc dust and ammonia ; but simultaneous loss of one or more of the nuclear hydrox^d groups is ver)^ apt to take place, so that the anthrol obtained often contains fewer hydroxyl groups than the anthra- quinone derivative from which it was made.i A nmch more generally useful method, however, is the fusion of the corre- sponding anthracene sulphonic acids with caustic potash, although, as the sulphonic acid groups are very firmly held, a rather high temperature is necessary. This method has been largely developed b}' Liebermann and his students, 2 and has been applied not only to the sulphonic acids obtained by sulphonating anthracene, but also to the anthracene sulphonic acids which are readily obtained by the reduction of the corresponding anthraqumone sulphonic acids. A third method which is sometimes useful, although limited in its application, consists in the reduction of derivatives of i.2-anthraquinone or 1.4-anthraquinone. Both these substances are true quinones, and their reduction apparently can be readily effected without danger of simultaneous loss of hydroxyl groups. So far, however, the method has been very little applied. ^
As would be expected, the anthrols resemble the phenols
1 Cf. pp. 264-266; Lagodzinski, A. 342, 104; B. 28, 1533.
2 Liebermann, B. 11, 1610. Liebermann and Boeck, B. 12, 185, 1613. Liebermann and Hormann, B. 12, 589. Schiiler, B. 15, 1807. R. E. Schmidt, B. 37, 70. Dienel, B. 38, 2863. Lampe, B. 42, 1414. Liebermann, A. 212, 43. Linke, J. pr. [2] 11, 227. Agfa, D.R.P. 21,178.
3 Lagodzinski, B. 39, 1717; A. 342, 59. Dienel, B. 39, 930. Has- linger, B. 39, 3537. Pisovschi, B. 41, 1436.
5
66 ANTHRACENE AND ANTHRAQUINONE
very closely in their deportment. Thus they are soluble in caustic alkali, give nitroso compounds i with nitrous acid, and in alkaline solution couple with diazo- solutions to produce h}-droxy azo compounds.^ The corresponding alkyl ethers are very readily prepared, it being sufficient to saturate the warm alcoholic solution with hydrochloric acid gas. 3 By this procedure the alk3iated anthrol is usually obtained in almost quantitative 3ield, whereas the phenols of the benzene series are almost unaffected?. The naphthols can be alk^'lated by saturating their alcoholic solutions with hydrogen chloride, but the reaction takes place with some difficulty and the fields are poor.
The following anthrols have been described : —
Position |
M.p. |
Acetyl derivative, |
Methyl |
Ethyl |
|
of OH. |
m.p. |
ether, m.p. |
ether, m.p. |
||
I |
_ |
152° decomp. |
128-130° decomp. |
70° |
69° |
2 |
Decomp. at 200° |
198° |
175-178° |
145-146° |
|
1.2 |
— |
131° decomp. |
145° |
||
1.4 |
■ — ■ — • |
169° |
— ■ |
— |
|
1-5 |
Rufol > 265° decomp. |
196-198° |
224° |
179° |
|
1.8 |
Chrysol 225° decomp. |
184° |
198° |
139° |
|
2-3 |
— Decomp. 180° |
155-160° |
204° |
||
? ? |
Flavol 260-270° |
254-255° |
" |
229° |
Flavol was described by Schiiler,* who reduced com- mercial anthraquinone disulphonic acid to anthracene disul- phonic acid and then fused this with caustic potash. It is probably either 2.6-dihydrox3' anthracene or 2.7-dihydroxy anthracene, or it may be a mixture of the two.
Of the anthracene mercaptans very little is known, but Heffter,^ by reducing anthracene-/S-sulphinic acid with zinc and hydrochloric acid, obtained anthracene-j3-mercaptan. Kehrmann and Sava,^ by treating its lead salt with dimethyl sulphate, obtained dimethyl-j8-anthraquinonyl sulphonium salts.
' Dienel, B. 39, 930. Lagodzinski, A. 342, 59. - Lagodzinski, B. 39, 1717. Agfa, D.R.P. 21,178.
' Liebermann and Hagen, B. 15, 1427 ; B. 21, 2057. Dienel, B. 38, 2863. Lampe, B. 42, 1413.
« B. 15, 1807. 6 B. 28. 2263. 6 B. 45, 2898,
SIMPLE DERIVATIVES OF ANTHRACENE 67
Aminoantpiracenes
Methods iuvolviug the reduction of nitro groups are not, as a rule, available for the preparation of anthramines, as anthracene is only nitrated with difficulty, and the ws-nitro- anthracenes are the only known nitro compounds. The anthr- amines, however, are fairly easily prepared by other methods.
Wis-Anthramine (ws-aminoanthracene) was first prepared by Goldmann 1 by heating anthranol with concentrated aqueous ammonia at 200°, and later was prepared by Meisenheimer 2 and Dimroth ^ by the reduction of ms-nitro- anthracene with tin and Itydrochloric acid, or with zinc dust and ammonium chloride. It is a rather unstable substance, which melts indefinitely at about 115°. When treated with acetic anhydride at the ordinary temperature it gives a stable monoacetyl derivative (m.p. 273-274°), whereas when treated with boiling acetic anhydride it readily gives a diacetyl derivative (m.p. 159°). N-Arylanthramines have been prepared by Padova * by heating anthranol with excess of primary aromatic amines, such as aniline and a- and j3- naphthylamine.
The B^-anthramines are best obtained from the anthrols by heating with aqueous ammonia, ^ calcium chloride am- monia,^ or acetamide,"^ but 0- and p-Simmo anthrols and 0- and /)-diamino anthracenes are more readily obtained b}- the reduction of the corresponding nitrosoanthrol,^ or the hydrox}^ or amino azo- compound. ^
Anthramines can also sometimes be obtained by reducing the corresponding aminoanthraquinone, e.g. Romer 10 obtained ^-anthramine by heating j8-aniinoanthraquinone with hydriodic acid and phosphorus ; but the method is not
^ B. 23, 2522; A. 330, 165; By. D.R.P. 127,399. = B. 33, 3548. » B. 34, 220.
* C. r. 149. 217.
•" Liebermann and Bollert, B. 15, 8i6. « Pisovschi, B. 41, 1434. Liebermann, loc. cit. (footnote). ' Liebermann and Bollert, B. 15, 226; A. 212, ^6. Dienel, P.. 38, 28G3. Liebermann, li. 41, 1434 (footnote).
« Dienel, B. 38, 930. Lagodzinski, A. 342, 73.
* Pisovschi, B. 41, 1434. Lagodzinski, B. 39, 1717. A. 342, 75. " B. 15, 223.
68 ANTHRACENE AND ANTHRAQUINONE
a satisfactor}^ one, and Graebe and Blumenfeld i failed to reduce a-aminoanthraquinone to a-antliramine.
The antliramines are very weak bases, and consequently are scarcely soluble in hydrochloric acid, although salts can be precipitated by adding an acid to the ethereal solution of the anthramine. These salts, however, are at once hydro- lysed by water. 2 They give monoacetyl derivatives on prolonged boiling with acetic anhydride, and in this way the B2-anthramines differ from ws-anftiramine, this latter, as stated on p. 67, readily yielding a diacetyl derivative.
The primary anthramines pass with great ease into the dianthramines, boiling for a short time with glacial acetic acid being sufficient to bring about the change; but in the case of a-anthramine the reaction is considerably slower than with jS-anthramine.s The primar>^ anthramines react very readily with methyl iodide and pass directly into quaternary ammonium salts, C14H9N (€113)31, from which the quaternary base can be liberated by means of silver oxide. This when boiled with water, or, more readily, when heated with water to 120-130°, loses methyl alcohol, and passes into the dimethylanthramine.4
The anthramines do not seem to be readily diazotised, although Pisovschi ^ states that he obtained aminoazo anthracene by treating a-anthramine with amyl nitrite in alcoholic solution. Bollert,^ on the other hand, states that j3-anthramine when treated in alcoholic solution either with nitrous acid or amyl nitrite yields (Ci4H9NH)2NO. In Bollert's compound, however, it is not improbable that one of the ws-hydrogen atoms had been affected.
The following simple anthramines have been described : —
Position of NHj. |
M.p. |
Acetyl derivative, m.p. |
I 2 1.4 ms. |
119" 236-237° About 113° |
198° 240° 322° ( Monoacetyl, 273-274° I Diacetyl, 115° |
1 B. 30, iiiS. 2 Liebermann and Bollert, B. 15, 226; A. 212. 56.
3 Bollert, B. 16, 1634. Dienel, B. 38, 2863. * Bollert, B. 16. 1634.
5 B. 41. 1434. « B. 16, 1634.
SIMPLE DERIVATIVES OF ANTHRACENE 69
NiTRILES AND CARBOXYWC AcIDS
The ms-nitrile of anthracene has not been described, but several nuclear nitriles have been prepared. They are usually best obtained by distilling the potassium salts of the corresponding sulphonic acids with potassium cyanide. 1 They are of no particular interest, and, like the naphtho- nitriles, are very difficult to hydrolyse.
Anthracene-ws-carboxylic acid (anthroic acid) was first obtained by Graebe and Lieberniann ~ b}^ heating anthra- cene under pressure with carbon3'l chloride at 180°, and at a later date Behla ^ and Liebermann and Zsuffa * showed that if the temperature is raised simultaneous chlorination takes place, the product being ?«s-clilor anthroic acid. The yields of anthroic acid obtained by this method are very poor, but more recently Liebermann and Zsuffa ^ have obtained it in eighty per cent, yield b}' heating anthracene with oxalyl chloride to 160-170°. If oxalyl chloride is used in conj miction with aluminium chloride the yield of anthroic acid falls to about thirty per cent., but aceanthrene quinone is simultaneously formed in sixty per cent. 3'ield :
and this, on careful oxidation in neutral or alkaline solution, gives anthracene-i.Q-dicarboxylic acid.^ The behaviour of anthracene homologues and halogen substitution products * towards oxalyl chloride is very similar.'
The anthroic acids are somewhat unstable, and lose carbon dioxide readily when heated, loss of carbon dioxide commencing at 150° in the case of anthroic acid itself. On oxidation the 7ns- carboxyl group is lost, anthroic acid itself being quantitatively converted into anthraquinone. As
1 Liebermann and Rath, B. 8, 246. Liebermann and Bischoff, B. 13, 47. Liebermann and Pleus, B. 37, 646. Dienel, B. 39, 932.
» A. 160, 137; B. 2. 678. 8 B, 18, 3169: 20, 704.
^ B. 44, 202. s B. 44, 202.
« B.A.S.F., D.R.P. 280,092. ' B. 45. 1213.
70 ANTHRACENE AND ANTHRAQUINONE
would be expected from stereochemical considerations, the anthroic acids are only esterified with the utmost difficulty, prolonged heating of the silver salt with the alkyl iodide under pressure usuall}' being necessary.
The nuclear carboxylic acids cannot be obtained directly by the oxidation of the methyl anthracenes, as simultaneous oxidation of the ws-carbon atoms always takes place, the product invariabh' being an anthraquinone carboxylic acid. These, however, are readily reduced* to the anthracene derivative, e.g. by zinc dust and ammonia, and the reduction of the anthraquinone carboxylic acids forms the easiest means of obtaining the anthracene carbox3dic acids, i The acids can also be obtained by the hydrolysis of the nitriles, and this method has been applied in several instances by Liebermann and his students.
The following nuclear carboxylic acids have been described : —
Position of GOGH. |
M.p. of acid. |
I |
245° |
2 |
— |
1-3 |
Above 330° |
1.4 |
320° approx. |
2-3 |
345° |
1.2.4 |
Aldehydes and Ketones
No aldehydes of the anthracene series have been described, and ver}' little is known of the ketones. Perrier 2 condensed anthracene with benzo}^ chloride in the presence of alumi- nium chloride, and obtained three compounds, having melting points of 75°, 143°, and 203°. Lippmann and Fleisser,^ and lyippmann and Keppich * also obtained three compounds, viz. a monobenzoyl derivative melting at 148°, a dibenzoyl
1 Elbs, B. 20, 1363; J. pr. [2] 41, 6, 121. B. 30, 1 1 18. Lavaux, C. r. 14.3, 687.
' B. 33, 816. 3 B. 32, 2240.
Graebe and Blumenfeld, * B. 33, 3086.
SIMPLE DERIVATIVES OF ANTHRACENE 71
derivative melting at 158°, and a tribenzoyl derivative melting over 300°. All three componnds gave antlira- quinone on oxidation, and hence it would appear that in all of them the benzo}-! groups are attached to the ws-carbon atoms. It is somewhat difficult, however, to account for three benzoyl groups. In a later paper Lippniann and Pollok 1 claim that better 3'ields of the monobenzoyl com- pound, anthraphenone, are obtained by warming anthracene with benzoyl chloride and zinc dust in carbon bisulphide solution for 480 consecutive hours.
1 13. 34. 2766.
CHAPTER IV
THE ANTHRAQUINONES AND DIANTHRAQUINONYLS
ThKoretically six monoquinones might be derived from anthracene, viz. four homonuclear quinones :
o o o
:0 |
:0 :0 |
o |
0 |
||
.2-Anthra |
i.4-Anthra» |
2.3-Anthra- |
9.10-Anthra |
quinone. |
quinone. |
quinone. |
quinone. |
and two heteronuclear quinones
O
O
O
O
1 .5-Anthraquinone. 2 .6-Anthraquinone.
Of these 9.10-anthraquinone is by far the most important
and is what is ordinaril}^ understood by the term " anthra-
quinone." Of the other isomers 1.2-anthraquinone and 1.4-
anthraquinone have both been prepared, but 2-3 anthra-
quinone is unknown, and the same apphes to the heteronuclear
quinones.
^3
ANTHRAQUINONES—DIANTHRA QUINONYLS 73
In addition to the monoquinones there is a possibility of the existence of numerous diquinones, some of which are known, and a triquinonc has also been described.
1.2-Anthraquinone
This was obtained by Dienel 1 and I.agodzinski 2 by oxidising 2-amino-i-anthrol with ferric chloride and hydro- chloric acid. It crystallises from water in red needles, which melt with decomposition at 185-190°. It is not volatile with steam, and on reduction with zinc dust and acetic anhydride passes into i. 2 -diacetoxy anthracene. Like all a-diketonic compounds it condenses with o-phenylene diamine to form an azine, Lagodzinski ^ endeavoured to obtam 2.3-anthraquinone by oxidising 2 ^-dihydroxy anthra- cene, but without success.
1 .4-ANTHRAOUINONE
This was first described almost simiiltaneously by DieneH and Ivagodziuski,^ both of whom obtained it by oxidising 4-amino-i-anthrol with ferric chloride, and shortly after Pisovschi 6 obtained it by oxidising 1.4-diamino anthracene. It forms ^^ellow needles which, according to Dienel, melt at 206°, whereas Pisovschi states that the com- pound darkens at 210° and melts with decomposition at 218°. Like all true ^-quinones it is very volatile. It is converted into quinizarin by reduction with zinc dust and acetic anhydride, and subsequent oxidation and hydrolysis. '^
9 . 10 - AnTHR AOUINONE
Synthetic methods for building up the anthraquinone ring are discussed in Chapter VI., and although the synthesis from phthalic acid is useful in the laboratory, the only method of any technical importance is the oxidation of anthracene.
In the laboratory the oxidation is best brought about by
1 B. 39, 930. • B. 27. 1438; 28, 1422; A. 342, 59.
3 B. 28. 1533. * B. 39. 931. 5 B. 39, 1717.
«* B. 41, 1430. ' Pienel, B. 39, 931. Haslinger, B. 39, 3537.
74 ANTHRACENE AND ANTHRAQUINONE
an excess of chromic acid in boiling glacial acetic acid solution,! but on the manufacturing scale the cost of the acetic acid is prohibitive, and in addition sufficient chromic acid must be used not only to oxidise the anthracene but also to oxidise the impurities present. The acetic acid method, however, gives quantitative results, and is uni- versally used for the estimation of anthracene in commercial samples of the hydrocarbon.
Anthracene can be oxidised by aqueous solutions of chromic acid (bichromate and sulphuric acid) provided it is first reduced to a state of fine subdivision, and this method has the advantage that the anthracene is attacked more readily than the impurities, so that it is only necessar}^ to use the calculated amount of chromic acid. In order to reduce the anthracene to the desired physical condition it is sublimed in a current of superheated steam and the vapour condensed by fine jets of water. The paste thus obtained is oxidised with sodium bichromate and sulphuric acid, and the chromic acid regenerated from the liquors electrically. 2 The crude anthraquinone, the purit3^ of whicii depends, of course, on the grade of anthracene used, is filtered off, washed, dried, and then dissolved in concentrated sulphuric acid at 130°. Tliis treatment does not affect the anthraquinone, but sulphonation of most of the impurities takes place, and at the same time the acridine is converted into the soluble sulphate. The acid solution, without cooling, is run into boiling water, when the anthraquinone is precipitated, and the sulphonated impurities and the acridine sulphate dissolve. It is necessary to run the hot acid solution into boiling water, as otherwise the anthra- quinone separates as a fine sludge, which is very difficult to filter. After washing the anthraquinone is quite pure enough for all ordinary purposes, but can be further purified by sublimation or by recrystallisation, e.g. from tetrachlor- ethane, aniline, nitrobenzene or nitrotoluene.^
^ Kopp, Monit. Sci. [3] 8, 1159. Graebe and Liebermann, ibid. [3] 9, 421.
* By. D.R.P. 252,759. This patent describes a continuous electrical recovery process. ^ Sadler & Co., D.R.P. 137,495.
A NTHRA Q UINONES—DIA N THRA Q UINON YLS
/.~)
Further purification can be effected if desired by reducing the anthraquinone to the alkali soluble anthraquinol, filter- ing off impurities and then oxidising the clear alkaline solution with atmospheric ox^^gen. On a technical scale it is stated that the reduction can be effected with finely divided iron and alkali. i
In addition to the chromic acid method, several other processes have been described for oxidising anthracene to anthraquinone. Thus, Hofmann, Ehrhart, and Schneider 2 have described the oxidation with potassium chlorate in the presence of a trace of an osmium salt, and Hofmann, Quoos, and Schneider 3 have described the oxidation by sodium nitrate or clilorate in the presence of a large excess of molten crystallised magnesium chloride. They state that the reaction starts at 125°, and is almost quantitative at 300°, whereas without the magnesium chloride no anthra- quinone at all is formed, even at 330°. Hofmann and Ritter * have described the oxidation at the ordinary temperature by the use of aqueous sodium hypochlorite in the presence of a trace of an osmium salt, and Hofmann and Schumpelt 5 have described the oxidation by potassium chlorate in formic acid solution.
The electrolytic oxidation of anthracene has been described, and quantitative yields with a current efficiency of almost 100 per cent., have been claimed by carrying out the oxidation in 20 per cent, sulphuric acid suspension in the presence of a little eerie sulphate as a catalyst. ^
Several patents have been granted for the use of nitric acid and oxides of nitrogen under various conditions. The action of nitric acid in the presence of a solvent such as nitro- benzene, with or without the use of mercury as a catalyst, has been investigated by the Chemische Fabrik Griesheim- Elektron, and good results claimed.'^ Probably ms-miro-
^ Lewis and Gibbs, A. P. 1,293,610 (191S).
- B. 45, 3334 ; 46, 16G9.
^ B. 47, 1991. Hofmann, D.R.P. 277,733.
^ B. 47, 2238.
=* B. 48, 821.
8 E.P. I9,i78«2.
" D.R.P. 283,213; 284,083-4; 284,179. Cf. A.P. i,ii9.54<^'
76 ANTHRACENE AND ANTHRAQUINONE
compounds are first formed and then pass into anthra- quinone.
The use of oxides of nitrogen has been described in several patents, and is of considerable interest in view of the read}- production of these by the catalytic oxidation of ammonia. The Badische Anilin u. Soda Fabrik claim the use of nitrogen dioxide in the presence of a suitable solvent such as nitro- benzene, i and the Aktien Gesellschaft Griinau, Landshoff u. Meyer,2 claim oxidation by nitrogen "dioxide at a tempe- rature of 100-200°, preferably at 200°, and state that an improved quality of anthraquinone is obtained if the anthra- cene is mixed with zinc dust or other substance which will destroy nitric acid. 3
In addition to the experiments of Hofmann and his students referred to on p. 75, Meister, Lucius, and Briinning have developed the use of chlorates, and in two patents * claim the use of the chlorates of iron, nickel, cobalt, man- ganese, and chromium.
Attempts have been made to carr}^ out the oxidation with oxygen, and it has been stated that anthracene can be oxidised in aqueous suspension at 170° with oxygen under pressure if a suitable catalyst is used.^ The best catalyst is said to be cupric oxide, but nickel, cobalt, iron and lead compounds are also effective. The oxidation in the vapour phase has also been described, the Barrett Co. (New York) ^ claiming oxidation by air or oxj-gen by passing anthracene vapour over a vanadium catalyst at 300-500°.
The use of ozone has also been claimed.'^
Anthraquinone is a yellow cr>^stalline soHd which melts at 280°. 8 It can be sublimed fairly easily, but is not nearly as volatile as most /)-quinones, and in this respect differs
1 D.R.P. 268,049.
* D.R.P. 234,289 ; 254,710.
2 M.L.B., i3.R.P. 256,623 (taken over from Akt. Ges. Griinau, Lands- hoff u. Meyer).
* D.R.P. 273,318-9.
6 M.L.B., D.R.P. 292,681. 6 E.P. 134,52218. ' Heinemann, E.P. 5514^^.
8 Phillipi, M. 33, 373. Kempf, J. pr. [2] 78, 257. The melting point usually given in the hterature, viz. 278°, is too low.
A NTHRA QUINONES~DIA NTHRA Q UINON YLS 77
sharply from the isomeric 1.4-anthraquinone. It is a very stable substance and is only attacked by oxidising agents with great difficulty, and then yields phthalic acid. Its behaviour towards reducing agents is discussed in detail elsewhere, but attention may here be drawn to the fact that the formation of a deep red solution by reduction in the presence of alkali (zinc dust and ammonia or caustic soda, or sodium hydrosulphite and caustic soda) serves as a con- venient test for anthraquinone, and as the " vat " is very easily oxidised by air or weak oxidising agents, such as hydrogen peroxide, reduction and subsequent oxidation is often a convenient method of getting rid of impurities.
Anthraquinone hardly behaves like a true quinone, nor does it behave like a true ketone. It forms no phenyl hydrazone, and only reacts with hydroxylamine to form a monoxime. Even this monoxime is only formed with great difficulty,! and it is only obtained directly by heating anthraquinone with alcoholic solutions of hydroxylamine hydrochloride in sealed tubes at 180°. Indirectly, however, both the monoxime 2 and the monophenyl hydrazone 3 can be obtained fairly easily by treating dibromanthrone with h3-droxylamine or phenyl hydrazine. The monoxime melts at 224°. The phenyl hydrazone is identical with the azo- dye obtained by coupling benzene diazonium salts with anthranol in alkaline solution.
Although the anthraquinone itself only undergoes oxime formation with the greatest difficulty, this is not the case when chlorine atoms are present in the a- position, and Fremid and Achenbach ^ have found that i-chloranthra- quinone gives a monoxime quite easily, and that 1.5-dichlor- anthraquinone readily forms both monoximes and dioximes. The monoximes of i-chloranthraquinone and of 1.5-dichlor- anthraquinone both exist in two isomeric forms, of which one gives an isoxazole, whereas the other does not, and the dioxime also exists in two forms. The isomerism is
2
> Goldschmidt, B. 16, 2179. Cf. Schunck and Marchlewski, B. 27, 2125.
2 Kurt Meyer, A. 396, 165.
' Kaufler and Suchanck, B. 40, 51S.
* B. 43. 3251-
I
^% ANTHRACENE AND ANTHRAQUINONE
probabl}- geometrical, although, in the case of the oxime of i-chloranthraquinone positional isomerism is not impossible :
HON NOH
II II
C CI C CI
CO CO
Gives no isoxazole. Gives isoxazole.
»
The formation of isoxazoles by one isomer and not by the other is in agreement with Victor Meyer's observation i that one of the oximes of o-chlorbenzophenone will give an isoxazole whereas the other will not.
Freund and Achenbach have also studied oxime forma- tion with other a- derivatives of anthraquinone. They find that erythroh^^droxy anthraquinone will give no oxime, whereas its alkyl and ar}^ ethers give monoximes with difficulty, and anthrarufin dimeth^^l ether will give a mon- oxime. No oxime could be obtained from 1.5-diamino anthraquinone or from i-chlor-5-amino anthraquinone.
Although the carbonyl oxygen atoms in anthraquinone are not very reactive, they readily enter into the formation of new rings and, as will be seen in the sequel, some of these ring compounds have proved to be very valuable dyestuffs. Staudinger 2 has found that anthraquinone will react with diphenyl ketene, but only with difhcult}^ and analj-sis and molecular weight determinations point to the formula :
Ph— C— Ph
^6^i\^y^G^4
Ph— C— Ph
for the product. The substance obtained, however, forms colourless needles which melt at 302-303°, and in view of the lack of colour vStaudinger is doubtful of the quinonoid formula.
J B. 25, 1498 ; 3293- ■ B. 41, 1362.
ANTHRAQUINONES—DIANTHRAQUINONYLS 79
Goscli 1 has found that aiithraquinone condenses with aldehyde ammonia if heated with it for six hours at 220°.' The product mehs at 281°, and he ascribes to it the formula :
H— C— CHO
c |
|
C6H4<(^( |
-6^4 |
C |
|
li |
|
H C |
CHO |
Bayer & C0.2 state that if anthraquinone is boiled with primar}' aromatic amines and a condensing agent such as boric acid, products are obtained in which both the carbonyl oxygen atoms have been replaced b}^ ArN: groups. They state that the reaction is facilitated by the presence of reducing agents, such as stannous chloride, but do not describe the resulting compounds in detail. Ver^^ similar products seem to be obtained from anthraquinone-jS-sul- phonic acid, 3 but as these are practically insoluble in dilute caustic soda, it would seem that the sulplionic acid group had also reacted. This is supported by the analytical figures given for the condensation product with _/)-toluidine. These point to the presence of three toluido groups, and are in approximate agreement with the formula C35H33O2N3VS.
Anthraquinone, when fused with caustic potash, yields benzoic acid,^ and caustic fusion has been applied in some cases for determming the constitution of anthraquinone derivatives. Owing to the stability of the anthraquinone ring, however, the method is rather tedious to carr^- out, and in the case of dimethyl anthraquinone I^avaux found it necessary to heat to 260° for three hundred consecutive hours.
Homologous Anthraouinones
The alk}-! anthraquinones are of no great importance, and have not been studied in detail. Most of the methyl
1 Soc. Ill, Gio. - D.R.P. 148,079. 3 By. D.R.P. 136.872 ; 147,277.
* Graebe and Liebermann, A. 160, 129.
So ANTHRACENE AND ANTHRAQUINONE
anthraquinones have been already mentioned in connection with the methyl anthracenes. The most important is j3- meth3'l anthraquinone, and this can be obtained by the oxidation of the j3-methyl anthracene obtained from coal tar, or from toluene by the phthalic acid method. When treated with caustic alkali it gives anthraflavone. P- Ethyl anthraquinone and ^-propyl anthraquinone were prepared by Scholl 1 from ethyl benzene, and propyl benzene, but are of no great interest. Of greater interest are the benzanthra- quinones (naphthanthraquinones) , and these are treated in a separate chapter.
Reduction Products. — Unlike true quinones, 9.10- anthraquinone and its derivatives are not reduced by sulphurous acid or the sulphites. 2 They are, however, readily reduced by other reducing agents, such as hydriodic acid, stannous chloride or tin and hydrochloric acid, zinc dust and caustic soda or ammonia, sodium hydrosulphite, etc., and a considerable variety of products can be obtained according to the conditions under which the reduction is carried out. In studying the reduction of anthraquinone derivatives it must be borne in mind that the partial reduc- tion of the cyclic carbonyl groups often has a great influence on the stability of groups attached to the nucleus, so that such groups are frequently split off. 3
Rosentiel 4 seems to have been the first to make use of hydriodic acid and phosphorus, but Liebermann ^ and his students made a much more thorough examination of the reaction. They found that when the reduction is carried out in open vessels the product formed depends on the concentration of the acid, on the temperature used, and on the time of heating, but that as a rule reduction cannot be taken beyond the dihydro-anthracene stage.' Bj' working
1 M. 32, 687.
2 In the abstracts published by the Chemical Society statements will sometimes be found, e.g. Soc. 94 (i), 786, that anthraquinone derivatives are reduced by sodium hydrogen sulphite. Reference to the original or to the Zentralblatt, however, will show that in these cases the abstractor has wrongly translated " hydrosuhit " as " hydrogen sulphite."
3 For example see pp. 179, 265. * C. r. 79. 764.
^ A. 212, 5. B. 9, 1202; 10, 607; 11, 1610; etc.
C6H4N
ANTHRAQUINONES—DIANTHRAQUINONYLS 8i
in sealed tubes, however, they were able to obtain more highly hydrogenated substances, i By carrying out the reduction with a more dilute acid, less fully reduced products are obtained, and it is possible to isolate the anthraquinol, anthrone and hydroxydihydroanthracene compounds : 2
OH H H H H
1 \/ \/
c c c
C6H4 -> C6H4<^^C6H4 -» CfiH^^^CeH^
C CO C
I /\
OH HO H
Anthraquinol. Anthrone. Hydroxydihydro-
anthracene.
Compounds of this last type are somewhat unstable, and very readily lose a molecule of water.
Liebermann 3 has more recently studied the mechanism of the reduction of anthraquinone compounds with h}- driodic acid, and has isolated several addition compounds containing iodine and hydriodic acid.
Much more interesting results have been obtained with other reducing agents. Thus Liebermann,* by reducing anthraquinone with tin and hydrochloric acid, obtained anthrone in good yield ; and more recenth' Kurt Meyer 5 has improved the method by using tin and hydrochloric acid in boiling glacial acetic acid. Zinc dust and ammonia or caustic soda has been emploj-ed by a very large number of investigators, 6 and if the reaction is carried sufficienth- far, almost invariably leads to the anthracene derivative, this being one of the most convenient methods of preparing anthracene derivatives from the corresponding anthra- quinone compounds, as there is no danger of the production of more highly hydrogenated derivatives. It is not applicable,
' See Chapter III.
- Liebermann and Pleus, B. 35, 2923. =» B. 37. 3341; 38. 1784. ' B. 20, 1854. » A. 397. 55.
» E.g. Elbs, J. pr. [2] 41, 6, i2i ; B. 20, 1365. Lampc, B. 42, 1414, etc. R. E. Schmidt, B. 37, 70.
6
82 ANTHRACENE AND ANTHRAQUINONE
however, to anthraquinone derivatives in which there is a methyl group in the a- position, as Elbs i has found that these on alkaHne reduction pass into hj-drocarbons in which one of the ms- carbon atoms seem to be affected. These are monomolecular and form picrates, and Elbs considers that they are probably formed by the loss of a molecule of water between the methyl group and the ws-hydrox}-l group of the anthranol, e.g.
OH CH,
Moderated reduction with zinc dust and an alkali leads first to the anthraquinol,^ and Perger 3 has found that further reduction leads to the wks-hydroxydihj'droanthracene, which b}' loss of water passes into the anthracene. The course of the reduction is, therefore, very similar to that pursued in the case of hydriodic acid.
Schulze 4 has repeated Perger's work, and finds that in addition to hydroxydihydroanthracene, anthrapinacone is also formed :
C6H4 OH OH C6H4
CH2<^\c C<(^CHo
which by loss of water passes into dianthr\'l :
Ct}H4 C6H4 CH^C— CACH
C6H4 C6H4
This Liebermann and Gimbel ^ managed. to obtain direct from anthraquinone by reduction with tin and hydrochloric acid ; and more recently Eckert and Hofmann ^ have repeated Liebermann's work and find that much better yields are
1 J. pr. [2] 41, <), 121 ; B. 20, 1365.
* Graebe and Liebermann, A. 160, 126. Liebermann, A. 212, 65. Romer and Schwazer, B. 15, 1040.
» J. pr. [2j 23. 127. * B. 18. 3034. * B. 20. 1854. « M. 36. 497.
ANTHRA Q UINONES—DIANTHKA Q UINON YLS 83
obtained if the reduction is carried out in the presence of a trace of a platinum salt.
Hans Me3'er,i by reducing anthraquinone with zinc and caustic soda under pressure at a high temperature, has obtained dianthrol, which by prolonged heating with hydrochloric acid passes into the ketonic isomer, dianthrone. caustic alkali causing the reverse change :
CoH, CgHt HCi CoH, H H e,M,
HO— Cf->C— Cf^C— OH NaOH 0=C< >C-C< )C=0
^1)^4 C6H4 C6H4 C6H4
Dianthrol. Dianthrone.
This latter on reduction in glacial acetic acid v\itli liu and hydrochloric acid gives tetrahydrodianthrol, which passes into dianthryl very readily by loss of water : 2
pj ^6^4 H H C6H4 -^j- CoH4 C0H4
HO c„H4 C,H4 OH ^^jj^ ^.^^^
From a commercial point of view alkaline sodium hydro- sulphite (Na2S204) is the most important reducing agent for anthraquinone derivatives, as it readily converts them into the soluble vats, these being readih- oxidised to the original substance on exposure to the air. The reaction has been examhied by Grandmougin,^ who has found that the reduction product is the anthraquinol :
OH
I C
C I
OH
As will be seen later, the anthraqiiinone vat dyes often
1 B. 42, 143. M. 30, 165.
* M. 36, 497.
> J. pr. [2] 76, 138; R.G.M.C. 12, 44.
84 ANTHRACENE AND ANTHRAQUINONE
CH,-
contain two or more anthraquinone groups, either or both of which may become reduced in the vat.
The alkaline reduction of anthraquinone derivatives is sometimes hindered by the presence of substituents in the a-position. The abnormal behaviour of anthraquinone derivatives in which there is a methyl group in the a- position has already been mentioned, and Seer i has shown that none of the following compounds will give " vats " :
CHs NHCHaCfiHg W CH,
I
CHc
I
-CH. CeHsCHoNH
CeHgCO.
\
CH2C6H5
I
/
N
C6H4[/>]CH3
C6H5CH2^
In the case of this last compound it is curious to notice that the dicarbox34ic acid obtained by oxidation :
COOH
can be reduced in alkaline solution.
The use of amalgamated zinc and hydrochloric acid has been advocated by Clemmensen,^ who claims that by this means both anthraquinone and alizarin can be reduced to dihydro- and hexahydro-anthracene.
The results obtained with other reducing agents will be foimd discussed in the chapter dealing with the anthrones and dianthr>d derivatives ; but mention may be made here of the fact that all hydroxyanthraquinones when distilled with zinc dust yield anthracene, a reaction which has
1 M. 31, 379; 33, 33, 546; 34, 579.
« B. 47, 684. Cf. By., D.R.P. 296,091 ; 301,452; 305,886.
A NTHRA Q UINONES—DIA NTHRA Q UINONYLS 85
proved of the utmost value in the study of naturally occurring anthraquinone compounds.
Action of Grignard's vSolution. — Anthraquinone reacts with either one or two molecules of magnesium alkyl halides, the products being alkyl hydroxy anthrone and dialkyl- dihydroxydihydroanthracene :
R OH |
R OH |
c |
C |
C6H4<^P>C6H4 CO |
CeH^^CcH^ C |
R OH |
With magnesium ar}-l haHdcs the reaction is similar, anthraquinone, for example, reacting with two molecules of phem'l magnesium bromide to form : 1
HO Ph
C
c
/\
HO Ph
In these compounds in which an ar^-l and a hydroxy- 1 group are attached to each ;;js-carbon atom, the hydroxyl groups are ver}- reactive and are readity replaced by chlorine by treatment with alcoholic hydrochloric acid, 2 and can be methylated by methyl alcohol and hydrochloric acid. The dichloro compounds thus formed are not ver}^ stable, and on treatment with potassium iodide readily spUt off their chlorine and pass into sym-diaryl anthracenes. By starting with a diar^'l anthrone and treating this with an ar>4 mag- nesium bromide, a compound containing three ar^'l groups
1 C. r. 138, 327, 1251 ; 139. 9; 150, 1290; Bl. [3] 33, 1104. Clarke, B 41, 935. Am. Soc. 33, 1966. * Loc. cit.
86 ANTHRACENE AND ANTHRAQUINONE
and a hydrox>'l group attached to the two ws-carbons is obtained,! e.g.
Ph Ph
C
c
/\
Ph OH
In these the hydrox}^! group is very easily etherilied by alcohol and h3'drochloric acid, but a fourth ar^d group cannot be attached to the 7»s-carbon atom unless this ar>'l group contains an amino group or a phenolic hydrox3'l group 2 (see p. 89).
By treating anthraquinone with a molecule of magnesium benzyl chloride, HaUer and Padova 3 obtained benzyl hydroxy anthrone, which under the influence of hydro- chloric acid readily lost a molecule of water and passed into benzylidene anthrone, the same compound being also obtained b}' condensing anthrone with benzaldehyde :
^O ^^sCeHg CHCeHg
C C CH2
C6H4<()CoH, Z^ CeH.^CeH, S^J^"^ CeH^^CgH, CO C CO
o
Benzylidene anthrone was also obtained by Levi * and by Bach ^ by benzylating alkaline solutions of anthraquinol with benzj'l bromide and subsequently treating the benzyl hydrox}^ anthrone with concentrated sulphuric acid, and their description of the substance is in close agreement with that given b}- Haller and Padova. Tschilikin,^ however, has recently prepared the substance by treating anthraquinol with dimethylphenj'lbenzyl ammonium chloride (leuco-
1 C. r. 139, 9- ' C. r. 140, 2S3, 343. =» C. r. 141. 857.
* B. 18, 2152. 5 B. 23. 1567. « B. 47, 1055.
A NTHRA Q UINONES-^DIA NTHRA Q UINON YLS 87
trope D) and gives the melting point as 117° in place of the 126-127° found by Ivcvi, Bach and Haller, and Padova. Tschilikin obtained benzylhydroxy anthrone simidtaneously. By treating anthraquinone with two molecules of magnesium methyl iodide, Guyot and Stahling 1 obtained a dimethyl dihydroxy derivative which, like its phenyl analogue, is very readily methylated by alcohol and hydro- chloric acid. Both the hydroxy compound and its methyl ether are decomposed by heat :
CPI;, OH CH3 OCH3
C C |
|
CH3 OH |
CH3 OCH3 |
^ |
1 |
CHo |
CH2 |
C |
C |
CoH,<^\c6H, |
|
C |
c |
CH3 OH |
CH3 0CH3 |
the reaction being exactly similar to that midergone by the benzyl derivative described on the previous page.
Similar compormds were obtained by treating phenyl methoxy anthrone with an alkyl magnesium iodide and then boiling the resulting substance with glacial acetic acid :
CaHg OCH3 CeHg OCH3
C C
CeH / XoH, -> C6h/\c6H4
c c
CH3 OH
CHo
* Bl. [3] 33, 1 144. Cf. Clarke, B. 41, 935; Am. Soc. 33, 1966 (corre- sponding ethyl compounds). ,
88 ANTHRACENE AND ANTHRAQUINONE
Haller and Guyot i have studied the action of Grignard's solutions on other anthrones. Starting with diphen^-l- anthrone they treated this with magnesium phenyl bromide, and obtained a triphenyl hydroxy' dihydroanthracene, which on reduction with zinc and acetic acid gave triphenyl dihydroanthracene :
Ph Ph Ph Ph Ph Ph
\/ \/ \/
C C . C
CeH^/ \C6H4 -^ CgH^/ >C6H4 -> CgH^/ \C6H4
CO c c
Ph OH Ph H
This latter compound they were also able to sjmthesise by treating the methyl ester of triphenylmethane-o-carboxylic acid with magnesium phen3-l bromide :
Ph Ph Ph Ph
Q \/ \y
C.OCH3 C— OCH3 c
C,-H,<^yCeH, -^ C6H4<^C6H5 -> C6H4<^C6H4
C C C
/\ /\ /\
Ph H Ph H Ph H
This latter synthesis closely resembles the synthesis of ?«s-diphenylanthracene by Simonis and Remmert.2 These investigators found that o-brombenzyl triphenyl carbinol loses hydrobromic acid ver^^ readily when treated with sulphuric acid and passes into 7>2S-diphenylanthracene :
H Ph Br Ph
\;/ I
c c-
C6H4<^/C6H5 -> C6H4<^|^CgH4
C C
/\ 1
Ph OH Ph
1 C, r. 139, 9. - B. 48, 20S. C/. C. r. 138. 1252 ; 140. 1461.
ANTHRA Q UINONES—DIA N THRA Q UINON YLS 89
and i.2-dimethoxy-wis-diphenylanthracene can be obtained in a very similar manner :
HO Ph H Ph
C C
(CH3O) oC6H2<(^C6H5 -> (CH3O) 2C6H2<^|)>C6H4
c c
^\ I
Ph OH Ph
As stated on p. 86, the h5'drox}'l group in triphenjd hydrox}- dihydroanthracene cannot be replaced by an ar>'l group, but these compounds react readily with compounds of the type ArX when Ar is an ar}d group and X an hydroxyl or primar}^ secondary or tertiary- amino- group. The con- densation is brought about by boiling in glacial acetic acid solution, 1 and leads to compounds of the type :
Ph Ph
C
C
Ph ArN(CH3)2
The diphenyl dihydrox}- dihydroanthracene which is obtained b}- the action of magnesium phen3-l bromide on anthraquinone will also condense with tertiar}^ amines. The products are compounds of the type :
Ph CeH^N^Ieo C
C
Ph C6H4NMe2 and exhibit geometrical isomerism. 2
' Haller and Guyot, C. r. 140, 283. ^ C. r. 140, 283, 343.
90 ANTHRACENE AND ANTHRAQUINONE
The dihj-droxy compound can also be converted into the dichlor- compound by means of alcohohc hydrochloric acid, and from this the chlorine is readil}- spht off by potassiimi iodide, the product being ws-diphenyl anthracene :
Ph OH |
Ph CI |
Ph |
\/ |
\/ |
1 |
C |
C |
C |
C6H4<^C6H, -> C6H4<0>C6H4^ |
- CeH,<|> |
|
C |
C |
C |
/\ |
y\ |
1 |
Ph OH |
Ph CI |
Ph |
C«H.
From this it will be seen that the use of Grignard's solu- tion forms a convenient means of synthesising both complex and simple derivatives of anthracene in which the meso- carbon atoms are involved. A considerable number of such compounds have been prepared by Haller and his co-workers, for details of which reference must be made to the literature. ^
The DlANTHRAQUmONYLS
The dianthraquinonyls are the anthraqmnone analogues of diphem-l and are not to be confused with the dianthra- quinones (p. ii6). There are three possible isomeric di- anthraquinonyls, viz. i.i'-dianthraquinonyl, 2.2'-dianthra- quinonyl, and i.2'-dianthraquinonyl, but neither this last-named substance nor any of its derivatives have been described :
i.i'-Dianthraquinonyl. 2.2'-Dianthraqumonyl.
The dianthraquinonyls can, of course, be built up from diphenyl by the phthalic acid s^-nthesis, and this method is discussed on p. 135. The results, however, are not satis- factory-, and the dianthraquinon3'ls are much more readily
1 Bl. [3] 25, 315; Bull. Soc. ind. Mulhaus, 72, 268.
A NTHRA Q UINONES—DIA NTHRA Q UIXON YLS 91
obtained by reactions which lead to the union of two anthra- quinone residues. In some cases the union of two anthra- quinone molecules can be effected by oxidation, and this is particularly the case when h3'drox3'l groups are present in the molecule. Thus er5-throhydrox5^ anthraquinone on fusion with caustic potash gives i.i'-diliydrox>"-2.2'-dianthra- quinonyl,! the structure being proved by its giving a fur- furane derivative by loss of water, and by its giving 2.2'- dianthr}d on distillation with zinc dust. 2 In the case of quinizarin, dianthraquinonyl formation takes place more readily, heatmg with aqueous sodium carbonate at 120°, sufficing to produce a tetrahydroxy dianthraquinonyl. 3 This also gives 2.2'-dianthryl on distillation with zinc dust, and as it passes into a furfurane derivative by loss of water it must be i.4.i'.4'-tetrah3-drox3--2.2'-dianthraquinonyl.* The oxidation of hydrox^-anthraquinones by hypochlorites usuaU}- leads either to halogenation or to complete rupture 'of the ring s^'Stem, but Scholl 5 has foimd that alizarin can be oxidised to i. 2.1'. 2 '-tetrahydrox3'-3. 3 '-dianthraquinonyl by treatment under suitable conditions with potassium hj'pochlorite and caustic potash. The proof of the structure of the product rests on its conversion into a furfurane deriva- tive by loss of water, and into 2.2'-dianthr>'l by distillation with zinc dust.
Dianthraquinonyls can be obtained from the anthra- quinone diazonium salts b}^ treatment with copper powder or with cuprous salts. Thus diazonium sulphates when warmed with cuprous chloride or bromide in aqueous solution or suspension pass very readil}' into the dianthra- quinonyl, provided that no very considerable quantity of halogen acid is present,^ and diazonium sulphates can also be converted into the dianthraquinomd by treating them with copper in the presence of acetic anhydride.'^
« By., D.R.P. 167.4G1.
2 Scholl, B. 52. 2254.
3 By., D.R.P. 146,223. * SchoU, B. 52, 2254.
5 B. 52, 1829; D.R.P. 274,784. « B.A.S.F., D.R.P, 215.006. ' SchoU, B. 40. 1696. B.A^.F., D.R.P. 184,495. Cf. Knoevenagel, B. 28, 2049
92 ANTHRACENE AND ANTHRAQUINONE
Although all the above methods of preparing dianthra- quinonyls have proved useful, the most general method consists in heating a halogen anthraquinone with copper powder, either alone or in the presence of some indifferent solvent such as nitrobenzene or naphthalene, i Both a- and ^- halogen compounds can be used, and although, as would be expected, the reaction takes place most rapidly in the case of the iodo- compounds, both chlor and brom com- pounds can be used, and in many cas^s give yields amounting to 70-80 per cent, of the theoretical. If the halogen atom is in the a- position and there is also an amino group in the ortho- position to it, dianthraquinonyl formation is accom- panied by the production of a flavanthrone, and in order to avoid this the amino group must be protected by the use of the benzylideue derivative. 2
The dianthraquinonyls themselves are of no great im- portance, their chief interest lying in their relation to the helianthrones (p. 333) and fiavanthrones (p. 301). They are readily nitrated, but the nitration products have not been studied in detail. 3 Methyl groups when present can be oxidised to carboxyl groups. *
The Anthradiquinones
Polyhydroxy anthraquinones in which two hj'droxyl groups are in the para- positions to one another, e.g. quini- zarin, readily yield anthradiquinones when oxidised. The oxidation can be brought about in concentrated sulphuric acid solution by means of various oxidising agents such as manganese dioxide, arsenic acid, lead dioxide, etc., but under these conditions simultaneous hydroxylation by oxida- tion is very apt to occur, & Lesser, ^ and Dimroth and
1 SchoU. B. 40. 1696; 43, 355, 1738; 44, 1086; 51. 452; M. 32. 687. Seer, M. 34, 631. Benesh. M. 32. 447. Eckert and Tomaschek, M. 39, 843. UUmann. B. 45. 689; 49. 740, 2161 ; A. 399. 332; D.R.P. 248,999. B.A.S.F., D.R.P. 180,157; 241,472.
2 SchoU, B. 51, 452. Ullmann, A. 399, 332. D.R.P. 248,999. => SchoU, B. 43, 355, 1738.
* SchoU, B. 40. 1696.
^ By., D.R.P. 66.153 ; 68.113; 68,114; 68,123; 69.842
« B. 47. 2526.
A NTHRA Q UINONES—DIA NTHRA Q UINON YLS 93
Schnitzel obtained 1.4.9.10-anthradiquinone by oxidising quinizarin with lead dioxide, the former investigator using benzene as a solvent, whereas the latter worked with glacial acetic acid solutions. It is a not very stable substance which melts at 211-213° when rapidly heated, the bath being preheated to 205°. When its aqueous suspensions are heated it undergoes decomposition with simultaneous oxidation and reduction, part being reduced to quinizarin at the expense of another part, which becomes oxidised to phthalic acid.
All the anthradiquinones are true quinones and, like 1.4-anthraquinone, show the usual quinone reactions. Thus, 1.4.9.10-anthradiquinone is rapidly reduced to quinizarin by sulphurous acid, it adds on a molecule of h5'drochloric acid to form 3-chlorquinizarin, and when warmed with concentrated sulphuric acid takes up a molecule of water and passes into purpurin. This last reaction is a somewhat important one, for, as will be seen later, the formation of many polyhydroxyanthraquinones is probably due to the addition of the elements of water to a diquinone.
When _^-diaminoanthraquinone or _/)-h3^droxyamino- anthraquinone is treated with sodium chlorate and hydro- chloric acid 2.3-dichlor-i.4.9.io-anthradiquinone is obtained, simultaneous chlorination and oxidation taking place, and diaminoanthrarufin under similar treatment yields tetra- chlor-i.4.5.8.9.io-anthratriquinone.2
The anthradiquinones when treated with phenols yield violet or blue mordant dyes, which are probably similar in nature to phenoquinone. Up to the present i. 2. 9.10- anthradiquiiione has not been isolated, but Dimroth and Schultze have obtained a straw-yellow solution b}" oxidising alizarin suspended in a mixture of equal volumes of glacial acetic acid and ether with lead dioxide. This solution exhibits all the properties of a true quinone, viz. it liberates iodine from potassium iodide, is at once reduced to alizarin by sulphurous acid, and gives chloralizarin when treated with hydrochloric acid. It undoubtedh' consists of a solution
1 A. 411, 345. ' M.L.B., D.R.P. 258,556.
94 ANTHRACENE AND ANTHRAQUINONE
of 1.2.9.10-anthradiquinone, but the quinone is so unstable that it was found impossible to isolate it.
Anthraflavones
If ^-meth}'! anthraquinone is fused with caustic potash, or better if it is heated with alcoholic caustic potash, a yellow vat dye is obtained. 1 This has come into fairly general use under the name Authraflavone G, and! was originally believed to have the structure :
although Scholl 2 showed that neither /3-ethylantliraquinone nor j8-propylanthraquinone gave an}' trace of an authra- flavone compound when treated with caustic potash. A compound of the structure shown above would pass on oxidation into a new complex containing a third quinonoid group, whereas Ullmann and Klingenberg 3 found that the oxidation product consisted onl}- of anthraquinone-j8-car- boxylic acid. Further, they pointed out that authraflavone adds on a molecule of bromine without au}^ evolution of hydrobromic acid, and that the dibromo- product thus obtained is quantitatively changed back to authraflavone b}' treatment with diethylaniline. These facts all point to authraflavone being really dianthraquinonyl eth3dene, and this is in agreement with the observation of Ullmann and Klingenberg, 4 that authraflavone is obtained when cu- dibrom-^-methyl anthraquinone is heated with dimethyl- aniline, or better with dieth3daniline.
The stilbene structure has been full}' confirmed by the work of other investigators. Thus, Hepp, Uhlenhuth and
1 B.A.S.F., D.R.P 179.893; 199,756. Bohn, B. 43, 1001. - M. 32, 690. ' B. 46, 712. * Loc. cit.
A NTH R A Q UINONES—DIA NTHRA Q UINON YLS 95
Romer 1 obtained anthraflavone by heating w-dibrommethyl anthraquinone with sodium iodide in acetone solution, or by treating it with copper powder; 2 and UUmann^ has employed this method for preparing dicliloranthraflavone from 2-chlor- 3-dibrommethyl anthraquhione.
Scholl ■* condensed phthalic acid with j3- methyl naphtha- lene, and from the 3-methyl-i.2-benzantliraquinonc thus obtained he got an anthraflavone which no doubt had the structure
CO
-CH=CH CO
although vScholl gave it c\ clic formula in conformity with the then belief that anthraflavone contained a seventh ring. Scholl's product was a vat dye, and gave reddish shades of yellow. A vat dye which gives orange shades is said to be obtained b}- adding bromine to a boiling solution of i-chlor- 4-niethyl anthraquinone in nitrobenzene. & The constitution of the dye is unknown, but it ma}- be a stilbene derivative.
1 B. 46. 709. M.L.B., D.K.P. 260,662 ; 267,546.
2 Cf. Eckert, iM. 35, 300. ^ B. 47, 560.
* M. 32. 997. * M.L.B., D.R.P. 259,881.
CHAPTER V
ANTHRONE, ANTHRANOL, AND ALLIED PRODUCTS
These are all reduction products of anthraquinone and several of them have been mentioned already. Many of them, however, are of considerable importance, and as they exhibit extremely interesting dynamic isomerism they will be discussed in some detail.
Anthrone and Anthranol
Anihrone itself was first obtained by Liebermann i by the moderated reduction of anthraquinone with h3^driodic acid or with tin and hydrochloric acid in glacial acetic acid solution. More recently the experimental details of this latter method have been improved by Kurt Meyer, 2 but as a rule the reduction is best carried out by means of copper or aluminium bronze ^ and concentrated sulphuric acid at 30-40°. This last process has been investigated b}^ Eckert and Pollak,4 who find that the first product formed is the anthraquinol (hj^droxy anthrone ?), the anthrone then being formed by further reduction.
Baeyer & obtained ms-phenyl anthrone by heating tri- phenylmethane-o-carbox34ic acid with dehydrating agents :
H Ph H Ph
COOH CO
1 A. 212, 5 ; B. 20, 1854. » A. 397. 55.
3 B.A.S.F., D.R.P. 190,656; By., D.R.P. 201,542. ^ M. 38, II ; 39. 839. ^ a. 202. 54.
96
ANTHRONE AND ANTHRANOL 97
and Bistrzycki and Ulffers 1 have prepared hj-droxy- anthrone and one or two other anthrone derivatives by this method, although the reaction is often compHcated by phthalide formation.
A somewhat similar synthesis of more complex anthrone derivatives has been worked out by Haller and Guyot.2 They condensed 4'-dimethylaminobenzophenone-i-carboxylic acid with dimethylaniline by boiling in acetic anhydride :
CO <?6M«NMe2
c
COOH ^ ^
0 CO
The phthalide thus formed they reduced to the corre- sponding triphenylmethane carbox}4ic acid, which, on boiling with phosphorus oxychloride in dimethylaniline solution, lost a molecule of water and passed into an anthrone derivative :
COOH " CO
The same investigators ^ obtained ws-diphenylanthrone by condensing phthalyl tetrachloride with benzene in the presence of aluminium chloride :
COCl CO
CCI3 C
Ph Ph
and also by condensing dichloranthrone or phenylchlor- anthrone with benzene
CO CO
C6H4<^CcH4 -> CfiH/VeH^
C c
/\ /\
CI Ph ^ Ph Ph
1 B. 31. 2799. ' Bl. [3] 25, 315. » C. r. 121. 102.
98 ANTHRACENE AND ANTHRAQUINONE
Baeyer i had previously obtained the same compound by heating phenyl hj'droxyanthrone with benzene and sulphuric acid although he did not describe it in detail.
Anthrone itself is a colourless crystalline compound which does not exhibit fluorescence, and which melts at I54°.2 It is insoluble in cold alkali, but dissolves on heating owing to its conversion into the enolic form (anthranol), and when boiled with acetic anhydride it form§ the acetyl derivative of this latter compound.
Anthrone is not readily attacked by mild oxidising agents in the cold, and is only attacked comparatively slowly on heating, the reaction being most rapid in those solvents which favour enolisation. Goldmann 3 has studied the action of chlorine and bromine on anthrone. He finds that bromine gives first a monobrom compound (m.p. 148- 151° decomp.), and then a dibrom compound (m.p. 157°). In both of these the halogen atoms must be imited to a m^so-carbon atom, as both give anthraquinone on oxidation. As was to be expected, chlorine reacts similarly, but much more vigorously, so that onl}^ the dichlor compound could be isolated. The same dichloranthrone (m.p. 132-134)° had previously been obtained by Thorner and Zincke * by treating o-methylbenzophenone with chlorine :
CO CO
,<^C,-H, -> C6H40C
CH, CCL
Nuclear chloranthrones have been obtained by Eckert and Tomaschek ^ by reducing chloranthraquinones with copper powder and concentrated sulphuric acid. Padova ^ has found that anthrone reacts with phosphorus penta- chloride, but the product he obtained was probably dianthryl, as it melted at 298-300" and contained no chlorine. The
1 A. 202. 65.
* Kurt Meyer, A. 397, 55. Liebermann, A. 212, 7, gives the melting point as 167-170*.
3 B. 20, 2436; 21, 1176. * B. 10. 1478.
5 M. 39, 839. 6 C. r. 149. 217.
ANT H RONE AND A NTH R A NO L 99
alk}'! chloranthrones are obtained by the action of phos- phorus pentachloride on the products obtained by alkylating hydroxy anthranol (anthraquinol),i and Liebermann and his students 2 have more recently found that the use of phosphorus pentachloride is superfluous, as the reaction is easily brought about by cold hydrochloric or hydrobromic acid. The halogen atoms in the halogen anthrones are extremel}' reactive, so that monobromanthrone is converted into hydroxy^anthrone by aqueous solvents, 3 and into methoxyanthrone by methyl alcohol.'^ Ammonia does not convert it into an amino compound, but into bromdianthrone, but arylamino anthrones are obtained b}- treatment with primary aromatic amines. ^ Copper powder converts it into dianthrone.6
Anthrone reacts normall}- with nitroso dimethyl aniline,*^ and Padova ^ has found that with benzaldehyde it gives phenj'lmethylene anthrone, and with benzophenone chloride ^ it yields diphenylmeth^-lene anthrone :
CHPh CPho
C C
C6H4\/C6H4 C6H4N. ^C(;H4
c c
• • « •
o o
It does not, however, react with aniline, dimethyl- aniline or with benzophenone itself. With benzo-trichloride, however, it gives phen3'ldichlormethyl anthrone, ^ which when heated with pyridine splits off a molecule of hydro- chloric acid and passes into phenylchlormethylene anthrone :
' A. 212. 67. B. 13, 1596; 15. 452, 455. 462. C. r. 121. 102.
"- B. 37, 3337.
3 A. 379, 45.
< A. 323. 23G ; 379, 45. Cf. also B. 38, 2868.
« A. 396, 133, 145.
« A. 396, 143.
' B. 40, 525. Cf. B. 32, 2341 ; 33. 959 : 34, iiS, 3047.
8 C. r. 141. 857. Cf. Weitz, A. 418, 29.
' C. r. 143, 121. In the abstract of this paper pubhshed by the Chemical Society (Soc. 90, (i) 741), " chlorure de benzophenone " is mistranslated as " chlorobenzophenone."
100 ANTHRACENE AND ANTHRAQUINONE
c *c
C C
• • • •
o o
Padova 1 also found that anthrone reacts with chloro- form in alcoholic solutions of caustic potash to form a com- pound :
CgH, C6H4
O =C<^^C =CH— C^C— OH
C6H4 C6H4
and Friedlander 2 and Kalle & Co.^ have obtained vat dyes by condensing it with isatine dichloride and dibromoxy- thionaphthene :
C6H4 NH C6H4 S
CO<(^)>C =C<(^)>C6H4 CO<'^C =C<f ^C6H4
C6H4 CO C6H4 CO
Meerwein * has studied the condensation of anthrone with unsaturated j3-diketonic compounds and finds that in the case of benzal malonic ester and benzal aceto acetic ester addition takes place verv^ readily :
/COCH3
COOEt
C6HgCHCH(COOEt)2 |
C6H5CHCH<^ |
CH C6H4\ /C6H4 CO |
CH C6H4^^C6H4 CO |
Attempts to hj^drolyse such compounds usually lead to the formation of anthrone, but in the case of the addition compound with benzalmalonic ester the hydrol3'sis could be effected by means of sulphuric acid in glacial acetic acid solution and lead to :
1 C. r. 140. 290. " B. 42, 1060.
3 D.R.P. 193.272. * J. pr. [2] 97, 284.
ANTHRONE AND ANTHRANOL loi
CeHgCHCH.COOH
1 CH
CO
Meerwein also found that anthrone forms an addition compound with benzalacetophenone.
The formation of benzanthrones from anthrones is an extremely important reaction, and is treated in detail in Chapter XVI.
Kurt Meyer i has found that dibromanthrone reacts easily with hydroxylamine and yields anthraquinone mon- oxime ; and Haller and Guyot 2 have shown that dichlor- anthrone condenses with dimeth34aniline in the presence of anhj'drous aluminium chloride to form a compoimd
Me2NC6H4 C6H4NMe2
C
CO Liebermann and Mamlock 3 found that bromanthrone reacts very readih" with resorcinol by simply boiling in benzene solution, no condensing agent being required. Under these conditions one would rather expect the hj'droxyl groups of the resorcinol to react with the production of a phenolic ether ; but as the product gives a triacetyl compound it must be regarded as a triphenyl methane derivative :
H C6H3(OH)2 C6H3(OH)2
c c
CeH^^CgH^ or C6H4<(|)>C6H4
C C
II I
O OH
As the compound apparently is not fluorescent the first
formula is the more probable. The triacetyl derivative,
1 A. 396. 152. = C. r. 136. 535. => B. 38. 1796.
102 ANTHR-iCEXE AXD AXTHRAOUIXOXE
which must conespand to the second formula, is ^; rough- flaorescent.
In phenylchloranthrone the reactivity of halogen atom is, as would be e^)ected, greater than it is ia the case of brom-anthrone. With resordnol condensation takes place in exactly the same way as vdth bromanthrone, but in the case of the simpler phenols, such as phenol and cresol. the reaction is different, the h\-drox\-l group reacting viixh the halogen atom and at the same time condensation taking place with the carbonyl group ; products of the stnictine :
Ph OR C
C
X\
RO OH being obtained.^
In the case of alcohols the hydrox\-l group reacts with the halogen atom, but simiiltaneous condensation with the carbonyl group does not take place, so that the products are alkoxyanthrones.
The structure of phenylchloranthrone is ver\- similar to that of triphem-lmethyl chloride, a compound which it resembles in many of its reactions. It is therefore not impossible that when treated with metals it might form a compound 'amilaT to triphenyl methyl. Liebermann 2 and his co-workers have found evidence that this is actually the case, and Sdblenk,* by boiling phenyl chloranthrone in petroleum ether solution with copper bronze, obtained a yeUow crystalline powder which, in the absence of air, gave a red solution in ether. The molecular weight was found to be 400, a figure which corresponds to about 33 1 per cent, of C20H13O and 66| per cent, of C40H26O2. vSchlenk has pointed out that if the bridge formiila for anthracene is correct wfs-di^henyl anthracene is really a derivative of the imknown hexaphenylethane :
1 B. 38, iSoo. * B. 37. 3337 i 38, 1799. * A. 394. 3340.
ANTHRONE AND ANTHRANOL 103
C6H4 CeHg CgHs
CeHs-Cf-^C-CeHs CeHg-C^l^C-CeHs
C0H4 CgHr, CgHs
Diphenylanthracene. Hexaphenyl ethane.
and consequently might readily form a compound containing two trivalent carbon atoms. He was unable, however, to bring about this change.
ms-Nitroanthrone is formed when anthracene is treated with nitric acid under certain conditions,! and also when anthrone is nitrated in glacial acetic acid solution. 2 On reduction it loses ammonia, anthrone and anthraquinol being formed respectively when the reduction is carried out in acid and alkaline solution. 3 The corresponding ms- amino anthrone has never been obtained pure, but by reducing phenyl-azo-anthranol Kurt Meyer * obtained an impure substance which lost ammonia very readily and formed anthraquinol. This was probabl}^ amino anthrone, but owing to its instability it could not be purified sufficiently for analysis.
The chlorine atoms in dichloranthrone are capable of reacting witli nuclear hydrogen atoms under the influence of aluminium chloride, and by this means Haller and Guyot ^ have prepared tetramethyl and tetraethyl diaminodipheu}! anthrone from dichloranthrone (anthraquinone dichloride) and dimethyl and diethyl aniline ;
CI CI MegNCsH^ CgHiNMeo
\/ \y
c c
C6H4<^^C6H4+2C6H5NMe2 -> C6H4<^C6H4 CO CO
In the case of aryl chlor anthranones the reactivity of the chlorine atom is very much greater, and by condensing phenyl chloranthrone with benzene m the presence of aluminium chloride diphenyl anthrone is produced, a compound
' Perkin, Soc, 59. 648 ; 61, 866. * Kurt Meyer, A. 396, 150.
' A. 396, 133. * Loc. cit. ^ C. r. 136, 535.
104 ANTHRACENE AND ANTHRAQUINONE
which had been previously obtained by them by con- densing phthalyl tetrachloride with benzene and aluminium chloride,! and by Bae5^er by condensing phenyl hydroxy anthranol with benzene in the presence of sulphuric acid : 2
Ph Ph CI Ph
CCI2 C C
C6H,<^^0+C6Ho -> C6H,<^CoH4 <- C6H6+C6H4<^C6H4 CCI2 CO * CO
t Ph OH
\/
C
CoH6+C6H4<(^C6H4
CO
Starting with this substance several interesting syntheses have been carried out.
Liebermann and Lindenbaum * found that it was ver^- readily reduced by zinc and acetic acid to the corresponding hydrocarbon, and that by treating this latter with bromine one, and onl}^ one, of the hydrogen atoms attached to the ;;is-carbon atom could be replaced :
Ph Ph Ph Ph
C |
C |
CeH.^CeH^ -> C,Jl^0C,il, |
|
C |
C |
/\ |
/\ |
H H |
H Br |
The bromine atom in this compound is very reactive and is readily replaced by hydroxyl and methoxy groups by treatment with water or alcohol. The most interesting reaction undergone by the compound is its behaviour when
1 c. r. 121, 102.
2 A. 202, 65. B. 38, 1799.
* Liebermann and Lindenbaum give it the formula CsjHjg and show- two extra hydrogen atoms. Such a compound would only be formed by loss of bromine and not by loss of bydrobromic acid, and the above formula is the more probable.
ANTHRONE AND ANTHRANOL 105
heated, as it melts at 214-216° with evolution of hydro- bromic acid and almost immediately solidifies, the same change being brought about by heating with neutral solvents of high boiling point, such as naphthalene. The resulting compound contains no bromine, and undoubtedly has the structure :
It is an extraordinarily stable substance which forms slightly yellow cr3'Stals which are practically insoluble in all media and which do not melt at 360°. It is hardly attacked by boiling concentrated sulphuric acid.
Anthranol and its derivatives are to be regarded as enolic tautomers of the corresponding anthrones (p. 118). They are much more sensitive to oxidation than to corre- sponding anthrones, and are usuall}' attacked by atmo- spheric oxygen. Anthranol itself on moderated oxidation passes into dianthrone, but the arylamino-anthranols pass into the corresponding anil : 1
OH
O
C«H.
C«H. -> C6H4<^C6H,
C NPh
NHPh
Goldmann 2 has studied the behaviour of anthranol when heated in alkaline solution with ethj^l iodide and has isolated three products. The first of these is anthranol ethyl ether (wzs-ethoxy anthracene). It reacts violently with bromine, but at —20° forms an mistable addition 1 A. 396. 147. * B. 21. 1 178. 2505.
io6 ANTHRACENE AND ANTHRAQUINONE
compound which evolves hydrobromiue acid at 0°, and passes into a more stable dibrom compound. This on oxidation 3delds, first, the monoeth}^ ether of B2:.-brom- anthraquinol and then bromanthraquinone. and hence must contain one bromine atom attached to the ws-carbon atom and one attached to one of the benzene rings.
The second compound isolated b}^ Goldmann is a ver}^ stable substance melting at 136°. It is unaffected b}^ bromine, boiling aqueous caustic «potash and alcoholic hydrochloric acid at 180°. It is very stable to both oxidising and reducing agents, but by boiling with chromic acid in glacial acetic acid solution it can be oxidised with difficulty to anthraquinone. When heated with hydriodic acid and phosphorus in a sealed tube it is reduced to tmsym-diethyl dihydroanthracene, and must, therefore, be diethylanthrone : Et Et Et Et
CO CH2
It is interesting to observe the diificult}- with which this reduction is effected in view of the fact that the correspond- ing diaryl compounds, e.g. diphenylanthrone, are very readily reduced to the i/HSj^m-diaryldihydroanthracenes by boiling with zinc and glacial acetic acid.i
The third compound isolated by Goldmann melted at 77°, and on moderated oxidation yielded C-ethyl hydroxy anthrone, a compound previously obtained by lyiebermann 2 by the ethylation of hydroxy anthrone. It must, therefore, be the ethyl ether of ethyl anthranol :
C2H5
./
C.H./ >C«H
.5J.X4
\
'6-^4
C
OC2H6 ^ B. 38. 1799. =« A. 212, 70.
ANTHRONE AND ANTHRANOL 107
Hallgarten 1 has carried out similar experiments with methyl iodide, »so-amylbromide and benzyl chloride, but has only been able to obtain the dialkylanthrones. These, like the diethyl compound, can only be reduced with difficulty.
Kurt Meyer 2 and his co-workers have carried out some very interestmg experiments on the action of diazonium salts on the anthranol ethers. They lind that, contrar^^ to the belief usually held, diazonium salts often couple quite readily with phenolic ethers and even with unsaturated aliphatic hj-drocarbons. The coupling is greatly facilitated by the presence of negative substituents such as nitro groups and halogen atoms, when in the ortho or para position to the diazo group, but is hindered by negative groups m the phenolic ether. Positive groups, especially alkoxy groups, in the phenolic ether greatly facilitate the coupling when m the meta position. In the case of the phenolic ethers derived from phenols and naphthols, dealkylation does not take place, the product being an alkox3^azo com- pound. When anthranol methyl ether is used, however, dealk3'lation does take place. Meyer suggests that the first stage of the reaction consists in the formation of an addition compound, which then passes into the azo com- pound either by loss of water, or, in the case of anthranol methyl ether, by the loss of a molecule of methyl alcohol :
MeO OH \/ C |
0 • • C |
C H N : NAr |
C6H4<^C6H4 c N . NHAr |
Methylanthranol methyl ether also couples with dizaonium salts, and it is probable that the mechanism of the reaction is somewhat similar :
^ B. 21, 2508.
* B. 47, 1741. e/. A. 898. 74; B. 52, 1468.
io8 ANTHRACENE AND ANTHRAQUINONE
CH3O OH Q
CgH^s
OCH3 I
c c
c c
I /\
CHo CHo N : NAr
^6^'i\ /CeH.i
CH3 N : NAr
Hydroxyanthrone and Anthraquinol
Hydroxyanthrone is to be considered as the tautomeric (ketonic) form of anthraqtdnol, although in this case the transformation of one isomer into the other is very slow, so that solutions only attain equilibrium after prolonged boiling (p. 121). Kurt Meyer 1 obtained hydrox3^anthrone by treating bromanthrone with water, and found it to be a colourless, non-fluorescent crystalline substance which melted at 167°. He obtained the acetate by treating bromanthrone with anhydrous potassium acetate and boiling glacial acetic acid, and also by oxidising anthracene in boiling glacial acetic acid solution with two and a half molecules of lead dioxide,2 or by treating it in aqueous suspension with chlorine or bromine below 25°. It is enolised b}^ hydro- chloric acid and by sodium acetate, and also dissolves in hot alkali owing to its conversion into the enolic form. The ketonic form is quite stable in the air, and is onl}'- attacked by mild oxidising agents when heated, oxidation being probably preceded by conversion into anthraquinol. On the other hand, it is readily reduced to anthranol by zinc and glacial acetic acid at the ordinary temperature.
The methyl ether (methoxy anthrone) is obtained by the action of methyl alcohol on bromanthrone 3 and is enolised by caustic soda.
lyiebermann ^ endeavoured to prepare alkoxy anthranols by heating alkaline solutions of anthraquinol with alkyl halides, but instead he obtained stable compounds which
1 A. 379, 63. » A. 397, 76. ^ a. 323. 236.
* A. 212, 67. B. 13, 1596 ; 15, 452, 455, 462.
A NTH RONE AND ANTHRANOL
109
must be regarded as C-alkyl hydroxy anthrones for the following reasons : —
(i) On reduction with hydriodic acid and phosphorus they are converted quantitatively into ms-alkyl dihydro anthracenes, which on oxidation with chromic acid first pass back into the original alkylhydroxy anthrone and then into anthraquinone. The composition of the alkyl diliydro- anthracenes is almost identical with that of the various hydroanthracenes, as will be seen from the following table, so that elementary' analysis is not sufficient to establish definitely that the products still contain the alkyl group : —
Ethyl dihydro anthracene.
Carbon Hydrogen
92-3 77
Butyl dihydro anthracene.
91-5
8-5
Amyl dihydro anthracene.
91 "2
8-8
Tetra hydro anthracene.
92-3 77
Hexa hydro anthracene.
913 87
Liebermann, however, carried out quantitative oxidations by chromic acid, and by weighing the amount of anthra- quinone formed, established beyond doubt that the sub- stances were not hydroanthracenes.
(2) On treatment with phosphorus pentachloride (one molecule) a vigorous reaction takes place and the hydroxyl group is replaced by a chlorine atom. A similar replace- ment is also brought about ver}' readily by cold hydro- chloric or hydrobromic acid.i
(3) Although the hydroxyl group cannot be acetylated in the ordinary way, Liebermann found that by treating the chloride with anhydrous sodium acetate he was able to obtain an acetyl compound, although he failed to obtain it in a state of purity. This difficulty of acetylation is in harmony with the fact that the C-phenyl hydroxy anthranol obtained by Baeyer 2 by oxidising ms-phenyl anthracene does not give an acetyl derivative.
(4) When reduced by zinc dust and ammonia, alkyl dihydroanthranols are formed which very readil}- split off water and pass into wzs-alkyl anthracenes :
1 B. 37, 3337-
A. 202, 5^.
no ANTHRACENE AND ANTHRAQUINONE
HO R
\/ C
HO R
c
R
1 C
H
c o
C6H4<J>C6H4
C
/\ H H
-H2O r^ TT
>C6H,
C I
H
The reaction here is exactly analogous to the reduction of anthraquinone to anthracene carried out by Perger.i It has received confirmation by Iviebermann,^ who alkylated Perger's hydroxy dihydro anthracene and obtained sub- stances which readily passed into ms-alkyl anthracenes by loss of water, and which on moderated oxidation yielded alkyl h^^droxy anthrones :
R
R OH
\/
C
C6H4< 1 >C6H4
c
/\
H H
o
C
I H
R OH
\/ C
C6H4<^C6H4
c
• •
O
The above reactions were all obtained with the ethyl, propyl, ^'so-butyl and iso-amyl compounds, but when alkaline solutions of hydroxy anthranol were heated with methyl iodide the reaction took a different course and a methyl compound was obtained which formed methyl iodide when heated with hydriodic acid, and which did not react with phosphorus pentachloride. Its melting point (187°) was also higher than the melting points of its homo-
1 J. pr. [2] 23. 137. * A. 212. G7. B. 13. 1596; 15, 452, 455. 462
A NTH RONE AND ANTHRANOL iii
logues. Obviously this is an 0-metliyl compound (methoxy
anthrone) :
H OMe
\/
C
CO
On one occasion, however, liebermann i obtained an isomeric substance which melted at 98°, and which behaved like a C-methyl compound, but he was unable to repeat his experiment.
It will be noticed that methoxy anthrone can be con- sidered as tautomeric with anthraquinol monomethyl ether :
H OMe OMe
\/ I
C C
C6H4<Q>C6H4 C6H.,<(^C6H4
CO c
I
OH
and this tautomerism is discussed on p. 121.
Kurt Meyer 2 has investigated the methylation and ethylation of anthraquinol by means of methyl and ethyl sulphate. With methyl sulphate he obtained a mono- methyl ether (m.p. 164°), and a dimethyl ether (m.p. 202°), and with ethyl sulphate a mono- and a di-eth)'l ether and also Iviebermann's C-ethyl hydroxy' anthrone.
The formation of C-alkyl compounds by the alkylation of hydroxy anthranol is ver>' similar to the formation of C-alkyl compounds from sodio-acetoacetic ester. In this latter case Saar has proposed that the transition from the enolic to the ketonic state and vice versa is so rapid that as soon as a molecule of one form enters into a reaction the equihbrium is restored by the rearrangement of a molecule of the other form. In the case of the hydroxy anthranols this theory is not applicable, as Kurt Meyer has shown that
1 B. 21. 1 175. * A. 379, 47.
112 ANTHRACENE AND ANTHRAQUINONE
the transition from the anthrone to the anthranol form and vice versa is slow. Claissen's theory that in the case of acetoacetic ester O-alkyl compound is first formed, and that this is at once rearranged into the C-alkyl compound, is hardly tenable in view of the fact that O-alkyl compounds of acetoacetic ester have been obtained and have been found to be stable substances, and the same objection of course applies to the monoalkyl ethers of anthraquinol. In the case of acetoacetic ester Michael has proposed that alkylation is preceded by addition, and in the case of the alkylation of anthraquinol this theory also furnishes the best explanation of the formation of C-alkyl compoimds :
ONa
CfiHZ^CaH
NaO R
\/ C
NaO R
.6x14
C
1 ONa
C6H4<' ^C6H4
c
/\
NaO Br
-> C6H4
6^4
o
The production of the 0-methyl compound is to be ascribed to the predominance of the " normal " reaction in this case :
0|Na IICH3
C I
ONa
OCH3
I C
CfiH
6^4
C
I
ONa
C6H4
The alkyl and aryl hydroxy anthrones can also be obtained by the action of Grignard's solutions on anthra- quinone, and this method of formation is discussed on p. 85.
The hydrox}'! group of the arj-l hydroxy anthrones is very reactive and, as is pomted out elsewhere (p. 85), is readily replaced by chlorine or bromine by treatment with halogen acid. The carbonyl group is also reactive and
A NTH RONE AND ANTHRANOL 113
Haller and Gu3''0t 1 have found that in some cases heating with concentrated sulphuric acid and an aromatic hydro- carbon such as benzene or toluene is sufficient to cause condensation to take place :
Me2NC6H4 OH Me2NC6H4 OH
C C
CO C
Ph OH
The anthraquinols are the enolic forms of the hydroxy anthrones and are of great importance, as they are readily soluble in dilute alkali and the alkaline solutions are very rapidly oxidised b}- the air or by weak solutions of h3^drogen peroxide with the formation of the corresponding anthra- quinone. The msoluble vat dyes are always applied to the fibre in the form of their anthraquinol derivative (" vat " or " leuco- compound "), the insoluble dyestuif being subse- quentl}^ precipitated on the fibre by exposure to the air or by after-treatment with a mild oxidising agent,
Anthraquinol itself was first prepared by Graebe and Liebermann - by the reduction of anthraquinone with zinc dust and caustic soda, and more recently Grandmougin ^ has shown that the reduction is better effected with sodium hydrosulphite in alkaline solution, the reducing agent alwa3^s used in vat d3-eing. Owing to the ease with which the anthraquinols are oxidised b3^ the air their isolation is a matter of some difficult3-, and for this reason Liebermann * introduced the method of carrying out the reduction with zinc dust in boiling glacial acetic acid solution in the presence of anhydrous sodium acetate. Under these conditions the anthraquinol is acetylated as soon as formed, and as the acet3'l derivatives are quite stable the3' can easih^ be purified. They can be hydrol3'sed b3- alkali, but owing to the sensitive- ness of the free h3^droxy compounds it is necessar3^ to work
1 C. r. 137. 606. » A. 160. 126.
' J. pr- [2] 76, 138; B. 39, 3963. * B. 21, 436, 1172.
8
114 ANTHRACENE AND ANTHRAQUINONE
in an inert atmosphere if pure products are to be obtained. The behaviour of the anthraquinols when alkylated with alkyl halides and with dimethyl and dieth}l sulphate has already been described (p. iii).
DlANTHRYL AND ITS DERIVATIVES
Dianthryl is the hydrocarbon formed b}- the imion of two anthracene residues by their ws-carbon atoms, and corre- sponds to anthracene in much the same way that diphenyl corresponds to benzene :
CgH^ C6H4
CH^C— C^CH
^6^4 C6H4
Theoretically five other dianthryls are possible which may be represented as A[9][i]A, A[9][2]A, A[i][i1A, A[i][2]A and A[2][2]A, where A indicates an anthry (C14H9) group, and the numbers indicate the carbon atoms at which junction is effected. These compounds do not seem to have been described as yet, although some of the corre- sponding quinones of the three last are well known. Di- anthryl was first obtained by Schulze 1 by the action of dehydrating agents on anthrapinacone :
C6H4 OH OH C6H4 C6H4 C6H4
CH,/Nc_C<^^CH., -^ CH^V— C^CH
C6H4 CgH^j C6H4 C^Hi
and Liebermann and Gimbel 2 soon afterwards found that it could be obtained direct from anthraquinone by reduction with tin and hydrochloric acid in glacial acetic acid solution. More recently Eckert and Hofmann ^ have improved the experimental details by carrying out the reduction with tin and hydrochloric acid in glacial acetic acid solution in the presence of a trace of a platinum salt, and claim to have obtained excellent yields.
1 B. 18. 3035- * B. 20, 1854. =» M. 36. 497-
ANTHRONE AND ANTHRANOL 115
Dianthryl is a colourless fluorescent compound which melts at 300°. When nitrated in acetic acid solution it gives a dinitro compound,^ and as this on oxidation gives anthraquinone, the nitro groups must be attached to the ;;K-carbon atoms. The dinitro compound is quite stable, and melts at 337° decomp. On reduction the dinitro com- pound gives the corresponding diamino- compound (m.p. 307-309° decomp.), which by gentle oxidation passes into the di-imide, the tautomerism of which is discussed on p. 124.
Dianthranol corresponds to dianthr^'l in the same way that anthranol corresponds to anthracene :
HOC^C— C^-^COH
C6H4 CgH^
It was first prepared by Hans Meyer - by the reduction of anthraquinone with zinc and caustic soda under pressure at a high temperatiure, and more recently Eckert and Hof- mann ^ have obtained it by the alkaline hydrolysis of the diacetate obtained by oxidising dianthryl with lead dioxide in glacial acetic acid solution :
Ce^i CuH4 CyH4 C,jH.i
CHf-^C— Cf-^CH ^ CHaCO.OC^^C— C;^^;CO.COCPL,
^6^4 C,5H4 C6H4 C6H4
^6^4 CeH4
It melts rather indefinitely at 230°, its diacetyl com- pound melting at 273° and its dimethyl ether at 245°, It is easily oxidised to anthraquinone by chromic acid, but mild oxidising agents, such as ferric chloride, alkaline potassium permanganate or iodine in potassium iodide convert it into dianthraquinone : *
1 B. 20.243^ - B. 42, 143; M. 30, 165; Kinzlberger c1- Co., D.R. p. 221,210. 3 M. 36, 497. * B. 42, 143.
ii6 ANTHRACENE AND ANTHRAQUINONE
CqH.4^ C6H4
O : C/Nc=c/Nc : O C6H4 CeH.,
It has been stated that ;;z^so-ethers of hydroxylated dianthranols are formed when mandeHc acid is heated with p3-rocatechol or hydroquinone at 200-300°, although in the case of resorcinol the product is dih^^droxydfphenyl methane carboxyHc acid.^ The course of the reaction is not clear, and the results claimed cannot be unreservedh' accepted without further confirmation.
Diant krone is the tautomeric form of dianthranol, just as anthrone is the ketonic form of anthranol, and the two isomers are interconvertible b}^ the action of acids and alkalis (see p. 124). It is obtained by the action of copper on bromanthrone,2 and Dimroth ^ has obtained it in quantitative jneld by the action of ferric chloride on anthranol, and in smaller 3'ield by the action of nitric acid on anthracene :
C6H4 jj C6H4 H H C6H4
2 O : C< >C< -> O : Ci >C— C< >C : O
C6H4 C6H4 C6H4
Padova '^ has also claimed that it is obtained in good 34eld when dianthranol is oxidised with phenanthraquinone.
Orndorff and Bliss ^ have described a compotmd which they obtained by the action of simlight on benzene solutions of anthranol, and by boiling benzene solutions of the same substance. This the}' regarded as a bimolecular polj-mer of anthranol, and named it dianthranol, but there is little doubt that their substance was reall}- dianthrone.
Dianthrone melts rather indefinitely at 245-255°, and is insoluble in cold alkali.
Dianthraquinone is readil}- obtained b}' the oxidation of dianthranol, Eckert and Hofmann ^ finding that it is produced by the sulphuric acid hydrol3-sis of dianthranol
1 H. von Licbig, J. pr. [2] 78, 93. ^ A. 379, 44.
3 B. 34, 210. Cf. Scholl, B. 44, 1075. ^ C. r. 149. 217.
» Am. 18, 453- * M. 36, 497.
A NTH RONE AND A NT H RANG L 117
diacetate, although more readih' obtained by oxidising dianthranol in alkahne solution with potassium persulphate or hydrogen peroxide, ^ or, according to Kinzlberger & Co., by potassium permanganate : 2
^6^4 C6H4 CqH^ C6H4
HOC Ac— C(^^COH -> O : C<^^C=C<^^C : O C6H4 C6H4 C6H4 C6H4
Padova ^ has stated that it is also obtained when di- anthranol is oxidised by amyl nitrite in pyridine solution ; but according to Meyer, Bondy and Eckert ^ the substance obtained by Padova was really only a mixture of anthra- quinone and unchanged dianthranol. Eckert and Toma- schek 3 have studied the chlordianthraquinones. These thej' obtained by oxidising the chlordianthranols with potassium persulphate, and found that they are oxidised by atmospheric ox\'gen under the influence of light to more highly condensed compounds, e.g. —
CO ci
CO CI
Kurt Meyer ^ endeavoured to prepare aminoanthrone b)' the action of ammonia on bromanthrone, but always obtained brom-dianthrone, which b}' treatment with copper powder or when heated alone lost hydrobromic acid and passed into dianthraquinone :
C6H4 Br H C6H4 C6H4 C6H4
O : C Ac— C<^^C : O -> O : C Ac : C Ac : O
^6^4 C6H4 C6H4 CgHi
1 M. 33. 1447. - D.R.P. 223,210.
=" C. r. 148, 290. ^ ' M. 33, 1447.
5 M. 39, 839. • A. 396, 133.
ii8 ANTHRACENE AND ANTHRAQUINONE
Tautomerism
Kurt Meyer ^ lias studied the question as to what extent anthranol and anthrone compoimds can be considered to be tautomeric :
OH O
I 11
C G
Q)H4<' yC6H4 ^ C6H4\ /CeHi
C C
H H H
Anthranol. Anthrone.
He points out that the formation of soluble alkali salts with hot caustic alkali and the formation of acetyl deriva- tives point to the enolic formula, whereas the insolubilit}' in cold alkali points to the ketonic formula. Also Padova 2 has prepared condensation products with aldeh3'des and ketones (see p. 99), and Kaufler and Suchannek ^ have found that anthranol will not react with phenyl isocyanate. These facts point to the ketonic (anthrone) formula, as does also the absence of, or very slight, fluorescence shown by the compounds.
Kurt Me^-er found that if an alkaline solution of Lieber- niann's anthranol is acidified below —5° with dilute sul- phuric acid an isomeric substance separates out, which crystallises in yellow needles which melt at 120° when suddenly heated, whereas the original substance is colourless and melts at 154°.* The new substance has a very strong fluorescence and is easily soluble in cold aqueous alkali. On keeping it slowly changes back to the original substance, the change being much more rapid when the substance is amorphous than when it is crj^stalline. It is readil}^ soluble in most media, giving 3^ellow solutions with a strong blue fluorescence, but these fairly rapidly lose their colour and
^ A. 379. 37-
2 C. r. 141, 857; 143, 121.
^ B. 40, 518.
* Liebermann (A. 212, 7) gives the melting point as 167-170°.
ANTHRONE AND ANTHRANOL 119
fluorescence, especially when boiled, and the colourless solutions on cooling deposit the original colourless sub- stance.
Kurt Meyer therefore concludes that the colourless form (m.p. 154°) is anthrone, and the yellow fluorescent form anthranol :
OH
CO
^6^4^ /C6H4 CgH.i
OHo C
>CcH4
H Anthrone. Anthranol.
In the solid state each of these can exist, but in solution a state of equilibrium is reached, the change from enolic to ketonic form being accelerated by the presence of a trace of hydrochloric acid. At the equilibrium point the ketonic state is always predominant in the case of the unsub- stituted substances, but depends to some extent on the solvent. It seems that glacial acetic acid favours the enolic form more than other solvents, whereas chloroform and acetone are especially active in favouring the ketonic form.
The enolic but not the ketonic form is readily oxidised by bromine to the non-fluorescent dianthrone, and as the velocity of the change from ketone to enole is low, it is possible to estimate the amount of enole present by titration with bromine solution. This Kurt Meyer 1 has done by using the disappearance of fluorescence to determine the end point, as this is ver}- easily seen when the solution is strongly illuminated by an iron-arc. He compared various derivatives and determined the per cent, of enole present at the equilibrium point in i per cent, alcoholic solution at the ordinary temperature.
Equihbrium is also set up on fusion, and if anthrone is
1 A. 396, 140.
120 ANTHRACENE AND ANTHRAQUINONE
melted and then suddenty cooled it is foimd to be partiaUy soluble in cold alkali.
Compound. |
Per cent enole. |
Anthrone |
. . II |
Nitroanthrone . . |
.. 3 |
Phenylanthrone |
. . 30 |
A nilidoanthrone |
. . 80 |
Hydroxy^anthrone |
f . 96 |
In pyridine solution all the above seemed to be completely enolised.
Kurt Meyer 1 has noted the following differences between the reactions of anthranol and anthrone : —
(i) Anthranol is readil}' attacked by mild oxidising agents such as ferric chloride, bromine, am^^l nitrite, etc., whereas anthrone is not attacked in the cold and only with difficult}- on heating. As anthrone is most readily oxidised in those solvents which favour the change to the enolic form, it is probable that oxidation onh^ takes place subsequent to enolisation. It is noticeable that the oxidation product is always the ketonic dianthrone and never the enolic dianthra- nol, this being the case even when the oxidation is carried out with potassium ferricyanide in alkaline solution.
(2) Anthranol couples with diazonium solutions to yield azo- dyes, whereas the anthrone does not. Kurt Meyer 2 has examined these with a view to determining whether they are enohc or ketonic, but has been unable to come to any definite conclusion. He obtained the same product by coupling phenyl diazonium chloride with anthranol as he obtained by condensing dibromanthrone with phenj-l hydrazine. He obtained two isomeric benzoyl derivatives, however, one of which must be ketonic, as he obtained it b}' condensing dibromanthrone with benzoyl phen^-l hydrazine. The other isomer he obtained by coupling diazotised anUine with anthranol, and then benzoylating the azo dye. This latter must be enohc, and by comparing the properties of the two benzoj'-l derivatives Meyer formed the opinion that the
» A. 379. 37.
« A. 396. I5-J.
ANTHRONE AND ANTHRANOL 121
parent azo- dye was probably enolic. Kauffler and Such- annek,! and more recently Cliarrier,^ on the other hand, prefer the ketonic (hydrazone) formula. 3
(3) Anthranol condenses with nitroso dimethyl aniline to form an anil, whereas anthrone does not.*
Kurt Meyer ^ has also examined the isomerism of anthra- qninol :
OH I O
c c
OH . H OH
Anthraquinol. Hydroxyanthrone.
which is obviously enolic, as it is soluble in cold aqueous alkali, is fluorescent and is ver^- readily oxidised. If its alkaline solutions are acidified at a low temperature it is not precipitated in the ketonic form, nor is it ketonised by boiling with alcoholic hydrochloric acid. Meyer was imable to convert it into h^-droxA-anthrone, but succeeded in preparing this latter substance by treatmg bromanthrone with water :
H Br H OH
C
C6H4\/C6H4 "> C6H4<^^C6H4
CO CO
He found it to be colourless, non-fluorescent and stable to atmospheric ox>'gen. Unlike anthraquinol it is only attacked by bromine on heating, and even then the reaction is slow, and it is readily reduced by zinc and acetic acid to anthranol, whereas anthraquinol is not. It is insoluble in cold alkali, but is enolised to anthraquinol by boiling alcohoUc alkali. The intercon version of the isomers in this case is much
1 B. 40, 518. 2 G. 45, 502.
' For absorption spectrum see Sircar, Soc. 109, 762.
* B. 40. 525- * A. 379, 44.
122 ANTHRACENE AND ANTHRAQUINONE
more difficult than in the case of anthrone and anthranol, so that solutions do not reach the equilibrium point imtil after being submitted to prolonged boiling, imless a catalyst such as h^'drochloric acid or sodium acetate is present. This difficulty of interconversion renders the behaviour of the substances when heated different. Thus anthranol when heated slowly shows no sharp melting point owing to its gradual conversion into anthrone, whereas anthraquinol melts sharply at i8o°, and hydroxy anthrone at 167°, and on further heating both decompose into anthrone, anthra- quinone and water, without apparently first imdergoing any interconversion. An exactly similar isomerism is exhibited by methox}- anthrone and anthraquinol mono- methyl ether. Here the ketonic form is obtained b}' the action of methyl alcohol on bromanthrone,i and is enolised by warm dilute alkali, the enolic form being obtained direct by the action of methj-l iodide or dimeth5'l sulphate on anthraquinol. 2 This on oxidation gives dimethox}"- dianthrone, which cannot form an enolic isomer as it has no labile hydrogen atom : ^tt
H OMe
C6H4C
/\c«H
6^ A
OH -^
Sr.
NaOH
OH
C I
OMe
C6H4 OMe OMe C6H4
^CO
« A. 323, 236.
oc<Q>c
C6H4 C6H4
« A. 376, 47.
ANTHRONE AND ANTHRANOL 123
Baeyer 1 obtained phenyl anthrone by heating tri- phenyl methane-o-carboxyhc acid with sulphuric acid. Ph H Ph H
COOH CO
This is obviously ketonic, as it is not fluorescent, is in- soluble in cold alkali, and is not oxidised by cold alcoholic bromine. 2 It dissolves in hot alkali, and if the solution is cooled to —5° and acidified with dilute sulphuric acid, the enolic form separates out. This is strongl}- fluorescent, soluble in cold alkaU, and is readih- oxidised by bromine, or by air when in alkalme solution. It is much less stable than anthranol itself, and on keeping rapidly reverts to the ketonic form.
Kurt jNIeyer ^ endeavoured to prepare amino anthrone, but was unable to obtain it in a pure state. However, he was able to prepare ar3'lamino anthrones by treating brom- anthrone with primary- aromatic amines and found that they exhibit the same keto-enole tautomerism. As was to be expected, the ketonic form is non-fluorescent, and is not sensitive to bromine, whereas the enolic form, obtained from the ketonic form by boiling with a catalyst, such as hydro- chloric acid or sodium acetate, is fluorescent and sensitive to bromme. In most solvents the enolic form predominates, but in glacial acetic acid it is the ketonic form which is predominant. On oxidation the enolic form \ields the anil, and it is curious to note that whereas the monoanil is deep red, the dianil is only yellow :
0 |
NPh |
|||
c CgH4<0>CcH, c |
C C6H4<Q>CoH4 C |
|||
NPh Deep red. » A. 202, 54. |
* A. |
396, |
133 |
NPh YeUow. * Loc. ciU |
124 ANTHRACENE AND ANTHRAQUINONE
Dianthrauol and dianthrone exhibit the same form of isomerism as anthranol and anthranone. Thus, Hans Meyer i prepared dianthranol by reducing anthraquinone with zinc and caustic soda imder pressure, and foimd that it was ketonised by prolonged boiling with alcohohc h^'dro- chloric acid, the reverse change being brought about by caustic potash :
CgH^ C6H4 HCl CgH^ rt H C6H4
HOC^C— C^COH KOH O : C<^^C— C^^C : O CsH^ C6H4 C6H4 CeH^
and Ktut Meyer 2 has found that ms-anthramine when oxidised by amyl nitrite,^ or by other oxidising agents such as bromine, gives an imide (m.p. 205°), which is partially isomerised on melting or when boiled with sodium acetate or aqueous caustic potash, and is completely isomerised by alcoholic potash :
C6H4 H H C6H4 C6H4 C6H4
HX : C^^C— C<(^C : NH -> H^N.C^C— C^C.NHa C6H4 C6H4 C6H4 C6H4
This latter compoimd melts rather indefinitely at 324- 334°, and was obtained by Gimbel 3 by nitrating and reducing dianthr>-l. So far the reverse change has not been brought about.
1 B. 42, 143. 2 B. 46, 29. ^ B. 20, 2433.
CHAPTER VI ANTHRAQUINONE RING SYNTHESES
The synthetic methods which have been employed for the production of anthracene derivatives, and the oxidation of these to the corresponding anthraquinones, are described elsewhere, 1 and in this chapter only those methods will be treated by which an anthraquinone is formed without the previous production of an anthracene derivative. Some of the methods to be described have proved to be of the greatest assistance in the study of the more complex anthraquinone vat dyes ; but special methods of building up these complexes will only be mentioned very shortly, as they are more con- veniently treated in detail when dealing with the special classes of compounds involved.
I. P'rom Aromatic Monocarboxywc Acids
When aromatic monocarbox>-lic acids are heated with dehydrating agents, such as phosphorus pentoxide or an- hydrous zinc chloride, loss of two molecules of water between two molecules of the acid often takes place with the pro- duction of an anthraquinone derivative :
COOH <^°
HOO
CO
The production of anthraquinone itself by this method was achieved by Behr and van Dorp 2 by heating benzoic acid with phosphorus pentoxide, but the yieldsare exceedingly
1 Chapter II. » B. 7. 16, 578.
125
126 ANTHRACENE AND ANTHRAQUINONE
poor. The reaction takes place much more readily if a hydroxy benzoic acid is used in place of benzoic acid, and in some cases quite satisfactory yields are obtained by heating the hydroxy acid with concentrated sulphuric acid. Thus vSchunck and Romeri foimd that when m-hydroxy- benzoic acid is heated with concentrated sulphuric acid a mixture of various dihydroxy anthraquinones is formed in 42 per cent, yield. Of the isomers fornled anthraflavic acid is the most plentiful (82 per cent.), the remainder con- sisting chiefly of anthrarufin and a little 1.7-dihydroxy anthraquinone. They contradict Rosentiel's statement 2 that iso- anthraflavic acid is also formed. Other hydroxy benzoic acids behave in a similar way to w-hydroxy benzoic acid, e.g. 2-methyl-3-hydroxy-i-benzoic acid gives 1.5- dimethyl dnthraflavic acid,^ and gallic acid gives rufigallol.*
The above method can be extended by heating a molecular mixture of two different aromatic monocarboxylic acids with a dehydrating agent, although, as would be expected, this procedure often results in a complex mixture of various anthraquinone derivatives. As examples of this method may be mentioned the production of dimethyl anthragallol by Birukoff,5 by heating a mixture of benzoic acid and gallic acid with concentrated sulphuric acid, of trimeth3'l anthragallol by Wende 6 from durylic acid and gallic acid, and of anthragallol itself from benzoic acid and gallic acid.'^ The yields, however, are very poor ; Birukoff, for example, obtaining only a yield of two per cent. When, however, gallic acid is condensed with a hydroxy benzoic acid better results are obtained, e.g. gallic acid when condensed with 2-methyl-3-h3^droxy-i -benzoic acid and with 2-methyl-5- Itydroxy-i-benzoic acid gives respectively 5-meth3d-i. 2.3.6- tetrahydroxy anthraquinone and 5-methyl-i.2.3.8-tetra- hydroxy anthraquinone. ^
There would seem to be some possibility that the above
1 B. 10, 1225 ; 11, 969. 1225. 2 B 10, 1033. 3 K., D.R.P. 87,620. * Robiquet, A. 19, 204 (18^6). Schiff, A. 163. 218. 6 B. 20, 870. « B. 20, 867.
' Seuberlich, B. 10, 38. Auerbach, Ztg. 1882, 910. 8 K., D.R.P. 87,620.
ANTHRAQUINONE RING SYNTHESES 127
method of forming the anthraqiiinone ring could be carried out by a catal5'tic method, e.g. by passing the vapour of the aromatic monocarboxyhc acid over a suitable catalyst, such as precipitated silica or aluminium or calcium phosphate, although no such method has been recorded.
II. From Phthalic Acid by the Direct Method
It is usually best to build up anthraquinone derivatives from phthalic acid in two steps, by first forming the phthaloyl derivative (o-benzo}-l benzoic acid), and then subsequently closing the anthraquinone ring by treatment with a de- hydrating agent. This method is treated in detail in the next section mider the heading " Phthalic Acid Synthesis," and in the present section onl}- those methods will be men- tioned by which an anthraquinone derivative can be obtained from phthalic acid in one step. The method is confined to the production of Itydroxyanthraquinones.
In some cases phthalic acid will condense with a phenol to form a hj-drox^^ anthraquinone simply under the in- fluence of heat, no dehydrating agent or catalj^st being used. Thus, Baeyer and Drewson ^ obtained 4-methylerythro- hydroxy anthraquinone by heating phthalic anhydride with ^-cresol for two days at 160-200°, and more recently Ull- mami 2 has found that when phthalic anhydride is heated with /)-clilorphenol a mixture of 4-chlorer3'throh3-droxy anthraquinone and of o-hydroxychlorbenzojd benzoic acid is obtained. As a rule, however, the condensation only takes place in the presence of a condensing agent such as sulphiuric acid, although, as will be seen, boric acid or alu- minium chloride are often effective.
When sul])huric acid is used as a condensing agent phthalein formation takes place simultaneous!}', so that the yields obtamed are often extremely poor. Baeyer and Caro, and Liebermann and his students have studied the condensation of phthaHc anhydride with various phenols in the presence of concentrated sulphuric acid, and have
1 A. 212, 345. * D.R.P. 282,493.
128 ANTHRACENE AND ANTHRAQUINONE
obtained various li3'droxy authraquinones, such as erythro- hj-droxyantliraquinoue mixed with a little /3-hydroxyanthra- quinone from phenol itself, i alizarin and hystazarin from P3-rocatechol,2 and quinizarin from hydroquinone.3 The yields, however, never exceeded 5 per cent, of the theoreti- cally possible, and Birukoff * states that the condensation of phthahc anhydride with _/)-cresol gives a jdeld of only i J per cent, of 4-meth3derythrohydrox}'anthraqui»one. It should be noted that during the condensation of phthalic anhydride with ^-chlorphenol simultaneous replacement of the chlorine atom by hydroxjd takes place, the product being quinizarin. In this case the yield obtained is nearly 10 per cent, of that theoretically possible, and prior to the discovery of the direct oxidation of anthraquinone to quinizarin this was the best method of preparing the substance. ^
The condensation of phthalic anhydride with phenols under the influence of concentrated stdphuric acid has been extended to the preparation of 3-methyl quinizarin from phthalic anhydride and meth3'lh3'droquinone by Nietzki,^ and to the preparation of various heteronuclear methyl- dihydroxy authraquinones from s-meth^'l phthalic acid and pyrocatechol and h^-droquinone b>- Niementowski,' but the yields are imsatisfactory.
By using chlorphthalic acid in place of phthalic acid, heteronuclear chlorh}- droxy authraquinones can be obtained, and it has been claimed ^ that hydroquinone condenses readily- under the influence of concentrated sulphuric acid with chlorinated phthahc acids, in which not more than one chlorine atom is in the otiho- position to a h\'drox3'l group. The reaction is described as taking place readily with 3- chlorphthalic acid, and particularly readily in the case of 4.5-dichlorphthalic acid, but as failing completeh- in the case of 3.6-dichlorphthalic acid and tetrachlorf^hthalic acid.
1 Baeyer and Caro. B. 7, 972 ; 8, 152.
2 Baeyer and Caro, B. 7, 972 ; 8, 152. Schoeller, B 21, 2503. ^ Grimm, B. 6, 972; Baeyer and Caro, B. 7. 972.
* B. 20, 2068.
5 Liebermann, B. 10, 608 ; A. 212, 10.
« B. 10. 2011. ' B. 33, 1631.
8 M.L.B., D.R.P. 172,105.
\ \.
ANTHRAQUINONE RING SYNTHESES i2Q
Crossley i has investigated the condensation of 4-amino- phthalic acid with hydroquinone in the presence of sulphuric acid at 170-100°, and finds that the main product is 1.4.6- trihydrox^-anthraquinone, although some 6-aminoquini- zarin is also formed. Here apparently the amino group is replaced by hydroxyl, but the results must be accepted with some reserve, as Crossley states that his 1.4.6-trihydroxy compound did not melt at 300°, whereas Dimroth and Fick 2 give its melting point as 256°.
In some cases the yield of hydrox^^anthraquinone is greatly improved by carr^'ing out the condensation with concentrated sulphuric acid in the presence of boric acid, and by this means it has been claimed ^ that quinizarin can be obtained in 75 per cent, yield from phthalic anhydride and either hydroquinone or ^-chlorphenol. In this case the improved yield is no doubt due to the formation of a boric ester hindering phthalein formation, but there is no informa- tion available to say whether boric acid has a similar bene- ficial influence on the condensation of phthalic anhydride with other phenols.
Boric acid alone at about 210° can also bring about the condensation between a phthalic acid and a phenol. Thus, Dimroth and Fick * obtained i.2.4.6-tetrahydrox}'anthra- quinone by heating 4-hydrox3'phthalic acid with hydroxy- quinol triacetate and boric acid in benzoic acid solution. In the same way they obtained i.4.6-trihydrox\benzoic acid from hydroxj'phthalic acid and quinol, and i-methyl- 3.5.8-trihydrox\'anthraquinone from coccinic acid and quinol diacetate.
As will be seen later, anhydrous aluminium chloride is almost invariably used in the synthesis of anthraquinone derivatives by the indirect method. In some cases, however, it leads to the anthraquinone compound in one step, and it has recently been found that hydroxyanthraquinones can be obtained by heating phthalic anhydride with phenols, naphthols, anthrols or hydroxy anthranols at 180-250° in
1 Am. Soc. 40, 404. * A. 411, 330.
' By., D.K.P. 255,031. « A. 411, 325.
P
128 A^'
o^ ; y. AKTHkACL
liL k'Knusjc Ac:
rl
Tlw ' 'jtiy unportast nKtbod of
f{ntnfjnt ^tnvathn* cooasts m ficst rkrivattve {o-btnzoyl benzoic aidd) by coadensiq^ afi^ :« whbanarcmiat]ccooq>oiiiid.iBaaIK-intbeTieacoce
of aniiydroitt a! im cblonde, and then ckuqg the
anthraquim^c: ring oy treatment with a delr\*dratin. ageul, Aucb aA concent rated sulpbuhc acid :
CO CO
^ C^4<^6H:
COOH
c^n/^o-fCeH,
CO
•o
As tlic method is of very general application, au as the yields are often almost theoretical, it has met \\:h vei} extended use, and many investigations have beei carried out with a view to determining the optimum condiuns.
The lirst step of the process, viz. the formatioi of the ketonic acid, is brought about by anhydrous alniinium (hloiide. and usually starts at or about the ordinry tem- lierature, although as a rule is only completed by heting on the NViiter l);ith for 6-12 hours, viz. mitil the evoition of li\ (Iroehloric acid gas ceases. In carrsing out the taction it is absolutely es.sential to use a whole (double) m(t.cule of aluiuiiiiuin chloride, as although the action of the cloride is catalytic, it cond)ines with the ketonic acid to form n addi- tion compound, and is thus rendered inoperative. 2 lence, if less than a molecular proportion is used the yields otained are proportionally snuiU. As a ride, the best solvers to use during the condensation are carbon bisulphide or ligt petro- leum, but in some cases the use of a different solvat give*^- more Siitisfactory results. These will be discussed wen di 1 iug with the various classes of substance which hv^e if j
» r.y.. I'.K.IV i98.J45. * HeUer and Schulke, B 41;.6«7
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130 ANTHRACENE AND ANTHRAQUINONE
the presence of auhydrous aluminium chloride, i The reaction is best carried out by using a great excess of phthalic anhydride as a solvent. By this meaas hystazarin is ob- tained from pyrocatechol, no alizarin being formed.
III. Phthalic Acid Synthesis
This extremely important method of building up anthra- quinone derivatives consists in first forming a phthaloyl derivative (o-benzoyl benzoic acid) by condensing phthalic anhydride with an aromatic compound, usually in the presence of anhydrous aluminium chloride, and then closing the anthraquinone ring by treatment with a dehydrating agent, such as concentrated sulphuric acid :
CO CO CO
C6H4<(^0+C6H6 -^ Ceil,(^C,li, -> C6H4<^C6H,
CO COOH CO
As the method is of very general application, and as the yields are often almost theoretical, it has met with vei}' extended use, and many investigations have been carried out with a view to determining the optimum conditions.
The first step of the process, viz, the formation of the ketonic acid, is brought about by anhydrous aluminium chloride, and usually starts at or about the ordinary tem- peratmre, although as a rule is only completed by heating on the water bath for 6-12 hours, viz. imtil the evolution of hydrochloric acid gas ceases. In carrj^irig out the reaction it is absolutely essential to use a whole (double) molecule of aluminium chloride, as although the action of the chloride is catalytic, it combines with the ketonic acid to form an addi- tion compound, and is thus rendered inoperative. 2 Hence, if less than a molecular proportion is used the yields obtained are proportionally small. As a rule, the best solvents to use during the condensation are carbon bisulphide or light petro- leum, but in some cases the use of a different solvent give«- more satisfactory results. These will be discussed when d ing with the various classes of substance which have b 1 By., D.R.P. 298,345. * Heller and Schiilke, B. 41, 3627
ANTHRAQUINONE RING SYNTHESES 131 ^33
found to undergo the condensation. As a rule, the best pro- \
cedure is to add i part of powdered ahiminium chloride to (j
i|-2 parts of solvent, and then to add all at once an equimo- *'
lecular mixture of finely powdered phthalic anhydride with the substance with which it is to be condensed. The reaction sets in either at the ordinar^^ temperature or on gently warm- ing and is completed by boiling under a reflux condenser mitil no more hydrochloric acid is evolved. Water is then added to destroy the aluminium chloride, and the solvent removed by distillation with steam. It is not generally necessary to purify the ketonic acid before converting it into the anthraquhione derivative, but if desired to do so it will often be found that the most satisfactory results are obtained by cr^'Stallising the ammonium salt.
In carr^'ing out the above condensation it must be remembered that the aluminium chloride may bring about side reactions. Thus, if alkoxy groups are present in the molecule, partial or complete dealkylation will almost certainly be brought about, and if methyl groups are present intramolecular or intermolecular wandering of these may take place. The same remark also applies to some extent to halogen atoms, so that conclusions as to the orientation of groups in the finished product can only be drawn with great caution and, as far as possible, should be confirmed by independent methods. As the ketonic acids are stable substances it is often possible to introduce new groups into :he molecule before closing the anthraquinone ring.
For closing the anthraquhione ring concentrated sulphuric
cid (six to ten parts) is usualh' employed, but the ease with
hich water is lost varies ver\' much with the individual
mpounds. Thus, naphtho^-l benzoic acid loses water at
5-50°, whereas benzoyl benzoic acid requires a temperature
( about 120°, and in other cases the reaction only takes place
"v temperatures of 150° or above. W^hen this is the case
ilphonation frequently takes place simultaneously. If the
^tonic acid becomes sulphonated it is usualh^ impossible to
se the ring at all, whereas if ring formation precedes
)honation the finished product is a sulphonic acid.
\
^
132 ANTHRACENE AND ANTHRAQUINONE
When trouble is experienced through sulphonation taking place it will often be found advantageous to use oleum con- taining from 10 to 30 per cent, of free anhydride in place of concentrated sulphuric acid, as if this is done it is usually possible to work at a much lower temperature, and by selecting suitable conditions it will often Ije found possible to close the ring without appreciable sulphonation taking place. 1 In any case the addition of boric acid is frequently advantageous, and the same remark applies when ordinary concentrated sulphuric acid is being used.
In addition to the danger of sulphonation taking place, the use of sulphuric acid has the drawback that it often demethylates methoxy groups when these are present, even when they have escaped the hydrolytic action of the aluminium chloride, and also in some cases brings about simultaneous oxidation. Thus,- Gresly 2 condensed phthalic anhydride with pseudo-cuniene and obtained a trimethj'l benzoyl benzoic acid which, when heated with oleum, gave dimeth3^1- anthraquinone carboxylic acid and not the trimethylanthra- quinone as expected.
In order to avoid such side reactions phosphorus pent- oxide can be used in place of sulphuric acid,^ and Elbs * hcs used phosphorus pentoxide in conjunction with sulphuric acid. In this latter case it is difficult to see what advantage phosphorus pentoxide and sulphuric acid can have over oleum, unless phosphoric acid has a beneficial action re sembling that of boric acid.
Another method of closing the ring which has of^n proved of value in obstinate cases consists in reducing he ketonic group and thus obtaining the diphenyl methue derivative. The ring can then often be closed by meanpof sulphuric acid or oleum, zinc chloride or sodamide, and he
1 Bentley, Gardner and Weizmann, Soc. 91, 1630. Bentley and V>iz. mann, Soc. 93, 435. Harrop, Norris and Weizmann, Soc. 95, 12 12. Wgch and Weizmann, Soc. 97, 687. Bentley and Weizmann, Soc. 105, 748. HeUer and Schiilke, B. 41. 3627. Mettler, B. 45, 800. Gresly, A. 234 • i.
* A. 234, 238. Cf. also UUmann, A. 388, 217. er ' Behr and van Dorp, B. 7, 578. Bentley and Weizmann, Soc. ' lor,
M.L.B., D.R.P. 194,32s. -'
* J- pr- [2] 41, 122.
(
ANTHRAQUINONE RING SYNTHESES 133
lesulting antlirone then oxidised to the anthraquinone. This method has often proved useful in the S3'nthesis of the more complex anthraquinone derivatives, and is also often of service when it is desired to introduce a new group before closing the ring.i
H0MO1.OGOUS Anthraouinones. — The phthalic acid syn- thesis originated in an observation by Friedel and Crafts, 2 that small quantities of anthraquinone were present in the products formed by the action of anhydrous aluminium cliloride on phthalic anhydride in benzene solution, and at a later date 3 they extended their investigations to the products formed from toluene and xylene, and at the same time pointed out that acetic anhydride behaves in much the same way as phthalic anhydride, acetic anh^'dride and benzene giving acetophenone when treated with aluminium chloride. Previous to this Biircker * had showTi that succinic anhydride will condense with benzene in the presence of aluminium chloride to give /3-benzoyl propionic acid.
The preparation of anthraquinone ^ itself from benzene and phthalic anhydride has been investigated in great detail, as at one time it was proposed to manufacture anthraquinone by this process, although the scheme was abandoned on account of the cost of the aluminium chloride. 6 The yields, however, are excellent, about 97 per cent, of the theoretically possible, and there is no difhculty in closing the anthra- quinone ring by heating the benzoyl benzoic acid Avith ordinary- concentrated sulphuric acid at 125-150°. If oleum is used instead of concentrated sulphuric acid, simultaneous sulphonation takes place with production of anthraquinone- /3-sulphonic acid.' The condensation of the phthalic
^ Gresly, A. 235, 238. Bistrzycki and Schepper, B. 31, 2793. Scholl, B. 44, 1075. M. 32. 687. Limpricht, A. 309, 121. Weitz, A. 418. 29. Seer, M. 33, 540.
« Bl. 41, 323.
» A. ch. [6] 14, 446.
* A. ch. [5] 26, 435.
0 Friedel and Crafts, A. ch. [6] 14, 446. Pechmann, B. 13, 1612. Haller and Guyot, C. r. 119, 139. Gresly, A. 234, 238. Graebe and Ull- mann, A. 291, 9. Elbs, J. pr. [2] 41, x. Heller, Z. ang. 19, 669. Heller and Schulke, B. 41, 3627. Rubidge and Qua. Am. Soc. 36, 732.
8 HeUer, Z. ang. 19, 669.
' Liebermann, B. 7, 805.
134 ANTHRACENE AND ANTHRAQUINONE
anhydride with benzene is most conveniently effected by using a large excess of the hydrocarbon as a solvent, and the same is true when meth}^ anthraquinones are being prepared from toluene or the xylenes.
From toluene i the main product obtained is )S-methyl- anthraqiiinone, from o-xylene 2 2.3-dimethyknthraquinone, from m-xylene 3 i.3-dimeth3'lanthraquinone and from p- xylene ^ 1.4-dimethylanthraquinone. Pseudo-cumene gives i.2.3-trimethylanthraquinone,5 although, as has alread}'' been pointed out, the final closing of the ring b^^ means of sulphuric acid is apt to be accompanied by simultaneous oxidation of one methyl group to carbox>d. Scholl ^ has prepared ethyl, propyl and ^so-prop^d anthraquinone from phthalic anhydride and ethyl, propjd, and iso-propyl benzene. Condensation between phthalic anhydride and naphthalene ' takes place with great ease, and the resulting naphtho}^ benzoic acid loses water very readily when warmed to 45-50° with concentrated stdphuric acid, the product being i.2-benzanthraquinone. This compound and its derivatives are treated in greater detail in Chapter VII., but here it maj- be pointed out that so easily does naphthalene condense with phthalic anhydride that the reaction may be carried out in benzene, toluene or X3dene solution without the solvent being attacked, provided no excess of phthalic anh3'dride is used. Benzene, in fact, is the best solvent to employ.
Anthracene ^ also condenses readily \\ith phthalic anhj^dride, and here again benzene is the best solvent provided an excess of phthalic anhydride is avoided.
1 Friedel and Crafts, A. ch. [6] 14, 446. Limpricht, A. 299, 300. Limpricht and Wiegand. A. 311, 181. Heller and Schulke, B. 41, 3627. Elbs, J. pr. [2] 41, 4.
» F. Mej'er, B. 15, 636. Limpricht. A. 312, 99- Elbs, J. pr. [2] 41, 6 ; B. 20, 1361. HeUer, B. 43, 2891.
3 F. Meyer, B. 15, 637. Gresly. A. 234, 238. Elbs, J. pr. [2] 41, 13; B. 20, 1364. Scholl, B. 43, 353.
* Gresly, A. 234, 238. Elbs, J. pr. [2] 41, 27. Heller, B. 43, 2892.
6 Gresly, A. 234, 238. Elbs, J. pr. [2] 41, 122.
« M. 32, 687.
' Elbs, B. 19, 2209. Gabriel and Colman, B. 33, 448. Heller and Schulke, B. 41, 3627. Heller, D.R.P. 193-961.
8 HeUer and Schulke, B. 41, 3O27 ; 45, 669. Heller, D.R.P. 193.961. Cf also Schaarschmidt, B. 49, 381.
ANTHRAQUINONE RING SYNTHESES 135
Treatment of the product with dehj'dratmg agents, however, does not lead to an anthraquiuone, but to rupture of the mole- cule with formation of anthracene and phthalic acid, so that the phthalo^'l group is probably attached to the ws-carbon.
Phthalic anh3'dride will also condense with phenanthrene, 1 and the phenanthroyl benzoic acid, when treated with phos- phorus pentoxide, gives an anthraquiuone derivative which is probably 1.2.3.4-dibenzanthraquinone and has the structure CgH^— C— COv
I II /CeH^, although this has never been proved.
CeH4— C— CO^
Elbs 2 and Kaiser ^ were only able to condense one molecule of phthalic anhydride with one molecule of di- phenyl, thus obtaining phenylbenzoyl benzoic acid which they could not transform into an anthraquiuone derivative. Scholl 4 at a later date reinvestigated the subject and suc- ceeded in closing the ring by heating phenyl benzoyl benzoic acid alone at 340°, or with aluminium or zinc chloride at 150°. In both cases, however, the 3'ields were very poor. Benzoyl benzoic acid itself is readily and quantitatively reduced to the diphen^-l methane derivative by ammonia and zinc dust in the presence of copper sulphate, but in the case of phen3-l benzo^d benzoic acid the 3-ield by this method was only 15 per cent. By using a mixture of caustic soda, ammonia, ammoniacal copper sulphate and zinc dust, however, Scholl obtained an almost quantitative yield of the phenyl diphenyl methane carbox}-lic acid, although the reaction was slow and required 144 hours. From this compound he was unable to spht out water b}" means of siilphuric acid, owing to sulphonation taking place, but b}- heating with zinc chloride or sodamide at 190° he obtained phenyl anthrone, from which /3-phenylanthraquinone was obtained by oxidation. Scholl 5 also succeeded in con- densing one molecule of diphenyl with two molecules of phthalic anhydride, and from the product he obtained 2.2'- dianthraquinonyl.
1 M.L.B., D.R.P. 194,3".?. * J- V^- W 41, I45-
3 A 2.57, 95. « B. 44, 1075. • B 44, 1086.
i36 ANTHRACENE AND ANTHRAQUINONE
>
Scholl found that o-ditohl i will also condense with two molecules of phthalic anh^^dride, but a dimethj-l dianthra- quinonyl can only be obtained from the product with the utmost difficulty. As it gives no p3'ranthrone it must be 3.3'-dimethyl-2.2'-dianthraquinonyl. ^-Ditohd, on the con- trary'', will only condense with one molecule of phthalic anh3^dride, and the product tends to pass into a phthalide, rather than into an anthraquinone.2 By reduction, de- hydration, and subsequent oxidation, however, i-methyl- 4-/)-tolyl anthraquinone can be obtained. ^
as-Dix^dyl (2.4.2'.4'-tetramethyl diphenyl) condenses with two molecules of phthalic anhydride to produce a mixture of phthalo3dic acids. From these 2.4.2'.4'-tetra- methyl-i-i'-dianthraquinonyl 4 can be obtained by treat- ment with concentrated sulphuric acid at ioo°.
Halogenated Anthraquinones. — Homonuclear halo- gen anthraquinones can be formed by the phthalic acid syn- thesis either by condensing phthalic acid with an aromatic halogen compound, or b}^ condensing a halogenated phthalic acid with an aromatic h\'drocarbon. Heteronuclear halogen anthraquinones are, of course, obtained when a halogenated phthalic acid is condensed with an aromatic halogen com- pound. Halogen compounds are also sometimes obtained by halogenating the benzoyl benzoic acid and then closing the ring. By this last method Mettler ^ obtamed a dichior- dihydrox}- anthraquinone by chlorinating the dihydrox3' benzoyl benzoic acid obtained by the oxidation of fluor- esceine, and then closing the ring, and i-amino-4-chlor- anthraquinone has been obtained by preparing 3-acetyl amino benzophenone-3'-carbox3dic acid and- then treating with dehydrating agents. ^ The method, however, has been very little developed.
The formation of homonuclear halogen anthraquinones from phthalic anhydride and aromatic halogen compoimds has been fairly fully investigated. Chlorobenzene ' and
' B. 44, 109J. 2 Scholl, B. 44, 1091.
' Seer, M. 33, 540, * Scholl, B. 43, 512.
6 B. 35, 800. 6 Agfa, D.R.P. 254,091.
' M.L.B., D.R.P. 75,288.
ANTHRAQUINONE RING SYNTHESES 137
bromobenzcne 1 lead to the corresponding ^-halogen anthraquinones, and ^-chlortoluene leads, of course, to i- metliyl-4-cliloranthraquinone.2 From o-chlortoluene Heller and Scliiilke 3 obtained a methylchloranthraquinone which on oxidation and subsequent loss of carbon dioxide passed into jS-chloranthraquinone, thus showing that the product was either i-methyl-2-chlor-anthraquinone or 3-methyl- 2-chloranthraquinone. Ullmann ^ proved the latter of these to be correct by oxidising it to the corresponding carbox}'lic acid and then condensing with aniline. The resulting anilidoanthraquinone carbox^dic acid by loss of water passed into an acridone which was neither anthraquinone- i.2-acridone nor anthraquinone-2.1 -acridone, and hence must have been anthraquinone-2.3-acridone.
The condensation of phthalic anhydride with 0-, m-, and p-bxova. toluene has been studied by Heller, ^ who finds that in each case a mixture of methylbrombenzoylbenzoic acids is formed, but that from each of these mixtures the same methyl brombenzoyl benzoic acid can be isolated and that this by loss of water passes into 2.3-methylbromanthra- quinone. From this it is clear that in the case of m- and ;5)-bronitoluene the aluminium chloride has caused either the methyl group or the bromine atom to wander, and as the same phenomenon is not observed in the cases of the correspond- ing chlortoluenes, it is probable that it is the bromine atom that has changed its position. The wandering of bromine atoms under the influence of aluminium chloride has, of course, long been known ; Roux,^ for example, having shown that aluminium chloride is capable of converting a-bromnaphthalene into j8-broninaphthalene.
The condensation of 3.6-dichlorphthalic acid and 2.4- dichlorphthalic acid with aromatic hydrocarbons has been studied by several investigators,"^ without any results of
1 Ullmann, A. 380, 337.
a Heller and Schiilke. B. 41, 3627. Heller, B. 45, 792. » HeUer and Schulke, B. 41, 3627. HeUer, B. 45, 792. * B. 47. 553.
6 B. 47. 792. • A. ch. [6] 12. 334.
' Harrop, Norris and Weizraann, Soc. 95, 12 12. Ullmann and Billig, A. 381. I. Le Royer, A. 238, 356, Ree, A. 234, 239.
138 ANTHRACENE AND ANTHRAQUINONE
particular interest being recorded, altliough it is worth noting that the ketonic acid obtained from 3.6-dichlorphthalic acid and w-xylene only passes into the anthraquinone with the utmost difficulty, and yields of over 5 per cent, could not be obtained. 1 Tetrachlorphthalic acid h^as also been em- ployed for preparing homonuclear tetrachloranthraquinone.2
A large number of heteronuclear chloranthraquinones have been obtained by Hofmann 3 by condensing various chlorphthalic acids with aromatic halogen compoimds, but they are of no particular interest.
Hydroxyanthraquinones. — Phthalic acid as a rule will not condense with free phenols under the influence of aluminium chloride to produce a hydroxy benzoyl benzoic acid, as a phthalein is usually the sole product, although recently Ullmann and Schmidt * have found that in many cases a good yield of the hydroxybenzo}'! benzoic acid can be obtained if the condensation is carried out in tetra- chlorethane solution. It is too early to say if this method is a general one and is applicable to all phenols, but from the results already published its value is obvious. When phthalic acid itself is used the carbonyl group prefers the ortho- position with reference to the hydroxyl group, although small amounts of other isomers are formed simultaneously, and when tetrachlorphthalic acid is employed it is exclusively the ortho- position which is taken. It is interesting to notice that the condensation of phthalic anhydride with _/)-chlor- phenol under the influence of aluminium chloride leads to a mixture of _/>-clilorhydroxybenzoyl benzoic acid and i.4-h5'drox\xhloranthraquinone, the conversion of the former into the latter being completed by warming with concen- trated sulphuric acid,^ whereas as already stated the direct condensation of phthalic anh3^dride with ;/!)-chlorphenol by sulphuric acid leads only to quinizarin.^
^ Harrop, Norris and Weizmann, Soc. 95, 12 12.
* Kircher, A. 238, 344. ^ M. 36, 805.
* Ullmann and W. Schmidt, B. 52, 2098. Ullmann and Conzetti, B. 53, 830. Ullmann, D.R.P. 292,066.
6 Ullmann, D.R.P. 282,493.
' Liebermann, A. 212, 10; B. 10. 608. By., D.R.P. 255,031. See also pp. 128, 129.
ANTHRAQUINONE RING SYNTHESES 139
The condensation of phthalic anh5'dride with phenols can often be brought about with satisfactory results by first niethylating the hydrox^'l groups, as this hinders phthalein formation. During the condensation, however, the aluminium chloride usuall}- causes partial or complete demethylation, and methoxy groups which escape hydrolysis by the aluminium chloride are usually demethylated during the closing of the anthraquinone ring. This method was used by Lagodzinski,i who obtained quinizarin from quinol dimethyl ether, and hystazarin from veratrol, but Nourri- son 2 had previously shown that ^-hydroxy anthraquinone coidd be obtained from anisol. It has also been used to a considerable extent by Weizmann * and his students, who have obtained various hydrox}^anthraquinone derivatives by condensing phthalic acid or a methox}^ phthahc acid, such as hemipinic acid \nth aromatic hydrocarbons or phenolic ethers.
The preparation of hydroxy anthraquinones from phenols can also be effected without protecting the hydroxyl groups if boric acid is used in place of aluminium chloride. This method was first introduced b}'^ Deichler and Weiz- mann, * who obtained hydroxy naphthoyl benzoic acid by heating a-naplithol with phthalic anhydride and boric acid at 190°, and has been extended by Weizmann and his students, 5 who have prepared numerous hydroxy- anthra- quinone derivatives from phthahc acid or hydroxy phthalic acid and various phenols such as the cresols. Frey 6 has used the method for condensing various dichlorphthalic acids with hydroquinone, Hovermann "^ has condensed tetrachlorphthalic acid with hydroquinone, and Dimroth and Fick ^ have condensed phthalic acid, 4-hydroxyphthalic
1 B. 28. 117; A. 342. 90.
« B. 19, 2105.
' Bentley. Gardner and Weizmann. Soc. 91, 1630. Bentley and Weizmann. Soc. 93, 435. Walsch and Weizmann, Soc. 97, 687. Bradbury and Weizmann, Soc, 105, 2748. Cf. also Bistrzycki and Schepper, B. 31,
2793-
* Deichler and Weizmann, B. 36, 547.
* Bentley, Gardner and Weizmann. Soc. 91, 1630. « B. 45, 1358.
' B. 47, 1210. « A. 411, 315
140 ANTHRACENE AND ANTHRAQUINONE
acid and coccinic acid (6-metliyl-4-hydrox}'plithalic acid) with hydroquinone and hydroxyli3-droqiiinoue. In the case of hydroxy hydroquinone they find it best to use the triacetyl derivative, and find that the reaction takes place most easily when benzoic acid is used as a solvent.^ Even by the use of boric acid as a condensing agent phthalein formation camiot be altogether avoided, a phthalein, for example, being the sole product formed when 4-hydrox}- phthalic acid is condensed with o-cresol.
Schaarschmidt i condensed phthalic acid with a-anthrol by the use of boric acid, but was imable to close the ring.
MisCELL-\NEOUS SUBSTANCES. — Carhoxylic acids can sometimes be obtained b}- the phthalic acid synthesis, although the method has not been developed to any extent. The preparation of dimethyl anthraquinone carboxylic acid by Gresly 2 has already been mentioned, and the prepara- tion of anthraquinone-^-carboxy-lic acid by oxidising toluj'l benzoic acid and then closing the ring has been the sub- ject of a patent. 3 It is claimed that oxidising the methyl group before closing the ring leads to a much purer product, Graebe and Blumenfeld,* and Graebe and Leonhardt.^ obtained anthraquinone a-carboxylic acid from hemi- mellitic acid and benzene in the usual way, but in some cases the presence of the carboxyl group seems to hinder the closing of the ring. Thus, Heller and Schiilke ^ condensed phthalic acid with _/)-chlortoluene and then oxidised the meth}l group to carboxyl, but were unable to dose the ring although before oxidation the ring closed quite easily, and the}- experienced no difficulty in oxidising i-methyl-4-chlor- anthraquinone to the corresponding carbox^-lic acid.
One or two tertiary amino anthraquinones have been obtained by the phthalic acid s^mthesis, as Haller and Guyot '^ have found that phthalic anhydride will condense with tertian- aromatic amines which have a free para-
1 B. 49, 3S1. - Seep. 132.
' M.L.B., D.R.P. 80,407. * B. 30, 1116.
« A. 290, 231. « B. 41, 3627.
" Bl. [3] 25, 166; C. r. 119, 139. Cf. Societe anonyme des Matieres Colorantes, D.R.P. 108,8^7; 112,913; 112,297; 114.197-S. Also Weitz, A. 418. 29.
ANTHRAQUINONE RING SYNTHESES 141
position such as dimethyl aniHne, diethyl aniline and ethyl benzyl aniline, and Scholl and Neovious 1 have condensed two molecules of phthalic anhydride with one molecule of carbazol.
Thianthrene and thiodiphenylatnine will also condense with either one or two molecules of phthalic anhydride, and the rings can be closed b}- means of zinc cliloride or concen- trated sulphuric acid. 2
One or two variations of the usual phthalic acid synthesis have been described although they have not led to any important results. Thus, Louise 3 condensed benzoyl chloride with mesitylene and then oxidised one of the methyl groups of the resvdting trimethyl benzophenone to carboxyl. The monocarboxylic acid thus obtained when treated with dehydrating agents passed into 1.3-dimethylanthraquinone.
Ivimpricht * endeavoured to carry out a somewhat similar synthesis. He condensed phthalic acid with 0- x^'lene and then oxidised both methyl groups to carbox^-l. He then condensed the resulting benzophenone tricarboxylic acid wdth toluene, but subsequent treatment with a de- hydrating agent failed to give a diquinone. Methods of this nature would seem capable of further development and should lead to interesting results.
"^fci
^ B. 44, 1249. * Scholl and Seer, B. 44, 1233.
' A. ch. [6] 6, 233. « A. 312. 99.
T
v-rnH
CHAPTER VII THE BENZANTHRAQUI ONES
There are two possible anthraquinones i which one of the benzene rings has been replaced b: a naphthalene ring, viz. —
CO
CO
CO
I
n
CO
and both arc known. In the literature hey are usually designated respectively as naphthantraquinone and uaphthacenquinone ; but this nomenclatre is open to many objections, and it is much better t adopt Scholl's system and denote them as 1.2-benzathraquinone or awg'.-benzanthraquinone (I) and 2.3-benzathraquinone or //w.-benzanthraquinone (II).
Compounds containing five rings hav< also been pre- pared, and of course the isomerism in tls case becomes more complicated. Most of the derivatiTJS described up to the present, however, are linear, the pamt quinone (III) being named dinaphthanthraquinone, altbugh here again it is preferable to adopt Scholl's systenii^nomenclature and designate it as /i«.-dibenzanthraq^^^Btt)r 2.3.6.7- dibenzanthraquinone-
co
CO
m
m
litk
m
THl BENZANTHRAQUINONES
143
Compounds of tls nature are, of course, capable of forming numerous mono di-, and tri-quinones, and several such derivatives have been isolated.
/mMS-6/saw^.-»ibenzanthraquinone or 1.2.5.6-dibenz- anthraquinone V) has also been synthesised, but its derivatives haveiot been studied.
'16
I. awg.-BENZATHRAOUINONE (NAPHTHANTHRAQUINONE)
aw^.-Benzanlraquinone is extremely easily obtained from naphthale- by the phthalic acid synthesis, 1 either by using carbo disulphide as a solvent, 2 or, preferably, by carrying out he reaction in benzene or toluene solution, as the phthalic nhydride condenses with the naphthalene so readily that the solvent remains tmaffected provided no excess of puhalic anhydride is used.^ The structure of the quinoncvvas proved by Scholl,'^ who showed that oxidation with potassium chlorate, nitric acid, chromic acid or potassim permanganate and sulphuric acid led to anthraquinor-i.2-dicarboxylic acid, yields of 75 per cent, being obtainab' when the oxidation is carried out v\'ith permanganate.
««^.-Benzaniraquinone is a powerful vat dye (Sirius Yellow G) am has considerable affinity for vegetable fibres although sed chiefly as a pigment. On reduction by distiUation withdnc dust ^ or by boiling with zinc dust and ammonia ^ it ^elds the parent hydrocarbon [ang.-benz- anthracene), wlch reverts to the quinone when oxidised.
Very few htnologues of (xwg.-benzanthraquinone have been describe From a-methylnaphthalene Scholl ' obtained a mciometh}^ compoimd which was probably 3-methyl-i .2-be zanthraquinone. j8-Methyl naphthalene also readily condensi with phthalic anhydride, but the resulting methylnaphtho benzoic acid would not pass into a quinone.
448.
1 See p. 134.
* Graebe, A. 34 249.
Elbs, B. 19, 2209. Gabriel and Colman, B 33,
3 Heller and Sc"ilke, B. 41, 3627. * B. 44, 2992 ; R.P. 241,624. « Elbs, B. 19, 239.
Heller, D.R.P. 193,961. * Graebe, A. 340, 249. » M. 32, 996.
H
CHAPTER VII THE BENZANTHRAQUINONES
There are two possible anthraquinones in which one of the benzene rings has been replaced by a naphthalene ring, viz. —
CO
CO
I
and both are known. In the literature they are usually designated respectively as naphthanthraquinone and naphthacenquinone ; but this nomenclature is open to many objections, and it is much better to adopt Scholl's system and denote them as 1.2-benzanthraquinone or awo'.-benzanthraquinone (I) and 2.3-benzanthraquinone or lin . -benzanthraquinone (II) .
Compounds containing five rings have also been pre- pared, and of course the isomerism in this case becomes more complicated. Most of the derivatives described up to the present, however, are linear, the parent quinone (III) being named dinaphthanthraquinone, although here again it is preferable to adopt SchoU's system of nomenclature and designate it as /m.-dibenzanthraquinone or 2.3.6.7- dibenzanthraquinone —
CO
CO
in
142
THE BENZANTHRAQUINONES 143
Compounds of this nature are, of course, capable of forming numerous mono-, di-, and tri-quinones, and several such derivatives have been isolated.
/m«s-6iS««jg'.-Dibenzanthraquinone or 1.2.5.6-dibcnz- anthraquinone (IV) has also been synthesised, but its derivatives have not been studied.
I. ang.-BENZANTHRAOUINONE (NaPHTHANTHRAQUINONE)
a«^.-Benzanthraquiuone is extremely easily obtained from naphthalene by the phthalic acid synthesis, ^ either by using carbon disulphide as a solvent, 2 or, preferably, by carrying out the reaction in benzene or toluene solution, as the phthalic anhj^dride condenses with the naphthalene so readily that the solvent remains unaffected provided no excess of phthalic anh3-dride is used.^ The structure of the quinone \vas proved by Scholl,-* who showed that oxidation with potassium chlorate, nitric acid, chromic acid or potassium permanganate and sulphuric acid led to anthraquinone-i.2-dicarbox>dic acid, yields of 75 per cent, being obtainable when the oxidation is carried out with permanganate.
a«g.-Benzanthraquinone is a powerful vat dye (Sirius Yellow G) and has considerable affinity for vegetable fibres although used chiefly as a pigment. On reduction by distillation with zinc dust ^ or by boiling with zinc dust and ammonia ^ it 3'ields the parent hydrocarbon (a«g.-benz- anthracene), which reverts to the quinone when oxidised.
Verv' few homologues of awg.-benzanthraquinone have been described. From a-methylnaphthalene Scholl ' obtained a monomethyl compound which was probabh'' 3-methyl-i.2-benzanthraquinone. ^-Methyl naphthalene also readily condensed with phthalic anhydride, but the resulting methylnaphthoyl benzoic acid would not pass into a quinone,
1 See p. 134.
* Graebe, A. 340, 249. Elbs, B. 19, 2209. Gabriel and Colman, B 33. 448.
3 Heller and Schulke, B. 41, 3627, Heller, D.R.P. 193,961.
* B. 44, 2992 ; D.R.P. 241,624. * Graebe. A. 340, 249. « Elbs, B. 19, 2209. 1 M. 32, yy6.
144 ANTHRACENE AND ANTHRAQUINONE
so that in this case it is probable that the carbonyl group had become attached to the a-carbon atom which was next to the meth}-! group.
From a-chlomaphthalene and phthaHc anhydride Heller ^ obtained 3-chlor-i.2-benzanthraquinone, but ^-chlomaphtha- lene led to a chlor-2.3-benzanthraquinone. Graebe and Peter - condensed 3.6-dichlorphthahc acid with naphthalene, but the closing of the anthraquinone ring was accompanied b}^ sulphonation, so that dichlor-i.2-benzanthraquinone sulphonic acid was obtained. As naphthanthraquinone itself is not sulphonated under similar conditions it is probable that the sulphonic acid group enters the benzene and not the naphthalene ring.
The hydroxy- a;z^.-benzanthraquinones have been very little investigated. Scholl 3 condensed phthahc anhydride with i-meth3-l-2-methosy- naphthalene and then, after reducing the ketoni< acid, closed the ring and final!}- oxidised to the quinone. As the quinone when oxidised gave anthra- quinone-i.2-dicarbox\-lic acid, the methox}- and meth}-! groups must be in the benzene ring, and the quinone probably has the structure I.
CO
OCH3 CH3
CO
I
By demethylating the free hydroxy- compound coiild be obtained, but it was found impossible to replace the hydrox^-l group by an amino group. If, however, the methyl methox\- naphtho}-! benzoic acid was demethylated there was no difficulty in replacing the hydroxyl group by an amino group, and the anthraquinone ring could then be closed by the action of dilute oleum. By this means Scholl was able to obtain an amino meth^-l benzanthraquinone in which the amino group could be replaced by chlorine or iodine in the
1 B. 45, 669. Cf. G.C.I.B., D.R.P. 230,455. * A. 340, 265.
9 M. 33, 507.
THE BENZANTHRAQUTNONES 145
usual way. The iodo compound when heated with copper powder gave a dimethyl di-benzanthraquinonyl (II), and the fact that this gave no pyranthrone dye when fused with caustic potash supports Scholl's views as to the position of the methyl groups.
When fl«^.-benzanthraquinone is nitrated ^ two mono- nitro compounds (IV^ and Y) are formed :
CO
m
CO
V
The structure assigned to these is based on their behaviour when reduced, as one of them (IV) gives a pyrrol derivative whereas the other (V) gives an amino compound. As this amino compound gives no vat dye either when fused with caustic potash or when heated with antimony pentachloride, it is extremely improbable that the amino group is in the anthraquinone ring, and as the nitro group invariably enters the naphthalene ring in the a-position formula V is reasonably certain.
II. /iU.-BENZ.\NTHRAQUINONE (NaPHTHACENEQUINONE)
\\'hen phthaUc anhydride is condensed with succinic acid by heating with sodium or potassium acetate, a sub- stance is formed which is now known to be ethine diphtha- lide (I) although it was originally regarded as bisdiketo- hydrindene 2 —
C=CH CO CO CO
C6H40O j O0C6H, C6H4/ >CH-CH/ }C,H,
CO CH—C CO CO
I II
1 Scholl, B. 44. 2370.
2 Gabriel and Michael, B. 10, 1559. Gabriel, B. 17, 2531. Gabriel and Leupold, B. 31, 1159. Roser, B. 17, 2619. Cf. also B. 10, 391, 2199 ; 11, 1007.
10
146 ANTHRACENE AND ANTHRAQUINONE
Nathanson, 1 and Gabriel and Leupold 2 have shown that this substance undergoes a remarkable rearrangement when treated with sodium methylate, both the lactone rings being opened and loss of two molecules of water subsequently' taking place between the carbox}^ groups and the hydrogen atoms of the aliphatic chain, with the formation of bisdiketo hydrindene (II) and iso-eihme diphthalide, the ketonic form of this latter substance being identical with dihydro /*'«.-benzanthradiquinone :
OH CO ^ Op 99
CO OH ' CO CO
fso-Ethinediphthalide or dihydro-ZfM.-Benzanthradiquinone. Enolic form. Ketonic form.
Dihydro-/i7?.-benzanthradiquinone is, of course, also the ketonic form of dihydrox\^-/w.-benzanthraquinone.
The above rearrangement is fairly general and is shown also by the condensation product obtained by heating phthalic anhydride with acetic acid and sodium or potassium acetate, although in this case the formation of only one compound is possible, viz. diketohydrindene :
OH
C=CHCOOH C6H4<^0 ->
CO
OH
I .C=CH2
C6H4\ +CO0
XOOH
C
-^C6H4<^^CH CO
Diketohydrindene. Enolic form.
As would be expected, this compound is formed directly by the action of metallic sodium on a mixture of ethyl phthalate and ethyl acetate, 3
Kaufmann * by oxidising diketohydrindene obtained two products, one of which he regarded as bisdiketohydrin- dene, although it differs completely from Nathanson's
1 B. 26.2582. ' B. 31, 1 160.
» Wislicenus, B. 20, 593 ; A. 246, 347 ; 252, 72. « B. 30, 382.
THE BENZANTHRAQUINONES 147
product, and the other of which he named indenigo and ascribed to it the formula :
CO CO
C6H4^^C =Cv ^C6H4
CO CO
although Gabriel and Leupold ^ have since shown that indenigo is almost certainly identical with their uo-ethine diphthalidc.
The reduction of jso-ethine diphthalidc was also effected by Gabriel and Leupold, 2 who thereby obtained two hydro- carbons, viz. C18H12, which they named naphthacene (/i'n.-benzanthracene), and its dihydro compound C18H14 (dihydronaphthacene or dihydro-^nz.-benzanthracene) . Both on oxidation give /w.-benzanthraquinone (naphthacen- quinone). This latter substance forms yellow needles which melt at 294°, and when fused with caustic potash is decomposed into benzoic acid and j3-naphthoic acid.
Nothing is known of the homologues of /m.-benzanthra- quinones, and in fact, up to the present the hydroxyl de- rivatives are the onl}' ones which have been studied in any detail. By treating tso-ethine diphthalidc with phosphorus pentachloride Gabriel and Leupold obtained 1.4-dichlor- 2.3-benzanthraquinone. In this the chlorine atoms are fairly reactive, so that boiling for ten minutes with aniline sufficed to convert it into the dianilido compound.
The hydroxy derivatives have been studied chiefly by Weizmann and his students, although Liebermann and Voswinckel,3 by heating i-methyl-3-hydroxybenzene-4.5.6- tricarbox}'Hc acid to 200° with succinic acid and potassium acetate, obtained a substituted ethine diphthalidc which by treatment with sodium methylate gave a dimethyltetra- hydroxy-/i«.-benzanthraquinone :
CHj OH CO
^ " "10H
OH CO CH3
' B. 31, 1272. ' Cf. also Deichler and Weizmann, B. 36, 547.
» B. 37, 3344-
148 ANTHRACENE AND ANTHRAQUINONE
This very closely resembled the substance obtained by heating carminic acid to 200° in the air, although owing to the insolubility of the substance in all solvents except caustic alkali the identification could not be made complete.
Deichler and Weizmann ^ found that phthalic acid would condense with a-naphthol when heated inr the presence of boric acid, and the resulting i-hydroxy-2-o-naphthoyl benzoic acid when heated with concentrated sulphuric acid passed into i-hydroxy-2.3-benzanthraquinone, and the synthesis of hydroxy /m.-benzanthraquinones by this method is fairly general. Thus Deichler and Weizmann 2 condensed phthalic acid with i-naphthol-4-, 5-, and 8-sulphonic acids, and Bentley, Friedl, Thomas, and Weizmann ^ ex- tended the method to 1.5-dihydroxy naphthalene. In this latter case two molecules of phthalic acid condensed with one molecule of the naphthol; but subsequent treatment with sulphuric acid led to the closing of only one ring, as the second phthaloyl group split off and was replaced by a hydroxyl group, the final product obtained being 4-hydroxy- Bz.-i.2-dihydroxy-2,3-benzanthraquinone.
Hydroxy derivatives have also been obtained by con- densing 4-hydroxy phthalic acid, 4 3-methoxy phthalic acid,^ and hemipinic acid ^ with naphthols, and nitro-hydroxy compounds have been obtained from nitrophthalic acid,' and chlorhydroxy compounds from 3.6-dichlorphthalic acid and tetrachlorphthalic acid.^ In some cases the closing of the anthraquinone ring can only be effected by very drastic treatment, such as heating to 130° with oleum containing 70 per cent, of free anhydride, and under these conditions sulphonation and hydroxylation often take place simultaneously. To some extent this can be avoided by dissolving the naphthoyl benzoic acid in concentrated sulphuric acid and boric acid, and then adding oleum slowty.
1 B. 36, 547. ^ D.R.P. 134,985. => Soc. 89, 115 ; 91. ^5^8.
* Orchardson and Weizmann, Soc. 89, 115. ^ Ibid.
6 Bentley, Friedl, and Weizmann, Soc. 91, 1588. ' Ibid. ^ Harrop, Norris, and Weizmann, Soc. 95, 279.
THE BENZANTHRAQUINONES 149
Hydrox}'! groups can also be inserted into the molecule b}' direct oxidation with oleum and boric acid, nitrosyl sulphuric acid, or by fusion with caustic potash and potassium chlorate, and by this means i.4-dihydrox3-2.3-benzanthra- quinone (iso-ethinediphthalide) has been obtained from i-hydrox3'-2.3-benzanthraquinone.i
When sulphonic acid groups are present in the molecule they can be replaced by hydrox^-l groups by fusion with caustic alkali, although this method has been ver\' little appUed.- Weizmann ^ records one case in which an amino group is replaced by hydrox^d by fusion with caustic alkali, but as a rule he appears to find it best to carr^- out the replacement by means of the diazo- reaction.*
Halogen atoms when present in a hydrox}'naphthoyl benzoic acid are often replaced by hydroxyl groups when the ring is closed, and Weizmann has obtained several hydroxy- 1.2-benzanthraquinones b}- brominating the hydrox^-naphthojd benzoic acid and then closing the ring. 5 Under suitable conditions it is usually possible to obtain a certain amount of the bromohydroxy- quinone at the same time, and chlorine atoms seem to be much more firmly bound than bromine atoms, as i-hydrox\--4-chlor- naphthoyl-(2)-o-benzoic acid, obtained by treating the hydrox^-naphthoyl benzoic acid with sulphured chloride, gives 1 .4-hydroxychlor-2.3-benzanthraquinone.6
As regards the relationship between the colour of the hydroxy- compounds and the position of the hydrox}*! groups, Weizmann ' considers that hydroxy 1 groups in the naphtha- lene ring tend to deepen the colour, whereas when in the benzene ring the tendency is rather to lessen it. Bal}- and Tuck 8 have examined the absorption spectra of some of
1 Deichler and Weizmann, B. 36, 719. D.R.P. 138,324-5.
* Deichler and Weizmann, B. 36, 719. Bentley, Friedl, Thomas, and Weizmann, Soc. 91, 411.
3 Soc. 91, 411.
* Deichler and Weizmann, B. 36, 2326.
* Orchardson and Weizmann, Soc. 89, 115. Bentley, Friedl, Thomas, and Weizmann, Soc. 91, 4it. Harrop, Norris, and Weizmann, Soc 95, 279.
* Geigv, D.R.P. 226,230. '> Soc. '91. 411.
» Soc. 91, 426.
150 ANTHRACENE AND ANTHRAQUINONE
the liydrox>^ compounds, but as ver>' few of the large number of possible compounds have been described, the data avail- able are insufficient to justify any generalisation.
Very few halogen derivatives other than hydroxy- halogen compounds have been described, but Orchardson and Weizmann,! by treating hydroxynaphthoyl benzoic acid with phosphorus pentachloride, obtained th^e corresponding chloro acid, from which i-chlor-2.3-benzanthraquinone was obtained. At the same time they obtained a bright red compound which they regarded as an isomeric chloro- benzanthraquinone although their analytical figures hardly support this assumption (found, Cl=ii'2 ; calculated, Cl=i2"i). By brominating their chlornaphthoyl benzoic acid Orchardson and Weizmann obtained a bromo com- pound from which they obtained i-chlor-3-brom-2.3-benz- anthraquinone, but could not obtain it in a pure condition owing to the tendency to split off hj^drobromic acid.
Heller, 2 by condensing phthalic acid with /3-chlomaphtha- lene, obtained a chlornaphthoyl benzoic acid from which a quinone was obtained by loss of water. This he originally believed to be 4-chlor-i.2-benzanthraquinone, but at a later date found that on oxidation it gave anthraquinone- 2.3-dicarboxylic acid, and hence must be Bz.-2-chlor-2.3- benzanthraquinone.3 The preparation of the 1.4-dichlor compomid by the action of phosphorus pentachloride on tso-ethinediphthalide has already been mentioned.*
A mononitro compound was obtained by Gabriel and lycupold 5 by nitrating //«.-benzanthraquinone, but they did not determine the position of the nitro group. Deichler and Weizmann, 6 by nitrating i-h3^droxy-2.3-benzanthra- quinone, obtained i-hydrox>^-4-nitro-2.3-benzanthraquinone, from which by reduction and diazotisation the dihydroxy compotmd (tso-ethinediphthalide) was obtained, thus determining the position of the nitro group. Further
^ Soc. 89, 115. Cf. Pickles and Weizmann, Proc. 20, 220.
* B. 45, 669. s B. 46, 1497. * Page 147.
? B. 31, 1272. « B. 36, 2326,
THE BENZANTHRAQUINONES 151
nitration led to a dinitro compound. The analj-tical values found for both the mono- and the dinitro com- pounds are in very poor agreement with the calculated values, so that pending further investigation it cannot be assumed that either compound was obtained in a state of purity.
By nitrating methoxy naphthoyl benzoic acid Orchardson and Weizmann ^ obtained a nitro compound but were unable to convert it into the quinone, as sulphuric acid caused decomposition.
Hydroxy amino derivatives have been obtained by Deichler and Weizmann, 2 and by Bentley, Friedl and Weizmann ^ by the reduction of the nitrohydroxy com- pounds, although here again the analytical figures given leave the purity of some of the substances described open to doubt. Amino groups have also been introduced into the molecule by coupling the hydroxy compounds with benzene diazonium chloride and then reducing the azo dye formed.^ Negative groups or atoms when present in the molecule are usually fairly readily replaced by arylamino groups by boihng with primar}^ aromatic amines, ^ although in those chloro- compounds obtained from chlorinated phthalic acid the data available point to its only being those chlorine atoms which are in the a-position which react in this way.
Amino groups can also be introduced into the molecule before closing the anthraquinone ring, either by nitration and reduction, or by forming an azo- dye and then reducing this. In the case of 4-aniino-i-hydrox3'-naphthoyl (2) -benzoic acid the formation of the quinone takes place with very great ease, it being sufficient to boil with nitro- benzene,^ and the same amino-h3'drox)' quinone is formed
1 Soc. 89, 115.
* B. 34, 2326.
» Soc. 91, 1588.
* Harrop, Norris, and Weizmann. Soc. 95, 279.
' Gabriel and Leupold. B. 31, 1272. Orchardson and Weizmann, Soc. 89, 115. Bentley, Tfiomas, Friedl. and Weizmann, Soc. 91, 411. Harrop, Norris, and Weizmann, Soc. 95, 279.
« Bentley, Friedl, Thomas, and Weizmann, Soc. 91, 411.
152 ANTHRACENE AND ANTHRAQUINONE
directly when the corresponding hydroxy nitrouaphthoyl benzoic acid is reduced with zinc and acetic acid.i
The only amino-/w.-benzanthraquinone which contains no other substituents to have been described up to the present seems to be i-amino-2.3-benzanthraquinone,2 which was obtained by heating the corresponding hydroxys com- pound with aqueous ammonia at 200°. ^
III. /^w.-Bknzanthradiquinone (Naphthacendiquinone)
Of the numerous /iVi.-benzanthradiquinones which are theoretically possible, only one, viz. 2.3-benz-i.4.9.io- anthradiquinone, has been described up to the present. This was obtained by Gabriel and lycupold 3 by oxidising 1 .4-dihydrox>'-2.3-benzanthraquinone (/so-ethinediphtha- lide) with nitric acid, and Deichler and Weizmann * have shown that the reverse change can be brought about by mild reducing agents such as ammonium sulphide or ferrous salts.
The reactions of the diquinone have not been studied in any great detail, but from the investigations which have appeared it would seem that one of the quinone rings is somewhat easily ruptured. Voswinckel ^ has studied the action of the halogens on the diquinone and has found that treatment with chlorine leads to the addition of two chlorine atoms with the formation of a dichloride (I), which when warmed with caustic soda rmdergoes rupture of one ring with the formation of a ketonic acid (III), although at the same time a small quantity of tso-ethinediphthalide (IV) is formed. Probably the first action of the alkali is to bring about the formation of a ketone hj-drate ^ (H)^ subsequent loss of two molecules of hypochlorous acid then taking place.
^ Orchardson and Weizmann, Soc. 89, 115.
2 Bentley, Friedl, Thomas, and Weizmann, Soc. 91, 411.
' B. 31. 1272.
« B. 36. 719.
5 B. 38, 4015.
6 Cf. Zincke, B. 20. 3229.
THE BENZANTHRAQUINONES
153
CO OH
With bromine a somewhat similar reaction takes place, but in this case the dibromide cannot be isolated although Voswinckel obtained a monobromketone monohydrate :
HO OH
This is very readily decomposed with rupture of the quinone ring, and apparently gives the same ketonic acid as is obtained from the dichloride. On this point, however, Voswinckel could not be absolutely certain, as the melting points of the acids from the two sources differed somewhat, that from the bromo- compoimd melting at 199°, whereas that from the dichloride melted at 185°.
The bromo-compound is much more reactive than the dichloride, and when treated with aqueous sodium acetate is readily converted into iso-ethinediphthalide. As obtained by this means, however, the substance is almost black, and its appearance is not appreciably altered by several re- crystallizations from nitrobenzene or ethyl benzoate, whereas a single recr^-stallisation from pyridine suffices to convert it into the usual red needles. The black substance may possibly represent one of the numerous possible tautomeric forms, but Voswinckel ^ inclines to regard it as quinhydrone
1 B. 42. 465.
154 ANTHRACENE AND ANTHRAQUINONE
in nature. The tendency of the diquinone to form ketone hydrates is very considerable, and Voswinckel has found that such compounds are very readily formed by boiling with phenol in glacial acetic acid solution in the presence of a little sulphuric acid. The following scheme shows their chief reactions ^ : —
HO C6H4OH
HO C9H4OH OH
CH3OOO OH
JNoOH
HOCeHs OH qq
Ph^\ /OCOCM3
C Ph
HO OH N^o
CH3COOC6H, Ph £.Q
By the action of bleaching powder on the diquinone Voswinckel obtained an internal cyclic oxide which, when treated with caustic soda, gave the same ketonic acid that he obtained from the dichloride (formula III, p. 153). The acid when prepared in this way melted at 199°.
IV. tmnS-bisang.-'DlBT.NZANTKRAQUlNONZ (DlNAPHTH-
anthraquinone)
trans - 6iS«wg.-Dibenzanthraquinone (1.2.5.6. - dibenz- anthraquinone) has been S3'nthesised by Weitzenbock and Klinger " as shown by the following scheme : —
1 Voswinckel, B. 42, 458, 4648.
' Weitzenbock and Ivlinger, M. 39, 315.
THE BENZA NTHRA Q U I NONES
O")
COOH
3-4-5-e-0iben2phenanihr8ne.
■Z-S-G-Dibenzcfnihrcucene
i-Z-5-6-Dibenzanihraciuinom
The closing of the rmgs in the diainiuo compound was effected by Pschorr's method, i viz. by treating the diazonium salt with copper powder. Two alternative reactions were possible and both took place, both an anthracene and a phenanthrene being formed. It should be observed that in the dibenzphenanthrene obtained there are two carbon atoms in the peri- position to one another, so that when heated with aluminium chloride a highly condensed hydrocarbon, indicated by the dotted line, should be
^ Pschorr, B. 29, 496.
156 ANTHRACENE AND ANTHRAQUINONE
obtained,! although this does not seem to have been attempted.
trans-bisang.-'Dihenza.nthraqmD.one melts at 248-249°. It should be a powerful vat dye judging from its structure, but no information regarding its tinctorial properties has been published.
V. /w.-DlBENZANTHRAQUINONE (DiNAPHTHANTHRAOUINONE)
By condensing p3'romellitic acid with benzene, Philippi 2 and, at a later date, Mihs and Mills ^ obtained two isomeric ketonic acids, both of which when treated with sulphuric acid gave /w.-dibenz-i.4.5.8-anthradiquinone (dinaphth- anthradiquinone) :
CO CO
CO CO
Philippi 4 also found that pyromellitic acid wlU condense with toluene, but he was unable to obtain a quinone from the ketonic acid. Scholl & obtained the same diquinone by a different means. He condensed the chloride of anthra- quinone-^-carboxylic acid with naphthalene and then heated the resulting 2-anthraquinonYl-i-naphthyl ketone with aluminium chloride. Here ring formation might take place in either of two directions, as indicated by the dotted lines in foimulae I and II ; but as the product on oxidation gave a diquinone monocarboxylic acid, which by loss of carbon dioxide passed into Philippi's diquinone, the reaction in- dicated by I must be that which actually takes place.
CO CO ^ ^ CO
CO
1 See pp. 324, 328. Scholl, A. 394, iii ; B. 44, 1656. ^ M. 82, 624, » Soc. 101, 2194. 4 M. 34, 705. 6 A. 394, 159.
THE BENZANTHRAQUINONES 157
It will be observed that the substance represented by I can be regarded as a benzanthrone, and for a matter of fact vScholl found that when fused with caustic potash it gave a bluish-black vat dye which is probably a highly complex violanthrone.
A substance which is probably a dihydroxy derivative of the above diquinone is said to be obtained by condensing phthalic anhydride with /^^/co-quinizarin and then oxidising the product, 1 and compounds of similar structure are claimed as being obtained by using hydroxyanthracenes or other /ci^co-hydroxyanthraquinones in place of /^^wco-quinizarin.
By reducing their diquinone Mills and Mills 2 obtained a hydrocarbon and an anthrone, the latter on oxidation giving a monoquinone, viz. /i«.-dibenzanthraquinone :
CO
CO
PhLlippi,3 however, has criticised Mills and Mills' work, and has concluded that some of their reduction products were impure. Russig ^ when studying the action of carbon dioxide under pressure on naphthoquinol obtained, in addition to i.4-dihydrox>'naphthalene-2-carbox>dic acid, a yellow substance which was probably a i.4.5.8-tetraliydrox3- /jw.-dibenzanthraquinone (III) and a green substance which he regarded as 5.8-dihydrox\^-/2.'w.-dibenz-i.4.9.io-anthradi- quinone (IV) :
HO CO OH CO CO OH
3H CO OH CO CO OH
m IV
By treating i.4-dih3^drox>'naphthalene-2-carboxylic acid with sulphuric acid he obtamed the triquinone, hn.-dibenz- 1.4,5.8.9.10-anthratriquinone (V). By distilling his dihydroxy
1 By., D.R.P. 298,345. * Soc. 101, 2194. ^ M. 35, 380.
J. pr. [2] 62, 44. Cf. Hartenstein, Dissertation, Jena, 1892.
158 ANTHRACENE AND ANTHRAQUINONE
diquinone with zinc dust he obtained what appeared to be the parent hydrocarbon, /m.-dibenzanthracene (VI).
CO CO CO
CO CO CO
V VI
The compHcated conjugation of carbonyl groups with
double bonds which appears to exist in the triquinone renders
it an interesting substance.
CHAPTER VIII
ALDEHYDES, KETONES, AND CARBOXYLIC ACIDS
I. Aldehydes
Comparatively little is known of the aldehydes of the authraquiiione series, as they are somewhat troublesome to prepare, although several members have been described.
The direct oxidation of methyl groups to the aldehydic group can be effected by means of manganese dioxide and sulphuric acid,^ although, as in the aromatic series, there is considerable difficulty in preventing the oxidation going too far. Ullmann and Klingenberg 2 have endeavoured to avoid this by carr>^ing out the oxidation by Thiele and Winter's method, i.e. by oxidising with chromic acid in glacial acetic acid solution in the presence of acetic anhydride and concentrated stdphuric acid, and subsequently hydro- lysing the resulting acetate, and by this means have pre- pared anthraquinone-j3-aldehyde from j3-methylanthra- quinone. The method, however, is verv- troublesome ov>'ing to the very slight solubility of methylanthraquinone.
The cu-dihalogen methyl anthraquinones do not give the aldehyde on hydrolysis with alkali, but do so readily when heated with concentrated sulphuric acid to 130°, with or without the addition of boric acid, and this forms the most convenient method of preparmg the aldehydes. 3 It has also been applied to the preparation i.i'-dianthra- quinonyl-2.2'-dialdehyde from 2.2'-diclilormethyl-i.i'-di- anthraquinonyl.4
1 Agfa, D.R.P. 267,081. » B. 46, 712.
' Ullmann. B. 47, 559 ; 49, 744. B.A.S.F., D.R.P. 174.984.
* B.A.S.F., D.R.P. 241,472.
^59
i6o ANTHRACENE AND ANTHRAQUINONE
Amongst other methods of preparing aldehydes may be mentioned the preparation of i-mtroanthraqmnone-6- aldehyde by Eckert i by the action of nitric acid on j3-anthra- quinonyl-j3-acrylic acid, and of i-aminoanthraquinone-2- aldehyde by KaHscher 2 by treating with acids the con- densation products obtained by heating i-amino-2-methyl- anthraquinone with aromatic nitro compoimds and alkalis, with or without the addition of primary aromatic amines.
The anthraquinonyl aldehydes form oximes, semicar- bazones, phenylhydrazones and azines (two molecules of aldehyde with one molecule of hydrazine) in the usual way, 3 and with dimethyl aniline green dyes of similar structure to malachite green are obtained. These are somewhat yellower in shade than malachite green, are difficultly soluble, and are not at all fast.
II. Ketones
Extremely little is known of the anthraquinone ketones, and it seems that the only substances described so far are anthraquinonyl aryl ketones. These are prepared by the action of the chlorides of the anthraquinone carboxylic acids on aromatic compounds such as hydrocarbons, chloro- hydrocarbons, etc., in the presence of aluminium chloride.* The chlorides of both anthraquinone-a-carboxylic acid and anthraquinone-j8-carboxylic acid react, but the latter reacts most readily. Ullmann ^ condensed the chloride of 2-chlor- anthraquinone-3-carboxylic acid with benzene and then converted the resulting chloranthraquinonyl phenyl ketone into the corresponding aminoketone by his sulphonamide process.6 From this by diazotising and then treating the diazonium salt with copper powder he was able to close the fluorenone ring :
1 M. 35, 290.
= A. P. 1,285,726-7 (1918)-
3 Ullmann and Klingenberg, B .46, 712. B.A.S.F., D.R.P. 240,520; 241,786.
4 Ullmann, B. 47, 566, Schaarschmidt, B. 48, 831.
5 B. 47, 566.
6 See p. 197.
KETONES
i6i
CO
CO
NH,
CO CO CO CO
The product was found to be a yellow vat dye, but the tinctorial properties were very feeble.
Schaarschmidt ^ iiuds that the ketones derived from anthraquinone-a-carboxy^lic acid react quite differently from those derived from anthraquinone-^-carboxylic acid when reduced in acid solution, e.g. with concentrated sul- phuric acid and aluminium bronze. The latter compounds behave quite normally and are converted into the colourless anthrones, whereas the former give highly coloured products. These are green when dissolved in sulphuric acid of over 50 per cent, strength, but become violet when the solution is diluted. They are insoluble in alkali, but behave like other anthra- quinone compounds towards alkaline reducing agents.
Schaarschmidt regards the violet compotmd as the pinacone and the green compound as its cyclic anhydride :
OH OH O
• I I /\
— c — c— — c — c-
!
Ar Ar
I
I
Ar Ar
I
Violet compound.
Green compound.
but this theory seems somewhat improbable, as it provides no explanation of the failure of the ^-ketones to form similar compounds. It is much more probable that condensation has taken place between the ketonic carbonyl group and the reduced cyclic carbonyl group, with the production of some such structure as
1 B. 48, 972 ; 1226 : 49, 3SO.
n
i62 ANTHRACENE AND ANTHRAQUINONE
the change in colour in strongly acid solution being due to the formation of a carbonium sulphate. It should be noted that the a-methylanthraquinones behave abnormally when reduced in alkaline solution.
III. Carboxylic acids
In a few cases anthraquinone carbox>4ic acids have been built up by the phthalic acid synthesis, e.g. from hemi- mellitic acid,i but as a rule it is much better to introduce the carbox}-l groups into the molecule after the formation of the anthracene or anthraquinone ring. In the case of the a-carbox3'lic acids this can be done by treating anthracene wdth oxalyl chloride and aluminium chloride and then oxidising the resulting anthracene carbox3'lic acid or ace- anthrenequinone,2 but the method is of no great importance.
As a rule the anthraquinone carboxylic acids are obtained either by the hydrolysis of the nitriles or by the oxidation of the meth}^ anthraquinones. The hydroh'sis of the nitriles takes a perfectly normal course, and the method has been made use of by several investigators. ^
In preparing carbox\dic acids by the oxidation of methyl compounds, either the method anthraquinone can be used, or the methyl anthracene can be oxidised, when simultaneous oxidation of the methyl groups and quinone formation takes place. This latter method has been utilised to a considerable extent as a means of identifying the homologous anthracenes, and references will be found in Chapter II.
The oxidation of methyl anthraquinones to the corre- sponding carboxjdic acids can be effected by boihng with chromic acid in glacial acetic acid solution ; but as a rule the best results are obtained by heating to 200-230° in a sealed tube with dilute nitric acid * (D=iioo), although in some cases it is preferable to use other means. Thus i-nitro-2-
1 See p. 140.
^ See p. 69. Also Butescu, B. 46, 212.
» Dienel, B. 39, 932. UUmann, B. 49, 735, 746 ; A. 388, 205 ; D.R.P. 243,788.
* Elbs, J. pr [2] 41, 6, 121. Heller and Schiilke, B. 41, 3627. O. Fischer and Ziegler, J. pr. [2] 86, 293.
CARBOXYLIC ACIDS 163
methyl anthraquinoue is only oxidised with difficult)-, and when heated under pressure with nitric acid the yield of carboxylic acid does not exceed 30 per cent. In this case the oxidisation is best brought about by boiling with nitric acid (0=1383) and slowly adding chromic acid.i
a-Methylanthraquinone and its derivatives are usually rather stable towards oxidation, 2 and although the carboxylic acid can usually be obtained by heating under pressure with dilute nitric acid, it has been claimed that treatment with chlorine in nitrobenzene solution at 160° gives the most satisfactorj' results.^ In other cases it is claimed that oxida- tion can best be effected by the use of oxides of nitrogen, ^ preferably in conjunction with some indifferent solvent.
The ease with which oleum, nitrosyl sulphuric acid and manganese dioxide bring about hydroxylation w^ould point to these reagents as being tmsuited for the purpose of oxidising methyl groups to carbox^d groups. This, however, is not altogether the case, as Ullmann ^ has found that i-methyl-4-chloranthraquinone is oxidised to the carbox\dic acid when heated with concentrated sulphuric acid or oleum to 120°. In the case of 2-methyl quinizarin the correspond- ing carboxylic acid, quinizarin-2-carboxy-lic acid, can be obtained by oxidation with nitrosyl sulphuric acid in the presence of boric acid.^
Instead of oxidising a meth3danthraquinone directly to the carboxjdic acid it is, of course, possible to convert it first into the aldehyde and then to oxidise this. As a rule this method has but little advantage over those depending on direct oxidation, but in some cases Ullmann ' has found it useful, particularly when dealing with large quantities. It seems probable that in many cases the benzanthrone derivative is a suitable source of anthraquinone-a-carboxylic
» B.A.S.F., D.R.P., 229,394. Tcrres, B. 46, 1638. ^ Birukoff, B. 20. 2068. 3 B.A.S.F., D.R.P. 259,365. * B.A.S.F., D.R.P. 250,742.
^ A. 388, 217. Cf. O. Fischer and Sapper, J. pr. [2], 83, 207. Gresly, A. 234. 238.
« Ullmann, B. 52. 511, 2111 ; By., D.R.P. 273,341. ' B. 47, 561 ; 49. 735. 746.
i64 ANTHRACENE AND ANTHRAQUINONE
acids, as Perkin i has found recentl}'- that anthraquinone-i- carboxyHc acid itself can be obtained in 85 per cent, yield by oxidising benzanthrone with chromic acid in acetic acid solution.
A few carbox>"Hc acids have been described in which the carboxyl group is situated in the side chain, and is not directly attached to the nucleus. Thus jS-(f)-anthraquinonyl acrylic acid can be obtained from /3-dichlormethyl anthra- quinone 2 or anthraquinone-/S-aldehyde 3 by heating w4th sodium acetate and acetic anhydride.
The individual anthraquinone carboxylic acids are of no particular interest, and for a description of them the reader is referred to the original Uterature.* It should be noted, however, that they aU lose carbon dioxide rather easily, so that samples which have been purified by subhmation fre- quently show a low melting point. ^ One of the most readily accessible acids is anthraquinone- 1. 2 -dicarboxj'lic acid, which is very easily obtained by oxidising 1.2-benzanthra- quinone.6 Like the isomeric anthraquinone 2.3-dicarboxyHc acid, it readily gives a cjxlic anhydride. From this latter acid WiUgerodt and MaffelzzoU '' endeavoured to prepare the anthraquinone analogue of indigo, but failed, as they could not get the glycine. By fusing the acid with zinc chloride and resorcinol they obtained anthraquinone fiuores- ceine, which, however, was onl}' feebly fluorescent.
The halogen carboxylic acids can be obtained from a halogenated nitrile by h3'drolysis, or from a halogenated methylanthraquinone by oxidation. Dichloranthraquinone
1 Soc. 117, 706.
2 By., D.R.P. 282.265. ' Eckert, M. 35. 290.
* In addition to those already given, the following are the more im- portant references : Limpricht and Wiegand, A. 311, 180. Weiler, B. 7, 1 185. O. Fischer, B. 7, 1195. Liebermann and Rath, B. 8, 248. Schiiltz, B. 10, 118, 1049. Nietzki, B. 10, 2013. Wachendorfi and Zincke, B. 10, 1481. Ciamician, B. 11, 269. Hammerschlag, B. 11, 82. Bomstein, B. 15, 1821. Liebermann and Clock, B. 17, 888. Elbs, B. 17, 2848; 20, 1361. Heller, B. 43, 2891. Elbs, J. pr. [2] 35, 471. O.Fischer, J. pr. [2] 79, 561. Fischer and Reinkober, J. pr. [2] 92, 53. Seer, M. 32. 163. Eckert. M. 35, 299. Lavaux, C. r. 143, 687.
* Limpricht and Wiegand, A. 311. 180.
« Scholl. B. 44, 2992. D.R.P. 241,624 ; 243,077. ' J. pr. [2] 82, 205.
CARBOXYLIC ACIDS 165
carbox3'lic acids ^ can also be obtained by chlorinating the anthraquinone carbox^-lic acids themselves in concentrated sulphuric acid solution at 125°.
Nitrocarhoxylic acids can be obtained from nitro nitriles or nitromethylanthraquinones by the usual methods, and Eckert 2 obtained 6-nitroanthraquinone-i-carboxylic acid by treating j3(2)-anthraquinonylacr5'lic acid with nitric acid, and then oxidising the resulting nitro aldeh^'de.
Liebermann and Clock ^ nitrated anthraquinone-jS- carboxj-lic acid and obtained a uitro acid, but did not determine the position of the nitro group. Ullmann * nitrated authraquinone-a-carboxyhc acid and obtained 5-nitroanthraquinone-i-carboxylic acid, the structure being proved bj^ its preparation from 1.5-dinitroanthraquinone through the nitro amino compoimd and nitro nitrile.
Acid chlorides and acid amides are obtained by the usual means,^ e.g. by phosphorus pentachloride and ammonia. They are much more stable than the corresponding com- pounds of the benzene series. Thus Liebermann and Clock foimd that the chloride of anthraquinone-jS-carboxyUc acid, after remaining in contact with water at the ordinary temperature for 120 hours, was only hydrolysed to the extent of 7 1 per cent. The corresponding amide they found was not hydrolysed by cold concentrated sulphuric acid or by boiling dilute alkali, although it was hydrolysed by hot concentrated alkali.
The anthraquinone nitriles can be obtained from the anthraqtiinone sulphonates by heating with potassium C3-anide or, in some cases, from the chloranthraquinones by heating with cuprous cyanide and an indifferent solvent. ^ They can also be obtained from the anthracene sulphonates by distilling these with potassium cyanide and then oxidising the resulting anthracene nitrile. According to Ullmann,''
1 By., D.R.P. 255,121. 2 M. 35, 290.
3 b: 17. 891. * A. 388, 207.
* Liebermann and Glock, B. 17, 888. Graebe and 131umenfeld, B. 30, 1 1 16. Wilgerodt and Mafielzzoli, J. pr. [2] 86, 205. Seer, M. 32, 163. Eckert, M. 35, 290.
6 M.L.B., D.R.P. 271,790 ; 275,517.
' A. 388, 204. Cf. Dienel. B. 39, 932.
i66 ANTHRACENE AND ANTHRAQUINONE
however, the product obtained from anthracene-a-sulphonic by this method consists chiefly of anthraquinone itself.
The usual method of preparing the nitriles, however, is by treating the diazonium salts with potassium cupro- cyanide, although the yields obtained are often very poor, e.g. Ullmann ^ obtained a yield of only i6 per cent, from 2-amino-i-chloranthraquinone. In some cases the poor yield obtained is due to the reducing action of the cupro- cyanide, and Terres 2 has found that the diazonium salt from 2-methyl-i-amino anthraquinone when treated with potassium cuprocyanide gives jS-methylanthraquinone.
A considerable number of nitriles have been prepared by Schaarschmidt,3 who finds that their tinctorial properties are very feeble, although this can be remedied to some extent by halogenating.
1 B. 49. 735, 746. Cf. also A. 388, 203. 2 B. 46, 1646. 3 A. 405, 95.
CHAPTER IX
THE NITRO, NITEOSO, AND HALOGEN ANTHRAQUINONES
I. The Nitro Compounds
When anthraqiiinone is nitrated the a-position is first attacked exclusively, no /3-nitroantliraquinone being formed. The preparation of a-nitroanthraquinone has been described by several investigators, i the most recent descriptions being those by Ullmann 2 and Lauth.3 Both of these last carry out the nitration by the addition of nitric acid to anthra- quinone dissolved in concentrated sulphuric acid, the former specifying a temperature of about 50°. Ullmann states that the crude product contains about 8 per cent, of dinitro compounds, all of which, with the exception of the i.8-dinitro compound, can be got rid of by recrystallisation from toluene. In order to remove the i.8-dinitroanthraquinone he suggests distillation m vacuo, ^ and gives the boiling point as 270-271° at 7 mm. Lauth does not state the amount of dinitro compounds formed under the conditions he uses, but as his crude product melted at 218° instead of at 220° the quantity must have been very small. This is in accordance with the author's experience, who has prepared several pounds of nitroanthraquinone in the laboratory by adding potassium nitrate in 5 per cent, excess to anthraquinone dissolved in concentrated sulphuric acid, the whole being allowed to stand at the ordinary temperature for 48 hours.
The further nitration of anthraquinone leads to a mixture
1 Bottger and Petersen, A. 166, 147. Romer, B. 15, 1786. Graebe and Blumenfeld, B. 30, 11 18.
2 A. 388, 203 » C. r. 137, 6G2. " D.R.P. 281,490.
167
158 ANTHRACENE AND ANTHRAQUINONE
of dinitro compounds. ^ According to a patent specification ^ this contains 60 per cent, of 1.5- and i.S-dinitroanthra- qninone, the remainder being chiefly i.6-dinitroanthra- qninone with small quantities of 1.7-dinitroanthraquinone and very small quantities of 2.6- and 2.7-dinitroanthra- quinone. Eckert,^ who gives full details of the nitration, separated the isomers by fractional crystallisation from glacial acetic acid and arrived at a different result. He found 75 per cent, of the 1.5-dinitro compound, 10 per cent, of the i.6-dinitro compound, and 5 per cent, each of the 1.7- and 1.8- isomers. Holdermann * nitrated anthraquinone in the presence of mercury, but failed to detect any directing influence.
j3-Nitroanthraquinone cannot be obtained by the nitration of anthraquinone, but has been prepared by Kauffler ^ by heating anthraquinone-j8-diazonium nitrate with copper nitrite, 6 and by Scholl ' by nitrating j3-aminoanthraquinone and then removing the amino group from the resulting 2-amino-3-nitroanthraquinone by the diazo- reaction. It is much less reactive than a-nitroanthraquinone and does not react with primary- aromatic amines, although it is readily con- verted into^-methoxy anthraquinone by potassium methoxide.
The nitration of a-methylanthraquinone has been carried out by O. Fischer and Ziegler.^ They obtained a mononitro compound but did not determine the position of the nitro group.
i|;!^The dinitration of /3-meth3'l anthraquinone has been effected by Schaarschmidt,^ who fotmd that the product contained 65 per cent, of 2-methyl-i.5-dinitroanthraquinone and 30 per cent, of 2-methyl-i.8-dinitroanthraquinone.
By the nitration of 1.3-dimethylanthraquinone Scholl 'o
1 Fritsche, J. pr. [i] 106, 287. Bottger and Petersen, A. 160, 185 ; B. 8, 16. Graebe and Liebermann, B. 3, 905. Romer, B. 16, 363.
* M.L.B., D.R.P. 167,699. » M. 35, 297.
* B. 39, 1256. 5 B. 37, 63.
* Cf. Sandmeyer, B. 20, 1495 ; 23, 1630. Hantzsch and Blagden, B. 33, 1544.
' Scholl, M. 32, 1037. Scholl and Eberle, B. 37, 4434.
» J. pr [2] 86. 292. 9 B. 45, 3452. lo B. 43, 353.
THE NITRO COMPOUNDS 169
obtained i.3-dimeth3'l-4-nitroantliraquinone and 1.3- dimethyl-2.4-dinitroantliraquinone, and from 2.6-dimetliyl- anthraquinone Seer ^ obtained 2.6-dimetliyl-i.5-dinitro- anthraquinone. By nitrating 1.3.5.7-tetramethylanthra- quinone Seer ^ obtained a mixture of the 4.8-dinitro com- pound and the tetranitro compound.
The reduction of the nitro compounds to amino com- pounds is discussed in the chapter deaHng with these latter substances, the reduction being particularly easily effected by boiling with aqueous sodium sulphide solution. The change of dinitroanthraquinone into polyhydroxyanthra- quinones when heated with concentrated sulphuric acid or oleum, with or without the addition of sulphur, will be found described on p. 242.
The nitro groups in the nitroanthraquinoiies, especially when in the a-positions, are decidedly more reactive than is usually the case with aromatic nitro compounds. Thus they are often readily replaced by arylamino groups when boiled with primary aromatic amines such as aniline,^ and are very easily replaced by methoxy groups b}- treatment with alcoholic solutions of potassium methoxide.^
II. The Nitroso Compounds
Scarcely anything is known of the nitrosoanthraquinones. Walker ^ found that i-nitroanthraquinone-2-sulphonic acid, when reduced with glucose in alkaline solution, gave the corresponding hydrox3damine derivative, which on oxidation passed into i-nitrosoanthraquinone-2-sulphonic acid. From this the hydrox3lamine derivative could be regenerated by reduction with glucose. As stated elsewhere,^ 1.5-dinitro- anthraquinone when heated to 50° with oleum containing 30 per cent, of free anhydride passes into i-nitro-5-nitroso- 8-hydrox}-anthraquinone, reduction of this leading to the corresponding diamine compound.
» M. 32, 158. 2 M. 33, i3. ' See p. 198. * See p. 287.
6 B. 35, 666. « Seep. 244. By., D.R.P. 104,282.
170 ANTHRACENE AND ANTHRAQUINONE
III. The Halogen Compounds
Direct Halogenation. — Anthraquinone itself is only attacked by halogens with the greatest difficulty, although Diehl,! by the action of bromine in the presence of iodine, obtained di-, tri-, tetra-, and penta-brom compounds. The attack takes place somewhat more readily when con- centrated stdphuric acid or oleum is used as a solvent, and it is claimed that under these conditions anthraquinone can be chlorinated in steps. 2 The reaction is carried out at a temperature of 60-130° and is facilitated by the use of iodine as a catalyst. The entering halogen atom seems to prefer the a-positions, as it is stated that a-chloranthra- quinone is converted into 1.4.5.8-tetrachloranthraquinone, whereas 2.6- and 2.7-dichloranthraquinone yield hexachlor compounds.
According to another patent specification ^ anthraquinone can be brominated at 50-60° when dissolved in oleum containing 80 per cent, of free anhydride, and then leads to a tetrabromanthraquinone (m.p. 295°) and a heptabrom- anthraquinone (m.p. over 350°) ; but Eckert and Steiner ^ have repeated the work and have stated that the tetrabromo compound is not formed.
The chlorination of anthraquinone can also be effected by means of antimony pentachloride, and by this means Diehl 5 obtained di-, tri-, tetra-, and penta-chlor compounds although he did not determine the positions occupied by the chlorine atoms. There can be no doubt, however, that Diehl's tetra-chlor compound was 1.4.5.8-tetrachloranthra- quinone. More recently Eckert and Steiner ^ have re- investigated the action of antimony pentachloride on anthra- quinone. By heating the two substances together in the presence of a trace of iodine they w^ere able to obtain a heptachlor compound, but all attempts to obtain an octa- chlor compound failed, as further chlorination led to the rupture of the anthraquinone ring and formation of perchlor-
1 B. 11. 179. 2 By., D.R.P. 228,901.
3 Bv.. D.R.P. 107,727. * M. 36, 269.
■* B. 11, 179. « M. 35, 175 ; 36, 269. B. 47, 2628.
THE HALOGEN COMPOUNDS 171
benzoyl benzoic acid and tetraclilorphthalic acid. The heptachlor compound melted at 380°, and in view of the fact that halogens first attack the a-positions, it would seem probable that the unchlorinated position was a j8-position, i.e. that the compound was 1.2.3.4.5.6.8-heptachloranthra- quinoue. Eckert and Steiner, however, prepared this compound from tetrachlorphthalic acid and 1.2.4-triclilor- benzene and found that it melted at 302°, although by heating with phosphorus pentachloride it was converted into the isomeric compound melting at 380°. By heating 1.2.3.4-tetrachloranthraquinone with antimon}^ pentachloride a mixture of the two heptachlor compounds was formed. From the above facts it would seem that the chlorination of anthraquinone leads first to 1.2.3.4.5.6.8-heptachloranthra- quinone (m.p. 302°), which then passes into 1.2.3.4.5.6.7- heptachloranthraquinone (m.p. 380°) by the wandering of a chlorine atom. Reactions of this type are not new, as it has long been known that a-bromnaphthalene passes into j3-bromnaphthalene under the influence of aluminium chloride.
When methyl anthraquinones are halogenated the halogen atom can enter either the nucleus or the side chain, which reaction takes place depending on the conditions of the experiment, although owing to the paucity of the data available it is impossible to draw any very definite con- clusions as to the conditions which favour each t5'pe of reaction. Ullmann ^ finds that when /S-methyl anthra- quinone is heated on the water bath with sulphur\'l chloride in nitrobenzene solution, 2-methyl-i-chloranthraquinone is formed in 80 per cent, yield. On the other hand, sulphur\'l chloride at 175° appears to convert /3-methylanthraquinone into jS-dichlormethylanthraquinone. 2
jS-Methylanthraquinone when chlorinated in nitrobenzene solution at 100° with molecular chlorine yields nuclear methylcliloranthraquinones,3 whereas with chlorine at 175° halogenation seems to take place in the side chain.* The action of bromine at 1^0-175°, with or without a solvent
1 B. 49, 737. Agfa, D.R.P. 269,249. * B.A.S.F., D.R.P. 216,715.
» Agfa. D.R.P. 293,156. * B.A.S.F., D.R.P. 216,715.
172 ANTHRACENE AND ANTHRAQVINONE
such as nitrobenzene, seems to be very similar, UUmann and Klingenberg,! and Hepp, Uhlenhuth, and Romer ^ obtaining ^-dibrommethylanthraquinone, and Eckert ^ ob- taining jS-tribrommethyl anthraquinone, although unable to obtain the jS-monobrommeth3'l anthraquinone described in the patent literature.* Among other similar results may be mentioned the preparation of a»-dibcom compoimds from 2-methyl-i-chloranthraquinone and from 2-methyl-3- chloranthraquinone by Ullmann,^ b}" the action of bromine at 160-170° in nitrobenzene solution. These brominations can be carried out in open vessels and the yields are often excellent.
The presence of an amino group in the anthraquinone nucleus greatly facilitates the entrance of halogen atoms, and use has been made of this in the preparation of nuclear halogen anthraquinones. Thus Ullmann ^ was able to prepare 1.3-dibromanthraquinone by brominating S-aminoanthraquinone and then removing the amino group from the resulting 2-amino-i.3-dibromanthraquinone in the usual way by diazotising and reducing. ^
Retrogressive Substitution. — Halogen atoms when in the a-position are fairh- easily removed by reduction, whereas those in the j3-position are much more firml}- bound. Retrogressive substitution, therefore, sometimes forms a convenient method of preparing the lower halogenated compounds and also furnishes some indication of the positions occupied by the halogen atoms. Kircher ' reduced 1.2.3.4-tetrachloranthraquinone with zinc dust and ammonia and obtained a dichloranthracene (m.p. 255°), which on oxidation gave a dichloranthraquinone (m.p. 261°), which he believes to be 1.2-dichlor anthraquinone, but which Ullmann ^ has since shown to be 2.3-dichloranthraquinone. More recently- Ullmann ^ has found that chlorine atoms when in the a-position, but not when in the jS-position, can be removed by heating the compound, e.g. in nitrobenzene solution, with potassium acetate and a trace of copper powder. Thus,
1 B. 46, 712. - B. 46, 709. 3 M. 35, 299.
* B.A.S.F., D.R.P. 216,715. ' B. 47, 558 ; 49. 737- * B. 49, 2157. ' A. 238, 344 « A. 381. 26. • B. 45, 687.
THE HALOGEN COMPOUNDS 173
although /S-chloranthraquinone is unaffected, a-chloranthra- quinone is reduced to anthraquinone itself, and i-metliyl- 4-chloranthraquinone to a-methylanthraquinone. In the case of 1.2.3.4-tetrachloranthraquinone only two chlorine atoms are removed, the product being 2.3-dicliloranthra- quinone.
Replacement of Group. — Amino groups are usually quite readily replaced by halogen atoms by first preparing the diazonium salt and then treating this with cuprous halide in the usual way.^ In some cases, however, there is a tendency for the cuprous halide to form a dianthraquinonyl derivative. 2
Hydroxyl groups can be replaced by chlorine atoms by treatment with phosphorus trichloride, phosphorus penta- chloride or phosphorus oxy-chloride.^ The cjxlic carbonyl groups are unaffected.
Niiro- groups either in the a-position or in the jS-position can be replaced by chlorine atoms by dissolving the nitro compound in some suitable solvent such as trichlorbenzene, and then treating it at 160° with chlorine.'* Meth3-1 groups if present are simultaneously chlorinated, but in the case of nitroanthraquinone sulphonic acids, the sulphonic acid groups are replaced before the nitro groups.
Sulphonic acid groups^ either in the a-position or in the j3-position, are verj- readily replaced by chlorine or bromine atoms, and in many cases this reaction forms the most convenient means of preparing halogen anthraquinones. The reaction can be brought about by heating to 170° with thionyl chloride,^ nitro groups if present remaining un- affected ; but it is much more convenient to treat a boiling aqueous solution of the sulphonic acid with molecular or nascent chlorine or bromine. ^ The nascent chlorine can
1 Kauffler, B. 36. 60. SchoU, B. 40, 1696 ; 43. 354. Laube. B. 40. 3566. By., D.R.P. 131,538.
» B.A.S.F.. D.R.P. 215,006.
3 Ullmann and Conzetti, B. 53, 832. Afga. D.R.P. 290,879.
•" B.A.S.F.. D.R.P. 12S.845, 252,578, 254,450.
* M.L.B., D.R.P. 267.544, 271.681, 284,976.
« Ullmann, A. 381. 2. Wolbling. B. 36, 3941. Heller, B. 46, 2703, By., D.R.P. 205,195, 205,913, 214,150. M.L.E., D.R.P. 77,179, 78,^2, 97.287.
174 ANTHRACENE AND ANTHRAQUINONE
be generated by allowing sodium hypochlorite solution, or sodium chlorate solution, to run slowly into a boiling solution of the sulphonic acid in dilute hydrochloric acid, and the author has found that the use of sodium chlorate gives particularly good results. The reaction proceeds quite readily and the chloro compound usually separates out in the crystalline condition, but it is "advisable to use rather dilute solutions. There is no necessity to isolate the sulphonic acids, it being sufficient to pour the crude sulphonation melt into water and then treat the resulting solution with molecular or nascent chlorine or bromine. In the case of polysulphonic acids either one or more sulphonic acid groups can be replaced by halogen, and if nitro groups are present these remain unaffected. Sulphonic acids when treated with halogens in concentrated stdphuric acid are halogenated without the stdphonic acid group being affected, so that by halogenating an anthraquinone sulphonic acid in concentrated sulphuric acid solution and then running the melt into water and again treating with halogen, a very large number of halogen anthraquinones can be obtained with very little trouble, i Another very fruitful method is to sulphonate, with or without the addition of mercury-, a halogen anthraquinone and then to dilute the melt and treat it with a halogen. 2
If an anthracene sulphonic acid is treated with sodium chlorate in boiling dilute hydrochloric acid solution, simulta- neous replacement of the sulphonic acid group and oxidation take place, the product being a chlorinated anthraquinone. 3 Properties. — Halogen atoms when situated in a side chain seem to be rather less reactive than would be expected, and as a rule the ctj-dLhalogenmeth)^ anthraquinones are unaffected by dilute alkali and can only be converted into the corresponding aldehyde by heating to 130° with con- centrated sulphuric acid.* Eckert,^ however, states that /3-tribrommethyl anthraquinone gives the carboxylic acid
1 B.A.S.F., D.R.P. 214,714, 216,071.
2 Hepp, Uhlenhuth, and Romer, B. 46, 709. Schilling, B. 46, 1066.
3 B.A.S.F., D.R.P. 228,876.
* See p. 159. 5 M. 35, 299.
THE HALOGEN COMPOUNDS 175
when heated to 180° with milk of Hme. In some wa^^s the a>-dibrommethyl compounds, however, are very reactive, and jS-dibrommethj^anthraquinone when heated to 240- 250° evolves torrents of hydrobromic acid and passes into dianthraquinonyldibromethylene,Ci4H702CBr : CBrCi4H702, from which diauthraquinonyl acetylene can be obtained by the action of diethylaniline or sodium phenolate.^
Halogen atoms when directly attached to the nucleus are somewhat less firml}^ bomid than is usually the case with aromatic halogen compomids. When in the a-position they are decidedly more reactive than when in the j3-position.
Halogen atoms in the a-position direct the entering nitro group to the /(-position, so that a-chloranthraquinone gives i-chIor-4-nitroanthraquinone, and 1.5- and i.8-dichlor- anthraquinones give corresponding compounds.^ From 1.4- dichloranthraquinone Walsch and Weizmami ^ obtained a mononitro compound (m.p. 238°), but did not determine the position of the nitro group. From i.4-dichlor-5.8- dimethyl anthraquinone Harrop, Norris, and Weizmann ^ obtained a dinitro compound, but offer no information as to the position of the nitro group. Heller ^ by nitrating 3-chloralizarin obtained a mononitro compound which must be 3-chlor-4-nitroalizarin, as it gives phthalic acid when oxidised.
^ UUmann and Klingenberg, B. 46, 712.
* Eckert and Steiner, M. 35, 1138. By., D.R.P. 137,782, 249,721.
3 Soc. 97, 687. ■» Soc. 95, 1318. * B. 46, 2703.
CHAPTER X
THE SULPHONIC ACIDS, MERCAPTANS, AND SULPHIDES
I. The Sul,phonic Acids
Anthraquinone is not very easily sulphonated, but treat- ment with oleum leads first to the ^-monosulphonic acid and then to a mixture of disulphonic acids in which the 2.6- and the 2. 7-disulphonic acids predominate.! If it is desired to prepare anthraquinone monosulphonic acid reasonably free from disulphonic acid it is absolutely essential to interrupt the reaction while some 20 per cent, of the anthraquinone is still unchanged, as if the process is carried on until the whole of the anthraquinone has been attacked the product will be foimd to contain considerable quantities of disulphonic acid. In an}- case the sulphonation of anthraquinone is always accompanied by a certain amount of simultaneous hydroxylation, and consequentl}^ a deep purple colour is developed when a portion of the melt is made alkaline. Under suitable conditions, however, the loss by hydrox3da- tion is only slight.
Both the j3-sulphonic acid and the two disulphonic acids are manufactured on the technical scale and are used in the manufacture of alizarin dj-es. The monosulphonic acid is isolated by diluting the stdphonation melt, filtering off the unchanged anthraquinone and then saturating the solution with sodium chloride. Under these conditions the sodium
^ Perkin, A. 158, 323. Graebe and Liebermann, A. 160, 130. Caro, Graebe, and Liebermann, B. 3, 359. Liebermann and Bollert, A. 212, 56; B. 15, 229. Schunck and Romer, B. 9, 679. Liebermann and Dehnst, B. 12, 1288. Perger, B. 12, 156O. Romer, B. 15, 224. Crossley,Am. Soc, 37, 2178.
176
THE SULPHONIC ACIDS 177
salt of the monosulphonic acid separates out in silvery- scales, the silvety appearance having given rise to the technical name " silver salt." The disulphonic acids are more soluble, and to isolate them it is best to neutralise the solution and then remove the sodium sulphate by fractional crystal- lisation.
It should be noticed that when anthraquinone is sulphonated without the use of a catalyst only two sulphonic acid groups can be introduced into the molecule, and that the products formed are almost exclusively /3-sulphonic acids although verj^ small quantities of a-sulphonic acids are also formed. 1
If the sulphonation of anthraquinone is carried out in the presence of a small quantity of mercuric sulphate a totall}' different result is obtained, the sulphonic acid groups under these circumstances exclusively entering the a-positions.2 The first product formed is anthraquinone- a-sulphonic acid, further sulphonation leading to a mixture of the 1.5- and i.8-disulphonic acids. All these are easily salted out as their potassium salts by adding potassium chloride to their solutions in dilute sulphuric acid. The two disulphonic acids are readily separated by taking advantage of the fact that the 1.5-disulphonic acid is insoluble in con- centrated sulphuric acid, whereas the i.8-disulphonic acid is soluble. If, therefore, the sulphonation melt is diluted with concentrated sulphuric acid the former acid crystallises out and can be filtered off and washed with concentrated sulphuric acid and finally dissolved in water and salted out by the addition of potassium chloride. The concentrated sulphuric acid mother liquors contain the i.8-disulphonic acid, and when they are diluted and treated with potassium chloride the potassium salt of this acid separates.
By sulphonating anthraquinone itself in the presence of mercury only two sulphonic acid groups can be introduced into the molecule, but trisulphonic acids, presumably the 1.3.6- and the 1.3.7-tTisulphonic acids, can be obtained
^ Diinschmann, B. 37, 331. Liebermann and Pleus, B. 37, 64G. » Iljinsky, B. 36, 4194. R. E. Schmidt, B. 37. 66. By., D.K.P. 149,801.
12
178 ANTHRACENE AND ANTHRAQUINONE
either by snlphonating an a-sulphonic acid without the addition of mercuty, or by snlphonating a j3-sulphonic acid in the presence of mercury. i
By sulphonating anthraquinone itself in the presence of mercuric sulphate which is only coarsely powdered, it has been claimed that anthraquinone-i.6- and 1.7-disulphonic acids can be obtained in one operation. 2 •'
The directing influence of mercury is not confined to anthraquinone itself, but also extends to anthraquinone derivations, and Ullmann ^ has foimd that when halogen anthraquinones are sulphonated in the presence of mercury the sulphonic acid group enters the a- position.
It has been claimed that the sulphonation of anthra- quinone is facilitated by the catalytic action of vanadium, but experiments w^hich have been made by the author fail to support this claim. *
Although direct sulphonation is by far the most im- portant method of preparing anthraquinone sulphonic acids, sulphonic acid groups can also sometimes be intro- duced into the molecule by other means. Thus halogen atoms are sometimes replaced by sulphonic acid groups by treatment with sulphiiric acid,^ although the reaction is by no means a general one, and many halogen compoimds can be sulphonated in a normal manner. ^ In the case of i-amino-4-ar>damino-2-halogen anthraquinones the halogen atom can be replaced by the sulphonic acid group by heating with aqueous sodium sulphite solution.'^
Boihng with aqueous sodium sulphite solution in many cases leads to the production of sulphonic acids by replace- ment of the nitro group, i-nitroanthraquinone, 1.5- and i.8-dinitroanthraquinone and some hydrox>'nitroanthra- quinones reacting in this way .» In the case of i .4-dihydroxy-
1 Wed.. D.R.P. 170,329; 202,398.
2 Wed., D.R.P. 202,398.
3 D.R.P. 223,642.
* Thiimmler, D.R.P. 214,156.
* Perkin, A. 158, 319. Graebe and Liebermann, A. 160, 137.
« E.g. Walsh and Weizmann, Soc. 97, 688. By., D.R.P. 217,552. Ullmann, D.R.P. 223,642. ' By., D.R.P. 288,878. 8 R. E. Schmidt, B. 36, 39. By., D.R.P. 164,292, 167,169.
THE SULPHONIC ACIDS 179
anthraquinones, i.4-aminohydrox>'antliraquinones and 1.4- diaminoanthraquinones, treatment with aqueous sodium sulphite solution will bring about sulphonation without replacement. 1 Here the reaction is no doubt due to the formation of a true quinonoid compound, ^-quinone, quinone-imide or quinone di-imide, and then addition to this of sodium bisulphite. This view of the reaction is supported by the fact that sulphonation takes place most readily in the presence of an oxidising agent such as manganese dioxide. In the absence of an oxidising agent the formation of the quinonoid compound is no doubt brought about at the expense of part of the ox>'gen of the cyclic carbonyl groups. The anthraquinone sulphonic acids are usually fairly easily dcsulphonated by hydrolysis, although the ease with which the sulphonic acid group is split off varies to a great extent in different mdividual substances. As a rule, the hydrolysis can be effected by heating to 170-190° with sulphuric acid of 80 per cent, strength,^ but sulphonic acid groups in the a-position are somewhat less firmly held than similar groups in the jS-position and are usually readil}- split off by treatment with sulphuric acid of 50-80 per cent, strength. 3 The addition of boric acid sometimes has a favourable effect, and in man}- cases the addition of a reducing agent such as a phenol, amine, sugar, metal, or stannous chloride greatly assists the reaction. The effect of the reducing agent is largely catalytic, as only relatively small amounts are required. ^ The presence of other groups in the molecule also renders hydrolysis more easy, a notable example being that of i.3.5.7-tetrahydroxy-4.8-dinitro- anthraquinone-2.6-disulphonic acid, which is dcsulphonated when boiled with sulphuric acid of 20 per cent, strength. ^ It should be remembered that during hydrolysis bromine atoms if present are apt to wander. ^
» B}'., D.R.P. 287,867 ; 288,474; 289,112.
» By., D.R.P. 56,951 ; 172,688. Wed., D.R.P. 210,863.
» By., D.R.P. 160,104.
* By., D.R.P. 190,476.
* M.L.B., D.R.P. 71,964 ; 77,720.
« B.A.S.F., D.R.P. 263,395 ; 265,727 ; 266,563. M.L.B.. D.R.P. 253.683. G.E., D.R P. 277.393
i8o ANTHRACENE AND ANTHRAQUINONE
Desiilpiionatioii of sulphonic acids can also sometimes be brought about by reduction. Thus hexahydroxy anthra- quinone is obtained when its disulphonic acid is reduced in acid solution by zinc, iron, or aluminium, the sulphonic acid group being split off in the form of sulphuretted hydrogen. ^
The anthraquinone sulphonic acids are converted into the sulphochlorides by treatment with pHbsphorus penta- chloride and phosphorus oxy chloride, 2 sulphochlorides also being obtained in many cases by the action of chlorsulphonic acid on the anthraquinone sulphonic acids. ^
These sulphochlorides behave like other sulphochlorides. On reduction with sodium sulphide they give the corre- sponding sulphinic acids.*
The nitration of anthraquinoue-a-sulphonic acid leads to a mixture of 1.5- and i.8-nitroanthraquinone sulphonic acids, the isomers being very easily separated owing to the insolubility of the former in the nitrating acid.^ The nitration of anthraquinone-/3-sulphonic also leads to two isomeric raononitro compounds, one of which, according to Claus 6 and lyifschtitz,'^ can be converted into alizarin. R. E. Schmidt,^ however, has found that the two nitro compounds formed are really i-nitroanthraquinone-6- sulphonic acid and i-nitroanthraquinone-7-sulphonic acid, and Frobenius and Hepp ^ have severely criticised Claus' work and have shown that what Claus described as erythro- hydroxyanthraquinone sulphonic acid is really the diazo sulphonic acid, Claus having overlooked the presence of nitrogen.
II. The Sulphinic Acids
The anthraquinone sulphinic acids are of no particular interest and can be obtained either by reducing the sulpho- chlorides with sodium sulphide, 10 or by the oxidation of the sulphenic acids (sulphoxylic acids). They behave very much like other aromatic sulphinic acids. Thus anthra-
1 Bv-.D.R.P. 103,898. * Ullmann, B.52, 545. ^ m.L.B.. D.R.P. 266,521. « M.L.B., D.R.P. 26^,340. Cf. M.L.B.. D.R.P. 224,019. 8 R. E. Schmidt, B. 37, 71. « B. 15, 1521.
» B. 17, 899. » B. 37, 69. » B. 40, 1048.
»» M.L.B., D.R.P. 263,340. Cf. M.L.B., D.R.P. 224,019.
THE SULPHENIC (SULPHOXYLIC) ACIDS i8i
quinone-j3-sulphinic acid very readily condenses with tetramethyldiaminobenzhydrol (Miscliler's hydrol) to form an ester, i Ci4H702.SOOCH(C6H4NMe2)2, and also readily adds on to quinonoid compounds, 2 e.g. with benzoquinone it gives Ci4H702.S02.C6H3(OH)2.
III. The Sulphenic (vSulphoxylic) Acids
When an anthraquinone mercaptan or disulphide is treated with chlorine or bromine in chloroform solution an anthraquinone sulphur halide, Ci4H702.SHlg, is often obtained, although the reaction is by no means a general one and several exceptions are known. ^ The bromides are also often obtained by reducing the sulphinic acids in glacial acetic acid solution by means of hydrobromic acid.*
The sulphur halides of the anthraquinone series usually show reactions ver}^ similar to those of other aromatic sulphur halides, s although the}- are much more stable than is usually the case with compounds of this class. Thus anthraquinone-j3-sulphur chloride reacts with acetone to form an acetyl compound, and with water to give the anhydride of the sulphenic acid (Ci4H702S)20. With alcohol it gives a mixture of disulphide, disulphoxide, and sulphinic acid.^
Anthraquinone-a-sulphur chloride is not nearly so reactive as the j8-compound and will not react with acetone, phenyl benzyl ketone, acetophenone, or acetoacetic ester, although it behaves normally towards ammonia with the production of a sulphamide which under the influence of mineral acids readily passes into a thiazole :
* Hinsberg, B. 50, 472. ^ Hinsberg, B. 50, 953. ^ Friess, B. 45, 2965. Friess and Schurmann, B. 52, 2182.
•• Friess and Schiirmann, B. 47, 1192. M.L.B., D.R.P. 277,439.
* Cf. Zincke, A. 391, 55 ; 400, i ; 416, 86.
* Friess, B. 47, 2965. Friess and Schurmann, B. 52, 2170.
i82 ANTHRACENE AND ANTHRAQUINONE
The a-sulphur chloride is quite stable towards water and only reacts with alcohol after prolonged boiling, and then gives the ester of the sulphenic acid, from which the free acid can be obtained by hydrolysis although it cannot be obtained from the chloride directly by the action of water. The alkali salts of the acid when treated with dimethyl sulphate give the methyl ester of the acid, -but the free acid itself gives methyl anthraquinonyl sulphoxide, so that salt formation is probably accompanied by a change in structure :^
/O
CuHvOa.Sf ^ CuH^O^.S-OH
Normal form. Pseudo form.
Alkaline solutions of the acid are readily oxidised by th-e air with the production of the sulphinic acid. When the acid itself is boiled in glacial acetic acid solution simulta- neous oxidation and reduction takes place with the pro- duction of a mixture of sulphinic acid and disulphide.
As stated above anthraquinone-a-sulphur chloride will not react with acetoacetic ester. It will react, however, with sodioacetoacetic ester, the product on hydrolysis giving an acetyl thiopheneanthrone :
COQLi
^S CH,COCr
ch,ccch:^
CO
CO
IV. The Mercaptans
The anthraquinone diazonium salts do not give the mercaptan when treated with potassium sulphydrate, although, as will be seen later, they readily give mixed sulphides when treated with aromatic alkali mercaptides. The mercaptans can, however, be prepared from the diazo- nium salts b}^ indirect methods. The diazonium salts react
^ Friess, B. 45, 29G5. Friess and Schiirmann, B. 52, 2170.
THE MERCAPTANS 183
only very slowly with copper thiocyanate, but react readily with potassium thiocyanate, and this is especially true when the diazonium group occupies an a-position. The resulting thiocyanate cannot be hydrolysed by acids but can be hydrolysed by alcoholic caustic potash, and then yields the mercaptan.i A second method of obtaining the mercaptan is to treat the diazonium salt with potassium xanthate and then to hydrolyse the resulting anthraquinone xanthate by boiling with aqueous alcoholic alkali. 2 Another alternative method is to treat the diazonium salt with thiourea, no catalyst being necessary, and then to hydrolyse the carbamyl derivative thus formed. ^ In this case, however, there is some tendency when dealing with a-derivatives of a side reaction taking place with the formation of a heterocyclic compound in which one of the cyclic carbonyl groups is involved :
Both a-cliloranthraquinone and iS-cliloranthraquinone give the corresponding mercaptan when heated with alkali sulphide, sulp hydrate, or poly sulphide, * and anthraquinone- i-mercaptan and anthraquinone-i.5-dimercaptan can be obtained in the same way from anthraquinone- i-sulphonic acid and from anthraquinone-i.5-disulphonic acid.^ Mer- captans can also be obtained by reducing the corresponding sulphochlorides ^ or disulphides,'^ and in the case of a- hydrox>'anthraquinones and j6-hydroxyanthraquinones a mercaptan group can be directly inserted into the molecule in the ortho- position by fusing with sodium sulphide at 150°.
» Gattermann, A. 393, 113. By., D.R.P. 206,054 ; 208,640.
* M.L.B.. D.R.P. 241,985. 3 M.L.B., D.R.P. 239.762.
♦ By., D.R.P. 204,772 ; 206,536. « By.. D.R.P. 212.857. ■
« M.L.B., D.R.P. 292.457. By., D.R.P. 281.102.
» Gattermann, A. 393, 113. UUmann, B. 49, 739. Friess and Schiir- mann, B. 52, 2176, 2186.
t84 anthracene AND ANTHRAQUINONE
When two hydroxyl or amino groups are present in a- positions, if these two groups are attached to different benzene nuclei, two mercaptan groups can be inserted ; but if the amino or hydrox}4 groups are attached to the same nucleus, e.g. as in quinizarin, only one mercaptan group enters the molecule. ^ Finally, anthraquinone mercaptans have been obtained by inserting the mercaptan group into the benzoyl benzoic acid and then closing the anthraquinone ring. 2
The anthraquinone mercaptans are rather troublesome substances to handle as they are very readily oxidised to the corresponding disulphide, in the absence of an external oxidising agent the oxidation often being brought about at the expense of the cj-clic carbonyl groups. Those mercaptans in which the mercaptan group is in the a-position are much more easily oxidised than those compounds in which the mercaptan group occupies a ^-position.
The mercaptans have great affinity for the fibre but are scarcely to be regarded as dyes, as the shade obtained is that of the corresponding disulphide owing to oxidation taking place in the dye bath. Thus, if a dyeing is carried out with anthraquinone-a-mercaptan at a temperature of over 50° the shade obtained is fast, but is that of the disul- phide owing to oxidation taking place. Even if the dyeing is carried out in an atmosphere of carbon dioxide the disulphide is formed owing to intermolecular oxidation and reduction. If the dyeing is carried out at a temperature below 50° the shade obtained is that due to the mercaptau but is very loose to soap. Owing to their greater stability it is somewhat easier to apply the j3-mercaptans to the fibre, but the shades obtained are very poor. The benzoyl derivative of anthraquinone-a-mercaptan has been prepared ^ but was found to have no tinctorial properties.
The mercaptans are, as would be expected, much more highly coloured than the corresponding oxygen compounds,
1 G.E,, D.R.P. 290,084. - B.A.S.F , D.R.P. 247.412.
' Seer and Weitzenbock, M. 31, 371.
THE MERC APT ANS
185
and this is particularly true of the alkali salts. This will be clearly seen by comparing the following substances, the colours given being in all cases those of the solutions in caustic soda : —
OH
Red.
SH
Violet.
OH
Yellowish- Red.
SH
Bluish-Red.
OH
OH
Violet.
OH
SH
Blue.
OH
SH
SH Green.
SH
HO Yellowish- Red.
HS
Violet.
V. The SeIvEnophenols
Selenophenols of the anthraquinone series have been obtained by treating anthraquinone diazonium salts with potassium selenocyanide and then hydrolysing the seleno- cyanide,* and also from negatively substituted anthra- quinones, such as a-chloranthraquinone and ^-chloranthra- quinone, by heating with alkali selenides.2 They are of no particular interest.
^ By., D.R.P. 264,940, 2 By., D.R.P. 264,941.
i86 ANTHRACENE AND ANTHRAQUINONE
VI. The vSui^phtdes
Sulphides of the anthraquinone series can be obtained by condensing anthraquinone mercaptans with alkyl, arv^l, or anthraquinonyl halides,i but when an anthraquinone- a-mercaptan is condensed with an alykl hahde there is often a great tendency for loss of water to take place with forma- tion of a thiophene anthrone.2 When preparing dianthra- quinonyl sulphides it is often imnecessary to isolate the mercaptan, dianthraquinonyl sulphides, for example, being obtained in one operation when either a- or /3-chloranthra- quinone is boiled with potassium xanthate in some suitable solvent such as amyl alcohol or nitrobenzene. 3 The dianthra- quinonyl sulphides are also obtained from the mercaptans when these latter are heated to about 320°, either alone or with some substance such as an alkali or a metal which is capable of combining with sulphuretted hydrogen.*
The sulphur chlorides of the anthraquinone series also condense qiiite readily with aromatic substances such as benzene under the influence of aluminium chloride, and in the case of dimethyl aniline and phenols, especiall}- resorcinol and ^-naphthol, the sulphide is formed without the use of any condensing agent. ^ Very similar to this is the formation of sulphides ^ by condensing anthraquinone mercaptans with aromatic compounds such as benzene, toluene, naphtha- lene, phenol, etc., by treatment with concentrated sulphuric acid at about 30°. Here no doubt the sulphuric acid first oxidises the mercaptan to the sulphenic acid, sulphide formation then taking place by loss of water. ^ All the above methods involve the preparation of anthraquinone mercaptans, but sulphides can also be obtained from anthraquinone compounds containing negative substituents,
^ Gattermann, A. 393, 113. Friess and Schiirmann, B. 52, 2194. By., D.R.P. 213,960; 272,300; 274,357. M.L.B., D.R.P. 249,225 ; 253,507.
- See p. 370.
3 UUmann and Goldberg, D.R.P. 255,591. By., D.R.P. 272,298.
* By., D.R.P. 254,561.
5 Friess and Schiirmann, B. 52, 2179, 2194. M.L.B., D.R.P. 277,439.
« M.L.B., D.R.P. 262,^77.
' Cf. Davis and Smiles, Soc. 97, 1220. Prescott, Hutchison, and Smiles, Soc. 99, 640.
THE BISULPHIDES
187
such as sulphonic acid groups, 1 nitro groups,^ or halogen atoms, 3 by condensing them with an alkali salt of an aromatic mercaptan.
The sulphides are usually yellow vat dyes, although of no technical importance. The presence of a hydroxyl or an amino group in the para- position to the sulphur atom changes the shade to violet or blue.
VII. The Bisulphides
The anthraquinone disulphides are easily obtained from the halogen anthraquinones by the action of alkali di- suljDliides,'* and as already stated are VQTy readily produced by the oxidation of the mercaptans either by atmospheric cxj'gen or by potassium ferricyanide.s Ullmann ^ has found that a-chloranthraquinone will condense with thiol- benzoic acid, and that the product on hydrolysis yields a disulphide. Here probably the mercaptan combines with the thiolbenzoic acid to form 5-benzoylanthraquinone- I -mercaptan, hydrolysis of this leading to the mercaptan, which under the experimental condition undergoes intra- molecular oxidation with the formation of a disulphide :
SCOCeHg
SH
/3-Chloranthraquinone does not condense with thiolbenzoic acid, but from ^-bromanthraquinone 2.2'-dianthraquinonyl disulphide can be obtained.
The sulphonic acids of the disulphides have very great
1 Decker and Wursch, A. 348, 238. By., D.R.P. 224,589.
2 By., D.R.P. 116.951 ; 224,589.
* Harrop, Norris, and Weizmann, Soc. 95, 1316. Schaarschmidt, A. 409, 59- B.A.S.F., D.R.P. 250,273; 251,115; 251,709. By., D.R.P. 224,589.
* Friess, B. 45, 2967 ; 52, 2176, 218G. Ullmann, B. 49, 739. By., D.R.P. 204,772 ; 206,530.
* Gattermann. A. 393, 113. "A. 399. 352.
i88 ANTHRACENE AND ANTHRAQUINONE
affinity for animal fibre, the dyestuff being taken up quanti- tatively and the dyebath left completely colourless.
A large number of sulphur containing dyes have been described as being obtained by heating anthraquinone derivatives with sulphur chloride or sodium sidphide and/or sulphur. 1 The constitution of these compounds is quite imknown, but they are probably sulphides, 'disulphides, or mercaptans. In a number of cases it is claimed that a brighter shade and improved fastness is obtained by treating the dye with a mild oxidising agent such as a hypochlorite, 2 and this improvement in the tinctorial properties is probably due to the oxidation of a mercaptan to a disulphide.
Yellow and brown vat dyes have also been claimed as being obtained when anthraquinone diazonium salts are treated with sulphur chloride 3 or with a thioarsenate, thiostannate, or thioantimonate ; ^ nothing whatsoever is known of the constitution of these bodies. The same remark also applies to the dyes obtained by treating anthraquinone derivatives with sodium thiosulphate.s
VIII. The Diselenides
The diselenides are of very little interest, but have been obtained by the action of alkali diselenides on a-chloranthra- quinone and on jS-chloranthraquinone.^
IX. The Thianthrenes
From thianthrene itself by the phthalic acid synthesis Scholl ' obtained a compound which was probably lin.-
^ The following are the chief patents relating to this class of compound : Agfa, D.R.P. 240,792 ; 246,867. B.A.S.F., D.R.P. 91,508 ; 186,990 ; 242,621. By., D.R.P. 172,575 ; 175,629; 176,641; 176,955; 178.840; 179,608; 179,671; 180,016; 226,879; 226,957. Cassella, D.R.P. 242,029; 247,416. G.C.I. B., D.R.P. 204,958; 205,212; 205,217-8; 208,559; 209,231; 209,232-3; 209,351; 211,967; 213,506; 223,176; 243,751 ; 254,098 ; 261.557 ; 265,194- M.L.B., D.R.P. 251,234-5 ; 311,906. Wed.. D.R.P. 237,946; 293,970; 311,906.
* E.g. G.C. I.E., D.R.P. 209,231-2-3 ; 211,967; 213,506; 265,194.
3 Agfa, D.R P. 229,465. * Agfa, D.R.P. 229,110.
6 Wed., D.R.P. 296,207 ; 297,079 ; 297,080 ; 297,567 ; 298,182-3 ; 290. "iio,
» By., D.R.P. 264,941. ' B. 44, 1233.
THE THIANTHRENES 189
diplithaloylthiauthrene (I.), whereas from methylthianthreiie he obtained what was most probably trans, bisang.-^.^'- dimethyldiphthaloylthianthrene (II.) :
CO CHj CO s CO
CO S CO
trans. ^tsan^g-Diphthaloylthiauthrene itself can be obtained by condensing 1.2-dichloranthraquinone with anthraquinone- 1 .2-dimercaptan. ^
All three of these substances are red in colour, but only the two trans, bisang. compounds are capable of being used as dyes, as the /zw.- compound has no tinctorial properties.
> B.A.S.F., D.R.P. 248,171.
CHAPTER XI
THE AMINOANTHRAQUINONES AND DIANTHRAQUINONYLAMINES
The aminoanthraquinones are of great importance, as they form the starting-out point in the synthesis of a very large number of important anthraquinone derivatives. The simple primary aminoanthraquinones as a rule have nc tinctorial properties, although some of the amino-hydroxy compounds are valuable dyes, e.g. Alizarin Saphirol.i The sulphonated aryl aminoanthraquinones are used as acid wool dyes to a considerable extent, the best known being Alizarin Cyanine Green ^ : ,
/CH3 NHC6H3/
^SOsH
CH.
I
NC«H.NH
SO3H'
'6-^-^3
This dyes in yellowish-green shades which become faster when after-chromed.
The dianthraquinonylamines are vat dyes, but as a rule the tinctorial properties are feeble unless three anthra- quinon5'l groups are present, these dianthraquinon3^1amino anthraquinones actmg as a rule as vat dyes giving bordeaux shades, e.g. Indanthrene Bordeaux B :
1 Solway Blue (Scottish Dyes, Ltd.). * Kymric Green (Scottish Dyes, Ltd.). iqo
THE A MI NO A NTHRA Q U I NONES -NH—
IQI
I
I
— NH-
I
Although neither the primary aminoanthraquinones nor their acetyl derivatives have any tinctorial properties, the acylamino anthraquinones, in which the acyl group is derived from a dibasic fatty acid, or from a mono- or di-basic aromatic acid, are powerful vat dyes, and by selecting a suitable aminoanthraquinone all shades from yellow to blue and violet can be obtained. Two of the simplest dyes of this class which have found technical application are Algol Yellow W.G (a-benzoyl aminoanthraquinone) and Algol Yellow 3G (a-succinyl aminoanthraquinone) :
NHCOCgHg NH.CO.CH2.CH2.CO.NH
Algol Yellow W.G.
Algol Yellow 3G.
The anthraquinonyl ureas also belong to this class and are vat dyes.
The two chief methods which are utilised for introducing the amino group into the anthraquinone molecule are the reduction of nitro groups, and the replacement of negative atoms or groups such as halogen atoms or nitro, hydroxyl, or sulphonic acid groups. In addition amino and hydroxyl groups can often be introduced simultaneously by reducing the nitro compomid to the hydroxydamine derivative and then treating this with an acid in order to cause the hydroxyl group to wander to the para- position. This last type of reaction will be discussed in the section dealing with the aminohydroxy anthraquinones.
The reduction of the nitro group leads, of course, only to piimar>' amino compounds ; but the second method, viz.
192 ANTHRAC3NE AND ANTHRAQUINONE
the repiacemeut oi negative groups, can be used for the production of primarx-, secondary, or tertiary amino com- pounds, and as the reaction usually takes place very easily it has been widely applied.
The primary aminoanthraquinones are extremely weak bases, but the basicity increases with the entrance of alkyl groups, the alkylaminoanthraquinones being more strongly basic than the primary compounds, and the di- alkylamino anthraquinones being sufficiently basic to form salts which are not hydrolysed.
Reduction of Nitro Groups
Although nitro groups when attached to the anthra- quinone nucleus can be reduced by tin and hydrochloric or acetic acid,i it is much better to carr>^ out the reduction in alkaline solution by means of sodium stannite,^ glucose and caustic soda, 3 zinc dust and caustic soda or ammonia,* or sodium sulphide or sulphydrate.^ Of these sodium sulphide gives by far the best results, and is to be regarded as the standard reagent for the reduction of nitroanthraquinones. As a rule, the reaction is carried out by making the nitro compound into a thin paste with cold aqueous sodium sulphide solution and then pouring this into boiling water and boiling the whole for a few minutes. The action of the cold sodium sulphide on the nitro compound usually pro- duces a highly coloiired solution owing to reduction to the hydroxylamine derivative, reduction to the amino compound only taking place on the application of heat. As a rule, the yield of amino compound obtained by the above method is almost quantitative, but in some cases the production of substances containing sulphur has been recorded. Thus
^ Bottger and Petersen, A. 160, 149. Walsh and Weizmann, Soc. 97, 687. Lifschutz, B. 17, 899.
* Bottger and Petersen, A. 160, 149. R6mer, B. 15, 1790 ; 16. 366. " Wacker, B. 34, 3922.
4 Claus, B. 15, 1517. Przibram, D.R.P. 6,526.
* Bottger and Petersen, A. 160, 149 ; 166, 149. UUmann, A. 388, 203. Schaarschmidt, A. 407, 184. Claus. B. 15, 1517. R. E. Schmidt, B. 37. 171. SchoU and Kacer, B. 37. 4531. Noelting and Wortmann, B. 39, 637. Scholl, B. 40, 1696 ; 43, 354. Schaarschmidt and Stahlschmidt, B. 45. 3454. Seer, M. 32. 160. Eckert, M. 35, 298. Bv.. D.R.P. 100,138; 119,228. Lauth, C. r. 137. 662.
THE AMINOANTHRAQUINONES 193
Terres ^ states that when i-nitro-2-ammoanthraquinone is reduced with sodium sulphide side reactions take place with the production of compounds containing sulphur, but that this is not the case if ammonium sulphide is used in place of the sodium salt. 2 Schaarschmidt/'^ on the other hand, reduced both 2-nitro-3-aminoanthraquinone and i-nitro-2-aminoanthraqmnone with sodium sulphide and does not seem to have noticed any marked tendency to produce sulphur compounds. In the case of the former sub- stance he states that the 3deld of the diamino compound was almost theoretical, but that in the preparation of 1.2-dianiino- anthraquinone the yield was not quite so good. He gives the melting point as 301° as compared with 297-298° found by Terres.
Although the use of sodium sulphide may in some cases lead to an impure amino compomid, the results as a rule are excellent, the preparation of a-aminoanthraquinone from a-nitroanthraquinone being particularly easy.'* In this case there is no need to purify the nitroanthraquinone before reduction, as the author has found that reduction of a crude nitro compound melting fifteen or twenty degrees below the correct temperature will give an amino compound, which without recrystallising will melt within three degrees of the correct melting point.
In some cases the reduction of nitroanthraquinone sulphonic acids is accompanied by simultaneous loss of the sulphonic acid group, although this can usually be avoided by carr3'ing out the reduction under carefiilly controlled conditions. Claus ^ for example, finds that i-nitro-anthra- quinone-2-sulphonic acid is best reduced to the amino acid by means of sodium amalgam.
The partial reduction of dinitroanthraquinones can in some cases be effected by heating under pressure with sodium sulphite, 6 although there is considerable danger
1 B. 46, 1641. C/. Schaarschmidt. A. 407, 84. M.L.B., D.R.P. 72,552; 73.6S4; 77.720; 81,741; 145. 237-
- Cf. Romer, B. 15, 1790. ' A. 407, 1S4.
* Lauth, C.r. 137, G62. Ullmann, A. 388, 203.
fi B. 15, 1517. " M.L.B., D.R P. 78,772-
13
104 ANTHRACENE AND ANTHRAQUINONE
that the reaction will take a different course, the nitro groups being replaced by sulplionic acid groups. ^ In the case of 1.5-dinitroanthraquinone and i.8-dinitroanthra- quinone reduction of one nitro group is easily and quanti- tativel)' brought about by heating with secondary or tertiar\^ aromatic amines, especially dimethyl aniline. 2 This is a rather remarkable reaction and merits gfeater attention than it seems to have received.
The simultaneous reduction and sulphonation of nitro- anthraquinones is sometimes brought about by the use of sodium bisulphite. This is particularly the case with dinitrodiaminoanthraquinone,3 dinitroanthrarufin, and di- nitroanthrachrysazin,^ although not confined to these substances.^ The simultaneous reduction and sulphonation of nitro compounds by the action of sulphites is, of course, a well-known reaction in the aromatic series, one of the best known examples being the formation of ?;?-nitraniline sulplionic acid from w-dinitrobenzene.o
The simultaneous reduction and bromination of nitro- anthraquinones can be effected by heating under pressure with h3'drobromic acid with or without the addition of bromine.''
Instead of preparing aminoanthraquinones by nitrating and then reducing an anthraquinone compound, a benzoyl benzoic acid can be nitrated and reduced, ^ and the amino- benzo}^ benzoic acid then converted into the aminoanthra- quinone by closing the anthraquinone ring in the usual way, viz. b}^ heating with sulphuric acid.^ In many cases the aminobenzo3'l benzoic acid can be readily purified by converting it into its well-cr^^stallised. and sparingly soluble lactam. 10
When crude dinitroanthraquinone, obtained b}' the nitration of anthraquinone, is reduced with sodium sulphide a mixture of diaminoanthraquinones is obtained. This has been examined by Noelting and Wortmann,ii who found that
1 By., D.R.P. 164,292; 167,169. 2 By., D.R.P. 147,851.
3 M.L.B.. D.R.P. 126,804. « Bv., D.R.P. 103,395 ; 152,013.
6 See p. 283. 6 Nietzki, B. 29, 2448. D.R.P. 86,097.
' B.A.S.F., D.R.P. 128,845. 8 Agfa, D.R.P. 248,838.
» Agfa, D.R.P. 260,899. See also p. 140. '» Agfa, D.R.P. 258,343.
1' B. 39, 637.
THE AMINO ANTHRAQUINONES 195
if the crude bases are recrj^stallised from aqueous sulphuric acid (1:1 by volume) the dilHcultly soluble sulphate of 1.5-dianiinoanthraquinoiie separated. The free bases could then be precipitated from the mother liquor and boiled in equal volumes of glacial acetic acid and acetic anhydride. On cooling the acetyl derivative of i.8-diaminoanthraquinone separated. Fritzsche ' obtained a dinitroanthraquinone by boiling anthracene with dilute nitric acid, and this on reduc- tion gives a diaminoanthraquinone, which Noelting and Wortmann2 have identified as 2.7-diaminoanthraquinone, as they find that it gives isoanthraflavic acid when diazotised and boiled with water.
vScholl has found that i-nitro-2-methylanthraquinone is reduced to i-amino-2-methylanthraquinone when boiled with methyl alcoholic caustic potash of 30 per cent, strength. In relation to this he discusses the mechanism of the change of o-nitrotoluene to anthranilic acid when heated with aqueous or alcoholic alkali, or even with water at 500- 1000° C, and concludes that the first step is the formation of the quinonoid o-meth5dene nitrolic acid, which then passes into the nitrosobenzyl alcohol by the wandering of the hydroxyl group ; but for details the reader is referred to the original literature. ^
RepIvAcement of Negative Groups
Negative atoms and groups, especially when m the a-position, are very readil}- replaced by primary' amino groups by heating with ammonia, and if a primary- or secondar}- amine is used in place of ammonia, secondary' and tertiar}' amino compounds can be obtained. Piperidine behaves like a secondan.- amine and leads to N-anthra- quinonyl piperidines.
Owing to the importance of the reaction the number of patents which have been taken out is extremely large, and
1 Z. 1869, 114, Cf. E. Schmidt, J. pr. [2] 9. 26O.
- B. 39, 637.
» SchoU, M. 34, loii.
196 ANTHRACENE AND ANTHRAQUINONE
only the more important of these will receive individual notice in the text.i
The dianthraquinonylamines will receive separate treat- ment, as they are somewhat less readily obtained than the other amino and alkyl- and aryl-aminoanthraquinones, although of considerable importance as vat dyes.
In addition to their preparation directly from negatively substituted anthraquinones, the secondary and tertiary compounds can, of course, also be obtained by the alkylation and arylation of the primary compounds, and reactions of this nature will be discussed after the description of the direct method.
REPI.ACEMENT OF HALOGEN ATOMS. — Halogen atoms are usually fairly easily replaced by amino groups when the halogen compound is heated with aqueous ammonia, 2 the reaction in many cases being facilitated by the use of metallic copper as a catalyst. ^ In preparing i-aminoanthraquinone- 2-carboxylic acid from the corresponding chloro acid, UUmann * found that the best results were obtained by using an ester instead of the free acid, and according to the Badische Anilin u. Soda Fabrik,^ esters with aromatic alcohols such as benzyl alcohol are the most suitable.
Halogen anthraquinones will not usually react with secondary aromatic amines, but will react with primary aromatic amines and with primary and secondary aliphatic amines, including piperidine, and here again the reaction is facilitated by the use of a copper catatyst.^ The ease with
1 In addition to those mentioned in the sequel, the following are the more important patents and for the most part deal with alkyl and arylamino anthraquinone sulphonic acids. Agfa, D.R.P. 261,885, B.A.S.F., D.R.P. 106,227; 108,274; 108,873; 111,866; 113,011; 113,934; 121,155; 206,645. By., D.R.P. 101,805-6; 103,396; 107,730; 116,867; 125,578: 125.666 ; 126,542 ; 127,458-9 ; 127,532 ; 137.078 ; 142,052 ; 145.239 ; 148,767; 151,511; 159,129; 163,646; 165,140; 166,433; 216,773; 263,424. M.L.B., D.R.P. 99,078 ; 108,420; 144,111; 149,780; 158,257; 183. .395; 185,546; 191. 731 ; 209,321; 265.725; 268,454; 269.749; 272.614 ; 282,672 ; 286,092.
- Frey, B. 45, 1360. UUmann, P.. 47, 561. Schaarschmidt, A. 405, 95. M.L.B., D.R.P. 231,091. By., D.R.P. 295,624.
3 UUmann. B. 49. 747. By., D.R.P. 195,139 ; 295,624.
" B. 49, 747. Cf. B. 47, 561. 6 D.R.P. 247,411 ; 256,344.
6 UUmann, B. 52, 2109. B.A.S.F.. D.R.P. 247,411. Agfa, D.R.P, 280,646; 288,665. By., D.R.P. 195.139; 295,624. M.L.B., D.R.P. 270,790.
. THE AMINOANTHRAQUINONES 197
which, the reaction takes place depends also on what other groups are present in the molecule. Thus Schaarschmidt ^ finds that the bromine atom in i-nitrilo-2-bromanthraquinone is very reactive and is very easily replaced by an amino or alkyl or arylamino group. With ammonia, however, the condensation is accompanied by the hydrolysis of the nitrile group, the product being the amide of 2-aminoanthraquinone- i-carboxylic acid. With methylamine the tendency to hydrolyse the nitrile group was not so great, and fair yields of the N-methylamino nitrile could be obtained. The bromine atoms in 4.8-dibromanthrarufin-2.6-disulphonic acid are also extremely reactive and are readily replaced by amino groups by heating to 30-40° with aqueous ammonia of 20 per cent, strength in the presence of copper.
In some cases the use of boric acid has been recommended as facilitating the replacement of halogen atoms by arylamino groups, and Harrop, Norris, and Weizmann 2 have applied this method to various derivatives of 1.4-dichloranthra- quinone.
In the great majority of cases alkylamines will only react with chloroanthraquinones when heated with them under pressure, 3 and in order to prepare alkylamino anthra- quinones from chloroanthraquinones without the necessity of using an autoclave Ullmann * introduced what is usually known as the sulphonamide process. This elegant method is based on the fact that sulphonamides will condense with chloroanthraquinone at the ordinary pressure, and that the sulphonic acid group is then readily split off by hydrolysis. The sulphonamide generally employed is that of the easily accessible _^-toluene sulphonic acid. If ^-toluene sulphon- amide itself is used the condensation product with a chloro- anthraquinone on hydrolysis gives a primary aminoanthra- quinone. If, however, ^-toluene sulphochloride is first con- densed with a primary amine, a N-alkyl sulphonamide is
1 A. 405. 95-
2 Soc. 95, 1313.
3 By., D.R.P. 136,777-8.
* A. 380, 317 : 381, 17. B. 49, 741, 2158 ; 52, 2112 ; 53, 834. D.R.P. 224.982 ; 227,324. Cf. B.A.S.F., D.R.P. 293,100.
igS ANTHRACENE AND ANTHRAQUINONE
obtained, and this can then be condensed with a chloro- anthraquinone to a product which on hydrolysis gives an N-alkylaminoanthraquinone :
CI n/ NHR
CHsCeHiSOoNHR
^S02C6H4CH3
An exactly similar reaction takes place with N-aryl sulphonamides, the final product in this case being, of course, an N-ar\4 aminoanthraquinone. The sulphonamide process has proved to be of the utmost use in the study of the second- ary^ aminoanthraquinones, and vSchaarschmidt i attempted to apply it to the preparation of i-nitrilo-2-aminoanthra- quinone. In this case, however, it was not successful, as the hydrolysis of the anthraquinonyl sulphonamide was always accompanied b}' the h3-droh'sis of the nitrile group.
The replacement of halogen atoms b}' heating halogen anthraquinones with amines has been applied to the manu- facture of one or two d3^estiiff s. Thus Alizarin Pure Blue B is obtained from 2.4-dibrom-i-aminoanthraquinone b}' heat- ing it with _/)-toluidine and then sulphonating the product, and Anthraquinone Blue SR Extra is obtained by heating tetrabromdiaminoanthraquinone with aniline and then sulphonating^
Replacement of Nitro Groups. — Nitro groups can be replaced b}^ amino groups b}^ heating the nitro compound with ammonia, 3 or with primary 4 or secondary- aliphatic amines, 5 or primar^^ aromatic amines. ^ An amino compomid is not formed, however, when a nitroanthraquinone is heated with a secondary' aromatic amine. The reaction in the case of i-nitroanthraquinone-2-carboxylic acid is particularly
1 A. 405, 95-
2 B.A.S.F.. D.R.P. 121,684.
3 Przibram, D.R.P. 6,52b.
* By.. D.R.P. 139,581 ; 144.634-
* By.. D.R.P. 136.777-8. Cf. D.R.P. 151,512-3. « Heller. B. 46, 2702. By.. D.R.P. 125,578 ;
M.L.B., D.R.P. 150.332.
126,803 ; 148,767.
THE AMINOANTHRAQVINONES
199
easy and can be brought about simply b}- boiling this substance in aqueous solution with the amine. ^
It is vety doubtful if a nitro group in the ^-position is sufficiently reactive to be replaced by an amino or an alkyl or ar\lamino group. All the examples of the replacement of the nitro group by heating with a base seem to be confined to compounds in which the nitro group occupies an a- position,- and Kauffler 3 states that ^-nitroanthraquinone is unaffected by boiling with aniline or toluidine, although similar treatment of a-nitroanthraquinone leads to the production of phenyl and tolyl aminoanthraquinone. In this connection it is notable that the nitro group of ^-nitro- anthraquinone is very readily replaced by the methox>' group by boiling with methyl alcoholic caustic potash.
The most important application of replacement of nitro groups by arylamino groups is the preparation of Anthra- quinone Violet, which is obtained by heating 1.5-dinitro- anthraquinone with _/'-toluidine and then sulphonating the product. 4 It is used as an acid dye for wool and silk, and gives fast shades of violet. The fastness of the dye is increased by chroming, although the shades are scared}- altered. The difference in colour between Anthraquinonc Violet and the isomeric 1.4-compound (Alizarin C}-anine Green, p. 203) should be noted.
I
Anthraquinone Violet.
I
Hoi
CcHgNH
ISO3H
Erweco Acid Alizarin Blue R.
Erweco Acid Alizarin Blue R is obtained by heating dmitroanthraflavic acid disulphonic acid with aniline. 5 It
» B.A.S.F., D.R.P. ^47,411.
» Cf. Wed., D.R.P. 235,776 ; 244,372 ; 245,014 ; 247,245. ^ B. 36, 65. * B.A.S.F., D.R.P. 108,274.
' Wed., D.R.P. 235,776.
200 ANTHRACENE AND ANTHRAQUINONE
dyes wool from an acid bath in violet-red tones which change to deep blue on chroming. The shades are very fast.
RepIvACEment of Hydroxyi. Groups. — The replacement of hydroxyl groups by amino groups by heating hydroxyl- anthraquinones with ammonia or primary or secondary aliphatic amines or primary aromatic amines is a reaction of very considerable importance in view of the ease with which hydroxyl groups can be introduced into the anthraquinone molecule by direct oxidation. The replacement of a hydroxyl group by an amino group appears to take place with rather greater difficulty than does the replacement of a nitro group or a halogen atom. Thus Heller ^ was able to replace the nitro group in 3-chlor-4-nitroalizarin without affecting the hydroxyl groups or the halogen atoms, and Ullmann ^ found that when i-chlor-2-methyl-4-hydroxy anthraquinone was heated with ^-toluidine and copper only the chlorine atom was affected. The production of 2-phenylamino- quinizarin from 2-bromquinizarin and aniline, 3 and the conversion of 4-nitroalizarin monoalkyl ethers into the 4-arylamino compounds * also supports this view, and other instances could be cited. The data available, however, do not justify any definite conclusions being drawn, and in the above cases the increased reactivity of the nitro groups or halogen atoms may be due to their orientation and to the effect of other groups present in the molecule.
The replacement of hydroxyl groups can be brought about simply by heating the hydroxy compound with the base, but in many cases the reaction is facilitated by the presence of acids, ^ such as hydrochloric, sulphuric, phos- phoric, and, in particular, boric acids. The sulphite esteis of the hydroxy compounds react much more readily than the hydroxy compounds themselves, and it is claimed that amino compounds can be obtained from sulphite esters by the action of ammonia at the ordinary temperature. ^
Replacement of hydroxyl by amino groups is also
1 B. 46, 2702. 2 B 52, 2109.
3 By., D.R.P. 114,199. * M.L.B., D.R.P. 150,322.
■' By., D.R.P. 86,150. 6 By., D.R.P. 61,919 ; 65.650 ; 66,917.
THE AMINOANTHRAQUINONES 201
greatly facilitated by first reducing the hydroxyl anthra- quiuoiie to its leiico- compound, and then treating this with ammonia or an amine, the product being finally converted into the aminoanthraquinone by oxidation. 1 The increase in reactivity of nuclear hydroxyl groups which takes place on the reduction of one or both of the cyclic carbonyl groups is remarkable, condensation with ammonia and aliphatic amines often taking place at or about the ordinar^^ tempera- ture, and condensation with primary aromatic amines being rapidly effected at or below 100°.
In some cases it is not necessary to reduce the whole of the hydroxy compound in order to take advantage of the increased reactivity of the reduction product. Thus it has been claimed 2 that if a mixture of quinizarin and leuco- quinizarin is heated with _/>-toluidine, the /^wco-quinizarin reacts with the toluidine to produce /ewco-ditolylamino anthraquinone, which then reduces an equivalent amount of quinizarin to /ewco-quinizarin. being itself thereb}^ oxidised to 1.4-ditolylamino anthraquinone. The /<?zfco-quinizarin thus produced then reacts with ^-toluidine and the process is repeated until the whole of the quinizarin has been converted into ditolylamino anthraquinone. It wiU be seen that the action of the /^wco-quinizarin is purely catalytic.
When the /ewco-hydroxyanthraquinones are heated with ammonia or an amine the h5^drox5d groups attached to the wts-carbon atoms remain unaffected, although under more drastic conditions it is probable that the}- would be involved in the reaction, as it has been found that such compounds can be obtained from the reduction products of anthraquinone and anthraquinone sulphonic acid by heating with ^-toluidine. 3 Even without reduction there is danger of the cyclic carbonyl groups becoming involved if too drastic conditions are employed. Thus von Perger,^ by heating alizarin with
1 Schrobsdorf, B. 35, 2930. By., D.R.P. 91. MQ- M.L.B., D.R.P. 205,096; 205,149; 205,551;
2 By., D.R.P. 91,150-
3 By.. D.R.P. 136,872 ; i.|7.277 '. 148.079.
4 J. pr. [2] 18, 133-
202 ANTHRACENE AND ANTHRAQUINONE
aqueous ammonia, obtained a substance which he considered to be i.2-diaminoanthraquinone, and lyiebermann and Troschke i by the same method obtain a substance which they considered to be an ammonium salt of an imide of aHzarin. More recently Scholl and Parthey - have shown that the substances obtained by von Perger and by lyieber- mann and Troschke are really identical. They state that it is not i.2-diaminoanthraquinone, and as it is soluble in alkali it apparently contains a hydroxyl group. As on hydrolysis it loses a molecule of ammonia and passes into i-hydrox>^-2-aminoanthraquinone Scholl and Parthey con- sider that it must be :
f^ OH CO OM
or I A A /
CO L
Prudliomme,3 by the action of ammonia on /^wco-alizarin, claims to have isolated both of these isomers, and states that he has obtained similar compounds from anthrapurpurin. In the case of hydroxy^anthraquinones in vvhich two or more hydroxyl groups are present, it is often possible to replace onl}' one group by heating with an amine.* The remaining hydroxjd groups can then be replaced by treatment with a different base if desired, and by this means a great variety of amino compounds can be prepared. ^
Alkoxy groups and ar3doxy groups can also be replaced by amino groups b}^ heating with primary or secondary- amines, and in mau}^ cases the reaction takes place more readily than when the free hydroxyl compound is used.^
The replacement of hydroxyl groups by ainino or alkyl or arylamino groups has been used for the preparation of a number of dyestuffs of which the following are the more important.
1 A. 183, 209.
2 B. 39, 1201.
3 Bl [3] 35, 71.
* Schrobsdorf, B. 35, 2930.
5 By.. D.R.P. 86,539.
« By., D.R.P. 165,728 ; 205,881.
M.L.B., D.R.P. 201,905.
THE AMINOANTHRAQUINONES
20'
Alizarin Irisol 1). ' — This is obtained by heating quinizarin with one molecule of /)-toluidine and then sulphonating the product. 2 It dj^es silk and wool from an acid bath in bluish-violet vShades which are fast to light, and which become greenish-blue when after-chromed. Alizarin Direct Violet R and Alizarin Cyanol Violet R are very similar and differ only from Alizarin Irisol D in the position of the sulphonic acid group. They are obtained by condensing leuco-qmnizann with ^-toluidine-2-sulplionic acid.
^«W^^"'[3]s5h
I
NH[4]C„H3WCH^
OH
Alizarin Irisol D.
OH Alizarin Direct Violet R. Alizarin Cyanol Violet R.
By replacing both the hydroxyl groups in quinizarin several important dyestuffs have been obtained. B}^ far the most important of these is Alizarin Cyanine Green or Quinizarin Green, ^ which is obtained by heating quini- zarin * or much better /cwco-quinizarin ^' with /)-toluidiue and then sulphonating the product, ^ but 1.4-dichloranthra- quinone or i-chlor-4-nitroanthraquinone can be used in place of quinizarin.'^ The product dyes wool green from an acid bath, the shades being very fast and becoming even more so by chroming.
Alizarin Direct Green G and Alizarin Brilliant Green G are isomeric with Alizarin Cyanine Green and are obtained by condensmg /^wco-quinizarin with ^-toluidine-2-sulphonic acid : ^
1 Solwav Purple (Scottish Dyes, Ltd.).
^ By., D.R.P. 86,150 ; 91,149.
' Kymric Green (Scottish Dyes, Ltd.).
« By., D.R.P. 86,150; 86,539.
5 By., D.R.P. 91,149 ; 91,150; 91.152;
» By.. D.R.P. 84, 509 : 89,862 ; 93.3io-
' By., D.R.P. 125,698 ; 126,803.
8 B.A.S.F., D.R.P. 128,753 : 137.566 ;
92,591 ; 93.223 ; 94.396.
155.572. C/. M.L.B., D.R.P. 172,464; 181,879; 201,905.
148,306; 151.018; 151,384;
204 ANTHRACENE AND ANTHRAQUINONE
NHWCeH^WgHs^
NHMCgHg
[i]CH3 [3]S03H
NH[4]CeH3[^]^^H3^
Alizarin Cyanine Green. Quinizarin Green.
NHMCeHsWCH.^
Alizarin Direct Green G. Alizarin Brilliant Green G.
Isomeric green dyes in which the snlphonic acid groups are in the anthraquinone nucleus are obtained by condensing /^wco-quinizarin sulphonic acid with ^-toluidine.i They are said to give purer shades of green than either of the above but do not seem to have come into technical use. In this connection it is interesting to notice that it has been claimed that 1. 4-ditoluido-8-hydroxy anthraquinone is sulphonated in the anthraquinone nucleus when the sulphonation is carried out in the presence of boric acid. 2 If this is the case it is no doubt due to the directing influence of the hydrox>'l group, or rather of its boric ester.
As stated on p. 202, the two hydrox}^ groups in quini- zarin and other polyhydroxy anthraquinones can be replaced by different aryl or alkj'lamino groups. This has been done in the case of Alizarin Astrol, in which one hydroxyl group has been replaced by a meth3^1amino group and the other by a tolylamino group, the sulphonated product being a greenish-blue wool dye. It is interesting to notice the transition in colour from Alizarin Pure Blue through Alizarin Astrol to Alizarin Cyanine Green :
/CH3 /CH3 /CH3
NHC6H3<' NHCgHa^ NHCeHg^
'SO.H
Br NH2
I
^SOgH
NHCHo
I
.CH,
Alizarin Pure Blue. Alizarin Astrol.
1 By., D.R.P. 95.625 ; 101,919.
NHC6H3<
Alizarin Cj-anine Green. « By., D.R.P. 170,113.
THE AMINOANTHRAQUINONES
205
Of the various other dyes which have been obtained by heating hydroxyanthraquinones with bases only two call for special notice. Alizarin Viridine is 5.6-dihydroxy- quinizarin green and is obtained by heating Alizarin Bordeaux with ^-toluidine and then sulphonating the product. It is a mordant dye and is used for producing green shades on chrome mordanted cotton. Alizarin Blue-Black 1 is obtained by heating purpurin with aniline and then sulphonating the product. As it is also obtained by sulphonating the condensation product of 2-bromquinizarin and aniline it must have the formula 2 :
NHCcHiSOsH — NHC6H4SO3H
I
or
OH NHC6H4SO3H
I
OH
NHC6H4SO3H
and cannot be a sulphonation product of 2-hydrox5'-i.4- diphenylaminoanthraquinone as originally thought.
Replacement of Sulphonic Acid Groups. — The re- placement of sulphonic acid groups by amino groups is of ver}^ considerable importance, as a very large number of sulphonic acids can be readily obtained by sulphonating with or without the addition of a mercury catalyst (p. 176). As stdphonic acid groups enter the anthraquinone nucleus in the j3-position when the sulphonation is carried out in the absence of mercur>^ the replacement of the sulphonic acid group renders ^-amino compounds easil)^ accessible, although they are often troublesome to obtain by other methods. Thus jS-aminoanthraquinone, the mother substance of many of the valuable Indanthrene colours, is easily obtained from sodium anthraquinone-j8-sulphonate (the "silver salt" of commerce) by heating with aqueous ammonia, although it is expensive and troublesome to produce by other methods. The conversion of the sulphonic acids into the amine is also the best method of characterising the sulphonic acids, the
» Solway Blue-Black (Scottish Dyes, Ltd.). • By., D.R.P. 114,199-
2o6 ANTHRACENE AND ANTHRAQUINONE
methylamiuo compounds, obtained by the use of meth^'l- amine, being specially suitable for this purpose.
The sulphonic acid group can be replaced by the primary amino group by heating the sodium salt with sodamide,^ but it is much simpler and better to use aqueous ammonia ; 2 and primary and secondary alkylamines and primarj'- arylamines react in the same way. It is Usual to employ aqueous solutions, and to obtain a sufficiently high tempera- ture it is necessary to work under increased pressure.
In all these reactions sodium sulphite is formed, and at the high temperatures used (about 180-220°) this attacks the anthraquinone nucleus unless it is destroyed or rendered inactive as rapidly as formed. This can be done by the addition of barium chloride, 4 as this reacts with the sulphite to form the barium sulphite, which being almost insoluble is more or less harmless. Much better results are obtained, however, by adding an oxidising agent, & such as manganese dioxide (preferably in the form of Weld on mud), which is capable of oxidising the sulphite to sulphate. Attempts have also been made to utilise the reducing power of the sulphite. Thus it has been stated ^ that satisfactorj^ yields of j8-aminoanthraquinone are obtained by heating sodium anthraquinone j8-sulphonate with aqueous ammonia and nitrobenzene. In this case the nitrobenzene acts as an oxidising agent and is thereby reduced to anilme, so that the manufacture of aniline and of /3-aminoanthraquinone is combined in one process. As the aminoanthraquinones are not volatile with steam there is no difficult}^ in separating the j8-aminoanthraquinone from the aniline and imchanged nitrobenzene.
Hofmann's Reaction. — Aminoanthraquinones can be prepared from the amides of the anthraquinone carboxj-Uc acids by Hofmann's method (treatment with hypochlorite or hypobromite) , but the method has not been extensivel}- used
1 Sachs. B. 39, 3019.
2 R. E. Schmidt, B. 37. 70.
3 By., D.R.P. 135,634 ; 142,154 ; 175,024 ; 181.722. B.A.S.F., D.R.P. 288,464. Cf. D.R.P. 77,721 ; 90,720.
* M.L.B., D.R.P. 267,212. Cf. Geigy, E.P. I27,223i».
' B.A.S.F., D.R.P. 256,515, fi G.C.I. B., A.P. 1,255.719.
THE AMINOANTHRAQUINONES 207
as the amides are not particularly accessible and the amino- authraquinones are usually more easily obtained by other methods. Hofmann's method, however, has been employed by Eckert 1 and b}' Willgcrodt and Maffelzzoli,2 who prepared 2-aminoanthraquinone-3-carbox3dic acid from the amide of anthraquinone-2.3-dicarboxylic acid. Other investigators have also made use of the method ^ although to no consider- able extent.
Alkylation and Arylation.
So far the methods which have been discussed have been those by which an amino group is introduced into the anthraquinone molecule. The primary amino anthra- quinones can, however, be converted into secondary' and tertiary- compounds b)' the usual methods of alkylation and arylation, and attention will now be directed to some of the more interesting results which have been obtained. The description of compounds in which two anthraquinone residues are attached to the same nitrogen atom (the di- anthraquinonylamines) will, however, be reserved for a separate section (p. 231) as the}- merit special treatment.
The alkylation of the aminoanthraquinones can be brought about in the usual wa}- by means of alkyl halides, but in some cases abnormal results are obtained. Eckert,"* for example, endeavoured to prepare the glycine of 2-aniino- anthraquinone-3-carbox3-lic acid by treating it with chlor- acetic ester, but instead of the glycine the chloracetyl compound Ci6H60.(COOH)(NHCOCH2Cl) was obtained. Seer and Weitzenbock ^ succeeded in preparing glycines from monamino and 1.5-diamino anthraquinone and found that the diglycine of the latter compound had tinctorial properties and was capable of dyeing wool m red shades. They also prepared some benz}^ derivatives and found that 1.5- and i.8-dibenzylaminoanthraquinone could not be reduced in alkahne solution.
1 M. 35, 290. 2 J. pr. [2] 82, 205.
' Scholl, B. 40, 1691. Schaarschmidt, B. 50, 294 ; 51, 1074. Terres, B. 46, 1640. Graebe and Blumenfeld, B. 30, iini.
« M. 35, 290. - M. 31 379.
2o8 ANTHRACENE AND ANTHRAQUINONE
Methylation with dimethyl sulphate sometimes leads to abnormal results as i-amino-4-ar}damino anthraquinones are simultaneously sulphonated, i the product being a i-methylamino-4-ar>4aminoanthraquinone sulphonic acid, although it is doubtful whether the sulphonic acid group is attached to the anthraquinone nucleus or to the aryl group. The sulphonation can hardly be a side reaction due to liberation of srdphuric acid from the dime thy Isulphate, as it takes place even in the presence of excess of sodium carbonate. Other amino anthraquinones are conveniently meth^^lated by heating to 180-200° with methyl alcohol or dimethyl sulphate in the presence of concentrated sulphuric acid or oleum, this procedure rendering possible the use of open vessels. 2
Alkylene oxides will combine with primary aminoanthra- quinones, a-aminoanthraquinone and ethjdene oxide ^ giving C14H7O2NHCH2CH2OH, and epichlorhydrin * giving a com- pound which contains chlorine and probably has the formula C14H7O2NHCH2CHOHCH2CI. On sulphonation this yields a yellow acid dye.^
Glyoxylic acid combines with a- and /i-aminoanthra- quinol to form the glycine of a- and jS-aminoanthraquinone.^ Here probably the azomethine compoimd of anthraqumo] is first formed, the azomethine group then being reduced at the expense of the quinol group :
OH
I
C CO
CeH^^nCcHgN : CHCOOH -> C6H4<>C6H.3NHCH2COOH C CO
1
OH
In some cases primary aminoanthraquinones can be converted into secondary- and tertiary^ compounds by diazotising and then treating the diazonium salts with a
1 M.L.B., D.R.P. 174. 131. 2 By., D.R.P. 288,825.
3 By., D.R.P. 235,312. * By., D.R.P. 218,571.
5 Bv., D.R.P. 220,627. 6 M.L.B., D.R.P. 232,127.
THE AMINOANTHRAQUINONES
209
primary or secondary amine, and this process has been investigated b}- WackerJ He found that i-aminoanthra- quinone-2-sulphonic acid when diazotized gave an internal anhydride which reverted to the original amino compound when treated with ammonium carbonate, but which gave the methylammo and diethj-lamino sulphonic acid when treated with methylamine carbonate or diethylamine :
NHCHa SO3H
CHjNHj <
3 (C.HJaNH
N(C2H5), SO3H
HNO.f |(NH4)X03 HNo
When treated with aniline, however, the diazo anhydride gave lirst the diazoamino compoimd, which under the influence of acids broke down into the original amino- sulphonic acid, phenol and nitrogen.
The above reactions are by no means general, as 1.5- and i.8-diaminoanthraquinone when tetrazotized gave with ammonia a mixture of the original diamino compound and an aminohydrox>'- compound, with methylamine the original diamino compound only, and with diethylamine only the dih3-drox5' compound, whereas the diazonium salt of i-amino- 4-hydrox}-anthraquinone when treated with methylamine gave quinizarin.
Primar3^ aminoanthraquinones combine with aldeli}dcs and compounds of the type Ci4H70oNHCH2[i]C6H4[4]NRo are obtained by condensing a-aminoanthraquinone with formaldehyde and tertiary' aromatic amines such as di- methyl aniline. 2 Kauffler ^ has studied the benzylidene 1 B. 34, 2593, 3922. 2 xM.L.B., D.R.P. 236.769. ' F.T. 2. 471.
14
210 ANTHRACENE AND ANTHRAQUINONE
aminoanthraquinones but without obtaining results of any particular interest.
The arylation of the aminoanthraquinones can be carried out in the usual way by heating the amino compound with the aryl halide in the presence of a copper catalyst such as copper powder, copper acetate or cuprous chloride, and a substance such as sodium acetate which is'capable of com- bining with the halogen acid split out during the reaction.^ The same compounds can, of course, also be obtained by condensing the halogen anthraquinone with a primary or secondary arylamine.2 When the condensation is being carried out with a primary amine either the chlor- or the brom-anthraquinone can usually be used, but when a secondary amine is employed it is usuallj- necessar}- to make use of the iodo- compound. Thus carbazol and diphenylamine will condense with a-iodoanthraquinone,3 but if chlor- or brom-anthraquinone is used little or no reaction takes place. Aminoanthraquinones also condense with benzoquinone and a-naphthoquinone to give compounds of the type (HO)2[i.4]C6H3[2]NHCi4H602NH2, from which vat dj^es giving fast shades of bordeaux can be obtained by condensation with halogen anthraquinones so as to form a dianthraquinonylamine derivative. -^
Tinctorial Properties.
Although the primar}- aminoanthraquinones are liiglily coloured substances, the}- have little or no afEnit}^ and con- sequentl}' are useless as dyestuffs. To a certain extent the same is true of the secondary and tertiar>^ compounds, but in some cases these show very considerable affinity, and as has already been shoM^n (p. 203), valuable acid dyes are formed by sulphonating the secondary 1.4-diamino- anthraquinones.
1 Laube, B. 40, 3564. By., D.R.P. 175,069. B.A.S.F., D.R.P. 280,881. For further references see p. 211.
2 Laube and Konig, B. 41, 3874. Agfa, D.R.P. 243,489. M.L.B., D.R.P. 255.821.
3 Laube, B. 40, 3564. * Cas., D.R.P. 267,414-5-6 ; 269.801.
THE AMINOANTHRAQUINONES 211
When the uitrogen atoms of two molecules of an amino- anthraquinone are jomed by a carbon cham so as to produce a compound of the type C14H7O2NH— X— NHC14H7O2, tmctorial properties are often developed and some of the products thus formed are said to act as very fast vat dyes, although they do not seem to have been placed on the market. One of the simplest of these is sym-dianthraquinonyl- ethylenediamine, which Ullmann and Medenwald ^ prepared from j3-aminoantliraquinone and ethylene dibromide by the sulphonamide process. When used as a vat dye it gives orange shades, but the affinity is very poor. Cuiiously enough, the corresponding compound derived from a-amino- anthraquinone does not seem to have been described, although it should be of considerable interest, as it would no doubt readil}' pass into a complex heterocyclic com[)oimd.
In the above type of compound much greater aflinity is obtained when X represents an aryl residue, and at the same time the colour is shifted towards the violet end of the spectrum. Such compounds can be obtained by condensing two molecules of a halogen anthraquinone with one molecide of an aromatic diamine such as /^-phen^'lene diamine, benzi- dine, 2 etc., or by condensing two molecules of an amino- anthraquinone with one molecule of an aromatic dihalogcn compound such as ^-dichlorbenzene ^ (violet shades), po- dichlorbenzil * (red shades), /Jo'^iclilordiphem-lmethanc ^ (bordeaux shades), diclilorphenanthraquinone 6 (red shades), diclilorbenzophenone " ' ' (red shades) , or />2-dichlordiphen\-i ^ (violet shades). The condensation product from amino-
anthraquinone and ^2"<iiclil^r^^iph^^i3'l ^^^^ ^^^^ ^^ obtained from cliloranthraquinone and benzidine, and Brass ^ has obtained it and similar compounds b}' oxidising diaryl- amhioanthraquinones with manganese dioxide and sulphuric acid.
Vat dyes have also been obtained ^^ by condensing
I B. 46, 1798. - Agfa, D.R.P. 24^,489.
* By., D.R. p. 215,294. « B.A.S.F., D.R. P. 222,205; 230,400.
• B A.S.F., D.R.P. 230,411. « B.A.S.F., D.R.P. 222,206; 230,40c. ' n.A S.F., D.R.P. 220,579; 2:50,399. « Bv., D.R.P. 230,409. ' B. 46, 2907. W.T.M., D.R.P. 251,845. " By.. D.R.P. 248,655
212 ANTHRACENE AND ANTHRAQUINONE
two molecules of a primary aminoantliraqmnone with one molecule of a compound of the general formula CL'^.r — X — ArCl, where Ar represents an aryl residue and X is O, S, or NH, and may or may not form part of a ring, e.g. a carbazol ring.
Of somewhat different structure are the vat dyes which are obtained by condensing two molecules of an ammo- anthraquinone with one molecule of a sym-dihalogen diaryl urea.i or with compounds of the type 2 HlgRNHC0(CH2)n- CONHRHlg, where w is 0, i, 2, 3, etc. Somewhat similar dyes are obtained by condensing dihalogen sulphones with aminoanthraquinones. ^
The shades produced by the diar>daminoanthraquinones depend to a considerable extent on the position of the arylamino groups. As already shown (p. 203) the 1-4- diarjdaminoanthraquinones give rise to green dyes, e.g. Alizarin Cj-anine Green. When the ar^damino groups are in the 1.5 positions, the shades are usually violet, e.g. Anthra- quinone Violet (p. 199), whereas when in the 1.8- positions they are red.
ACYLAMINOANTHRAQUINONES
Converting an aminoanthraquinone into an ac5damino compound is alwa3-s accompanied by a marked increase in tinctorial properties, powerful vat dyes being obtained when the acyl group is derived from an aromatic acid like benzoic acid, or from a dibasic fatty acid such as malonic or succinic acid. The acyl groups derived from the monobasic fatty acids, such as formic and acetic acid, also confer tinctorial properties, although to a much lesser degree, the afiinit}^ of the resulting acyl aminoanthraquinones being too slight for them to be of an}^ value as technical d3'es. Although the ac5d aminoanthraquinones derived from monobasic aromatic carboxylic acids have great affinity, this is not the case with the derivatives of aromatic sulphonic acids,
1 M.L.B.. D.R.P. 241,837. 2 M.L.B., D.R.P. 241,838.
" By.. D.R.P. 234,518.
THE AMINOANTHRAQUINONES 213
the N-anthraquiuon}-! sulphonamides as a rule having no tmctorial properties.^
The ac)4aminoanthraquinones are very readily obtained from the amino compound by heating it with the acid chloride 2 or with the free acid ^ in some inert solvent of high boiling point such as nitrobenzene or naphthalene. The acid chloride, of course, reacts most readily, sodium acetate being added in order to neutralise the hydrochloric acid liberated. When preparing acetyl derivatives it is often advantageous to dissolve the amino compound in concentrated sulphuric acid or oleum containing 10-25 P^r cent, of sulphur trioxide and then to add acetic anhydride, glacial acetic acid or anhydrous sodium acetate. By this means both primary and secondary compounds, including dianthraquinonyl- amines, can be acetylated, although in some cases acetylation only takes place with diihculty when less drastic methods are employed.'*
In some cases an ester or an amide of the acid can be used
for inserting the acyl group, -^ but in other cases the reaction
takes a different course. ^ Thus the aminoanthraquinones,
when heated with alkaline alcoholic solutions of ethyl
oxalate, do not give the oxalyl derivatives, but yield yellow
or red vat dyes which probably have the constitution
A — N=C — C=N— A, where A is an anthraquinone residue.
I 1 OEt OEt
Ac3daminoanthraquinones can also be obtained by condensing a halogen anthraquinone with an acid amide,*^ although this method has not been employed to any great extent. The condensation is carried out in the presence of a copper catalyst, sodium acetate being added to neutralise the hydrochloric acid liberated.
As stated on p. 212, the acj^laminoanthraquinones
1 Seer and Weitzenbock, M. 31, 371.
- By., D.R.P. 223,069 ; 225,232; 227,104; 227,398; 248,289. » By.. D.R.P. 210,019; 212,436; 216,980; 223,069; 223,510; 224.808 ; 226,940.
* B.A.S.F., D.R.P. 211.958.
* By., D.R.P. 210,019 ; 212.436 ; 216.980.
6 By.. D.R.P. 270,579. ' By., 216.772.
214 ANTHRACENE AND ANTHRAQUINONE
derived from the monobasic fatty acids are of but minor interest owing to their feeble tinctorial properties. Greater affinity is obtained by condensing one molecule of chlor- acetyl chloride with two molecules of aminoanthraquinone, the resulting N-anthraquinonylglycylaminoanthraquinones being brown or bordeaux dyes.i The shades, however, are rather weak, and not particularly fast to ligtt, so that the substances have but little technical interest.
Of the acylaminoanthraquinones derived from dibasic fatt}' acids, compounds derived from oxalic, malonic, suc- cinic, adipic, maleic, malic, tartaric, and camphoric acids have been described. 2 These are all vat dj-es, and are fairl}^ readily obtained by boiling an aminoanthraquinone with the acid in nitrobenzene solution, with or without the addition of a condensing agent such as phosphorus penta- chloride, zinc chloride, boric acid, etc. The reaction takes place in two steps, and if desired one molecule of the acid can be made to condense with two different aminoanthra- quinones.3 The only technical dyestuff derived from a dibasic fatty acid appears to be Algol Yellow 3G (succinyl- a-aminoanthraquinone) , although it is probable that Algol Brilliant Violet R is succin}^ diaminoanthrarufin,
Of the aromatic acids which have been used for pre- paring acylaminoanthraquinones, benzoic, phthalic, tere- phthalic, salicylic and cinnamic have all been used,* and 5'ellow and orange vat dyes have also been obtained b}- condensing the chloride of anthraquinone carboxjdic acid with diamines such as benzidine, ^ and also with amino- anthraquinone. ^ They are, however, of no technical im- portance. Only the benzoyl derivatives have met with an)- wide technical application, and these are almost invariably prepared b}' means of the readily accessible benzo}'! chloride. a-vSalicylaminoanthraquinone has, however, been used to a
' B.A.S.F., D.R.P. 248.997.
- By., D.R.P. 210,019; 212,436; 216,980; 223,069; 226,940. For ureas, thioureas, urea chlorides and iirethanes, see p. 219. ^ By., D.R P. 223,510; 224,808.
* For references see p. 213.
^ li.A.S.F., D.R.P. 215,182; 236.442.
* Seer and Weitzenbock, M. 31, 371.
THE AMINOANTHRAQUINONES
215
certain extent as a pigment colour under the name Helio Fast Yellow.
Of the technical dyes which are benzoylaminoanthra- quinones the following are the most important : —
NHCOCeHs NHCOCcHs NHCOC0H5
I
I
I
OH |
OCH3 |
Algol Yellow WG. Algol Pink R. |
Algol Scarlet G. |
NHCOC0H-, |
NHCOCoH^ |
NHCOCfiHr, CeHgCONH Algol Red 5G.1 Algol Yellow R.
HO NHCOCoHg HO NHCOCoHq
CeH^CONH
Algol Red FF.
CfiHgCONH OH
Algol Brilliant Violet 2B.
HO NHCOCoHg
HO OH Algol Violet B.
The position and nature of substituent groups has a considerable effect on tlie colour of the benzoylaminoanthra- quinones. Thus when there is a benzoylamino group at 1 :
1 Caledon Red 5G (Scottish Dyes LM.).
2i6 ANTHRACENE AND ANTHRAQUINONE
(a) Substituents at 2 have comparatively little effect.
(b) Substituents at 4, other than halogen atoms, have a great effect and shift the shade towards the violet end of the spectrum.
The effect of the h5^drox}^ and methoxy group is seen by comparing Algol Pink R and Algol Scarlet G with Algol Yellow WG. As would be expected, the effect of the hydroxy group is greater than that of the methoxy group, Algol Pink R giving bluish shades of pink, whereas Algol Scarlet G gives slightly yellowish shades of scarlet. The effect of an amino group is very pronounced, as will be seen b}^ com- paring the shades obtained from the following compounds :
NHCOC6H5 NHCOCeHg NHCOCsHg
I
I
NH2
Corinth.
NHCHc
Blue.
I
NHCOCgHg Yellowish-red.
It will be seen that benzoylating the second amino group lessens its effect. The influence of a nitro group in the para- position to the benzoylamino group is, as would be expected, ver}- great, i-benzoylamino-4-nitroanthraquinone dyeing in violet shades. The presence of a nitro group, however, is objectionable in a vat dye owing to its liabilitj^ to become reduced in the dyebath.
Although the above remarks refer to the benzoyl amiuo- anthraquinones, they are equally applicable to other acyl- aminoanthraquinones, as will be seen b}'- comparing the following succinyl derivatives :
NHCOCHoCH.,CONH NHCOCHoCH.CONH
YeUow.
OH HO
Scarlet.
THE AMINOANTHRAQUINONES 217
NHCOCH2CH2CONH NHCOCH,CH<.CONH
I
OCH,
I
CH,0
I
NO.
I
NO5
Orange.
Violet- red.
(c) Substituents at 5 have, as a rule, comparatively little effect on the colour, amino groups producing red shades.
The effect of the nitro group is extraordinarily small and merely changes the colour from yellow to orange or led. The very slight infliience of groups at 5 will be clearly seen by comparing the shades produced by the following com- pounds with those obtained from the isomers mentioned above :
NHCOCfiHs
NHCOCr.H,
NHCOCr.H-
CH3NH
HO
NO2
Orange-red.
Red. Yellow.
NHCOCH2CH2CONH NHCOCH2CH2CONH
I
NHo
I
I
NH., NO.,
I
NO.
Orange.
Red.
(c) But little information is available as regards the influence of substituents at 8, but the effect is probably decidedly less than that of substituents at 4, as the succinyl derivative of i.8-diaminoanthraquinone dyes only in yellow shades.
(d) When several substituents are present the case becomes somewhat complicated, as they often modify or
2i8 ANTHRACENE AND ANTHRAQUINONE
reinforce one another. In connection with this it will be sufficient to give five examples :
NHCOCgHg NHCOCgHs
NHCOCgHg
I
NHCOCgH,,
Orange. (Algol Brilliant Orange FR.)
CfiHsCONH NHCOC^Hg
I
CeHgCONH NHCOCeHg Bordeaux.
HO NHCOCcH^
CeHgCONH NHCOCaHg Red -violet.
CfiHgCONH OH
Blue-violet. (Algol Brilliant Violet 2B.)
HO NHCOCfiHs
HO OH
Red-violet. (Algol Violet B.)
One or two acylamino dianthraqmnon54s have been studied, e.g. 4.4'-dibenzoylamino-i.i'-dianthraquinonyl has been found to be a yellow vat d^^e, 1 but compounds of this nature have not been found to be of any technical value. It should be noted that the shades obtained from amino- benzoylaminoanthraquinones are usually rather loose to acids and chlorine, although this can be remedied to a large extent by acetylating the amino group. 2
The presence of a sulphonic acid group attached to the anthraquinone nucleus has the effect of reducing the colour slightly. The products, however, are readily soluble in
» By., D.R.P., 227,104. 2 M.L.B., D.R.P. 240,079.
THE AMINOANTHRAQUINONES 219
water and are not hydrolysed by boiling dilnte acids, and can, therefore, be used as acid wool dyes.i
Ureas and Thioureas
A considerable amount of work has been carried out in the study of the carbonic acid derivatives of the aminoanthra- quinones, but the whole of the work published so far has been in the form of patent specifications, and consequently the information available at present is far from complete.
Ureas are formed by the action of carbonyl chloride on the aminoanthraquinones at about 170° in solution or suspension in some indifferent solvent such as nitrobenzene. 2 In the case of j8-aminoanthraquinone the reaction takes place without the use of any condensing agent, but a urea can only be obtained from a-aminoanthraqmnone in the presence of anhydrous sodium acetate or other substance capable of neutralising the hydrochloric acid set free. The urea is not the only product obtained by the action of phosgene on aminoanthraquinones, as at the ordinary temperature a mixture of the urea chloride and the hydrochloride of the base is formed. 3 This latter substance by the prolonged action of excess of phosgene passes into the urea chloride, although the change is more rapid if the calctdated amount of phosgene is allowed to react with it at 40-120°. Anthra- quinone iso-cyanates do not seem to be formed directly by the action of phosgene on the amino compounds, although they are obtained in good yield by heating the urea chloride in nitrobenzene solution.*
Instead of treating the aminoanthraquinone with phos- gene the urea can be prepared by means of chlorcarbonic ester, ^-aminoanthraquinone", for example, giving the urea when boiled in naphthalene .solution with ethylchlor- carbonate.s although under less drastic conditions the urethane is produced.^' The urea is also formed when
» Bv., D.R.P. 22^.o6q. 2 M.L.B., D.R.P. 232,739.
3 M.L.B., D.R.P. 238,550 ; 241.822. " M.L.B., D.R.P. 224,490. « M.L.B., D.R.P. 242,292. <; By., D.R.P. 167,410; 171,588.
220 ANTHRACENE AND ANTHRAQUINONE
/S-aminoanthraquinone is heated to 70° with urea in nitro- benzene solution.!
Mixed ureas containing either two different anthra- quinone residues, or one anthraquinone residue and one aromatic residue, can be obtained by condensing the anthra- quinone urea chloride or the urethane 2 with a molecule of an aminoanthraquinone or an alk3damine or arylamine. By using ammonia a monoanthraquinonyl urea is obtained. ^ The procedure can, of course, be inverted and the urethane condensed with j8-aminoanthraquinone. In this case ure- thane itself gives dianthraquinonyl urea,^ whereas mixed aryl anthraquinonyl ureas are obtained from ar}d urethanes.^ Mixed ureas can also be obtained by condensing an amino- anthraquinone with an ar>4 iso-cyanate,^ or by condensing an anthraquinone-iso-cyanate with a primary or secondarj^ aliphatic amine or a primary- aromatic amine, "^ Finally, it may be pointed out that an aminobenzoyl benzoic acid can be converted into a urea derivative by any of the usual means, e.g. by treatment with phosgene, and the anthra- quinone ring then closed by treatment with a dehydrating agent, such as concentrated sulphuric acid at 90°. As a rule, the closing of the ring takes place ver^^ easil}^ and to avoid hydrolysis should be brought about at as low a tempe- rature as possible. 8
Sulphonated anthraquinonyl ureas can be obtained by converting an anthraquinone sulphonic acid into its urea derivative,^ or by sulphonating the anthraquinonyl urea, 10 but are of but little interest. The ureas can also be halo- genated. ^ ^
Very few of the anthraquinonyl ureas have been found to be of sufficient value to justify their use as commercial dyes, but 2. 2 '-dianthraquinonyl urea has been placed on the market as Helindon Yellow 3GN, and a more complex
1 M L.B., D.R.P. 238,551 ; 238,553. Cf. Sonn, B. 47, 2437.
2 M.L.B., D.R.P. 236,375 ; 236,978-9; 236.980; 236,983-4; 238.550.
3 M.L.B.. D.R.P. 236.978. * M.L.B.. D.R.P. 238,552. 5 M.L.B., D.R.P. 236,981. « M.L.B., D.R.P. 229,111. - M.L.B.. D.R.P. 231,853. 8 Agfa, D.R.P. 281.010.
9 M.L.B., D.R.P. 236.984. i« M.L.B.. D.R.P. 229,408.
" M.L.B., D.R.P. 240.192.
THE AMINOANTHRAQUINONES
221
dye, Helindon Brown 2GN, is obtained by condensing two molecules of anthraquinone-^-urea chloride with various diaminoanthraquinones :
-NHCONH-
Helindon Yellow 3GN.
I-NHCONHC14H6O2NHCONH-
I
Helindon Brown 3GN.
The urea chlorides condense readily with phenols and
naphthols when boiled with these in some indifferent solvent
such as xylene J The products are yellow vat dyes, but
are of no particular interest. They have the structure
C14H7O.NHC— OAr.
II O
Of greater interest are the yellow vat dyes which are obtained when the urea chloride is treated with a tertiary base such as dimethyl aniline or pyridine. 2 The reaction takes place at the ordinary temperature with the evolution of heat, but the constitution of the products obtained is not known. They are yellow, but become red or violet in the presence of strong alkali, the colour being discharged, however, on dilution. The urea chlorides also imdergo a little-understood condensation when boiled with sodium acetate or sodium carbonate and some indifferent solvent, such as nitrobenzene.'^ The products are vat dyes, Helindou Orange GRN being obtained from anthraquinone-^-urea chloride by this reaction. The same products are obtained from the /so-cyanates and from the dianthraquinonyl ureas themselves. *
The thioureas of the anthraquinone series have been much less studied than the ureas, and the information in the patent literature is often contradictory- . Thus, the Hochst colour works state that the thiourea is formed when an aminoanthraquinone is treated with thiocarbonyl cliloride,^
1 M.L.B , D.R.P. 242,291. 3 M.L.B.. D.R.P. 232,135.
' Loc. cil.
2 M.L.B., D.R.P. 236,982. ^ M.L.B., D.R.P. 232,791-2.
222 ANTHRACENE AND ANTHRAQUINONE
whereas the Badische Anilin u. Soda Fabrik state that the action of thiocarbon^d chloride on jS-aminoanthraquinone gives a substance which is useless as a vat dye and is certainly not the thiourea. 1 According to their patent the product consists of at least two substances, and can be separated into two parts b}' the action of alkali, the portion which is insoluble in alkali being converted into a fast orange-yellow vat dye when heated alone or with an indifferent solvent. It is probable that the action of thiocarbonyl chloride on aminoanthraquinone leads to a mixture of the thiourea and thiourea chloride, and this view receives some conj&rmation from the fact that Bayer & Co. claim the production of orange-yellow vat dyes b}- the prolonged heating of jS-amino- anthraquinone with excess of thiocarbon5'l chloride. 2
The anthraquinonyl thioureas can also be obtained b)^ heating the aminoanthraquinones with carbon bisulphide, best by using pyridine as a solvent, 3 or with sodium xanthate,^ and in addition also seem to be formed when ammoanthra- quinones are heated with perchlormeth}^ mercaptan in an indifferent solvent, such as nitrobenzene, with or without the addition of copper or copper salts ana basic substances. ^ They can also be built up from the thioureas of the amino- benzo^-l benzoic acids b}' closing the anthraquinone ring by means of sulphuric acid.^
As in the case of the formation of anthraquinonyl ureas by this method the ring closes ver}' easily, and as the thioureas are not very readily hydrolysed a higher tempera- ture can be used than is permissible in the case of the ureas themselves.
Mixed alkyl and ar^-l anthraquinonyl thioureas can be obtained b}' condensing the anthraquinonyl /so-thiocyanates with primary or secondary aliphatic amines or primary aromatic amines. '^ The reaction is lacilitated and a much purer product obtained if a condensing agent such as aluminium chloride is used.^
1 B.A.S.F., D.R.P. 246,086. ' By.. D.R.P. 271.475. 5 B.A.S.F., D.R.P. 234,922. '' M.L.B., D.R.P. 229,111.
2 Bv., D.R.P. 256,900. * G.E.. D.R.P. 291,984. « Agfa, D.R.P. 282,920. 8 M.L.B.. D.R.P. 254.744.
THE AMINO ANTHRAQUINONES 223
If an authraquiuoue aldehyde or an cu-dibronimethyl anthraquinone is heated to 120-130° with thiourea in a suitable solvent such as pyridine or quinoline, a compound which contains both the thiourea and the azo-methine group is obtained.! These are red vat dyes, the correspond- ing oxygen compounds, obtained in the same way from urea, being yellow :
CmH,0.,.C : N.C.N : CCi^H^O. CMH7O2.C : N.C.N : C.CHH7O., II II
s o
Addendum
At this point brief mention may conveniently be made of compounds which appear to be derived from the amidines of the aromatic acids. These can be obtained by con- densuig one molecule of benzotrichloride with two molecules j8-aminoanthraquinone :
^NC,4H70., C6H5CCI3+2CHH7O2NH0 ^ CoH^C^
^NHCuH702
or by condensing j8-ammoanthraquinone simultaneously with carbon tetrachloride or other derivative of carbonic acid, such as chlorcarbonic ester, and an aromatic h5-drocarbon such as naphthalene, diphenyl, etc., the condensation taking place in the presence of copper. 2 The reaction is an mterest- ing one and is worthy of further investigation.
Nitration
The nitration of the aminoanthraquinones is complicated by the fact that the position taken by the entering nitro group is influenced not only b\' the position of the amino group, but is also dependent to a considerable extent on the means, if any, which have been taken to protect this group, and further complications arise from the fact that in the anthraquinone series there is a considerable tendency towards the formation of nitramines. These latter, however,
1 B.A.S.F., D.K.P. 241.805. 2 B.A.S.F., D.R.P. 246.477 ; 248.656.
224 ANTHRACENE AND ANTHRAQUINONE
are only formed in nitration reactions after all the easily available ring positions have been occupied b}' nitro groups. They are briefly discussed on p. 226.
Primary aminoanthraquinones are much more stable than the majorit}- of primary- aromatic amines, and can often be nitrated without previousl}^ protecting the amino group. Thus, j3-aminoanthraquinone when treated 'with the calcu- lated amount of nitric acid in concentrated sulphuric acid at —5° is converted into 2-amino-3-nitroanthraquinone.^ Here the o-^ position is the only one readily available for nitration, and the further action of nitric acid leads to the formation of a nitramine.^ When the amino group is in the a- position, however, both the ortho- and para- positions are readily nitrated. Thus, 1.5-diaminoanthraquinone gives a tetranitro compound, the further nitration of this leading to nitr amine formation. ^
If the amino groups are protected by conversion into acyl amino groups, then the products obtained on nitration seem to depend ver37^ largely on the experimental conditions. By nitrating i-acetylaminoanthraquinone, and 1.5 and 1.8- diacetylamino anthraquinone, Eckert and Steiner * obtained nitro compoimds in which the nitro groups were in the para- position to the amino groups, but the nitration of i-acyl- alkylamino anthraquinones leads to a heteronuclear nitro compounds, the nitration product, after hydrolysis, being 5-nitro-i-alkylamino anthraquinone. 3 The nitration of the unacylated a-monalkyl aminoanthraquinones and of the a-dialkylamino anthraquinones, however, leads to homo- nuclear nitro compounds, the nitro group taking the ^im- position. ^ The nitration of 2-acet3'laminoanthraquinone leads to 2-aniino-i-nitroanthraquinone.'^
The products obtained by the nitration of 1.4-diacyl- aminoanthraquinone depend very largely on experimental
» M. 32, 1037. G.E., D.R.P. 290,814.
2 Scholl and Eberle, B. 37, 4434. M. 32, 1037.
3 B.A.S.F., D.R.P. 146,848.
* M. 35, 1 137. Cf. M.L.B., D.R.P, 158,076. Noelting and Wortmann, B. 39, 643.
5 M.L.B., D.R.P. 292,395.
6 By., D.R.P. 156,759. ■ Ullmann and Medenwald. B. 46, 1798.
THE AMINOANTHRAQVINONES 223
conditions, the action of mixtures of nitric and sulphuric acids leading to the heteronuclear nitration with the pro- duction of both i.4-diacylaniino-5- and 8-nitroanthra- quinone,^ whereas the action of nitric acid and an indifferent solvent such as nitrobenzene leads to homonuclear nitration, the product being i.4-diac3^1amino-2-nitroanthraquinone.2 If 1.4-dianiinoanthraquinone is heated to 50-60° with oleum containing 45 per cent, of free sulphur trioxide a sulphonamide, Ci4H602(N:S02)2, is formed. This is a perfectly stable compound which is insoluble in water, and its formation provides a convenient means of protecting the amino groups. On nitration and subsequent hydrolysis it yields i .4-diamino-5-nitroanthraquinone.
Amino groups can also be protected during nitration by converting the aminoanthraquinone into the urethane, either by treatment with clilorcarbonic ester or by the action of carbonyl chloride followed by treatment of the result- ing urea chloride ^ with alcohol. When nitrated the ure- thane of a-aminoanthraquinone gives a mixture i-amino- 2-nitroanthraquinone and i-amino-4-nitroanthraquinone, further nitration of both isomers leading to i-amino-2.4- dinitroanthraquinone. The diurethanes of both 1.5- and i.8-diaminoanthraquinone behave in the same way, the nitro groups takmg the ortho- and para- positions to the amino groups. The urethane of /5-aminoanthraquinone when nitrated gives first a mixture of 2-amino-i-nitro- anthraquinone and 2-amino-3-nitroanthraquinone. Both of these on further nitration yield the same dinitroamino compound which must, therefore, be i.3-dinitro-2-amino- anthraquinone.4 From this it is clear that the behaviour of the urethanes on nitration differs from that of other acj-lamino compounds. The diurethanes of the hetero- nuclear j8jS-diaminoanthraquinones behave in the same way. Ullmann and Medenwald ^ have also studied the nitration of the urethane of 2-aminoanthraquinone and find that the
1 By., D.R.P. 268,984.
* By., D.R.P. 267.445. Cf. M.L.E.. D.R.P. 254,185.
^ See p. 219.
« By.. D.R.P. 167.410; 171.58S. 6 B. 46, 1798.
15
226 ANTHRACENE AND ANTHRAQUINONE
chief product is 2-amino-i-nitroanthraquinone, but that about 20 per cent, of 2-amino-3-mtroanthraquinone is also formed. As the separation of the isomers is easy the nitra- tion of the urethane provides a ready means of obtaining this latter substance.
Amongst other methods which have been proposed for protecting amino groups during nitration m^y be mentioned the formation of the azomethine compound, obtained by warming the amino compound with formaldehyde or tri- oxymethylene and concentrated sulphuric acid, and the conversion of the aminoanthraquinone into the oxaminic acid by heating to 150° with oxalic acid. The nitration of a-methyleneaminoanthraquinone yields a mixture of the ortho and para nitro compound. ^ The oxaminic acids are said to be particiilarly suited for nitration purposes as they are readily obtained, and although the free acids are almost insoluble their salts are often readily soluble and well crystal- lised. On nitration the nitro group enters the para- position to the amino group. ^
The Nitramines. — When a primary or secondar>^ amino- anthraquinone is nitrated, the nitro groups first enter the easily attacked ring positions, but when these positions are all occupied the nitro group enters the amino group. ^ Thus, if j3-aminoanthraquinone is nitrated first 2-amino-3-nitro- anthraquinone is formed.'* In this there is no readily nitrated ring position vacant, so that the further action of nitric acid leads to 2-nitramino-3-nitroanthraquinone. In the case of a-aminoanthraquinone there are two easily nitrated ring positions available so that first i-aniino-2.4-dinitro- anthraquinone is formed, and then i-nitramino-2.4-dinitro- anthraquinone. The behaviour of 1.5-dianiinoanthra- quinone is exactly similar, first diaminotetranitroanthra- quinone being formed and then the dinitramine. In 1.5- diamino-2.4.6.8-tetrabromanthraquinone, on the other hand,
1 B.A.S.F., D.R.P. 279,866.
2 M.L.B., D.R.P. 158,076.
3 B.A.S.F., D.R.P. 111,866; 121. 155; 146,848.
* Scholl and Eberle, B. 37, 4434. M. 32, 1037. Ullmann and Meden- wald. B. 46. 1798.
THE AMINO ANTHRAQVINONES
227
no readily nitrated ring position is available so that nitration leads at once to the diuitraniine.
The sodium salts of the uitramines can be obtained by the action of sodium hypochlorite on the anthraquinonediazonium sulphates, and the free uitramines can be liberated from these salts b}' the action of weak acids such as carbonic or acetic acid J This reaction, however, seems to be confined to the anthraquinone-a-diazonium sulphates, as in another patent 2 it is stated that under similar conditions the j3-diazonium sulphates give only unstable substances which smell of and contain chlorine. The authraquinone jS-nitra- mines can be obtained, however, by oxidising the iso- diazotates with hj-pochlorites.^
The uitramines are rather unstable compounds which are more or less explosive but can, as a rule, be nitrated, "* e.g. by the action of fuming nitric acid at 0°. Owing to their instabilit}' they act as nitrating agents towards easily nitratable substances,^ such as phenol, benzene, etc., and frequentl}^ undergo self-nitration when treated with con- centrated sulphuric acid.^ During this self-nitration the nitro group takes the ortho- position to the amino group, i-uitraminoanthraquinone passing into i-amino-2-nitro- anthraquiuone, whereas when the nitramine is treated with nitric acid the entering nitro group takes the para- position, i-nitraminoanthraquinone forming i-nitramino-4-nitro- anthraquinone.'^
The uitramines on reduction lose the nitro group and pass into the primary- amine, whereas when heated with water slightly soluble substances of unknown composition are formed which dve mordanted or unmordanted wool brown. ^
Halogenation
A considerable amount of work has been recorded dealing with the behaviour of the aminoanthraquinones when
1 M.L.B., D.R.P. 156,803. 3 G.E., D.R.P. 259.432. 5 B.A.S.F., D.R.P. 148,109. ' G.E., D.R.P. 156.803.
2 G.E., D.R.P. 262,076. * M.L.B., D.R.P. 156.803. 6 G.E., D.R.P. 259,432. » By., D.R.P. 220.032.
228 ANTHRACENE AND ANTHRAQUINONE
halogenated under various conditions, the subject being com- plicated by the great ease with which halogen atoms under ceitain conditions wander from one position to another. It should also be noted that aminoanthraquinones, at all events the a-amino compounds, can under certain con- ditions form N-halogen derivatives quite readity.^ Thus a-aminoanthraquinone when brominated under stdtable con- ditions yields N-brom-a-aminoanthraquinone, Ci4H702NHBr, and 1,5-diaminoanthraquinone gives an octachlor com- pound in which some of the chlorine atoms are attached to the nitrogen atoms. 2 SchoU and Berblinger 3 have also found that the bromination of 1.5-diaminoanthraquinone by molecular bromine without a solvent leads to a product which loses the whole of its bromine when kept in a vacuum. This ma}^ be merely a solid solution, although Scholl and Berblinger incline to the belief that it is a perbromide, although they were unable to obtain it in a pure state. Against the belief that the substance in question was a perbromide it must be pointed out that tertiary a-dialkylaminoanthra- quinones when treated with bromine are brominated in the para- position to the amino group, and at the same time add on two atoms of bromine to form a perbromide. * These perbromides are well crystallised substances and are stable towards water, although they readily lose bromine when treated with bases. The substance obtained by Scholl and Berblinger, on the other hand, was decomposed by water with the production of tetrabromaminoanthraquinone.
N-Chlor- compovmds can also sometimes be obtained by the action of hypochlorous acid, i-acet5daminoanthraquinone giving by this means N-chlor-i-acetaminoanthraquinone, In all these compounds the halogen is very easily removed by reduction.
The majority of investigators who have studied the halogen ation of the aminoanthraquinones have used molecular chlorine, although it has been claimed ^ that aminoanthra- quinones are ver^- smooth!}^ chlorinated b}' sulphury!
1 By., D.R.P. 104,901 ; 115,048; 126,392-3. - B.A.S.F., D.R.P. 125,09.1. » B. 37. 4180.
« By.. D.R.P. 146,691. ' B.A.S.F., D.R.P. 158,951.
THE AMINOANTHRAQUINONES 229
chloride, either at the ordinary temperature or on the water bath.
When a-aminoanthraquinonc is brominated in glacial acetic acid solution the first bromine atoms enter the ortho- position,^ further bromination (or chlorination) leading to i-amino-2.4-dihalogenanthraquinone.2 The alkyl and acyl a-aminoanthraquinones, however, differ from the primary compound as the para- position is first attacked, ^ this difference in behaviour probably being due to the primary compound first forming an N-halogen derivative, the halogen atom then wandering to the ortho- position.-* The exhaustive chlorination of a-aminoanthraquinone has recently been studied by Friess and Auffenberg,^ who find that the amino group is split out and then the anthraquinone ring opened, the products being 2.3.4.5.6-pentachlorbenzophenone and finally phthalic acid and pentachlorphenol.
The behaviour of 1.5-diaminoanthraquinone w'hen bromi- nated is analogous to that of a-aminoanthraquinone, the 2.4.6.8-tetrabrom derivative being formed. ^ On chlorination an octachlor compound is formed as mentioned on p. 228, and also a hexachlordihydrox}^anthraquinone and octachlor- anthraquinone."^ It is curious to notice that both dibrom- and tetrabrom-i-s-diaminoanthraquinone give tetra-acetyl derivatives, although the imbrominated product will give onl}' a diacetyl compound. ^
Probably owing to the instability of the N-halogen compounds the presence of a primar}^ amino group in the /3- position greatly facilitates the entrance of halogen atoms into the anthraquinone ring. The halogenation of /S-amino- anthraquinone has been studied in some detail by several investigators, and it has been found that its reactivity is so great that it is almost impossible to obtain a m^onohalogen
1 By.. D.R.P. 160,169.
2 Ullmann, B. 49. 2165. B.A.S.F.. D.R.P. 199,758.
3 By., D.R.P. 164,791.
* Compare the behaviour of the nitramines (p. 227).
6 B. 53, 23.
« SchoU and Berbhnger, B. 37. 4180. B.A.S.F., D.R.P. 137,783.
' B.A.S.F.. D.R.P. 125.094 ; 137.074.
8 Scholl and Berbhnger, B. 37, 4180. Romer, B. 16, 36G.
230 ANTHRACENE AND ANTHRAQUINONE
compound, the result of using only the calculated amount of the halogen being usually to produce a mixture of 2-amino- 1.3-dihalogenanthraquinone and unchanged 2-aminoanthra- quinone.i If, however, 2-aminoanthraquinone is treated with bromine dissolved in an organic solvent, such as glacial acetic acid or nitrobenzene, it is possible, tmder carefully controlled conditions, to obtain 2-amino-3-bromanthra- quinone, the position of the bromine atom being proved by the fact that the substance gives 2-bromanthraquinone when the amino group is eliminated b}' the diazo reaction. 2 As stated above, the usual product obtained by bromi- nating 2-aminoanthraquinone is 2-amino-i.3-dibromanthra- quinone. In this compound the bromine atom in the a- position exhibits remarkable reactivity, and is readily split off when boiled with compounds like acetic acid or aniline, these substances being brominated in the process and the aminodibromanthraquinone being simultaneously degraded to 2-amino-3-bromanthraquinone. The same reaction takes place when the aminodibrom compound is heated with 2-aminoanthraquinone, one molecule of 2-amino-i.3-dibrom- anthraquinone reacting with one molecule of 2-aminoanthra- quinone to produce two molecules of 2-amino-3-bromanthra- quinone, a reaction which has been made use of in the pre- paration of the last-named substance. ^
The acetyl derivative of 2-aminoanthraquinone is much less readity halogenated than the primary compound itself, and by chlorinating 2-acetaminoanthraquinone a monochlor compound can be obtained.* In this, however, the halogen atom is in the a-position, as Jimghaus has found that it gives i.2-diaminoanthraquinone when the chlorine atom is replaced by an amino group by the sulphonamide process. ^ It is interesting to observe that whereas a primar\- amino group in the ^- position directs the entering halogen atom first to the contiguous j8- position, the acetylamino group directs the halogen to the contiguous a- position, although
1 SchoU, B. 40. 1701. Junghaus, A. 399, 316. D.R.P. 273,809. M.L.B., D.R.P. 253,683.
- Junghaus, loc. cit. ^ B.A.S.F., D.R.P. 261,270-1.
« B.A.S.F.. D.R.P. 199.758. * A. 399, 316.
THE ANIMOANTHRAQUINONES 231
the 8-lialogen compound must be regarded as the more stable, as the halogen atom in all homonuclear halogen derivatives of both a- and j3- aminoanthraquinone wanders to the j8- position which is contiguous to the amino group if this position is unoccupied. ^ This wandering of the halogen atom is brought about by heating the substance alone or with sulphuric or phosphoric acids. If the ^- position con- tiguous to the amino group is occupied by a sulphonio acid group this latter is split off by heating with acids, and as a rule a simultaneous wandering of the halogen atom takes place, 2-amhio-i-bromanthraquinone-3-sulplionic acid, for example, passing into 2-aniino-3-bromantliraquinone when boiled with sulphuric acid of 80 per cent, strength. 2 This wandering of the halogen atom can often be avoided by carr5ang out the hydrol3^sis of the sulphonic acid at as low a temperature as possible, by avoiding prolonged heating or by carrying out the hydrolysis by means of concentrated sulphuric acid, monohydrate or dilute oleum, preferably in the presence of mercur\\3
When an aminoanthraquinone sulphonic acid is haloge- nated the halogen can enter the molecule either by the replacement of hydrogen or b}- the replacement of the sulphonic acid groups. Which reaction takes place depends ver>'' largely on the position of the groups present, and on the experimental conditions under which the halogenation is carried out, but for further information the reader is referred to the original literature. ^
The Dianthraquinonyi^amines
Although dianthraquinonylamines can be obtained b}' heating a-aminoanthraquinone or jS-aminoanthraquinone with a-nitroanthraquinone ^ or with an anthraquinone-a- or -j3-sulphonic acid,^ preferably in the presence of sodium
1 By., D.R.P. 275,299.
2 M.L.B., D.R.P. 253,683. B.A.S.F., D.R.P. 263,395. » B.A.S.F., D.R.P. 265,727; 266,563.
« Ullmann and Medenwald, B. 46, 1798. B.A.S.F., D.R.P. 113,292 ; 114.840; 128,196; 138,134; 138,166.
* M.L.B.. D.R.P. 201, 327. 8 M.L.B., D.R.P. 216,083.
232 ANTHRACENE AND ANTHRAQUINONE
carbonate, the reaction only takes place with some difficulty, so that they are always made by condensing a primary- aminoanthraquinone with a halogen anthraquinone. The condensation is usually brought about by heating the amine and the halogen compound together in some indifferent solvent of high boiling point, such as naphthalene or nitro- benzene, copper powder or cuprous chloride being used as a catalyst, and anhydrous sodium carbonate or acetate being added to neutralise the halogen acid liberated. ^ B}^ condensing two molecules of a halogen anthraquinone with one molecule of a diaminoanthraquinone,or, mutatis mutandis, by condensing two molecules of an aminoanthraquinone with one molecule of a dihalogen anthraquinone, dianthra- quinonylaminoanthraquinones * are obtained, several of which have found application as vat dyes. jS^-Dianthra- quinonylamines can also be obtained by condensing anthra- quinone-jS-diazonium salts with ammonia and then heating the resulting product with a solvent of high boiling point, with or without a condensing agent. ^
The ease with which dianthraquinonylamines are formed depends on the orientation of the amino group and of the halogen atom in the reacting substances. If both are in the a- position the reaction takes place easily, e.g. a-chlor- anthraquinone reacts readily with a-aminoanthraquinone to form 1 .1 '-dianthraquinonylamine.
If one group is in the ^- position the reaction takes place with rather greater difficulty, and in this case it is best to condense the /S-halogen compound with the a-amine.^ Thus, )8-chloranthraquinone and a-aminoanthraquinone yield 1.2' dianthraquinonylamine rather more readily than do a-chlor- anthraquinone and j3-aminoanthraquinone. When both
1 Seer, M. 32, 162. Eckert, M. 35, 762. Eckert and Steiner, M. 35, 1129. UUmann, B. 47, 564: 49. 2162. Frey. B. 49, 1363. B.A.S.F.. D.R.P. 184,905; 197,554; 206,717; 212,470; 216,280; 217,395-6; 218,161; 279,867; cf. also 176,956. By., D.R.P. 162,824; 174.699; 194,253; 208,162; 216,668; 220,581; 230,052; 240,276. M.L.B.. D.R.P.' 257,811.
* In the literature these are frequently described as trianthraquinonyl- amines, a nomenclature which would suggest that three anthraquinonyl groups are attached to the same nitrogen atom {cf. triphenylamine).
2 M.L.B., D.R.P. 308,666. ' By., D.R.P. 174,699.
THE DIANTHRAQUINONYLAMINES 233
the halogen atom and the ammo group are in the j3- position, e.g. j8-chloranthraquinone and iS-aminoanthraquinone, the re- action onl}^ takes place with great difficulty, ^ and under these circumstances it is advisable to use the iodo compound.
Hydroxydianthraquinonylamines can be obtained by condensing an aminohydroxyanthraquinone with a halogen anthraquinone, or a hydroxy halogen anthraquinone with an amino anthraquinone, but hydroxy 1 groups can also be introduced into the dianthraquinonylamine molecule by the usual methods, e.g. by direct oxidation with nitrosyl sulphuric acid in the presence of boric acid,^ or by the replacement of halogen atoms or nitro groups b}' heating with alcoholic caustic potash. ^
On nitration i.i '-dianthraquinonylamine gives a dinitro compound in which the nitro groups must be in the paya- positions to the imino group, as the same compound is obtained by condensing i-chlor-4-nitroanthraquinone with i-amiiio- 4-nitroanthraquinone. Further nitration leads to a tetra- nitro, and possibly also to a pentanitro, compound.*
The nitration of 1.2 '-dianthraquinonylamine gives first 4.i'-dinitro-i.2'-dianthraquinon3'lamine ^ and then 2.4.1'- trinit ro- 1 . 2 '-dianthraquinony lamine . 6
Reduction of 4. 4'-dinitro-i,i '-dianthraquinonylamine with sodium sulphide gives the corresponding diamino compound,"^ but reduction with boiling sodium stannite leads to replacement of the nitro groups by hydroxyl groups, the product being 4. 4'-dihydrox3^-i.i '-dianthraquinonyl- amine. ^ The tetranitro compound on reduction with alkaline stannite also loses two nitro groups and forms 2.2'-diamino- 4.4' - dihydroxy - i.i' - dianthraquinonylamine. ^ Reduction with sodium sulphide, however, appears to lead first to the
^ Eckert and Steiner, M. 35, 1129. - M.L.B., D.R.P. 249,938. See also p. 251 et seq. ' By., D.R.P. 232,262. Cf. Eckert and Steiner, M. 35, 1129. < Eckert and Steiner. loc. cit. By., D.R.P. 213,501. M.L.B., D.R.P. 254,186.
* Eckert and Steiner, loc. cit. B.A.S.F., D.R.P. 186,465.
* Eckert and Steiner, loc.xit. By., D.R.P. 178,129. ' M.L.B., D.R.P. 255,822.
» Eckert and Steiner, M. 35, 1129. Cf. By., D.R.P. 178,129.
* Eckert and Steiner, loc. cit.
234 ANTHRACENE AND ANTHRAQUINONE
tetramino compound, which at once loses a molecule of ammonia and passes into diaminoindantbrone : i
,NHx
/^'^\ |
||
NH. H2N |
||
1 |
1 |
I
NHo
HoN
NH,
I
HoN
The reduction of 4.i'-diniLro-i.2'-dianthraquinon3damine by sodium stannite also leads to the replacement of the nitro groups by hydroxyl groups (4.i'-dihydroxy-i.2'-dianthra- quinonylamine), although the diamine compound is obtained when the reduction is carried out in acid solution. 2 As would be expected, the trinitro compound on alkaline reduc- tion yields 2-amino-4.i'-dihydroxy-i.2'-dianthraquinonyl- amine, it being only nitro groups in the a- positions which are replaced. ^
Although the aminodianthraquinonylamines can be obtained in some cases by the reduction of the nitro com- pounds it is usually best to obtain them by condensing halogen anthraquinones with polyaminoanthraquinones, one or more amino groups being protected during the reaction by previous acylation.^
The dianthraquinonylamines when treated with con- densing agents such as caustic alkaH,^ aluminium chloride, 6 or zinc chloride,'^ give rather indefinite products, many of which have tinctorial properties. The constitution of these pro- ducts is unknown although some at least of them seem to be carbazol derivatives. ^ For further information the reader is referred to the original literature.
The tinctorial properties of the simple dianthraquinonyl- amines are, as a rule, somewhat feeble, although 1.2'- dianthraquinonylamine has been placed on the market under
^ Eckert and Steiner, loc. cit.
« Ibid. * Ibid.
5 M.L.B., D.R.P. 208,969 ; 251,021.
« M.L.B., D.R.P. 240,080 ; 262,788.
' M.L.B., D.R.P. 251,350. 8 M.L.B., D.R.P. 267,522 ; 267,833.
« By., D.R.P. 220,581. By., D.R.P. 230,407.
THE DIANTHRAQUINONYLAMINES 235
the name Algol Orange R, and Algol Red B is also a diantlira- quinon3^1amine although containing also a pyridone ring.i The introduction of a benzojdamino group, however, confers tinctorial properties,^ although the unbenzoylated amino- dianthraquinonylamines have little or no affinity, so that in this respect there is a close analogy between the aminodi- anthraquinonylamines and the aminoanthraquinones. The anthraquinonylaniinodianthraquinonylamines are usually powerful d3'es and, when other substituents are absent, produce red or bordeaux shades. Several dyes of this class have been placed on the market, of which the two following are typical :
1 |
__NH |
1 |
-NH |
1 |
1 |
— NH |
1 |
_NH |
1 |
Indanthrene Bordeaux B.
Indanthrene Red G.
Indanthrene Bordeaux R Extra is a dichlor compound somewhat similar to the above, and is derived from i-amino- 6-chloranthraquinone (2 molecules) and 2.7-dichloranthra- quinone (one molecule) . It would be interestmg to trace the relation between the colour and the constitution of the dianthraquinonylamines and the anthraquinonylamino- dianthraquinonylamines, but the data available at present are insufficient to render possible any generalisation.
The introduction of amino, hydroxy or alkoxy groups into the molecule often has a considerable effect on the shade of the resulting dye, and in many cases shifts the colour right into the violet end of the spectrum. A fair number of derivatives of this nature have been described, ^ but the subject is a ver}- complicated one and no inferences of the relationship between colour and constitution can be drawn profitably from the facts so far available.
1 By., D.R.P. 194.253. * By., D.R.P. 220,581 ; 238,488.
3 B.A.S.F.. D.R.P. 206,717 ; 212,470 ; 216,280. By., D.R.P. 208,162 ; 216, 668.
CHAPTER XII
THE HYDROXY- AND AMINOJIYDROX Y- ANTHRAQUINONES AND ETHERS
I. The Hydroxy Compounds
The hydroxy anthraquinones constitute a very important class of substances, partly on account of the valuable tinctorial pro- perties exhibited by many of them, and partly owing to their forming convenient starting-out substances in the synthesis of other anthraquinone derivatives, e.g. Alizarin C5'anine Green. The actual constitution of man}^ of the hydrox5'l com- pounds is open to some doubt, as although h3^drox>d groups in any position can be readily acylated, hydroxyl groups when in the ortko- position to a carbonyl group cannot be alk3dated, or can only be alkylated with the utmost difficult}-, by the usual means, e.g. b}^ treatment with dimeth}^ sulphate or methyl iodide and caustic potash. Hydroxj-l groups in the P- position, however, behave in a perfectly normal manner towards alkylating agents. The abnormal behaviour of hydrox}^ groups in the a- position is obviously due in some way to the influence of the carbonyl group, as the difficulty of alkylation disappears when the anthraquinone compound is reduced to the corresponding anthrone, and the corresponding hydroxy anthracenes, the a-anthrols, can be alkylated without an}- trouble. It has been suggested that the a-hj-droxyanthraquinones really have the tautomeric o-quinonoid structure :
CO OH OH P
CO CO
and this would explain the difficulty in alkylation.
Although, as stated above, hj-drox^-l groups both in the
236
THE HYDROXY COMPOUNDS 237
a- and /3- position can be acylated with ease, groups in the j3- position are more easily attacked than those in the a- position, so that by moderating the conditions of experiment it is often possible to acylate groups in the j3- position without affecting those in the a- position. In the case of acetyl derivatives Dimroth, Friedemann and Kammerer ^ have found that this is most readily effected by dissolving the hydroxy compound in pyridine and then, without heating, adding the calculated amount of acetic anhydride necessar}^ to acetylate the /S-hydroxyl groups. Only the calculated amount of acetic anhydride must be used, as otherwise all the hydroxy 1 groups will be attacked, although those in the a-position react only slowh" with acetic anliydride in cold pyridine solution.
In addition to methods based on the replacement of other groups such as amino groups, sulphonic acid groups, nitro groups, etc., the hydroxyd group can be inserted into the anthraquinone molecule with great ease by direct oxida- tion, and it is possible by this means to obtain a vers' large number of different hydroxys compounds according to the conditions employed. As has been already stated, hydrox}-- anthraquinones can often be built up from phenolic ethers by the phthalic acid S5-nthesis, and in many cases the reduc- tion of the higher hydroxylated anthraquinones leads to the loss of h^'droxyl groups. The oxidation of the h^-droxy anthracenes, or rather of their acetyl derivatives or meth}! ethers, also leads to hydroxyanthraquinones, although the method is of little importance except as a means of identify- ing the anthrols.-
A great many of the hydroxyanthraquinones have received special names, and for ease of reference these have been tabulated together with the melting ]:>oint of the hydroxy compound and its acetyl derivative. The prepara- tion of the acetyl derivatives is usually very easily effected by boiling the hydroxy' compound with acetic anhydride and anhydrous sodium acetate, and they often provide a ready means of characterising the hydroxy- compound.
» B. 53, 481.
* Lieberraann and Boeck, B. 11, 1616 ; 12, 185. Liebcrmann and Hormann, B. 12, 250. Dienel, B. 38, 2862.
238 ANTHRACENE AND ANTHRAQUINONE
HYDROXYANTHRAQUINONES.
Position of Hydroxyl. |
Usual name. |
M.p. |
Acetyl deriva- tive m.p. |
I- |
Erythrohydroxyanthraquinone |
190° |
176-179° |
2- |
— |
302" |
159° |
1.2- |
Alizarin |
289-890° |
184° |
1-3- |
j Piirpuroxanthin. Xantho- 1 ( purpurin J |
262-263° |
184° |
1.4- |
Quinizarin |
194° |
200° |
1-5- |
Anthrarufin |
280° |
244-245° |
1.6- |
1 |
276° |
205-206° |
1-7- |
— |
291-293° |
199° |
1.8- |
Chrysazin |
191° |
227-232° |
2.3- |
Hystazarin |
( Decomp. ) \ above 260°/ |
206-207° |
2.6- |
Anthraflavic acid |
Above 330° |
228° |
2.7- |
iso- Anthraflavic acid |
Above 330° |
About 195° |
1.2.3- |
( Anthragallol, | \ Anthragallic acid 1 |
310° |
181-182° |
1.2.4- |
Purpurin |
256° |
192-193° |
1.2.5- |
Hydroxyanthrarufin - |
278° |
228° |
1.2.6- |
Flavopurpurin |
Above 330° |
195-196° |
1.2.7- |
Anthrapurpurin. iso-Purpurin |
369° |
224° |
1.2.8- |
Hydroxychrysazin ^ |
239-240° |
219° |
I-4-5- |
3 |
— |
— |
1.4.6- |
4 |
256° |
|
1.4.8- |
5 |
— |
— |
1.2.3.4- |
— |
— |
205° |
1.2.4.6- |
Hydroxyflavopurpurin |
202° |
— |
1.2.4.7- |
Hydroxyanthrapurpurin |
— |
214° |
1.2.4.8- |
— • |
— |
— |
1.2.5.6- |
Rufiopin * |
— |
— |
1.2.5.8- |
Quinalizarin. Alizarin Bordeaux |
Above 275° |
201° |
1.2.7.8- |
7 |
— |
— |
I-3-5-7- |
Anthrachrysazin |
Above 360' |
253* |
1.4.5.8- |
246° |
j Decomp. 1 about 250° |
|
i.?.?.8- |
8 |
217° |
195" |
i.?.?.8- |
9 |
292° |
238-240° |
1.2.4.?- |
Hydroxypurpurin ^° |
Above 290° |
Above 240° |
1 Frobenius and Hepp, B. 40, 1048.
2 Wed., D.R.P. 205,965 ; 210,863. 2 By., D.R.P. 161,026; 163,041. * Dimroth and Pick, A. 411, 315.
Wed., D.R.P. 202,398.
Crossley, Am. Soc. 40, 404, states that the substance does not melt below 300°.
5 R. E. Schmidt, Bull. Soc. Ind. Mull. 84, 409.
^ Liebermann and Chojnacki, A. 162, 323 (from hemipinic or opianic acid and cone. H-,S04). By., D.R.P. 103,988 (from anthrarufin).
' By., D.R.P. 103,988. See also note 9.
8 Schrobsdorf. B. 36. 2936.
9 Wolbling, B. 36, 2941. Probably identical with 1.2.7.8-tetrahydroxy- anthraquinone.
10 Diehl, B. 11, 185. Gattermann, J. pr. [2] 43, 251.
THE HYDROXY COMPOUNDS
239
HYDROXYANTHRAQUINONES— co«/JHuecf.
Position of Hydroxy!. |
Usual name. |
M.p. |
Acetyl deriva- tive m.p. |
1.2.3.5 or 7- 1.2.3.5 or7- 1.2.3.5.7- 1.2.3.6.7- 1.2.4.5.8- 1.2.5. ?.8- 1.2.3.5.6.7- 1.2.4.5.6.8- 1.2.4.5.7.8- 1.2.3.4.5.6.7.8- |
a-Hydroxyanthragallol ^ ^-Hydroxyanthragallol ^ Dihydroxyanthragallol Alizarin Cyanine R 3 Rufigallic acid Anthracene Blue WR 4 5 |
Above 350** Above 380* Above 360" |
207-209" 189° 229° 282-283* ( Decomp. 1. at 330° |
Replacement of Groups
Replacement of Sulphonic Acid Groups. — The con- version of an anthraquinone sulphonic acid into a hydroxy- anthraquinone by fusion with caustic alkaH is complicated by the fact that during the alkali melt simultaneous oxida- tion takes place, so that the product usually contains more hydroxyl groups than there were sulphonic acid groups in the original acid, anthraquinone-2-sulphonic acid when fused with caustic soda giving alizarin, purpurin, and other polyhydroxyanthraquinones. Here it will be seen that replacement of the sulphonic acid group is accompanied by hydroxy-lation by oxidation, and this type of reaction is discussed in greater detail on p. 252.
By moderating the conditions under which the caustic melt is carried out, it is often possible to replace sulphonic acid groups in the /3- position without simultaneous oxidation taking place, although the yields are usually poor. Thus, Graebe and Liebermann ^ fomid jS-hj'droxj-anthraquinone in crude alizarin, and Liebermann and Simon ' were able to obtain the same substance from anthraquinone-^-sulphonic
1 From gallic acid and w-hydroxybenzoic acid. Noah, A. 241, 270.
' Bentley and Weizmannr Soc. 93, 438. (Tetramethyl ether.)
* R. E. Schmidt, J. pr. [2] 43, 242. Gattermann, ibid. 250.
* By., D.R.P. 103,988. 5 Georgie\ncs, M. 32, 347.
6 A. 160, 143. ' B. 14, 464 ; A. 212. 25. 53.
240 ANTHRACENE AND ANTHRAQUINONE
acid by fusion with caustic alkali. The anthraflavic acid and iso-anthraflavic acid which Romer and Schunck i found in commercial alizarin no doubt originated in the anthraqui- none disulphonic acids present in the crude monosulphonate from which the alizarin was made, and a few years later Romer and Schwazer 2 succeeded in making eso-anthraflavic acid from anthraquinone-2.7-disulphonic acfd. Since then many other cases have been discovered in which replacement of sulphouic acid groups takes place in the alkali melt without simultaneous oxidation, ^ but as a rule it is difficult to avoid oxidation taking place unless one of the modified methods described below is emploj^ed. It should be noted that the above remarks apply chiefly to anthraquinone sul- phonic acids in which the sulphonic acid group is in the j3- position. When the sulphonic acid group is in the a- position fusion with caustic alkali usually leads to rupture of the benzene ring, so that in these cases it is essential to use special methods in order to obtain a hj'drox}' anthraquinone.
Sulphonic acid groups in the a- position are somewhat more reactive than similar groups in the ^- position, and are usually replaced by hydroxyl groups when the compound is heated to about 200° with aqueous sodium carbonate, anthraquinone-i -sulphonic acid, for example, giving erv'thro- hydroxyanthraquinone . when treated in this way.^ They can also often be replaced by the use of caustic alkali, for although fused caustic alkali or highly concentrated solu- tions almost always cause rupture of the ring when there is a sulphonic acid group in the a- position, this is not the case when more dilute solutions are used at a comparativeh- low temperature, 5 and anthraquinone-a-sulphonic acids are often fairl}- readil}'^ converted into a-hydroxyanthraquinones when heated with ten per cent, caustic soda solution at about 150°.
Sulphonic acid groups in any position in the anthra-
1 B. 8. 1628 ; 9, 379- " B. 15, 1040.
3 Wolbling, B. 36, 3941- By., 103,686 ; 103,988; 178,631. C/. also Lifschiitz, B. 17, 901. Frobenius and Hepp, B. 40, 1048.
4 By., D.R.P. 197.649. M.L.B., D.R.P. 149,781. * By., D.R.P. 172,642.
THE HYDROXY COMPOUNDS 241
quinoiie molecule can be replaced by hydroxyl groups by the use of aqueous solutions of calcium or barium li5^droxide at temperatures of 150-180°. This method has the great advantage that in the case of anthraquinone-a-sulphonic acids rupture of the ring does not take place, and that in the case of anthraquinone-j8-sulphonic acids replacement of the sulphonic acid group by h^'droxyl can be effected without simultaneous oxidation taking place. 1 In many cases the sulphonic acid groups in aminoanthraquinone sulphonic acids can be replaced by hydroxyl groups by this means without afTecting the amino group, e.g. i-amino- anthraquinone 5- and -8- sulphonic acids give respectively i-amino-5- and -8- hydroxy" anthraquinone.^ As the sodium or potassium salt of the sulphonic acid is almost invariably used, hydrox^'lation by means of alkali earth hydroxide leads to the liberation of sodium or potassium sulphite :
2Ci4H702S03Na+Ca{OH)2=2Ci4H702.0H+CaS03+Na2S03
and it is advisable to destroy this or to render it harmless as rapidh- as formed by carrying out the reaction in the presence of an oxidising agent such as a chlorate or nitrate, or in the presence of calcium or barium chloride. ^
The alkali earth hydroxide method has been used to a considerable extent, and in the case of anthraquinone disulphonic acids it has been found possible to replace one group at a time,* e.g. in the cases of anthraquinone-2.6- and -2.7-disulphonic acids. From alizarin-5-sulphonic acid, hydroxy^anthrarufin has been obtained, alizarin-8-sulphonic acid giving hydroxy chrysazin.^ Sulphonic acid groups can also be replaced by heating the sulphonic acid with methyl alcoholic caustic potash, but in this case a methox\- and not a hydrox}- group is inserted. This type of reaction is treated in greater detail on p. 287, in connection with the ethers.
Replacement of Nitro- Groups. — Nitro groups can, of
1 R. E. Schmidt, B. 37, 69. Bv., D.R.P. 172,642 ; 197.607. M.L.B., D.R.P. 106,505 ; 145.188.
2 xM.L.B., D.R.P. 14S.S75.
3 Wed., D.R.P. 195.874.
* M.L.B.. D.R.P. 106.505.
5 Wed.. 170.329; 202,398 ; 210.863. Cf. Frobeaius and Hepp. B. 40, 1048.
16
242 ANTHRACENE AND ANTHRAQUINONE
course, be replaced by hydroxyl groups indirectly by first reducing the nitro compound to the amino compound and then treating this by any of the methods discussed on p. 249. The direct replacement of nitro groups can, however, often be effected. If the nitro groups are in a- positions heating with aqueous alkali or alkali earth hydroxide sometimes leads to their replacement by hydroxyl gfoups, e.g. 1.5- and i.8-dinitroanthraquinone give respectively anthrarulin and chrysazin, but the yields are usually very poor.* Alco- holic alkali reacts more readily, but unless water is carefully excluded simultaneous reduction is apt to take place and impure products are obtained. 2 When absolute alcoholic alkali is employed it is the alkyl ether of the hydroxy compound which is formed, the free hydroxy compound being liberated by subsequent hydrolysis. 2 The method, however, often gives excellent results and is applicable to the replacement of nitro groups in either the a- or the jS- position.3 Nitro groups can also be replaced by hydroxyl groups with great ease by heating the nitro compound in open or closed vessels with crude pyridine or quinoline, a-nitroanthraquinone giving er^^throhydroxyanthraquinone and 1.5- and i.8-dinitroanthraquinone giving respectively anthrarufin and chrysazin. * The reaction is an interesting one and deserves further investigation. The patent does not state if the method is also applicable to the replacement of nitro groups when in the )8- position, but in all the examples given the nitro groups occupy a- positions.
Much more important than the above is the replacement of nitro groups by hydroxyl groups by heating with concen- trated sulphuric acid or oleum. The reactions which take place are extremely complicated and are rendered more so by the fact that the nitrous acid liberated may react with the hydroxyanthraquinone, either reducing hydrox^-l groups present, 5 or inserting more hydroxyl groups into the molecule by oxidation. Sulphonation, of course, also often takes
1 By., D.R.P. 158,891. M.L.B.. D.R.P. 75,054.
* Kaufler, B. 37. 63. Eckert, M. 35, 290. M.L.B., D.R.P. 73.860; 75.054; 77.818; 167,699.
3 See p. 287. « By., D.R.P. 145, 238. " Nienhaus, B. 8, 778,
I
THE HYDROXY COMPOUNDS 243
place, aud insoluble products are then only obtained by subsequently boiling the hydroxyanthraquinone sulphonic acids with dilute sulphuric acid, although in many cases the sulphonic acid groups can be split off by heating with hydrochloric or phosphoric acid or even alone with water. ^
Work on the replacement of nitro groups has chiefly been published in patent specifications, and in many cases the nature of the product is not stated and no information is given as to whether it is nitrogenous or not. Also many specifications describe the reaction as being carried out by heating " nitroanthraquinones or partially reduced nitro- anthraquinones with concentrated sulphuric acid or oleum, with or without the addition of a reducing agent such as sulphur." As the mechanism of the reaction seems to depend very largely on whether a nitroanthraquinone or a partially reduced compound is used, and on whether a reducing agent such as sulphur is or is not added to the melt, it is difhcult to co-ordinate the various claims.
It appears that the nitro group is particularly easily replaced when it is in the para- position to a hydroxyl group, and under these circumstances the reaction is best carried out by heating with concentrated sulphuric acid in the presence of boric acid. 2 The action of the boric acid in this case seems to be specific and not to be limited to protecting hydroxyl groups, as dinitroanthrarufin is stable towards concentrated sulphuric acid at 100° in the absence of boric acid, but in the presence of boric acid one nitio group is replaced by a hydroxyl group at this temperature, and at higher temperatures both are replaced. Dinitro- anthrarufin disulphonic acid exhibits the same behaviour, as it is unaffected when heated for four hours at 150° with concentrated sulphuric acid in the absence ot boric acid, but in the presence of boric acid one nitro group is easily replaced at 80-90°, and both are replaced at 120°.
The action of concentrated sulphuric acid on nitroanthra- quinones was first studied by Graebe and Liebermann.^
1 B.A.S.F.. D.R.P. 76,941. 2 By., D.R.P. 125,570.
3 B. 3, 905 ; 4, 231.
244 ANTHRACENE AND ANTHRAQUINONE
Bottger and Petersen, i and Liebermann and Hagen.^ These last treated the product with nitrous acid and obtained erythrohydroxyanthraquinone and a dihydroxyanthra- quinone which thej^ regarded as xanthopurpurin. Their analyses agreed with the figures required by the formula C28H18O7N2, and they concluded that the substance in question was probably an amide of erythrohydroxyanthra- quinone and xanthopurpurin.
Claus 3 examined the action of concentrated sulphuric acid on nitroanthraquinone sulphonic acid and obtained two products to which he gave the formulas :
C14H5O,
OS03H |
r 'SO3H-1 |
|
OH |
and |
C14H4O2 OH |
INO2 |
INO2 . |
,0
but he was unable to obtain them in a state of purity ; and Lifschiitz,^ on repeating Claus' experiments, was unable to obtain either.
Lifschiitz ^ studied the action on concentrated stdphuric acidoni.5-dinitroanthraquinone and isolated four substances. All these when diazotised and reduced gave dihydroxy- anthraquinones, such as anthrarufin, and lifschiitz regarded them as anh3-drides (ethers) of aminohydroxyanthraquinones, ^•g- [Ci4H402(OH)(NH2)2]20- His analyses, however, do not agree sufficiently well either among themselves or with the figures calculated for the proposed formulae to allow these results to be accepted without further confirmation.
More definitive information concerning the action of sulphuric acid on dinitroanthraquinone is to be found in two patents. 6 In these it is stated that when 1.5-dinitro- anthraquinone is treated with oleum containing 30 per cent, of free anh^-dride at 50° a molecular rearrangement takes place and i -hydroxy -4-nitroso-8-nitroanthraquinone is formed, i.8-dinitroanthraquinone and also, apparently, 1,8-dinitro- naphthalene reacting in the same way. These ^-nitroso- phenols are, of course, tautomeric with the quinone mon-
1 A. 160, 155 ; 166, 152. B. 4, 229, 301. " B. 15, 1801. » B. 15, 1521. « B. 17, 902. » B. 17, 891. « By., D.R.P. 104,282 ; 105,567.
THE HYDROXY COMPOUNDS
245
oximes so that hydroxj^lation can take place by the addition of the elements of water, subsequent loss of water leading to the formation of a qiiinoneimide :
O
NO.,
HO NO,
O NOo HO NO.
NO.
1 |
-> |
1 |
-^ |
1 |
-> HO |
1 |
— > HO |
1 |
^2 |
NC |
) |
HON |
HONH |
NH |
Presumably the other nitro group reacts in exactly the same way, so that the final product is a bisquinoneimide, or its sulphonic acid :
O NH
I
OH
HO HN O
In support of this view of the reaction the patentees point out that although the final product of the action of oleum on 1.5-dinitroanthraquinone is 1.2.4.5.6.8-hexa- hydrox}' anthraquinone disulphonic acid, the absorption spectrum of the finished melt is quite different from the absorption spectrum of a solution of hexahydroxyanthra- quinone sulphonic acid in concentrated sulphuric acid. Also the solution at first obtained by running the melt into water is bluish-violet in colour although it changes almost at once to red. Finally, they claim that by running the melt into a saturated solution of sodium chloride or potassium chloride at —10° the disulphonic acid of the bisquinoneimide can be isolated.
The quinoneimide is unstable towards water and is very readily hydrolysed with loss of ammonia and production of the hexahydroxyanthraquinone, but if the solution in con- centrated sulphuric acid or oleum is run direct into a reducing
246 ANTHRACENE AND ANTHRAQUINONE
solution (e.g. sulphurous acid) reduction takes place, and diaminoanthrachrysazin disulphonic acid is obtained,^ which by oxidation with oleum or manganese dioxide and sulphuric acid is converted back into the quinone imide.
The above facts render it fairly certain that the con- version of dinitroanthraquinone into hexah3'drox>^anthra- quinone by concentrated sulphuric acid or oldum is preceded b}' the formation of a quinoneimide. This is also the case when the reaction is brought about by means of oleum and a reducing agent such as sulphur. 2 Here, however, it is probable that the formation of the quinoneimide is not due so much to the preliminary formation of a ^-nitrosophenol as to partial reduction of the nitro groups to hydroxy^lamine groups, and then immediate rearrangement of these hydrox^'l- amine compounds to ^-hydroxy^amines : ^
NO, HONH NHo OH NH O
H
NO,
o
HNOH HO NH2 o NH
The rearrangement of hydroxylamine derivatives into ^-aminophenols under the influence of acids is, of course, a well-known reaction which is common to the aromatic series. That the anthraquinonyl hydroxylamines react normally in this respect has been shown by several investigators. *
From the above it will be seen that the final product of the action of sulphuric acid or oleum, with or without the addition of sulphur, on 1.5 -dinitroanthraquinone is 1.2.4.5.6.8- hexahydroxyanthraquinone disulphonic acid, a water- soluble product used to some extent as a mordant dye imder various trade names such as Acid Alizarin Blue BB, Alizarin Cyanine WRS, BBS, 3RS and Anthracene Blue SWX.
1 By., D.R.P. 115,002.
=» B.A.S.F.. D.R.P. 76,262 ; 87,729 ; 88,083 ; 89.144 ; 92,800 ; 92,998; 109,613; 121,315. By., D.R.P. 96,197; 105,567; 108,362; 113.724; 116,746; 119,229.
* R. E. Schmidt and Gattermann, B. 29, 2934. By.. D.R.P. 81,694.
* R, E. Schmidt and Gattermann, B. 29, 2934. ^y.. D.R.P. 119,229.
THE HYDROXY COMPOUNDS 247
Hydrolysis, e.g. b}' heating with concentrated sulphuric acid, has the effect of removing the sulphonic groups and rendering the product insoluble (Anthracene Blue WR, WG, WB). The commercial dyes as a rule consist of mixtures of isomeric hexahydroxy and pentahydroxy compounds.
The production of polyhydroxj-anthraquinones by the action of sulphuric acid or oleum, with or without the addition of sulphur, on nitro compounds has been extended to sub- stances such as nitromethylanthraquinone, dinitroanthra- rulin, tetranitrochrysazin, nitroalizarin, nitroflavopurpurin, nitroanthrapurpurin, etc., but without results of any particidar interest. ^
Replacement of Halogen Atoms. — Halogen atoms when attached to the anthraquinone nucleus are not easil}- replaced by hydroxyl groups by the action of alkali, although the first synthesis of alizarin was effected by Graebe and Liebermann by fusing dibromanthraquinone with caustic potash. 2 Alcoholic alkali is much more effective than aqueous solutions and will attack halogen atoms when these are situated in a- positions, but as a rule the ether and not the free hydroxy- 1 compound is obtained, ^ although, of course, the alkyl group can be removed by subsequent hydroh'sis, and according to O. Fischer and Sapper ^ this is generally the most satisfactory method of replacing halogen atoms by hydrox^d groups. In some cases, however, alcoholic alkali can be emploj-ed for replacing halogen atoms directly by hydroxr\d groups, and Decker and Laube ^ have found that when i-chlor-2-methox5-anthraquinone is heated with methyl alcoholic caustic potash a mixture of alizarin dimeth>-l ether and alizarin j8-monomethyl ether is obtained. The use of solutions of caustic potash in ethyl alcohol gave ver>' similar results, viz. a mixture of alizarin methyl ethyl ether and alizarin /3-monomethyl ether. Schrobsdorf ^ has obtained a tetrahydroxy- compound from dibromchrj-s- azin by fusing it with caustic potash, and this tetrahydroxy
» By.. D.R.P. ior,^86; 119,229.
* B. 2, 14, 332. 505. Mon. Sci. 1869, 384.
» See p. 287. 4 J. pr. [2] 83. 206.
» B. 39. 112. • B. 36,2936.
248 ANTHRACENE AND ANTHRAQUINONE
compound is not identical with that obtained b}' Wolbling ^ from chtysazin disulphonic acid, as it melts at 217° and its acet^'l derivative at 195°, whereas Wolbling's product melts at 292° and gives a tetraacetyl derivative melting at 238-240°.
Halogen atoms can also sometimes be readily replaced by hydroxy^l groups by heating to 150-160° with concentrated sulphuric acid and boric acid, and in this way Ullmann and Conzetti 2 prepared quinizarin from i -hydroxy -4-chloranthra- quinone. Only halogen atoms which occupy a- positions are affected, so that i-hydrox)^-2.4-dichloranthraquinone gives 2-chlorquinizarin.
Although halogen atoms are only replaced by hydrox>-l groups with difficulty imder the influence of caustic alkali, it seems that in some cases solutions of the alkali earth hydroxides in the presence of a copper catalyst are effective, as Hovermann 3 obtained a dichlortetrahydroxy compoimd (probably 2.3-dichlor-i.4.5.8-tetrahydroxyanthraquinone) by heating tetrachlorquinizarin with lime-water and a trace of copper under pressure. It is probable in this case that the replacement was chiefly due to the catalytic action of the copper, as Frey ■* had previously obtained 1.4.5.8-tetra- h3'drox5^anthraquinone by heating 4.8-dichlorquinizarin with water and a trace of copper at 250°.
Halogen atoms w^hen in the a- position can sometimes be replaced b}* hydroxyd groups by heating with concentrated sulphuric acid or oleum, with or without the addition of boric acid. By this means quinizarin is readily obtained from 1.4-dichloranthraquinone or i-h3'drox>'-4-chlor anthra- quinone,5 and Ullmann ^ has found that 2-methyl-i-hydroxy'- 4-chloranthraquinone passes into 2-methyl quinizarin when heated to 150-160° with concentrated sulphuric acid and boric acid. Fuming nitric acid, with or without the addition of boric acid, can also in some cases cause the replacement of halogen atoms by hydrox>'l groups, O. Fischer and Rebsa- men "' having found that i-methyl-4-chloranthraquinone is
' B. 36, 2941. « B. 53. 833. Cf. By., D.R.P. 203,083.
3 B. 47, 1210. * B. 45, 1361. * By., D.R.P. 203,083.
• B. 52, 21 10. » B. 47, 461.
THE HYDROXY COMPOUNDS 249
converted into i-methyl-4-hydroxynitroantliraquinone under the influence of nitric acid and boric acid, whereas without boric acid a methyl dih3'droxynitroanthraquinone was obtained. The exact positions of the groups in these two compounds is uncertain, but they must all be attached to the same benzene ring, as both give phthalic acid when oxidised. The behaviour of the nitro compound, however, is peculiar, as it is slowly decomposed by alkali at the ordinary temperature and rapidly on heating, and decomposes with the evolution of nitrous fumes when boiled with acetic anhydride and sodium acetate. It is not tmlikely that the nitro group is situated in the side chain.
In the case of the phthalic acid s}-nthesis, when halogen atoms are present in the benzoyl benzoic acid there is a possibility of their being replaced by hydrox>-l groups during the closing of the anthraquinone ring, e.g. dichlordihydrox^-- benzoyl-benzoic acid when heated with oleum and boric acid gives chlorpurpurin.i
Replacement of Amino Groups. — Amino groups can be replaced by hydroxyl groups in the usual way by diazo- tising and then boiling the diazonium sulphates with water or dilute sulphuric acid, 2 but as a rule it is best to diazotise the amine in concentrated sulphuric acid solution, and then to heat to 90-100° without first diluting. ^ A large number of hydroxyanthraquinones have been obtained by this method, which has proved of considerable value as a means of determining the position of amino groups.
Amino groups can in some cases be replaced by hydroxyl groups by boiling with caustic alkali,* but the reaction takes place much more readily if the cyclic carbonyl groups are first partly reduced, the amino compounds in this way resembling other substituted anthraquinones. Advantage has been taken of this to combine the preparation of the amino compoimd and the replacement of the amino group in one
1 Mettler, B. 45, 8oi.
* Bottger and Petersen, A. 166, 151. Romer, B. 15, 1793 ; 16, 369 ; Lifschutz, B. 17, 900.
3 Eckert, M. 35, 290. Ullmann and Conzetti, B. 53, 828. M.L.B., D.R.P. 97.688. B.A.S.F.. D.R.P. 108,459.
* M.L.B.. D.R.P. 75,490 ; 81,742 ; 104,367.
250 ANTHRACENE AND ANTHRAQUINONE
operation, this result being achieved by reducing the corresponding nitro compound in boiling alkaline solution. ^ The majority of the cases recorded in which the above reaction has been applied refer to compounds in which the nitro (or amino) group occupies an a- position, but it appears also to be applicable to j8-nitro (or amino) compounds, as Simon 2 has found that 2-hydroxy-i.3-dinitJ'oanthraquinone gives anthragallol when reduced in boiling alkaline solution. Amino groups can also often be replaced by h^^drox}-! groups by reduction in acid solution, a good example of this type of reaction being the production of quinizarin by the reduction of i.4-aminoh3'drox3'anthraquinone, 1.4- hydroxynitroanthraquinone or 1.4-diamino anthraquinone by stannous chloride and hydrochloric acid.^
It must be borne in mind, however, that the reduction of the cyclic carbon3'l group also loosens other groups attached to the anthraquinone ring and these may be simultaneously split off. Thus, in the above reactions 1. 4-aminoalkoxy anthraquinone and i ,4-alkox}^nitroanthra- quinone are dealk5'lated on reduction and yield quinizarin and not quinizarin monoalkyl ether. Alkox\' groups if present at 2 or 3 are also dealkylated, and halogen atoms or nitro, amino or sulphonic acid groups if present in these positions, are replaced by hydrogen.* The production of h3'drox3^anthraquinones by the reduction of nitroanthra- quinones in concentrated sulphuric acid or oleum is usualh' accompanied b}' simultaneous h3"drox>4ation, the reaction being due to the production of hydrox\'lamine compounds and quinoneimides, and this reaction is discussed at greater length elsewhere. 5
Exhaustive chlorination of primary aminoanthraquinones in glacial acetic acid, chloroform, or other suitable solvent sometimes leads to the replacement of the amino group by hydroxyl, but in these cases replacement of amino b}' halogen also takes place, e.g. 1.5- and i.8-diamino anthraquinone
1 M.L.B.. D.R.P. 75,490. a D.R.P. 119,755.
» M.L.B., D.R.P. 148.792 ; 207.668. * M.L.B., D.R.P. 183,332.
' See p. 244,
THE HYDROXY COMPOUNDS 251
give a mixture of hexachloranthraruliii, hexachlorchtysazin, and octachlorantliraquinone.i In some cases the action of the halogen depends on the solvent used. Thus, 3-amino- alizarin when treated with bromine in a mixture of glacial acetic acid and concentrated sulphuric acid is brominated, 3-amino-4-bromalizarin being formed ; but if treated with bromine in aqueous solution the amino group is replaced by hydrox3'l, the product being anthragallol ; and other j8-amino- hydroxyanthraquinones behave in the same way. 2
Direct Oxidation
Anthraqumone differs from other aromatic compounds in the great ease with which hydrox>4 groups can be inserted into the molecule by direct oxidation, and use has been made of this reaction very widely both in the laboratory and on the large scale. In spite of the large amount of work which has been recorded on the preparation of hydrox>'anthra- quinones by direct oxidation, investigators seem to have paid little or no attention to the mechanism of the reaction, a fact which may be due to the ver}- great majority of the work having only been pubhshed in the form of patent specifications. Consequently there is little or no data on which any theor}' of the actual mechanism of the change can be based, and, mdeed, it is probable that the actual mechanism depends in some degree on the oxidising agent used.^
If the peroxide formula is adopted as representing one of the phases in the vibration of the anthraquinone molecule, then when the molecule is in this state one of the benzene rings will have an ortho- quinonoid structure. All quinonoid bodies show enhanced reactivity, and in this case addition of the elements of water would lead to a body which, by tauto- meric change, would pass into a hydrox3'anthraquinol. The anthraquinols are well-known compounds and are extremely readily oxidised to the correspondmg anthra- quinone, in this case the hydrox^-anthraquinone. On this
» B.A.S.F., D.R.P. 125.094; 137.074.
- By., D.R.P. 126,015. B.A.S.F.. D.R.P. 126.603.
9 Cf. Bucherer, " Lehrbuch der Farbeachemie " (1914). pp. 327-328.
252 ANTHRACENE AND ANTHRAQUINONE
basis the formation of a hydroxy anthraqtdnone would take place in successive stages thus :
H OH
H;0
OH OH
CO *H
OH
CO
Further h3^drox34ation might then take place in exactly the same way, or through the production of a compound of quinonoid structure by the wandering of the hydrox^l hydrogen atom :
H OH.
0
OH II
HjO
\.
CO
CO OH
OH
CO
It should be noted that when hydroxylation is brought about without the use of an oxidising agent, e.g. when anthraquinone-jS-sulphonic acid is fused v/ith caustic soda without the addition of a nitrate or chlorate, the hydroxyl compoimd is obtained as its reduction product.
Hydrox}'! groups can be introduced into the anthra- quinone molecule b3' direct oxidation in either alkaline or acid solution, the most interesting results being obtained by the latter means, although oxidation in alkaline solution is of great technical importance, as it is b}' this means that alizarin is manufactured.
Alkaline Solution. — As stated on p. '239, when an anthraquinone-^-sulphonic acid is fused with caustic alkali, not only are the sulphonic acid groups replaced by hydroxyl groups, but at the same time oxidation takes place and further hydroxyl groups enter the molecule. If no oxidising agent is present in the melt the hydrox}^ compotmd is ob- tained in the form of its reduction product, this being due either to the reaction having taken the course outlined
THE HYDROXY COMPOUNDS 253
above, or to the oxidation of one molecule having taken place at the expense of the ketonic oxygen atoms of another molecule, or to a combination of these causes. In order to obtain a more satisfactor\' jdeld of the hydrox}'anthra- quinone it is usual to carr>' out the alkali melt in the presence of an oxidising agent such as air or an alkali nitrate or clilorate, chlorates usually giving the most satisfactory^ results. The reaction obviously takes place in at least two steps, viz. replacement of the sulphonic acid groups followed by further hydrox}4ation, as further hydroxyl groups can be introduced into the hj-drox^-anthraquinones themselves by fusion with caustic alkali and an oxidising agent. Thus, Schunck and Romer ^ obtained fiavopurpurin and anthrapurpurin by fusing anthraflavic acid and zso-anthraflavic acid with caustic potash, and more recently several patents have been granted for improved methods of carr3-ing out these re- actions. 2 Anthraruiin and chrysazm are also readily con- verted into trihydroxy compomids (hydroxrs-anthrarulin and hydroxychrj'sazin) by heating with caustic alkali ^ and alkali nitrate, and many other examples of this type of reaction are known.
The most important product obtained by the fusion of an anthraquinone sulphonic acid with caustic alkali is, of course, alizarin, this d3'estuff being obtained almost universally by fusing the sodium salt of anthraquinone-)S-sul- plionic acid with caustic soda and sodium chlorate* As a rule the alkali melt is carried out with caustic soda solution of 30 to 40 per cent, strength, the heating being effected in an autoclave. 5 The alizarin obtained by this method is not pure and contains also higher hydroxylated anthraquinones such as fiavopurpurin and anthrapurpurin, derived from the disulphonic acid present as an impurity in the technical
1 B. 9, 678.
- Wed., D.R.P. 194.955- By., D.R.P. 205,097 ; 223,103.
3 M.L.B., D.R.P. 195,02s ; 196,980.
* For references to the literature dealing with the earlier history of alizarin, see Schultz, " Chenxie des Steinkohlenteers," vol. ii. pp. 250-J02, and Auerbach, "Das Anthracen."
* For technical details see UUmann, " Enzyklopadie der technischen Chemie."
254 ANTHRACENE AND ANTHRAQUINONE
mouosulphonic acid, and purpurin, derived from alizarin b}' oxidation. The presence of the flavopurpurin and anthra- purpurin causes the alizarin to dye in rather yellowish shades, and various mixtures of alizarin with flavopurpurin and anthrapurpurin are sold as Alizarin RA, RR, etc., the letters referring to the shades obtained from the difi'erent brands, i
Another method ^ of carrjang out the manufacture of alizarin is to mix intimately six parts of finely powdered caustic potash with six parts of sodium anthraquinone- j3-sulphonate and one part of alcohol. The mixing must be very intimate and must be carried out with the total exclusion of air. When the mixture is exposed to the air in thin layers it immediately warms up and alizarin is formed. This method of carrying out an " alkali melt " is not confined to the preparation of alizarin but seems to be fairly general, e.g. indanthrone can be made from j3-aminoanthraquinone, and pyranthrone can be obtained from 2.2'-dimethyl-i.i'- dianthraquinonyl by a similar procedure. The method is a rapid one and is well adapted for continuous working.
As stated above, anthraquinone-2.6- and -2.7-disulphonic acids when fused with caustic alkali 3'ield flavopurpurin (Alizarin RG, GI, SDG, etc.) and anthrapurpurin (Alizarin SX, GD, RX, etc.), but if the fusion is carried out in the presence of air under suitable conditions it is possible to replace only one sulphonic acid group, the products being alizarin - 6 - sulphonic acid and alizarin-7-sulphonic acid. 3
The insertion of hydrox>4 groups into the anthraquinone molecule by alkaline media is not confined to the hydroxy- anthraquinones, as anthraquinone itself can be hydroxylated under suitable conditions by fusion with caustic soda and a chlorate. The product in this case is alizarin of exceptional purity and free from anthrapurpurin and flavopurpurin. Such alizarine dyes in slightly bluish shades of red (Alizarin No. I, Alizarin V, Alizarin mit Blaustich), and the process
1 Schultz, " Farbstofftabellen." ^ B.A.S.F., D.R.P. 287,270.
» By., D.R.P. 50,164 ; 50,708.
THE HYDROXY COMPOUNDS 255
seems well adapted to its manufacture.! The alkaline oxida- tion of anthraquinone under other conditions can lead to various hydrox>'anthraquinones, and it is claimed that when the oxidation is brought about by heating to 200° for 3-4 days with caustic soda of 30 per cent, strength together with a sulphite, or compound capable of yielding a sulphite, and an oxidising agent such as potassium nitrate, the product is j3-hydroxyanthraquhione, alizarin, anthrapurpurin, flavopurpurin or anthraflavic acid or a mixture of these. 2
In connection with the preparation of hydroxyanthra- quinones by the alakli melt method it is interesting to notice that if lime, strontia, baryta., or magnesia is added to the alkali melt before heating, the hydrox}' anthraquinone is left as an insoluble lake which can be filtered off, and it is claimed that this procedure greatly facilitates the recovery of the excess of alkali. 3
Acid Soi^ution. — The preparation of hydroxy anthra- quinones by the direct oxidation in acid solution of anthra- quinone or lower hydroxylated derivatives is a reaction of the greatest importance and has been very widely applied. Here again, however, nearl}- all the work published has only been recorded in the form of patent specifications, with the usual result that the information available is in- sufficient to permit any general rules to be detected. Also the directions given in the specifications are often unsuitable for laboratory experiments, and in the majority of cases any statements as regards yield are conspicuous by their absence. The writer, however, has prepared several hydroxj^anthra- quinones by direct oxidation in acid solution and has found that the yields obtained are usually quite satisfactor}-.
Oxidation in acid solution is always brought about in concentrated sulphuric acid, and ma}^ be effected with concentrated sidphuric acid or monohydrate alone, ^^■ith oleum, with nitrosyl sulphiiric acid or with sulphuric acid and an oxidising agent such as nitric acid, manganese
1 B.A.S.F., D.R.P. 186,526.
2 By.. D.R.P. 241,806; 245,987; 249,368; 251,236. » M.L.B., D.R.P. 17.627.
256 ANTHRACENE AND ANTHRAQUINONE
dioxide, arsenic acid, amnioniuiii persulphate, etc. The introduction of hydrox>4 groups, of course, weakens the benzene ring, and to prevent further oxidation with rupture of the ring taking place it is usually necessary- to carry out the oxidation under such conditions that the hydroxy 1 group becomes protected. This is best done by carr^-ing out the oxidation in the presence of excess 'of boric acid, as under these conditions a boric ester is formed which is much more stable towards oxidising agents than the free hydroxy compounds. These boric esters, however, are easily hydro- lysed by dilute acids, so that when the oxidation is com- plete it is only necessary to dilute the solution and then boil for a few minutes in order to liberate the free hydroxy compound.
Concentrated Sulphuric Acid or Oleum. — Oleum of high concentration, viz. an acid containing about 80 per cent, of free anhydride, readily hydroxy lates anthraquinone and its derivatives, the reaction usually being carried out at 35°-40°, and never at a temperature exceeding 100°. With oleum of lower strength a higher temperature is necessar3^ and, of course, the same is true if the oxidation is brought about by means of ordinary concentrated sulphuric acid or sulphuric acid monohydrate,* in these cases temperatures of 260-280° usually being the most suitable.
When sulphuric acid acts as an oxidising agent it is, of course, reduced to sulphurous acid and this combines with the hydroxy- compound produced to form a sulphite ester, this ester formation to some extent protecting the hydroxy-l- ated anthraquinone from destruction by further oxidation. Much more satisfactory results are obtained, however, by carr^'ing out the oxidation in the presence of boric acid so that the boric ester is formed, and the same method is used when the oxidation is carried out with sulphuric acid and an oxidising agent. In any case when oxidation is complete the melt must be diluted and then boiled in order to hydrolyse
* The term " monohydrate " denotes an acid containing 100 per cent, of H0SO4, i.e. the monohydrate of sulphur tri oxide. This explanation appears necessary as in the abstracts published by the Chemical Society, e.g. Soc. 100, 548, it is sometimes quite wrongly taken to mean HjSOi.HoO.
THE HYDROXY COMPOUNDS 257
tlie ester present. When the boric acid method is employed it is usual to add one part of crystallised boric acid to twenty parts of concentrated sulphuric acid, monohydrate, or oleum, and then to add the anthraquinone compound (one part) which it is desired to oxidise. The temperature is then maintained at a suitable point until examination of a sample shows that oxidation has gone as far as desired, when the whole is cooled, diluted with water, boiled to hydrolyse the ester, and the hydroxy compound then liltered off.
The addition of boric acid also slows down the reaction and, if sufficient is added, may even in some cases inhibit it altogether. This retarding action of boric acid is often very useful in preventing the reaction going too far. Thus the oxidation of alizarin with oleum of high concentration leads to quinalizarin in the absence of boric acid, but with the addition of a suitable amount of boric acid the reaction is so retarded that an almost quantitative yield of hydroxy- anthrarufin can be obtained. In the same way the addition of boric acid renders it possible to oxidise chrysazin to 1 . 4. 8- trihydroxy anthraquinone.
It is impossible to detect with certainty any regularities in the positions taken by entering hydrox\'l groups, but it seems to be a fairly general rule that the a-position is pre- ferred, and that the ^-position is never taken unless there is a hydroxyd group in the contiguous a- position. Even when there is such a group present the entering hydroxyd group often prefers the a- position. The ease with which hydrox}d- ation takes place varies very much with the different compounds used as starting -out substances. Thus oleum of high concentration rapidly converts erythrohydroxy*- anthraquinone into anthrarufin, but the conversion of anthrarufin or quinizarin into 1.2. 4.5.6. 8-hexahydroxy- anthraquinone only takes place extremely slowly. On the other hand, this hexahydroxy compound is rapidh^ and quantitatively formed from chrs'sazin, and from anthra- chrj'sazin its formation is almost instantaneous.
Oxidation by means of sulphuric acid is a catalytic
17
258 ANTHRACENE AND ANTHRAQUINONE
reaction aud does not take place if chemically pure acids are used. When ordinar>^ commercial acids are employed the small quantities of selenium present act as the catalyst :
Se02=Se+02 Se +2SO3 =Se02 +2SO2
Oxidation by means of sulphuric acid is ajso facilitated by the presence of mercury compounds, ^ and bromine is stated to facilitate attack by oleum, although this can hardly be regarded as a catalytic effect as bromination and hj^droxy^ation take place simultaneously. 2 Hydrox>4ation by oxidation with sulphuric acid or oleum often leads to the production of polyhydroxy^anthraquinone sulphonic acids, but in mau}^ cases the sulphonic acid groups are readily removed by hydrolysis by heating the product with sulphuric acid of about 70 per cent, strength. ^
Hydroxylation by means of sulphuric acid or oleum often leads to the simultaneous replacement of other groups such as halogen atoms ^ and amino and nitro groups ^ when these are present in the molecule, and it is possible to obtain hydroxyanthraquinones from halogen derivatives of anthra- cene in which both ws-hydrogen atoms have been replaced by halogen atoms. ^ The behaviour of the nitroanthraquinones towards oleum is particularly interesting but has already been discussed."^ Amino groups in aminoanthraquinones, although often replaced by hydroxyl groups under the influence of oleum, b}^ no means always behave in this way, both a-amino and a-alkylaminoanthraquinones being often converted into ^ara-hydroxyaminoanthraquinones by treat- ment with 80 per cent, oleum at 30-40°, or with 20 per cent, oleum, monohydrate or concentrated sulphuric acid ^ in the presence of boric acid at 200°.
1 Georgievics, M. 32, 347. By., D.R.P. 162,035 ; 172,688.
a By., D.R.P. 97,674 ; 99,314-
3 By., D.R.P. 172,688. Cf. M.L.B., D.R.P. 71,964.
* By., D.R.P. 81,962 ; 83,055.
5 M.L.B., D.R.P. 75-490. By., D.R.P. 79,768 ; 81,244 ! 83,055 ; 83,085.
6 By., D.R.P. 68,775 ; 69.835. Page 242. By., D.R.P. T54,353 ; I55.440-
7
THE HYDROXY COMPOUNDS 259
Sulphonic acid groups when present in the molecule have a tendency to protect the benzene ring to which they are attached, and when there is only one sulphonic group present the hydrox}^ groups enter the other ring. Thus anthraquinone-a-stdphonic acid when treated with oleum gives alizarin-5-sulphonic acid ^ and purpurin-8-sulphonic acid,- the use of boric acid and mercury apparently not influencing the positions taken by the hydroxyd groups. The influence of sulphonic acid groups in the jS- position is micertain.
The data available as regards the product obtained when fresh hydrox>d groups are introduced into a molecule in which such groups are alread}- present are confusing and insufficient to allow any reliable deductions to be made. IMany of the hydroxyl compounds described in the patent literature are not characterised, and probably a large pro- portion of them are mixtures of isomers. It appears, how- ever, that when two hydrox>d groups are present in the para- position to one another, the tendency of the entering hydrox}d group is to attach itself to the same ring, e.g. quinizarin gives purpurin,^ and quinizarin-8-sidphonic acid gives purpurin-3.8-disulphonic acid.-* This is the behaviour that would be expected on the assumption that direct hydrox^dation is primarily the addition of the elements of water to a compound with a quinonoid structure, as quinizarin is fairly easily oxidised to anthradiquinone, a compound which is a true quinone in its chemical re- actions. Gattermann,5 however, finds that quinizarin when oxidised with oleum mider certain conditions gives quinalizariu.
Anthraquinone itself when oxidised with oleum containing about 80 per cent, of free anhydride and boric acid gives anthrarufin,^ whereas with more dilute oleum or with ordinary concentrated sulphuric acid it is first rapidly converted into quinizaiin and then more slowly into
1 By.. D.R.P. I72,68g. M.L.B., D.R.P. 158,413. '- R. E. Schmidt. B. 37, 71. By., D.R.P. 155,045. 3 By., D.R.P. 81.481. * By., D.R.P. 172.688.
5 J. pr. [2] 43, 246. « By., D.R.P. 101,220.
26o ANTHRACENE AND ANTHRAQUINONE
purpuriii.i Oleum of high concentration also seems capable of oxidising anthraquinone to a hexahydroxy compound, ^ probably Anthracene Blue WR.
Erythroltydrox3^anthraquinone on oxidation with oleum of high concentration gives anthrarufin,^ but the effect of more dilute acids does not seem to have been studied, and there appears to be no record of the hyflroxylation of j3- hydroxyanthraquinone bj^ acids.
Alizarin when oxidised by oleum of high concentration gives quinalizarin '^ (Alizarin Bordeaux B, Alizarin Cj^anine 3R) and hydroxyanthrarufin,^ chrysazin gives 1.4,5-tri- hydroxy anthraquinone, 6 and anthragallol when oxidised with dilute oleum or concentrated sulphuric acid in the presence of boric acid gives 1.2.3.4-tetrahydroxyanthra- quinone.'^
Oxidation with monohydrate in the presence of mercuric sulphate and boric acid has resulted in the preparation of octah3^droxyanthraquinone, Georgievics ^ having prepared this substance from rufigallic acid by this method.
Polyhydrox>'anthraquinones have also been obtained by the action of oleum or sulphuric acid upon purpurin,^ anthrapurpurin,io flavopurpuiin,^^ h5^droxyanthrarufin,^2 hydroxyclirysazin,i3 rufigallic acid,^* and manj- other similar compounds. 1^
NiTROSYi. Sui<PHURic AciD. — Nitrosyl sulphuric acid is a valuable reagent for inserting hydroxyl groups into the anthraquinone molecule and can be used either as chamber crystals or, more conveniently, simply as the solution obtained by slowly adding solid sodium nitrite to about 15 parts of cold concentrated sulphuric acid. Oxidation is usually carried out at a temperature of 180-230°, and
1 By., D.R.P. 81,960. " By., D.R.P. 65,182.
3 By., D.R.P. 97,674. * Bv., D.R.P. 6o,8^s5-
5 By., D.R.P. 156,960. 6 By., D.R.P. 161,026.
' By., D.R.P. 86,968. Cf. By., D.R.P. 60,855.
8 M. 32, 347- ° By., D.R.P. 60,855.
10 By., D.R.P. 60,855 ; 67,061. i' By., D.R.P. 60,855 ; 67,061.
1- By., D.R.P. 67,06^. 13 By., D.R.P. 67,063.
'■« By., D.R.P. 62, 531.
15 By., D.R.P. 63,693 ; 64,418; 65,375; 65,453; C9.013 ; 81,481; S1.959; 172.688.
THE HYDROXY COMPOUNDS 261
boric, arseuic, or phosphoric acid ^ is added to protect the hydrox}^! compound as formed by converting it into an ester. Boric acid is certainly the most efficient of these, and is usually added in the proportion of one part of crystallised acid to one part of substance to be oxidised, but it is probable that in many cases better results would be obtained b}^ using different proportions. Thus Dimroth and Fick 2 foimd that the oxidation of flavopurpurin and anthrapurpurin to the tetrahydroxy compounds by means of nitros3'l sulphuric acid was best effected when only one-tenth of the above proportion of boric acid was used, as if larger quantities were employed it was necessarj^ to carry out the oxidation at a higher temperature and the ^-ields obtained were much poorer.
Hydroxylation with nitrosyl sulphuric acid is a catalytic reaction and depends on the presence of mercurs'. If the nitros3-l sulphuric acid is made from pure sulphuric acid no h}'drox\^]ation takes place, but as a rule commercial sulphuric acid which has been made from pyrites contains sufficient mercur>'. In most cases, however, the addition of a mercury salt is advantageous, 3 and the study of the reaction under these conditions has thrown some light on its mechanism. Thus it has been found that the action of nitrosyl sulphiuric acid at 120° in the presence of boric acid and mercuric sul- phate converts anthraquinone into i-hydroxj^anthraquinoue- 4-diazonium sulphate,'* this being converted into quinizarin when heated with concentrated sulphuric acid at i70°-i8o°. This direct insertion of the diazonium group is rather remarkable, and the reaction is one which merits further investigation.
Other groups when present in the molecule are often affected during the process of h3'droxylation, ^-methyl- anthraquinone, for example, being converted into quinizarin carboxylic acid,^ and 1.5-dinitroanthraquinone 3aelding 5-nitroquinizarin.*^
» B.A.S.F.. D.R.P. 153,129 ; 154,337. * A. 411, 326.
3 B.A.S.F.. D.R.P. 153.129; 154.337- * By.. D.R.P. i6i.954-
* By.. D.R.P. 84,505. « By., D.R.P. 90,041.
I
262 ANTHRACENE AND ANTHRAQUINONE
Oxidation with nitrosyl sulphuric acid seems speciall}^ adapted to the preparation of hydroxj-anthraquinones in which two h3^droxyl groups are in the para- position to one another, and it appears that a hydroxyl group does not enter a j8- position unless both a- positions in that ring are already occupied b}^ hydrox}-!. Too great reliance, however, must not be placed on this rule, as the d^a available are insufficient to establish it beyond doubt.
Anthraquinone on oxidation with nitrosyl sulphuric acid gives quinizarin,i reference having already been made to the production of i -hydroxy anthraquinone-4-diazonium sulphate as an intermediate product. The production of quinizarin by this method takes place very readily, and as the yields obtained are quite satisfactory it forms the easiest means of obtaining quinizarin in the laboratory.
Erythrohydroxyanthraquinone also gives quinizarin 2 and, curiously enough, so does jS-hydroxy anthraquinone. 3 In this latter case it is probable that the nitrous acid first reduces the hydroxyl group and then oxidises the resulting anthraquinone, and this behaviour explains why hydroxyl groups so rarely take the j8-position.
Quinizarin on oxidation gives purpurin,.* although in poor yield, and this is one of the very few cases in which a hydroxyl group enters the jS-position.
Chrysazin gives 1.4.5-trihydroxyanthraquinone very readily and in a state of purity, as, curiously enough, no 1.4.5.8-tetrahydroxyanthraquinone is formed.^
Flavopurpurin on oxidation yields hydroxyflavopurpurin (1.2.4.6.), and anthrapurpurin yields hydroxyanthrapurpurin (1.2.4.7), the position of the h3'droxyl groups being proved by the fact that both hydroxyflavopurpurin and hydroxy- anthrapurpurin on reduction and subsequent oxidation of the leuco- compound give 1.4.6-trihydroxyanthraquinone, the orientation of the h3^droxyl groups in this compoimd
1 By., D.R.P. 81,245 ; i6i,954- B.A.S.F., D.R.P. 154.337-
- By., D.R.P. 162,792.
=* By., D.R.P. 86,630.
^ By., D.R.P. 86,630. B.A.S.F., D.R.P. 153,129.
* By.. D.R.P. 163,041.
THE HYDROXY COMPOUNDS 263
being known by its formation from 4-hyd.roxyphtlialic acid and hj'droquinone.i
Anthraquinone-j3-sulphonic acid when heated with nitrosjd sulphuric acid gives a purpurin sulphonic acid which is different from that obtained by the sulphonation of purpurin, as the sulphonic acid group is not removed by hydrolysis when the acid is heated with hydrochloric acid.2
Various Oxidising Agents. — Hydroxy^ groups have been introduced into the anthraquinone nucleus by the use of numerous oxidising agents in conjunction with con- centrated sulphuric acid, and in all of these cases it has been found that boric acid exerts a verj- beneficial influence by protecting the h3'droxy compounds formed from further attack. 3
Nitric acid in the presence of concentrated sulphuric acid can act on hydroxyanthraquinones either as a nitrating agent or as an oxidising agent or as both. Thus alizarin stdphonic acid when dissolved in concentrated stdphuric acid at 10° and then treated with nitric acid gives purpurin sulphonic acid, ^ alizarin itself when nitrated giving a mixture of nitroalizarin, purpurin, and nitropurpurin.^ Flavo- purpurin and anthrapurpurin are also oxidised by nitric acid when dissolved in concentrated sulphuric acid and give tetranitro compounds. ^ The action of nitric acid on the polyhydrox}^anthraquinones is often complicated by the formation of diquinones,"^ although to some extent this can be avoided by the protectmg influence of boiic acid. Highly hydroxylated derivatives often undergo complete decom- position, rufigallic acid giving only oxalic acid,^ and amino groups when present are often replaced b}' nitro groups.^
The action of nitric and sulphuric acids at a high tempera- ture on anthraquinone derivatives is in many cases similar to the action of sulphuric acid on the nitroanthraquinones,
1 Diraroth and Pick, A. 411, 326. - B.A.S.F., D.R.P. 154,337- 3 By., D.R.P. 102,638. * M.L.B., D.R.P. 84,774.
- M.L.B., D.R.P. 150,322. , '■■ M.L.B., D.R.P. 84,774.
' By., D.R.P. 70,782. * Klobukowski, B. 8, 931 i 9. 125O.
'' M.L.B., D.R.P. 104,244 ; 107,238; 111,919.
264 ANTHRACENE AND ANTHRAQUINONE
a somewhat important reaction which is treated in greater detail elsewhere. 1
Manganese dioxide in the presence of concentrated sulphuric acid oxidises hydrox5^anthraquinones to higher hydrox34ated compounds, the product usually being obtained in the form of an anthradiquinone, which can be reduced to the corresponding hydroxy anthraquinone by sulphur dioxide. 2 The most important application of this reaction is the oxidation of quinalizarin to i.2.4.5.8-pentah3^droxy- anthraquinone (Alizarin Cyanine R, 2R, RA Extra, etc.), the diquinone at first obtained being subsequently reduced. 3 The pentah5^droxy compound is a powerful mordant dye giving violet shades on alumina and blue shades on chrome.
Anthragallol is readily oxidised to i.2.3.4-tetrahydrox3-- anthraquinone by manganese dioxide and sulphuric acid in the presence of boric acid at or about the ordinar}- tempera- ture. The presence of boric acid is absolutely essential, as otherwise the anthragallol is completely destro3^ed.*
Alizarin-3-carboxylic acid is also oxidised b}" manganese dioxide and sulphuric acid at or about the ordinary tempera- ture and passes into purpurin-3-carbox3dic acid, a substance which has proved to be identical with the " ^sew^o-purpurin " present in madder.^
In addition to the oxidising agents mentioned above hydrox>4 groups can be introduced into the anthraqumone ring by means of lead dioxide, bleaching powder, arsenic acid, ferric salts, chromates, persulphates, and perchlorates,^ but for further details the reader is referred to the original literature. Electrolytic oxidation has also been described.'
Reduction of Polyhydroxy Compounds
Hydroxy anthraquinones can sometimes be obtained from the higher hydrox}4ated compounds by removing one
^ See pp. 242-247. 2 -Qy ^ D.R.P. 66,153 ; 68,113 ; 68,114. 3 By., D.R.P. 62.018. « By., D.R.P. 102,638. ^ By., D.R.P. 260,765 ; 272,301.
« By., D.R.P. 62,018 ; 62,504-5-6; 66,153; 68,123; 68,113; 68,114; 69,842; 69,933-4; 73.942; 102,638; 104,244; 107,238; 111,919- ' By.. D.R.P. 74,353.
THE HYDROXY COMPOUNDS 265
or more liydroxyl groups by reduction, although the method is not one of great importance. The cycHc carbonyl groups are, of course, simultaneously reduced, but if the reduction is carried out under suitable conditions it is usually possible to avoid their reduction being carried beyond the quinol stage, so that the product is readib,- converted into the anthraquinone derivative by air oxidation.
Exhaustive reduction of hydroxyanthraquinones by means of hydriodic acid and red phosphorus leads to hydrogenated anthracenes, ^ but imder less drastic conditions it is often possible to split off one ltydrox}4 group without reducing the carbonyl groups beyond the anthraquinol stage. Thus lyiebermann ^ and Pleus 3 by reducing qmni- zarin obtained i-hydroxy-anthraquinol from which er>'thro- hydroxyanthraquinone was obtained by mild oxidation. H3-driodic acid, however, is not a particularl}^ suitable reducing agent for removing h3^droxyl groups while avoiding complete reduction of the C3xlic carbonyl groups.
The reduction of purpurin with alkaline stannite solution leads to xanthopurpurin,'^ and the same substance is said to be obtained in quantitative 3'ield when the reduction is carried out by sodium hydrosulphite and ammonia, ^ In acid solution it seems, however, that a different hydroxyl group is split off, the product being quinizarin. According to one patent ^ the reduction of purpurin with zinc and glacial acetic acid leads to two products which are designated as leuco-qmnizann I and /cwco-quinizarin II. Of these the analytical figures and the melting point (150°) quoted in the specification for leuco-quimzann II agree closel)- with those of i.4-dihydrox5^anthraquinol.' The analytical figures quoted for /cz^co-quinizarin I, however, agree with those required for a trihydroxyanthraquinol,* so that the so-called " /e^^co-quinizarin I " would appear to be nothing but
^ Liebermann, A. 212, 26. ^ ^ 212, 14. B. 10, G07 ; 11, 1610.
» B. 35, 2923. 4 Plath, B. 9, 1204.
« M.L.B., D.R.P. 212,697 6 By.. D.R.P. 89,027.
' Liebermann, A. 212, 14. B. 10, G08. Grandmougin, J. pr. [2] 76,
138.
* Found 0 = 65-11, 6508; H=3'95, 3-90. Calculated forCuHioOj, 0=6512; H=3-88.
266 ANTHRACENE AND ANTHRAQUINONE
leuco-pnrpurin, tlie reduction not having been taken far enough to remove the hydrox^d group. In spite of this, however, the specification states emphatically in two places that " /^Mco-quinizarin I" is more readily oxidised to quinizarin than is /ewco-quinizarin II. This is rather difficult to understand if the analytical figures given were really obtained experimentally.* In a later patent ^ the same firm claims that the best yields of /ewco-quinizarin are obtained by reducing purpurin with aluminium bronze and concentrated sulphuric acid in the presence of boric acid. Elimination of hydrox}^ groups can also be brought about by reducing other polyhydroxyanthraquinones with zinc and glacial acetic acid, Dimroth and Fick,2 for example, obtaining 1.4.6-trihydroxyanthraquinone from both hydroxy- flavopurpurin and hydroxyanthrapurpurin by this method.
In some cases nitrous acid appears capable of removing hydroxyl groups from hydroxyanthraquinones, Nienhaus 3 having reduced both alizarin and purpurin by treating them with nitrous acid in concentrated sulphuric acid solution. The reaction is, however, not one that is likely to find an}' extensive use owing to the tendency of nitros}^ sulphuric acid to introduce fresh hydroxyl groups.'^
Hj^droxyl groups can in some cases be removed by an indirect method. Thus Schrobsdorf,^ by heating chrj^sazin with ammonia, replaced one hydroxjd group by an amino group, and by then diazotising and reducing the i.8-amino- hydroxyanthraquhione obtained erythrohydrox3^anthraqui- none.
M1SCE1.1.ANEOUS Methods
The hydroxyanthracenes can be converted into the
corresponding hydroxyanthraquinones by first protecting
the hydroxyl groups by acetylation and then oxidising. In
this way erythrohydroxyanthraquinone,^ ^-hydrox3'anthra-
quinone,' chrysazin,^ and other hydroxy^anthraquinones
* For explanation of this reaction see "Addenda."
1 By., D.R.P. 246,079. "- A. 411, 330.
3 B. 8, 778. 4 See p. 260.
5 B. 35, 2930. G Dienel, B. 38, 2862.
" Liebermann and Hormann, B. 12, 259.
8 Liebermann and Boeck, B. 11, 1616; 12, 185.
THE HYDROXY COMPOUNDS 267
have been obtained, but the method is chiefly valuable for determining the positions of the hydroxy^l groups in the hydroxy anthracenes. The ms-nitro derivatives of anthra- cene, such as dihydrotrinitroanthracene and Meisenheimer's nitroanthrone,! pass into alizarin when heated with alkali to temperatures exceeding 100°. The yield is said to be improved by adding lime, sodium nitrate, and sodium sulphite to the melt.^
Properties and Reactions
The h3-drox>-anthraquinones show the ordinary reactions of the phenols and dissolve in caustic alkali to form higlily coloured solutions. Hydroxyl groups when in the a- position are influenced by the cyclic carbonyl groups and are then only alkj-lated with the utmost difficulty, and are rather more difficult to acetjdate than when in the j3- position. Whether the influence of the carbon3'l group upon a hydrox}'! group in the ortho- position to it is due to the formation of a quinonoid compound or whether it is due to other causes cannot be decided with certainty from the data available at present.
The absorption spectra ^ of erythroltydroxyanthraquuione and anthrarufin in alkaline solution are almost identical, each showing one and only one broad band with its head at ^oofj-fx. In concentrated sulphuric acid solution erythro- hydroxj'anthraquinone shows a broad band with its head at 475/^/i and also two narrow bands with their heads at 305^^ and 260^/^/, and closely resembles that of anthraqiii- none in sulphuric acid solution. Anthrarufin, on the other hand, when in concentrated sulphuric acid solution has an absoq:)tion spectrum almost identical with that of quinizarin although the bands are slightly nearer the red end of the spectrum, whereas although the sodium salts of anthrarufin and quinizarin have absorption spectra which are somewhat
1 See p. 54. 2 G.E., D.R.P. 292,247.
» K. Meyer and O. Fischer, B. 46, 85. Meek and Watson, Soc. 109,
557-
268 ANTHRACENE AND ANTHRAQUINONE
similar, the addition of excess of alkali affects that of quiiii- zarin to a considerable extent.
The absorption spectrum of jS-li^-drox^'anthraquinone in alkaline solution differs from that of er}-throhydrox}'anthra- quinone by showing two narrow bands with heads at 305jU,u and 235^/^, whereas in concentrated sulphuric acid solution it shows very shallow bands at 410/^/^ and 325^fji, and a slightly deeper band at 290^/x, these in addition to the broad band with its head at 500^/x.
The spectrum of the sodium salt of alizaiin in the absence of excess of alkali resembles that of /3-hydroxy- anthraquinone, whereas when excess of alkali is present the absorption spectrum is ver)^ similar to that of purpurin, although the bands in the visible region are nearer the red end of the spectrum. The spectra of anthraflavic acid and iso-anthrafiavic acid in alkaline solution are, as would be expected, somewhat similar, although the bands differ in breadth and persistence. They both show absorption in the idtraviolet, and so far as alkaline solutions are concerned this type of absorption seems to be confined to hydroxy- anthraquinones in which there is at least one hj^droxyl group in the ^- position. In concentrated sulphuric acid solution, however, ultraviolet absorption seems to be exhibited by all hydrox3-anthraquinones including anthra- quinone itself. 1
A comparison of the absorption spectra of the h}- droxy- anthraquinones and their ethers would be interesting and might throw light on the constitution of the a-hydroxy compounds, but at present data are not available.
The presence of hydrox>d groups in the anthraquinone nucleus weakens the ring to which they are attached, although not to the same extent as is usually the case in the aromatic series. The weakening influence is especiall}^ marked when two groups are present in the p- positions to one another, this being no doubt due to the ease with which compounds pass into anthradiquinones on oxidation. Thus
1 R. Meyer and O. Fischer, B. 46, 90. Cf. Baly and Stewart, Soc. 89, 511-
THE HYDROXY COMPOUNDS 260
both purpurin and qiiinizarin are readilj' oxidised to phthalic acid by the action of atmospheric oxygen on their alkaUne solutions, whereas alizarin is not destroyed under similar conditions. 1
The further Itydroxylation of hydroxy- anthraquinones by direct oxidation has already been discussed,^ and so also has the fomiation of anthradiquinones,^ and but little information is available as to what products are obtained under different conditions.
SchoU ^ has found that when alizarin is oxidised in alkaline solution with a Iwpochlorite i.i'.2.2'-tetrahydroxy- 3.3'-dianthraquinonyl is formed, and that the same product is also formed to some extent when alizarin is fused with caustic soda under suitable conditions. Oxidation witli ferric3'anide in alkaline solution, on the other hand, leads to rupture of the benzene ring, the product obtained at the ordinary temperature being 2-hydroxy-(i.4)-naphthoquinonyl-3-acr}-- lic acid.''
Naphthoquinonyl derivatives have also been obtained by Dimroth and Schulze ^ by the degradation of carminic acid and other naturally occurring hydroxyanthraquinone derivatives, and Bamberger and Praetorius "^ have obtained 3-hydrox3^-(i.4)-naphthoquinonyl-2-acetic acid by the auto- oxidation of anthiagallol in alkaline solution. They explain the degradation as follows, anthragallol being assumed to be ^-qninonoid when in alkaline solution :
0
^^ ,CO-COOH IcOH
The same investigators have also fomid that the oxidation
1 Dralle, B. 17, 376. - Pp. 251-264. ^ pp t)2-<,4.
« B. 52, 1829 ; 2254. C/. By., D.R.P. 146.223 ; 167,461. ^ Scholl, B. 51, 1419. « A. 411, 339. ' M. 23, 688.
270 ANTHRACENE AND ANTHRAQUINONE
of piirpurin in alkaline solution by li5^drogen peroxide in the presence of a cobalt catalyst leads to 2-liydroxy-3-acet3-l- 1.4-naplithoquinone, a change which they explain by a similar series of reactions to those just given.
Wolft'enstein and Paar 1 have studied the action of boiling nitric acid on anthraflavic acid, 1.7-dihydroxy- anthraquinone and anthrarufin. The first action of the nitric acid is to nitrate the hydrox3^anthraquinone, but further action leads to the rupture of the central ring and formation of 3.5-dih3^drox3^-2.4.6-trinitrobenzoic acid.
The hydroxyanthraquinones in many cases combine with formaldehyde to yield h5^droxyanthraquiaonyl carbinols, and in this way resemble the ordinary phenols. Thus anthrachrj'sazin 2 combines very readily with formaldehyde to form a dicarbinol (I), which in turn will combine with tertiary aromatic amines, ^ such as dimethyl aniline, to produce compounds such as II, or with ammonia or with a primary or secondar^^ aliphatic amine ^ or a primary aromatic amine ^ to produce such compounds as III :
OH OH
HO CH5OH HO CHoCeH^NRa
HOCH HO
OH
R2NC6H4CH2 HO
OH
I.
II.
OH HO CHoNHAr
I
ArNHCH^ HO III.
OH
Attention has already been drawn to the acet5^1ation of hydroxyanthraquinones by means of acetic anhj'dride and
1 B. 46, 586. ■ B.A.S.F., D.R.P. 192,484. M.L.B.. D.R.P. 184,768.
3 M.L.B., D.R.P. 184,807; 188,597. * M.L.B., D.R.P. 188,189.
•■* M.L.B., D.R.P. 184,808; 188,596.
THE HYDROXY COMPOUNDS 271
pyridine, I but it ma}^ here be remarked that benzoylation can often be effected by heating at atmospheric pressure with 10-15 parts of benzoic acid with or without the addition of concentrated sulphuric acid, thus avoiding the use of benzo}'! chloride. 2 It is claimed that /3-hydroxy-anthra- quinone, anthraflavic acid, flavopurjnirin and anthra- purpurin are especially easily benzoylated by this method.
The reduction of the hydroxj^anthraquinones to the corresponding anthranols can be brought about in the usual way, although, as pointed out on p. 264, there is always a danger of partial dehydrox^-lation taking place simulta- neously. Reduction can also be effected by means of zinc dust and acid,^ and some of the hydroxy- anthranols have been recommended as valuable remedies for psoriasis and other skin diseases.
TiNCTORiAi, Properties
The absorption spectra of the h^'droxj-anthraquinones in alkaline and in concentrated sidphuric acid has been already discussed, and it need only be added that Meek and Watson 4 have measured the coefficient of absorption of light of various wave-lengths when reflected from fabric dyed with several of the more important hydrox^^anthra- quinones on various mordants. Georgievics » has discussed the position of hydrox}l groups in relation to the shade of the dye and has come to the general conclusion that hydroxyl groups in the a- position tend to produce red or blue shades, whereas hydroxyl groups in j3- positions favour the pro- duction of 3-ellows and browns, although too much reliance must not be placed on these conclusions, as one group may mask the effect of another. These conclusions have been criticised by Meek and Watson, ^ who consider that they have sufficient evidence to support the following conclusions : —
(a) Two homonuclear hydrox\'l groups in the ofiJio- or
1 Page 237. a Wed., D.R.P. 297,261.
3 By.. D.R.P. 296,091 ; 301,452 ; 305.886. ♦ Soc. 109, 545.
^ M. 32, 329. « Soc. 109, 545.
272 ANTHRACENE AND ANTHRAQUINONE
para- positions to one another are necessary in order to deepen the colour, i.e. to produce reds, violets, or blues,
[h) If both rings contain such pairs of hydroxyl groups, each pair reinforces the effect of the other.
(c) Three hydroxyl groups at i, 2, and 4 produce a greater effect than a pair in the ortho- or para- positions to one another. •
Id) Three hydroxyl groups at i, 2, and 3 produce a brown.
The connection between the position of the hj^droxj^l groups and the capacity of a h3'drox3'anthraquinone to form a lake is quite obscure, and is likel}- to remain so until some satisfactory^ definition as to the meaning of " mordant d^-e " is evolved. The old rule (Rule of Kostanecki and Lieber- mann) that two hydroxyl groups in the " alizarin position," i.e. at I and 2, are necessary in order to produce a mordant dye is certainly not a law of nature, although for a matter of fact aU the hydrox5'anthraquinones which have proved to be of commercial value have such hydrox}^ groups. Alizarin itself is a powerful mordant dye, but quinizarin, hystazarin and xanthopurpurin all have marked tinctorial properties, and the other dihydroxyanthraquinones, and even the monoh5'droxy compounds, have slight capacity for forming lakes. 1
Increase in the number of hydrox>-l groups does not necessaril}^ increase tinctorial properties, as although quini- zarin is a comparatively powerful mordant dye, 1.4.5.8- tetrahydroxj^anthraquinone has no capacity for formmg lakes 2 except, curiously enough, on a beryllium mordant, ^ and octah3^drox>'-anthraquinone has very feeble tinctorial properties. The presence of other groups or atoms in the molecule also affects the capacity for forming lakes, as although rufigaUol itself is a VQ.ry feeble mordant dye its affinity is very greatly enhanced by halogenating.*
1 Georgievics, F.T. 1, 623. 2 Georgievics, F.T. 4, 185.
3 Georgievics; Grand mougin, " Lelirbuch der Farbenchemie," fourth edition, p. 257.
«|By., D.R.P. 114,263. Cf. also L. B. Hollidav & Co., Ltd., and H. D. Law. E.P. 126,52818.
THE HYDROXY COMPOUNDS 273
The constitution of the lakes formed by the hydroxy- anthraquinones and, for example, the exact fmiction of the lime and Turkey red oil used in alizarin dyeing, has never been properly cleared up, although there is no doubt that the usual alumina lake is a complex aluminium calcium salt.i
For further information as to theories of lake formation the reader is referred to the original literature, 2 a good review of the subject having been recently published by Scholl and Zinke.^
Halogenation
A considerable amount of work on the halogenation of the hydrox}'anthraquinones has been recorded, but as in a great mam- cases the positions of the halogen atoms in the product have not been determined, it is difficult to detect with certainty an}^ rules relating to the directmg influence exerted by the hydroxjd groups, although from the data available one or two conclusions can be drawn.
When h3^droxyl groups are present only in a- positions the entering halogen atom is first directed to the para- position, the second atom entering taking the ortho- position. Thus er\' throh3'drox3-anthraquinone when treated with mole- cular or nascent halogen {e.g. NaBr04+HBr) gives first 4-brom-i -hydroxy anthraquinone and then 2.4-dibrom-i- hydroxj-anthraquinone,"* and anthrarufin and chrysazin behave in the same wa}'.^ The bromination can be carried out in boiling glacial acetic acid solution, but unless sodium acetate is added the reaction is ver}^ slow. In the presence of sodium acetate, however, the reaction is rapid and the bromo- compound cr^'stallizes out on cooling. ^ The reaction can also be convenient!}- carried out by suspending the
1 Mohlau, B. 46, 443. Wieland and Binder, B. 47, 977.
- Soc. 75, 433 ; 83, 129. J.S.C.I. 22, 600. A. 398, 151. B. 41, 1002, 3469 ; 44, 2653 ; 45, 148, III6; 47, 738, 977. F.T. 1. 624 ; 3, 366 ; 4. 186.
3 B. 51. 1419-1428.
' By., D.R.P, 127,532 ; 1^1,403. Wed., D.R.P, 202,770, Cf. Eckert and Steincr, M. 35, 1144.
^ Schrobsdorf, B. 35, 2930. By., D.R.P. 127,699 ; 197,082.
* Friess and Schiirmaun. B. 52, 2182.
18
274 ANTHRACENE AND ANTHRAQUINONE
hydroxy compound in boiling dilute sulphuric acid (45-50 per cent, strength) at 140° and then treating with molecular chlorine or bromine,! and in many cases molecular halogen can be used in aqueous solution 2 at the ordinar}^ temperature or at 100°. Krythrohydroxyanthraquinone, anthrarufin, and chr^^sazin have all been chlorinated and brominated by these methods, but the claim that chrj^sazin is chlorinated in aqueous suspension has been contradicted, ^ although it is said to yield a dichlor compound with great ease if sufficient sulphuric acid is added to raise the boiling point to 120- 140°.
Chlorination can also be effected convenient^ by heating with sulphuryl chloride in nitrobenzene solution, er^^thro- hydroxyanthraquinone being readily converted by this means into I -hydroxy -4-chloranthraquinone and i-hydroxy-2.4- dichloranthr aquinone . *
In the case of quinizarin, in which there is no vacant para- position, chlorination in glacial acetic acid ^ leads to 3-chlorquinizarin, the same product being obtained by the action of hydrochloric acid on i.4.9.io-anthradiqumone.6
Comparatively little work has been done on the chlorina- tion and bromination of hydroxyanthraquinones in which hydroxyl groups are only present in the j8- positions. It is claimed that j3-hydroxyanthraquinone and anthraflavic acid are readily brominated by the action of molecular bromine on their aqueous suspensions, and that the bromme atoms hrst attack those j3- positions which are contiguous to the hydroxyl groups, no a- position being entered until all such j3- positions have been occupied.' Anthraflavic acid is not chlorinated in aqueous suspension at 100°, but if sulphuric acid is added so as to raise the boHing point a dichlor compound is formed. ^ The melting point of this compoimd and also the melting points of its acet}'l and benzoyl derivatives agree with those of the dichlor compound
1 By., D.R.P. 197,082. Wed., D.R.P. 167,743 ; 172,300.
2 By., D.R.P. 127,699. 3 Wed., D.R.P. 172,300. * Ullmann and Conzetti, B. 53, 829. ^ Bv., D.R.P. 114,199.
« Diraroth and Schiilze. A. 411, 348. ' Wed., D.R.P. 175,663. 8 Wed., D.R.P. 187,685.
THE HYDROXY COMPOUNDS 275
obtained by the action of sodium hypoclilorite on anthra- flavic acid, but their sohibilities are different and their identity is questionable. If the chlorination of anthraflavic acid is carried out in suspension in calcium chloride solution a totally different reaction takes place, as under these conditions a hexachlor addition product is obtained. ^ This is resiniiied by treatment with alkali, but when heated with an inert solvent of high boiling point a trichlor- anthraflavic acid is obtained. 2
But little work has been recorded concerning the be- haviour of hystazarin when halogenated, but Schrobsdorff,-"^ by heating it to 140° with bromine in a sealed tube, obtained a dibromo compound, but did not determine the positions of the bromine atoms.
Although a-hydroxyanthraquinones are usually com- pletely destroyed by hypochlorites, the j8-hydroxy compoimds are often easily and smoothly chlorinated by the action of sodium hypochlorite on their alkaline solutions. B}^ this means Decker and Laube ^ obtained 2-hydrox3'-i-chlor- anthraquinone from j3-hydrox3'anthraquinone, and it has been claimed that the action of hypochlorite often leads to the entrance of one, two, or three chlorine atoms into the molecule. 5 The reaction seems to be restrained by alkali, and in the presence of excess of alkali as a rule only one chlorine atom is taken up.
In the case of h^-drox^-anthraquinones, in which hydroxyl groups are present both in a- positions and in j3- positions, the behaviour on halogenation becomes complicated and seems to depend on which hydrox}d groups have the pre- dominathig influence in the molecule, but the data available are too scanty to permit the detection of regularities. Flavopurpurin and anthrapurpurin are readily brominated in aqueous suspension, ^ the bromine entering the vacant /3- positions, and aqueous suspensions of flavopurpurin when treated with sodium chlorate and hydrochloric acid give a monoclilor derivative, the position of the chlorine
1 Wed., D.R.P, 179,916. - Wed., D.R.P. 181,659.
3 B. 36, 29:58. * B. 39, 112.
^ Wed.. D.R.P. 152.175 ; 153.194. ' Wed., D.R.P. 175.663.
276 ANTHRACENE AND ANTHRAQUINONE
being unknown, i Xanthopurpurin when brominated also gives a dibromo compound which is probably i.3-dihydrox3- 2.4-dibronianthraquinone.2 The chlorination of 1.7- di- hydroxyanthraquinone can be effected b}' sodium hypo- chlorite, but the reaction proceeds with difficult}^ and onty one chlorine atom is taken up.^ The chlorination of aUzarin in aqueous suspension b}^ sodium chlorate and hydrochloric acid leads to 3-chloralizarin/i
The bromination of hydrox5"anthraquinones such as alizarin, anthrapurpurin and flavopurpurin is often very greatly facilitated by first reducing to the corresponding anthranol and then treating this with bromine. Under these conditions the bromine both enters the nucleus and also becomes attached to the ^;?s-carbon atoms ; but subsequent oxidation leads to the brominated hydroxyanthraquinone, e.g. monobromalizarin.^
One of the most convenient methods of chlorinating the hydrox^^anthraquinones is to treat them with sulphur^-l chloride. The reaction takes place quite readily by heating the h3^drox}^anthraquinone on the water bath with sulphured chloride in nitrobenzene solution, and is facilitated by the presence of a trace of iodine. The method was first described by Ullmann,6 who by this means obtained 4-chlorerythro- hydrox>'^anthraquinone and 5.8-dichloranthrarufin, and has been extended b}^ L. B. Hollida}^ and Co., Ltd., to various polyhydroxj^anthraquinones such as alizarin, anthraflavic acid, iso- anthraflavic acid. Alizarin Bordeaux, etc. Ap- parently under some conditions one or more of the hydroxj-l groups is simultaneously replaced by chlorine.'^
SUI^PHONATION
Comparative!}^ little reliable information is available concerning the sulphonation products of the hydroxy- anthraquinones, but it has been claimed that a-hj-droxy
1 Wed., D.R.P. 189,937. ' Plath, B. 9, 1204.
3 Wed., D.R.P. 152,175 ; 153,194. * Wed., D.R.P. 189,937.
5 B)'., D.R.P. 117,923. « D.R.P. 282,494.
" L. B. HolUday and Co., Ltd., and H. D. Law. E.P. 126,727-8".
THE HYDROXY COMPOUNDS 277
compounds sulphonate in the j3- position, and that further sulphonation then leads to aj3-polyhydrox}'authraquinones.i Anthraruiin, for example, gives anthrarufin-2.6-disulphouic acid 2 and chr>^sazin gives chrysazin-2.7-disulphonic acid.^ Wolbling,-* on the other hand, by sulphonating chr}-sazin obtained a disulphonic acid from which a tetrahydroxy- authraquinone was obtained, which may or may not be identical with the i.2.7.8-tetrah3-drox>'anthraquinone de- scribed in the patent literature.^ They are both stated to give blue solutions in caustic soda, but whereas Wdlblmg characterises his product by its melting point and that of its acetyl derivative, the patentees confine themselves to describing the colour of its solutions in various solvents and its tinctorial properties, points concerning which Wolblmg gives no information except in so far as the blue solution in caustic soda is concerned. In connection with this it should be noted that simultaneously with Wolbling, Schrobsdorf <* described a dibromchr>'sazin which yielded a tetrahydrox>-- anthraquinone which one would expect to be 1.4.5.8-tetra- hydrox)'anthraquinone, but which differs widely from this substance in its properties,'^ and also cannot be 1.2.7.8- tetrahydrox^-anthraquinone ^ or i.2.5.8-tetrah3'drox3'anthra- quinone (quinalizarin),^ although it is conceivable that either of these might have been formed. As Schrobsdorf and Wolbling both carried out their work in the same laboratory at the same period, it is fair to assume that they both used the same sample of chr^'sazin, so that any error arising from their starting-out substance would vitiate both their results.
The sulphonation of anthraflavic acid ^^ and iso-anthra- flavic acid ^^ and their methyl ethers 12 also appears to lead to the entrance of sulphonic acid groups into the j3- positions.
1 By., D.R.P. 141,296. 2 Bv., D.R.P. 96,364.
3 By., D.R.P. 100,136. * B' 36, 2941.
s By., D.R.P. 103,988. « B. 36, 2936.
' B., D.R.P. 125,579 ; 143.804. 8 By.. D.R.P. 103,988.
» Bv., D.R.P. 60,855. 10 M.L.B., D.R.P. 99,6ii ; 99.874-
11 bV., D.R.P. 104,317. M.L.B., D.R.P. 99,612.
12 M.L.B., D.R.P. 143,858. Cf. also M.L.B., D.R.P. 139.425 (sulphona- tion of anthrachrj'sazin dimethylether).
278 ANTHRACENE AND ANTHRAQUINONE
In the case of 1.4.5- and i.4.6-trih3''droxyanthraqumone sulphonation under ordinary conditions leads to impure mixtures, but in each case if the sulphonation is carried out in the presence of boric acid a single stilphonic acid group enters at 7.1
On account of its technical importance the sulphonation of alizarin has attracted considerable attentioti, sulphonation with oleum leading to alizarin-3-sulphonic acid 2 (Alizarin Red vS), alizarin-6- and -7-sulphonic acids being only obtain- able from antliraquinone disulphonic acids by fusion with caustic potash under suitable conditions. ^ Further sulpho- nation of alizarin-3-sulphonic acid leads to disiilphonic acids, 4 from which, however, one sulphonic acid group can be split off by subsequent hydrolysis at 190° with sulphuric acid of 80 per cent, strength. ^
When alizarin is sulphonated in the presence of mercur\' the products obtained are not the same as those which are formed in the absence of mercury. Both alizarin and alizarin- 3-sulphonic acid when sidphonated in the presence of mercury give a mixture of alizarin-3.5- and alizarin-3.8-disulphonic acid, and as purpurin behaves in a similar way it must be concluded that as a rule a hydroxyl group in a ring directs to the j8- position more powerfully than the mercur>' directs to the a- position ; but in the ring free from hydroxyl groups the mercury exerts its usual influence. ^ Both these di- sulphonic acids also lose one sulphonic acid group when heated to 180-190° with sulphuric acid of about 80 per cent, strength,*^ alizarin thus yielding alizarin-5- and alizarin 8-sulphonic acids, and purpurin yielding purpurin-8-sulphonic acid.
Dihydroxyanthraquinones such as quinizarin in which the hydroxyl groups are in the para- position to one another
1 By., D.R.P. 165,860.
2 Graebe and Liebermann. A. 160, 144. Graebe, B. 12, 571. Perger, J. pr. [2] 18, 173. Pryzbram and Co., D.R.P. 3,565-
^ See p. 241.
^ By., D.R.P. 56,952.
5 By.. D.R.P. 56.951-
6 Wed.. D.R.P. 205.965 ; 210,863.
• By.. D.R.P. 172,688. Wed., D.R.P. 210.863. Cf. By., D.R.P. 160,104.
THE HYDROXY COMPOUNDS 279
can also be siilphonated by heating with solutions of sulphites. 1 In this case the reaction is no doubt due to oxidation to the anthradiquinone, followed by the addition of sodium sulphite, and as would be expected takes place most rapidly in the presence of an oxidising agent such as manganese dioxide. In the absence of an oxidising agent the necessary'- oxidation is brought about by the partial reduction of the cyclic carbonyl groups. The 1.4-hydroxy- aminoanthraquinones and the 1.4-diaminoanthraquinones are sulphonated in the same way, the intermediate product in these cases being the quinone imidc or di-imide.
Only a few hydroxj-anthraquinone sulphonic acids have found application as dyes, as the presence of the sulphonic acid group tends to decrease the fastness of the shades to washing. The best known are Alizarin Red vS (alizarin-3- sulphonic acid), which gives scarlet shades on an alumina mordant and is also used to a certain extent in the laboratory as an indicator, and Erweco Alizarin Acid Red BS, which is a mixture of alizarin-5- and alizarin-8-sulphonic acids and gives bordeaux shade on both chrome and alumina. Flavo- purpurin-3-sulphonic acid is used to a small extent under the names Alizarin Red 3WS or SSS, and gives brownish-red shades on alumina. The disulphonic acid of 1.2.4.5.6.8- hexahj'-droxyanthraquinone (Anthracene Blue WR) is ob- tained by the action of oleum on 1.5-dinitroanthraquinone, the subsequent hydrolysis being omitted. It has received several trade names, such as Acid Alizarin Blue BB, Alizarin Cyanme WRS, BBS, and 3RS, and Anthracene Blue SWX.
Nitration
The liydrox3'anthraquinones being much more stable than the phenols can often be fairly easily nitrated without protecting the hydroxyl groups, but under these conditions there is always considerable chance of simultaneous hydroxylation taking place, e.g. both alizarin and quini- zarin give 3-nitropurpurin. Protection of the hydrox^-l
» By.. D.R.P. 287,867 ; 288,474; 289,112.
28o ANTHRACENE AND ANTHRAQUINONE
group greatly lessens the danger of simultaneous li3^drox}'la- tion ; but, on the other hand, the directing influence of a protected group is often quite different from that of a free h3''drox34 group, and to some extent depends on how the protection is effected.
When h^'^drox}^ groups are present only^ in a- positions the}^ direct entering nitro groups to the para- position, but the oHho- position is also readil}- taken, so that there is usually no difficult}^ in inserting two nitro groups for each h3'droxyl group present. Er^^throhydrox^-anthraquinone, anthrarufin, and chr>'sazin i are fairly easily nitrated in the free state, although much purer products are obtained b}- nitrating the boric esters, 2 and the nitration and subsequent demethylation of chr>^sazin dimeth^^l ether has been recom- mended as the best method of obtaining mononitrochr3-sazin.3
In the case of quinizarin the nitration is somewhat more troublesome owing to the tendenc}' to form nitropurpurin, and in this case the boric ester method fails. B}^ nitrating in an organic solvent, however, such as glacial acetic acid or nitrobenzene, quinizarin can be converted into 2-nitroquini- zarm.4
When h3'drox3'l groups are present only in the ^- position the entering nitro groups take the ortho- positions to them, a- positions usualty being preferred to j3- positions. ^-TLydio-xy- anthraquinone itself readil)^ gives a dinitro compound, ^ the position of the nitro groups being proved by its conversion into anthragallol. Anthraflavic acid ^ and jso-anthraflavic acid '^ give both dinitro and tetranitro compoimds, and h3^stazarin gives a mono and a dinitro compound, ^ both of these latter giving phthalic acid when oxidised.
As would be expected from its technical importance, the nitration of alizarin has received most attention. If alizarin
1 By., D.R.P. 98,639.
^ Eckert and Steiner, M. 35, 1144. Bv., D.R.P. 163,042. 3 M.L.B., D.R.P. 193,104. « By., D.R.P. 272,299.
^ Liebermann and Simon, A. 212, 25, 53. B. 14, 464 ; 15, 692. Simon, D.R.P. 119,755.
« Schardinger, B. 8, 1487. M.L.B., D.R.P. 112,179. ' Romer and Sclnvazer, B. 15, 1040. 8 Schrobsdorf, B. 36, 2938.
THE HYDROXY COMPOUNDS 281
itself is nitrated in ordinary concentrated sulphuric acid solution a mixture of 3-nitroalizarin, purpuriu, and 3-nitro- purpurin is obtained owing to simultaneous liydrox^-lation taking place. ^ If, however, the boric ester of alizarin is nitrated, i.e. if nitric acid is added to a solution of alizarin in concentrated sulphuric acid containing an excess of boric acid, the side reactions are to a large extent avoided and almost pure 3-nitroalizarin results. 2 The same com- pound is also obtained by nitrating alizarin when dissolved or suspended in some suitable solvent such as ligroin, toluene, nitrobenzene, or, best of all, glacial acetic acid, and also b}' the action of nitrous acid on alizarin, 3 although the action of nitrous acid in concentrated sulphuric acid solution leads to 7-nitroalizarin.^
If the diacetyl derivative of alizarin is nitrated the nitro group enters a different position, and 4-nitroalizarin is obtained,^ but the nitration is rather troublesome to carry out, as the acetyl groups are readUy lost by hydrolysis during the nitration, and for this reason it is better to use the dibenzoyl derivative,^ the subsequent hydrolysis being ven- readily effected b}' cold caustic soda. This method has also been extended to the nitration of other hydroxy- anthraquinones such as anthrapurpurin, flavopurpurin,'' etc. Instead of protecting the hj^droxyl groups by forming an ester with an organic acid, the sulphate ^ or arsenate ^ can be used, i.e. the alizarin can be nitrated when dissolved in oleum of 20 per cent, strength at —5° to —10°, or when dissolved in concentrated sulphuric acid in the presence of arsenic acid below 0°. It is ver}^ remarkable that whereas the nitration ot the sulphate or arsenate gives 4-nitroalizarin,
1 Schunck and Romer, B. 12, 583. M.L.B., D.R.P. 150.322. Cf. also By., D.R.P. 50,164 ; 50,708. ■ "- By., D.R.P. 74.562.
3 Caro, B. 10, 1760; 12, 1008. Rosenthiel, C. r. 82, 1455 ; 83, 73. Ann. [5] 12, 519. B. 9, 1036. Cf. also Strobel, Mon. Sci. 1878, 1337.
B. 12. 584.
* Grawitz, B. 10, 1165. Xaro, Mon. Sci. 1879, 424. Girard and Pabst,
C. r. 91, 570.
* Perkin, Soc. 2, 578 ; B. 8, 780. Caro, A. 201, ^=53.
« M.L.B., D.R.P. 66,Sii. ' xM.L.B., D.i^.P. 70,515 ; 74,212.
« M.L.B.. D.R.P. 74,431. » By., D.R.P. 74,598.
282 ANTHRACENE AND ANTHRAQUINONE
the nitration of the borate gives the isomeric j3-nitroaHzarin, but other hydrox^^aiithraquinones such as flavopurpurin, anthrapurpurin, and AHzarin Bordeaux exhibit the same peculiarity. The a-nitro compound is also formed when alizarin monomethjd ether is nitrated, i although as already stated alizarin itself yields the ^-isomer.
Xanthopurpurin is fairly easily nitrated to a dinitro compoimd,2 and anthrachrj'sazin is easil}- and quantitatively converted into a tetranitro compound. ^
It is worth observing that methyl ethers are often de- methylated during nitration, especially when the methoxy group is in the a- position. Thus O. Fischer and Ziegier ^ found that i-methyl-4-niethox5'anthraquinone when gently warmed with excess of nitric acid of 70 per cent, strength gave a mononitro methyl hydroxy anthraquinone, although they did not determine the position of the nitro- group.
The chief technical interest in the nitroalizarins lies in the fact that they are intermediate products for the pro- duction of the important h3^drox3^antliraquinone quinolines (hydroxy pyridino anthraquinones) , but 3-nitroalizarm is used to a considerable extent as a d5^e under the name Alizarin Orange A, W, SW, Cy, etc. It gives orange shades in both chrome and alumina mordants.
II. Aminohydroxy Compounds
When 1.5-dinitroanthraquinone is reduced in alkaline solution a bishydroxylamine derivative is formed, which under the influence of acids is at once rearranged into 4.8-diaminoanthrarulin,5 the same product being obtained by oxidising 1.5-diaminoanthraqumone with manganese dioxide, etc., in concentrated sulphuric acid solution.^ This diaminoanthrarufin has scarcely any tinctorial pro- perties, but these are very greatly increased by the entrance of negative groups or atoms such as sulphonic acid groups
1 M.L.B., D.R.P. 150,322. 2 Plath, B. 9, 1204.
» M.L.B., D.R.P. 73,605, * J. pr. [2] 86, 292.
^ By., D.R.P. 81,694. 0 By., D.R.P. 106,034.
THE AMINOHYDROXY COMPOUNDS 283
or bromine atoms. ^ The bromo compounds are of but little importance, although it is worth remarking that the entrance of bromine into the molecule is accompanied by an increase in solubilit}^ a phenomenon not infrequently met with in the anthraquinone series. The diaminoanthrarufin sulphonic acids, especially 4.8-diaminoanthrarufin-2.6-disulphonic acid, have met with wide application as acid wool dyes under the name Alizarin Saphirol 2 and give reddish-blue shades which become greener and duller when chromed.
If anthraruhn is sulphonated by treatment with oleum the 2.6-disulphonic acid is obtained. This on nitration gives the 4.8-dinitro compound from which the dj-e is formed b}^ reduction, 3 but if the reduction is pushed too far one sulphonic acid group is split off.4 Alizarin Saphirol is also obtained direct from dinitroanthrarufin by heating on the water bath with aqueous solutions of alkali sulphites or bisulphites. 5 Here simultaneous reduction and sulphona- tion takes place, a reaction which is very common in the aromatic series, and this is probably the most convenient method of obtaining the dye. Of lesser interest is its forma- tion by the action of a sulphite on dibromdinitroanthrarufin, the sulphite reducing the nitro group and at the same time replacing the bromine atoms by sulphonic acid groups, ^ and from dibromanthrarufindisulphonic acid by heating with ammonia and a copper catatyst.'^ The dye can also be obtained by oxidising diaminoanthrarufin disulphonic acid with manganese dioxide and concentrated sulphuric acid, 8 and by the reduction of the quinoneimide sulphonic acid obtained by the action of oleum and sulphur on 1.5- dinitroanthraquinone.9
An isomer of Alizarin Saphirol is obtained from chrysaziu either by sulphonation, nitration, and reduction, ^o or by heating dinitrochrysazin with sulphites or bisulphites, ^ 1 or
> By., D.R.P. 102,532. 2 Solway Blue (Scottish Dyes, Ltd.).
' By., D.R.P. 96,364 ; 100,137; 105,501; 108,362; 119,228.
* By., D.R.P. 108.578. 6 By., D.R.P. 103,395.
« By., D.R.P. 163,647. " By., D.R.P. 195.139. « By., D.R.P. 106,034.
» By.. D.R.P. 113,724; 116,746. See also p. 245.
»» By., D.R.P. 100,136. " By.. D.R.P. 103,395.
284 ANTHRACENE AND ANTHRAQUINONE
by heating dinitrodibromchrysazin witli a sulphite. ^ It dyes in rather greener shades than Alizarin Saphirol itself. Isomers are also obtained by successive sulphonation, nitra- tion and reduction of anthraflavic acid 2 and «so-anthraflavic acid, 3 that from anthraflavic acid giving fiery red shades and that from ^'so-anthraflavic acid giving 3^ellowish-red shades. The formulae of the various dyes are * :—
NH2 OH |
HO OH |
NH2 |
NH. NHo |
||||||||
s |
S |
s |
s |
OH |
HO |
OH |
|||||
! |
1 |
1 |
1 |
||||||||
S |
HO |
S |
S |
S |
|||||||
OH NH2 |
NH2 NH2 |
NH2 |
|||||||||
Alizar From Red s] |
in Sa anth Idish tiade |
Lphirol. irarufin. -blue s. |
From Gre Alizai |
chr ener inS; |
^'sazin. than iphirol. |
From anthraflavic acid. Fiery red shades, bordeaux on chrome. |
From Mo-anthra flavic acid. Yellowish-red shades. Bordeaux on chrome. |
In addition to Alizarin Saphirol one or two hj'drox}-- aminoanthraquinones have found technical application as dyes. Of these may be mentioned 4-aminoalizarin (Alizarin Garnet R, Alizarin Cardinal) which is obtained by the reduction of 4-nitroalizarin,4 and gives bluish-red tones on an alumina mordant. The corresponding 3-amino- alizarin (Alizarin Maroon W) is used to a small extent in printing, but is of very minor importance. It gives rather loose shades of red on an alumina mordant. Alizarin Cyanine G and New Anthracene Blue WR may possibly be hydroxyimino compounds, although they are more probably imides. The former is obtained b}^ heating Alizarin C^^anine R with ammonia,^ the latter by heating Anthracene Blue with ammonia and caustic soda.^ Both give blue shades on alumina.
The other hydroxj^aminoanthraquinones which are of
1 By., D.R.P. 163,647. 2 M.L.B., D.R.P. 99,611 ; 99,874.
' M.L.B., D.R.P. 99,612. * S = SO,H.
* By.. D.R.P. 66,8x1. ^ gy^ D.R.P. 62,019,
« B.A.S.F., D.R.P. 119,959.
THE ETHERS 285
technical importance are chiefly secondary amino compounds and are mentioned in Chapter XI.
III. The Ethers
As already stated hydroxjl groups when in the /3- position are readily alkylated by heating with the alkyl iodide or dimethyl sulphate and caustic potash in alcoholic or aqueous alcoholic solution. ^ In the case of a-h3'drox3d compounds, however, this method fails, and although Plath 2 claimed to have obtained dimethyl and diethyl ethers of xanthopuqourin it is fairly certain that he really obtained only the mono- methjd and monoetltyl ethers. Methylation of a-hydroxy compomids, however, can be effected by heating the dry potassium salts with dimethyl sulphate, ^ and in many cases the alk>dation can be brought about without difficulty by first reducing the hydrox}-anthraquuione to the anthrone.^ These are usually easil}- alk3dated and the restdting ether can then be oxidised to the anthraquinone. The method fails, however, when there are h3'drox3d groups m the ortho- position to both C5-c]ic carbonyl groups. In spite of the weU-known difficult}- in alkylating hydrox}'l groups when in the a- position, it has been claimed that a cyclic ether is formed when alizarin is heated with ethylene dichloride or ethylene dibromide and sodium acetate, with or without the addition of a catalyst such as copper.^ This compotmd has been assigned the structure :
CHz
Oi^CHt 0
but this can only be accepted with reserve pending further conlirmation.
1 Graebe, A. 349, 201. Graebe and Aders, A. 318, 369. M.L.B., D.R.P. 158,277.
2 B. 9, 1205.
' O. Fischer and Gross, J. pr. [2] 84, 372. O. Fischer and Ziegler, J. pr. [2] 86, 297- M.L.B., D.R.P. 242,379.
* Graebe. A. 349, 201 ; B. 38. 152. ^ M.L.B.. D.R.P. 280,975.
286 ANTHRACENE AND ANTHRAQUINONE
But little work has been done on the direct arylation of hydrox>^anthraquinones, although it has been claimed ^ that hydrox>4 groups in the a- position are readily arylated when the alkali salt is heated with an alkyl ester of an aryl sulphonic acid, with or without the addition of a basic substance.
Dianthraquinonyl ethers are obtained by condensing a halogen anthraquinone with a hydroxy anthraquinone by heating in an inert solvent such as nitrobenzene with sodium acetate and a copper catalyst. 2 The patent does not state whether the reaction is confined to /3-hydroxy com- pounds, although this is probably the case. From i-chlor- 2-hydroxyanthraquinone and similar compounds cyclic ethers are said to be obtained. 3 These have the structure —
/0\
and are yellow vat dyes although apparently of no technical value. In their formation an a-halogen atom reacts with a jS-hydroxyl group so that aj8-dianthraquinonyl ethers would seem obtainable by this method. It is very improb- able, however, that an a-halogen atom would react with an a-hydrox}d group to produce an aa-dianthraquinonyl ether.
Cyclic dianthraquinonyl ethers are also formed from 02-dihydrox>"dianthraquinonyl compounds by heating with condensing agents such as zinc chloride.* Here loss of water takes place between two hydroxyl groups with the formation of a furfurane ring :
i M.L.B.. D.R.P. 243,649.
2 M.L.B. 216,268.
^ Wed., D.R.P. 257,832 ; 263,621; 265,647; 269,215.
^ Scholl, D.R.P. 274,783.
THE ETHERS
287
OH HO
^0\
According to one patent specification ^ when qiiinizarin is heated to about 120° with a salt of a weak acid such as a carbonate, borate, phosphate, or acetate, it is converted into two compounds. These are present in the melt more or less as reduction products, and the patent suggests that they are formed by the union of two molecules by self -oxidation at the expense of the cyclic carbonyl groups. If this is the case they ma}- or may not be ethers. The analytical figures given agree with the formulae C28H14O8 and C28H13O8. Both substances give blue alkali salts.
Both alkyl and aryl ethers can be obtained directly by the replacement of halogen atoms, 2 or svdphonic acid groups, 3 or nitro- groups. ^ The alkyl ethers are obtained by heating with a solution of caustic potash in the alcohol or with an alcoholic solution of the alkali alcoholate, and in the case of nitro- compounds it is very desirable to exclude all moisture, as otherwise simultaneous reduction takes place. The ar3'l ethers are formed by heating with the alkali pheno- late in alcohol or in some indifferent solvent of high boiling point, such as the phenol. The addition of a catalyst such as copper or copper acetate is often advantageous. In the case of halogen atoms and sulphonic acid groups the replace- ment takes place most readily when the atom or group is in the a- position, but in the case of nitro groups replacement when in the j8- position is most easy.^ The reaction with nitro compounds, however, although quite common, is by no means a general one. 6
' By., D.R.P. 146.223.
2 Frey, B. 45, 1359. UUmann, B. 49, 2162 ; 21G8. By., D.R.P. 158,531 ; 229,316; 263,423.
3 R. E. Schmidt, B. 37, 10. Laube, B. 39, 2245. By.. D.R.P. 156,762 ; 158.531 ; 166,748.
« By., 75,054; 77.818; 145,188; 158,531- M.L.B., D.R.P. 15S.278 ; 167,699.
6 M.L.B., D.R.P. 167.699- « M.L.B., D.R.P. 158,278.
288 ANTHRACENE AND ANTHRAQUINONE
In some cases heating a nitroantliraqvdnone witli potas- sium carbonate in nitrobenzene solution leads to a dianthra- quinonyl ether. ^
No great interest attaches to the ethers as a class. They are a great deal more easily hydrolysed than the phenolic ethers of the benzene or naphthalene series, and hence their formation is often a useful means of protecting hydrox)^ groups during nitration. On sulphonation the alkyl ethers are dealkylated, but the ar>^l ethers are more stable and can be sulphonated in the aryl group. ^
The methyl ethers of the a-hydroxyanthraquinones show considerable tendency to form oxonium salts such as hydro- bromides, zincibromides, and perchlorates.^ The hydro- bromides, however, are unstable and readily imdergo spontaneous demethylation.
1 Agfa, D.R.P. 283,482. 2 By., D.R.P. 164,129.
' O. Fischer and Ziegler, J. pr. [2] 86, 297.
CHAPTER XIII
PYRIDINE AND QUINOLINE DERIVATIVES
Compounds containing both an anthracene or anthraquinone residue and a pyridine ring can be conveniently divided into two classes, viz. compounds in which the ms-carhon atom of the anthracene residue forms part of the pyridine ring, and compounds in which the pj-ridine ring is fused into one of the benzene rings of the anthracene nucleus, both w7s-carbon atoms remaining intact. Compounds of the former class are very similar in structure to the benzanthrenes and benzanthrones and are known as pyridanthrenes and pyridanthrones —
CO I (N).9-Pyridanthrene. i (N).9-Pryidanthrone.
Compounds of the latter class are similar in structure to the benzanthracenes and benzanthraquinones and are known as anthraquinolines (pyridinoanthracenes) and anthraquinone quinolines (pyridinoanthraquinones) :
CO
CO
Anthraquinoline Anthraquinonequinoline
i(N).2-Pryidinoanthracene. i.2(N)-Pyridinoanthraquinone.
289
19
290 ANTHRACENE AND ANTHRAQUINONE
A third class of compound is also known in which two anthracene residues are united by one or two pyridine rings. In these each pyridine ring is present as a pyridanthrene with reference to one anthracene nucleus, and as an anthra- quinoline with reference to the other anthracene nucleus. The most important compounds of this nature are the pyranthridones and flavanthrones * :
CO
Pyranthridone.
CO
Flavanthrone.
I. The Pyridanthrones
When an a-acetylaminoanthraquinone is heated alone at 200-280°, or when it is boiled with aqueous caustic alkali, loss of water takes place with the formation of a pyridanthrone : ^
or
A similar reaction is also brought about when the a-acetyl amino compoimd is heated with a formate or acetate, 2 or with an acid chloride such as sulphur>''l chloride or phos-
* Intheliteraturethetermusually employed is "flavanthrene." Owing to the ketonic nature of the body the name should terminate in -one, and consequently the word " flavanthrone " has been adopted in the sequel. The term " flavanthrene " is reserved to denote the oxygen free reduction product. Flavanthrone itself was originally known commercially as Flavanthrene, spelt with a capital, but as the name has been altered to Indanthrene Yellow G confusion will not arise on this score. See also footnote on p. 342.
1 By., D.R.P. 185,548; 192,201; 199,713; 203,752. B.A.S.F., D.R.P. 212,204; 216,597. M.L.B., D.R.P. 280,190.
» B.A.S.F., D.R.P. 191,111 ; 192,970. By., D.R.P, 209,033.
PYRIDINE AND QUINOLINE DERIVATIVES 2qi
phorus oxycliloride.i lu a great many cases it is not necessaty to isolate the acetyl derivative as pyridone formation takes place simultaneously with acetylation when an a-aminoanthraquinone is boiled with acetic anhy- dride, 2 or is heated with acetic anhjdride and concentrated sulphuric acid or oleum. ^
Several variations of the above method of forming pyridanthrones have been described. Thus the a-amino- anthraquinone can be condensed with one molecule of diethyl malonate and the product then boiled with caustic alkali.^ Under these conditions the pyridoneanthrone carboxylic acid is first formed, but this readily passes into the pyridanthrone itself by loss of carbon dioxide :
CO
Another variation consists in condensing an aryl sulphone acetyl chloride of the type ArS02.CH2COCl with a primary or secondary a-aminoanthraquinone and then boiling the product with aqueous alcoholic alkali. f* Under these con- ditions the ar\'lsulphone group is split off, and at the same time the pyridine ring is closed, the product being a hyrlroxy- pyridone anthrone :
ArSOjCHiCO CO
NH
CO
Pyridoneanthronepyridinium chlorides are obtained when a-chloracetylaminoanthraquinones are treated with pyridine, formation of the pyridinium cHoride and of the pyridone ring taking place simultaneously ^ ;
' B.A.S.F., D.R.P. 198.048. 2 By., D.R.P. 209,033.
3 B..\.S.F., D.R.P. 198,025 ; 200,015. * M.L.B., D.R.P. 250,885.
* M.L.B., D.R.P. 284,209. « By., D.R.P. 290,984.
292 ANTHRACENE AND ANTHRAQUINONE
9 '\
PhNCHz ^NH CO
CO
Other tertiary bases behave in the same way..
The C-alkyl and aryl p^-ridanthrones can be obtainea by condensing a primary a-aminoanthraquinone with a ketone which has at least one methyl group directly attached to the carbonyl group, ^ such as acetone, acetoacetic ester, acetophenone, etc. When acetone itself is used the product is Py.a-methyl-i(N).9-pyridanthrone :
The above methods of preparing the pyridanthrones are of very general application and have been extended to a-aminoindanthrones, a-aminodianthraquinonylamines 2 and 1.4-diaminoanthraquinone, although in this last case it is not certain whether pyridanthrone formation takes place with both amino groups. 3
It will be observed that the compoimds prepared from primary aminoanthraquinones by all the above methods except the last can be regarded either as pyridoneanth rones or as hydroxypyridanthrones (see formulae on p. 290), although those prepared from secondar}^ aminoanthra- quinones must have the pyridone structure. Those prepared from the primary aminoanthraquinones are probabty tauto- meric, and react in the enolic form when treated with phos- phorus pentachloride, passing under these conditions in Py.a-chlor-i(N)-9-pyridanthrones.4 The Py-chlorpyrid- anthrones are also readily obtained by chlorinating the p3'ridanthrones.5 In them the chlorine atom is ver}'-
1 By., D.R.P. 185,548. 2 B.A.S.F., D.R.P., 198,025; 200 015.
» By., D.R.P. 185,548. « M.L.B., D.R.P. 256,297.
5 By., D.F.P. 264,010.
i
PYRIDINE AND QUINOLINE DERIVATIVES 293
reactive and is readily replaced b}' a hydrox>d group by boiling with 10 per cent, alcoholic alkali, 1 and by an aryl- aniino group by boiling with a primary aromatic amine. 2
The Bz-amino, alkylamino and arylaminopyridanthrones and the Bz-anthraquinonylaminopyridanthrones are easily obtained by the usual methods, e.g. by replacing negative groups attached to the benzene rings by heating with ammonia or with a primar}^ secondary amine, 3 or by condensing a Bz. -halogen or Bz.-aminopyridanthrone with halogen compounds or amino compounds. ^ Some of the products thus obtained have been described as vat dyes and their sulphonic acids as acid wool dyes,^ but they do not seem to have found any technical application.
II. The Anthraouinone Quinounes
There are three possible anthraquinone quinolines (pyridinoanthraquinones) viz. :
CO
CO N
N
i(N).2-Pyridinoanthra- 2.3-Pyridinoanthra- 2(N).i-Pyridinoanthra- quiaone, m.p. 169°. quinone, m.p. 322°. quinone, m.p. 185°.
and all three have been prepared although they have been comparatively little studied, the chief interest centring round the technically valuable hydroxy compounds.
The preparation of quinolines from aminoanthraquinones by Skraup's method often gives very satisfactory- results, but in other cases the quinoline is only obtained imder special conditions. Mejert ^ claimed to have obtained a quinoline from aminoanthraquinone b}^ Skraup's method, but his specification contains no details and his claims must
1 By., D.R.P. 268,793. 2 M.L.B., D.R.P. 256,297.
• By., D.R.P. 201,904. B.A.S.F. 205,095.
B.A.S.F./D.R. P. 217,395-6; 218,161. By., D.R.P. 194,252.
By., D.R.P. 194.253; 233,126. <= D.R.P. 26,197.
294 ANTHRACENE AND ANTHRAQUINONE
be accepted with considerable resen'e. Bally i was unable to obtain a quinoline from a-aminoanthraqninone b}- carr\-ing out Skraup's synthesis under the usual conditions, but a quinoline is readily obtained if sulphuric acid of 78 per cent, strength is used in place of concentrated sulphmic acid, and if nitrobenzene sulphonic acid is used as an oxidising agent. 2 By this means i(N).2-jA'ridinoanthra- quinone has been obtained from a-aminoanthraquinone and i(N).2.5(N).6-dipyridinoanthraquinone has been obtained from 1.5-diaminoanthraquinone. In the case of jS-amino- anthraquinone the tendenc}- to form a benzanthrone com- pound 3 is so great that it is almost impossible to obtain the pyridinoanthraquinone. A small amomit of a substance which melts at 322°, and which has the formula C17H9O2N, is obtained, however, and this is probably 2.3-pyridino- anthraquinone * although it has never been properly investi- gated. The third isomer, 2 (N) .i-pyridmoanthraquinone is best obtained from the corresponding 2(N).i-p3-ridmoanthracene (anthraquinoline) by oxidation by chromic acid.^ The pyridi- noathracene can be ODtained by distilling Alizarin Blue with zinc dust, 6 or from ^-authramine b}- Skraup's method."^
The p3-ridinoanthraquinones have been but little in- vestigated, although a certain amount of work has been recorded in connection ■v\-ith the technicall}- important hydroxy- derivatives. All three isomers are smoothly nitrated, the nitro group entering the benzene ring to which the quinoline group is not attached. ^ Dinitro compounds do not appear to have been described.
The hydroxyanthraqiii}ione qiiinolines can be obtained from the corresponding aminohydrox\-anthraquinones by Skraup's method, and by this means quinolmes have been prepared from 3-aminoalizarin,9 4-aminoalizarin,io amino-
1 B. 38, 194. - M.L.B., D.R.P. 189,234.
3 See p. 332. * B.A.S.F.. D.R.P. 171,939-
5 Graebe, A. 201, 349- ® Graebe. A. 201, 344.
• Graebe, B. 17, 170. Kniippel, B. 29, 70S.
8 B.A.S.F.. D.R.P. 218,476.
9 Pnid'homme, Bl. 28, 62. Graebe, B. 11, 522, 1646; 12. 1416; 15, 17S3 ; A. 201. r, V Kauppel, B. 29. 70S. Auerbach, Chem. Ztg. 3, 5-5. 682. C/. Ort, M.L.B.. D.R.P. 62,703.
10
M.L.B., D.R.P. 67,470.
PYRIDINE AND QUINOLINE DERIVATIVES 295
flavopurpurin, aminoanthrapurpiirin,^ aminoquinalizarin,^ and other similar compounds. 3 They are nearly all mordant dyes and several of them have found technical application, e.g.
OH OH OH
OH
,N— ^CH
^CH-CH
Alizarin Blue.
OH
.CH=CH
\
HO
N=CH
OH
/N=-CH
I
^CH-CH
Alizarin Black P.
Alizarin Green.
Of these Alizarin Blue is by far the most important and numerous brands are placed on the market, viz. Alizarin Blue ABi, X, R, RR, A, F, GW, WA, etc. It is manu- factured from ^-aminoalizarin by Skraup's method. The isomeric dye, Alizarin Green, is obtained from a-amino- alizarin, but is of much less importance, although it finds some little application in printing, being then used in con- nection with a nickel-magnesium mordant. Alizarin Black P is only very little used.
Another method of synthesising hydroxyanthraquinone quinolines has been described by Niementowski,^ who states that 3.7-dihydroxy-i.2(N).4.5(N)-dipyridinoanthra- quinone is obtained when 8-hydroxyquinoline-6-carbox}dic acid is heated with concentrated sulphuric acid and phos- phorus pent oxide. He describes it as an orange vat dye. Other dipyridinoanthraquinones have also been described.^
COOH
HOCO
Hydrox>l groups can be introduced into the anthra- quinoline molecule by sulphonating and then heating the
1 M.L.B., D.R.P. 54,624 ; 70,665. " B.A.S.F., D.R.P. 58,480.
8 Schaarschmidt and Stahlschmidt, B. 45, 3452. By., D.R.P. 50,164; 50,708. M.L.B., D.R.P. 149,781.
* B. 49. 23. » M.L.B., D.R.P. 189.234.
296 ANTHRACENE AND ANTHRAQUINONE
sulphonic acid with milk of lime at 180°, but more important results are obtained by direct hydrox5'lation by oxidation. If Alizarin Blue is oxidised under carefully controlled conditions, e.g. b}^ treatment with bromine, nitric acid, or manganese dioxide, it is converted into the corresponding diquinone 1 (3(N).4-pyridino-i.2.9.io-anthradiquinone) ; but if the oxidation is brought about by heating with oleum a tetrahydroxy compound (Alizarin Green X) and a penta- hydroxy compoimd (Alizarin Indigo Blue) are obtained ^ :
HO OH HO OH
OH HO OH
I
/
N=CH
I
HO V^_,
HO
.N=CH
^CH=CH
Alizarin Indigo Blue.
^CH=:CH
Alizarin Green X.
This last on oxidation with nitric acid very readily yields quinolinic acid.
When Alizarin Blue and similarly constituted dyestuffs are allowed to remain in contact with concentrated aqueous solutions of sodium bisulphite for several days they combine with two molecules of the bisulphite and pass into water- soluble products which are very largely used in printing 3 (Alizarin Blue S, Alizarin Green S, etc.). In text-books on tinctorial chemistry these soluble products are usually represented as being formed by union of the bisulphite with the cyclic carbonyl groups, but such a structure is very improbable as neither anthraquinone itself nor the hydroxy- anthraquinones combine with bisulphite. Quinoline itself, however, forms an addition product with sodium bisulphite, and this resembles Alizarin Blue S by being decomposed by water at 60°. It is therefore probable that in the soluble dyes the bisulphite is imited to the quinoline ring and not to the cyclic carbonyl groups. ^
1 By., D.R.P. 171,836.
2 Graebe and PhiUps, A. 276, 21. B.A.S.F., D.R.P. 46,654 ; 47,252.
3 B.A S.F., D.P.P. 17,695 ; 23,008. * Brunck and Graebe, B. 15, 17S3.
PYRIDINE AND QUINOLINE DERIVATIVES 297
III. Anthraquinone Phenanthridones
The anthraquinone phenanthridones are of no particular interest but are quite readily obtained from those benzoyl- aminoanthraquinones in which there is a halogen atom in the o-position to the nitrogen atom, either in the anthraquinone nucleus or in the benzene ring :
The reaction is brought about by boiling with sodium carbonate or sodium acetate, preferably in naphthalene solution. It is not necessary to isolate the benzoylamino anthraquinone as the phenanthridone is formed by the prolonged boiling of an aminoanthraquinone with o-chlor- benzoyl chloride in nitrobenzene solution in the presence of sodium carbonate. 1
IV. The Pyranthridones
The pyranthridones are intennediate in structure between the pyranthrones (p. 335) and the flavanthrones (p. 300), and were studied by Scholl during liis investigations on these substances. Scholl 2 found that when a mixture of 2-methyl- i-chloranthraquinone and 2-benzylideneamino-i-chloranthra- quinone is heated with copper powder, a mixture of three different dianthraquinonyl derivatives is formed, although
1 B.A.S.F., D.R.P. 236,857 ; 238,158.
= B.51,441. D.R.P. 307,399. C/. Ullmann, A. 399, 332 ; D.R.P. 248,999.
298 ANTHRACENE AND ANTHRAQUINONE
he was unable to separate them. When the mixture was heated with sulphuric acidi however, the benzylidene group was split off and simultaneous loss of water took place, and from the product he was able to isolate flavanthrone and 2'-meth3'l-i.2.a.j3-pyridanthrone anthraquinone. These two compounds had obviously been formed from two of the dianthraquinonyls thus : ••
CO CO
Flavanihrone CO
^-f^eiby\-\■^.<ji-pyndanihrone
The third dianthraquinonyl derivative was unaffected by the sulphuric acid under the conditions of the experiment, and was, of course, 2.2'-dimethyl-i.i'-dianthraquinonyl.
The pyridanthrone anthraquinone was found to be a 3'ellow vat dye although the tinctorial properties were ven.- feeble. When reduced with sodium hydrosulphite in alkaline solution it gives first a comparatively stable red vat and then a very easily oxidised blue vat. As each of these gives a di-brombenzoyl derivative they probably have the structures :
OH Red product.
OH Blue product.
PYRIDINE AND QUINOUNE DERIVATIVES 299
The chief interest attached to methylpyridanthrone- anthraquinone Hes in its behaviour when heated alone or with concentrated sulphuric acid or with alcoholic caustic potash, as under these conditions another molecule of water is lost and pyranthridone is formed :
This is a powerfrd vat dye which d3'es in orange-red shades which are somewhat yellower than those obtained from pyranthrone itself, but much redder than those obtamed from flavanthrone. Its bromo derivatives are also orange-red dyes. Pyranthridone when reduced by sodium h5'drosulphite in alkaline solution gives a violet-coloured vat, and since this gives a di-brombenzoyl derivative it probably has the formula :
Reduction with hydriodic acid and phosphorus leads to dihydropyranthridene, which when heated with copper powder loses two atoms of hydrogen and passes into P3'ranthridene itself :
H H
H H
Dihydropyranthridene.
Pyranthridene.
300 ANTHRACENE AND ANTHRAQUINONE
V. The Flavanthrones *
When /3-aminoanthraquinone is fused with caustic alkali a mixture of the reduction products of indanthrone and flavanthrone is obtained, ^ although when the fusion is carried out in the presence of a reducing agent, or more particularly when alcoholic solutions of caustic potash are used, the reduction product of flavanthrone becomes almost the sole product. 2 Flavanthrone, mixed with indanthrone, can also be made by oxidising j3-aminoanthraquinone,3 and when /3-aminoanthraquinone is heated with aluminium chloride without a solvent at 250-280° considerable quantities of flavanthrone are obtained. ^ Curiously enough the use of an indifferent solvent such as nitrobenzene leads to quite a different result, as under these conditions little or no flavanthrone is formed, the chief product consisting of a reddish-brown vat dye of unknown constitution. ^ The best method, both for laboratory and for manufacturing purposes, of obtaining flavanthrone is to boil /3-aminoanthra- quinone with antimony pentachloride in nitrobenzene solution.*^
None of the above methods of preparing flavanthrone throw any light on the constitution of the dyestuff, and the first direct proof of its structure was given by Scholl."^ He started with 2.2'-dimethyl-i.i'-dianthraquinonyl and first oxidised this to the corresponding dicarbox34ic acid. This he then converted into its amide and then endeavoured to obtain diaminodianthraqmnonyl from this by Hofmann's method. In this he was not successful as the diamino- dianthraqmnonyl proved to be unstable under the experi- mental conditions and at once lost two molecules of water and passed into flavanthrone :
* See footnote on p. 290, ^ See p. 343.
2 B.A.S.F., D.R.P. 133,686; 135,408.
3 B.A.S.F., D.R.P. 139,633 ; 141.355; 211,383.
4 B.A.S.F., D.R.P. 136,015.
B B.A.S.F., D.R.P. 138,119; 206,464.
« Scholl, B. 40, 1691. B.A.S.F.. D.R.P. 138.119
7 B. 41, 1691.
PYRIDINE AND QUINOLINE DERIVATIVES 301
CO
CO
CO
At a later date SchoU ^ showed that i.i'-dianthraqiiinonyl when nitrated gave a mixture of nitro compounds from which small quantities of flavanthrone could be obtained by reduction with sodium sulphide, the production of flavanthrone being no doubt due to the instability of 2.2'- diamino-i.i'-dianthraquinonyl. Behesh 2 also found that diaminodianthraquinonyl was unstable, as he obtained only flavanthrone by heating 2.2'-dimethoxy-i.i'-dianthra- quinonyl with ammonia.
To establish the structure of flavanthrone beyond all possible doubt it was desirable if possible to isolate the diaminodianthraquinonyl and prove that it did readily pass into flavanthrone. If 2-amino-i-bromanthraquinone is heated with copper powder this last acts as a catal5'St and splits out two molecules of hydrobromic acid, the product being indanthrone (see p. 345). If this catal3'tic eft'ect could be prevented it should be possible to split out the two atoms of bromine and thus obtain diaminodianthraquinonyl. Scholl 3 first tried to achieve this result by using the acetyl derivative of the aminobromanthraquinone, but was not successful. By using the benzylidene derivative, * however, he succeeded in preparing the dibenzylideneaminodianthra- quinonyl and was then able to hydrolyse this in alcoholic solution at the ordinary temperature. The resulting 2.2'-dianiino-i.i'-dianthraquinonyl was found to pass into flavanthrone when heated alone to 250° or when warmed to 50° with concentrated sulphuric acid. Boiling with solvents such as nitrobenzene, pyridine, or glacial acetic acid also effected flavanthrone formation, and reduction with sodium hydrosulphite in alkaline solution led at once
» B. 43, 1740. a M. 32, 447.
s B. 40. 1699. * B. 51. 452.
302 ANTHRACENE AND ANTHRAQUINONE
to the blue vat of flavanthrone. This method of preparmg flavanthrones has been used by Ulltnann ^ for the preparation of the dibromo derivative.
Flavanthrone is a yellow vat dye which yields extremely fast shades. It was originally put on the market under the name Flavanthrene, but this was subseqjiiently altered to Indanthrene Yellow G.2 The dibrom derivative gives orange shades. Flavanthrone itself is very stable towards nitric acid, but by prolonged heating a mixture of substances is obtained from which Scholl 3 has isolated a dihydroxy- dinitrosodinitro compound. This on reduction gives the corresponding tetraminodihydrox}- compoimd, and if boiled with a primary aromatic amine such as aniline or ^-toluidine the nitro groups can be replaced by arylamino groups.
The reduction products of flavanthrone have been very fully investigated by Scholl and his co-workers. Scholl * finds that reduction in alkaline solution with sodium hydro- sulphite gives a blue vat which is readily oxidised by the air. From this solution acetic acid precipitates a greenish- blue hydrate which loses water slowly at iio° and rapidl}'- at 150°. It gives a disodium salt but onl}^ a monobenzoyl derivative, and this monobenzoyl derivative is insoluble in alkali. Scholl therefore concludes that in the blue vat there is only one true hydroxy^ group present, and represents the hydrate by formula I and its disodium salt by formula II :
OH . ONa
CO I. Flavanthranol hydrate.*
Reduction of flavanthrone with zinc dust and caustic soda leads to a brown vat which is extremely easily oxidised
1 A. 399, 332. D.R.P. 248,999. Cf. By., D.R.P. 172,733-
2 Caledon Yellow G (Scottish Dyes, Ltd.). » B. 43, 340.
* B. 41. 2304, 2534. Cf. Potschiwauscheg, B. 43, 1748. By., D.R.P. 139.^34- ' Dihydroflavanthrene hydrate (Scholl).
PYRIDINE AND QUI NOLI NE DERIVATIVES 303
by the air. This vat seems to consist of at least four hydrated substances which lose their water at 160°. In alkaline solution they are all red, but are blue when pre- cipitated by acids, so that salt formation is probably ac- companied by enolisation. SchoU represents them by formulae III, IV, V, and VI :
OH . OH
ITT. Flavan-ihracujinol Hydrafe WM-Dihydroanihraquinol Hydraie.^ OH H
V Floivanflirenol Hydraie.^ ^ VJ.Flavanihrene Hydrate.'^
When flavanthrone is reduced with hydriodic acid and phosphorus, non-hydrated products are obtained. When the reduction is carried out at 170° a product is formed which is not particularly sensitive to oxidation by the air, and which is green when in the solid state, but red when in solution, particularly in the presence of alkali. The red and green forms are probably due to keto-enol tautomerism (formulse VII and VIII).
CO CO
Vn Dihydroflavanthranol.5 VIII
* a-Tetrahydroflavanthrene hydrate (Scholl). 2 a-Hexahydroflavan- threne hydrate (Scholl). ' Flavanthrinol hydrate (Scholl). * Flavan- thrine hydrate (Scholl). * ^-Tetrahydroflavanthrene (Scholl).
AX7Z?-^:i: I -r.::z- axze?
- *■ ■
-: _ * i - T ■»
i«
« •-
— 'v
— v^^
2^ —
Tfti~ "r:
■» nviut^
- — «. ~
304 ANTHRACENE AND ANTHRAQUINONE
This on alkaline reduction gives a product which is very sensitive to oxidation by the air, and which is probably represented by formula IX :
OH IX. j8-Dihydroflavanthraq\iinol.^
When the reduction of flavanthrone with hydriodic acid and phosphorus is carried out at 200° flavanthrene hydrate (formtila VI, p. 303) is obtained, which by loss of water yields flavanthrene 2 itself. This last is a base and is not sensitive to oxidation by the air.
Attention may here be directed to a bluish-grey vat dye which is obtained by converting chlorbenzanthraquinone, obtained by condensing phthalic anhydride with a-chlor- naphthalene, into the corresponding amino compound b}^ heating with ammonia, and then boiling this with antimony pentachloride in nitrobenzene solution. ^ Nothing is known of its structure, but it is improbable that it is a flavanthrone.
^ /3-Hexahydroflavanthrene (Scholl). ^ Flavanthrine (Scholl).
3 G.C.I.B., D.R.P. 230,455.
CHAPTER XIV
THE ACRIDONES, XANTHONES, AND THIOXANTHONES
I. The Acrid ones *
The anthraquiiione acridones are almost invariably obtained by loss of water from ar>^laminoantliraquinones or dianthra- quinonylamines in which there is a carboxyl group in the ortho- position to the imino group, although this carbox}! group may be either in the anthraquinonyl group or in the ar5'l group. Such carbox3dic acids can be obtained {a) by condensing an o-aminoanthraquinone carboxylic acid with an aromatic halogen compound or halogen anthraquinone ; (6) by condensing an o-halogen anthraquinone carboxy-lic acid with a primary aromatic amine or aminoanthraquinone ; (c) by condensing an aminoanthraquinone with an aromatic o-halogen carboxj^ic acid ; {d) by condensing a halogen anthraquinone with an aromatic o-amino carboxylic acid. Of these the last two methods lead only to acridones in which the heterocyclic ring lies between one anthraquinone residue and one aromatic ring. Such compounds, however, are readily obtained owing to the easy accessibility of o-chlorbenzoic acid and anthranilic acid. When the con- densation is being carried out with o-chlorbenzoic acid Ullmann ^ finds that improved 3'ields are obtained by using the methyl ester in place of the free acid. In cases in which the carboxj-l group is attached to the anthraquinone nucleus (methods {a) and (6)) the use of sodium acetate as a
* These can be named either as anthraquinone acridones or as phthaloyl acridones, and both methods of nomenclature are in use. 1 B. 51, 9. Cf. M.L.B., D.K.P. 254, 475.
305 20
3o6 ANTHRACENE AND ANTHRAQUINONE
condensing agent often leads to very poor jdelds owing to the tendency- of this substance to cause loss of carbon dioxide. This, however, can be avoided by replacing the sodium acetate by the carbonate, acetate, or hydroxide of calcium or magnesium. 1
The final closing of the acridone ring can usually be brought about by heating with sulphuric acid,^ but in many cases it is sufficient to boil the carboxj-lic acid with some indifferent solvent of high boiling point, such as nitro- benzene, ^ with or without the addition of acetic anh3'dride or acet}-! chloride. * The fact that the acridone ring can sometimes be closed merely by boiling with a solvent has enabled Eckert and Halla ^ to obtain an acridone by boiling i-aminoanthraquinoue-2-carboxylic acid with /3-chloranthra- quinone in nitrobenzene solution in the presence of cuprous chloride and sodium acetate.
In spite of the ease with which the acridone ring is often closed by the above methods, Ullmann ^ in many cases prefers to convert the carbox5'lic acid into its chloride by treatment with phosphorus pentachloride and then to obtain the acridone by boiling this with nitrobenzene. It has also been stated that the ring is closed when an ester of the acid is reduced by sodium hydrosulphite or by zinc dust and ammonia. 7
The above methods of preparing the acridones have given rise to several minor variations. Thus o-methyl dianthra- quinon34amines when oxidised in alkaline solution pass into the corresponding carbox>dic acid, from which simulta- neous loss of water takes place with the immediate pro- duction of the acridone. 8 In a ver>- similar way o-methyl- aryl amino anthraquinones, in which the methyl group ma\- be either in the anthraquinone residue or in the arj^l group,
1 B.A.S.F., D.R.P. 268,219.
2 Ullmann and Billig, A. 381, i ; B. 43, 538. Ullmann, B. 49, 2160. Ullmann and Dootson, B. 51, 9. Ullmann and Conzetti, B. 53, 836. Ullmann, D.R.P. 221,853. B.A.S.F., D.R.P. 240,002 ; 269,850 ; 287,614. M.L.B., D.R.P. 240,327 ; 243,586; 245,875; 254,475; 256,626. Brass, B. 46, 2907 ; D.R.P. 268,646.
3 B.A.S.F., D.R.P. 248,170. 4 Ullmann, B. 47, 748. » M. 35.. 755. « A. 381, I. B. 43, 538 ; 47, 553, 562. D.R.P. 221,853.
' B.A.S.F., D.R.P. 246,966. 8 B.A.S.F., D.R.P. 192,436.
THE ACRIDONES 307
pass into the acridone when treated with halogens or with sulphur}-! chloride. 1 Schaarschniidt,2 on the other hand, prepares acridones from the o-nitriles of the arylamino- anthraquinones or dianthraquinonylamines, the nitrile group being attached either to the anthraquinone nucleus or to the ar}'l group. Acridone formation takes place on heating with sulphuric acid, and according to Schaarschmidt is not preceded by hydrolysis of the nitrile, as he claims that acridones are formed in excellent yield under conditions under which little or no hydrolysis takes place. Ullmann, on the contrary-, is convinced that acridone formation only takes place subsequent to the hydrolysis of the nitrile to the carbox3-]ic acid, and a lively and somewhat heated polemical discussion has taken place between the two investigators. 3
A further variation consists in condensing an amino- anthraquinone with i.2-naphthoquinone-3-carboxy'lic acid by warming on the water-bath in aqueous solution, and then closing the ring by heating with sulphuric acid ^ :
The yields obtained at both stages are said to be almost quantitative and the method would appear to deserve more attention than it has received. A somewhat more compli- cated variation consists in first preparing an anthraquinonyl isatin, either by condensing a halogen anthraquinone with isatin, or by the action of oxalyl chloride on an ar}-lamino- anthraquinone. The isatin is then converted into the acridone b}- treatment with aluminium chloride, sulphuric acid or alkali ^ :
1 B.A.S.F., D.R.P. 272,296 ; 275,671 ; 283,724.
» A. 405. 95. D.R.P. 269,800.
' B. 49. 735 ; 50, 164. 403. 1356. 1360, 1526.
* Cas., D.R.P. 280,712. 5 By., D.R.P. 286,096.
3o8 ANTHRACENE AND ANTHRAQUINONE
coA^kO
A JCO
In all the above methods the acridone ring is closed through the carbon}^ group. In some cases, however, the ring can be closed through the imino group, although as a rule this method is only of minor importance. Thus aryl anthraquinonyl ketones in which there are amino groups present in the orlho- position to the ketonic carbonyl group both in the aryl group and in the anthraquinonyl residue pass readily into acridones by loss of ammonia, and com- poimds like 2-0-chlorbenzoyl-i-chloranthraquinone pass directly into the acridone when treated with toluene-/)- sulphonamide.i
The purification of the anthraquinone acridones can often be conveniently effected by taking advantage of the fact that the majority of them form almost insoluble salts when treated with sulphuric acid of y8 per cent, strength. 2
By the above methods a very large number of acridones have been prepared, some of them of very complex structure. Starting with 1.5-dichloranthraquinone and condensing this with anthranilic acid, Ullmann and Billig ^ were able to obtain a compound containing two acridone groups (formula I.), but from 1.4-dichloranthraquinone could only obtain a compound containing one anthraquinone ring, and onl}' a monoacridone was obtained from i .4-diaminoanthraquinone and o-chlorbenzoic acid.^ From this it would appear that two carbonyl groups in the ortho- position hinder one another (c/- P- 337) ' but Schaarschmidt ^ claims to have obtained a compound corresponding to formula II by his nitrile method :
1 B.A.S.F., D.R.P. 272,297. a B.A.S.F., D.R.P. 253,090.
« A. 381, I. * M.L.B., D.R.P, 243,586.
» A. 405, 95.
THE ACRIDONES
309
C6H4
\co/
C6H4
CO
•C0\ ■ /CO
\nh/' " "\nh/
I. II.
An acridone containing two anthraquinonyl residues (i.2.5.6-diphthalo3-l acridone) is obtained by oxidising 2 - methyl -1.2'- dianthraquinonylamine, ^ and Scliaar- schmidt 2 has obtained the same substance by his nitrile method :
CH3 — NH
CN
-NH
Both in the patent and in Schaarschmidt's paper this is described as an orange-red vat dye. On the other hand, Eckert and Halla 3 prepared the substance by two methods, viz. (i) by condensing i-aminoanthraquinone-2-carbox5-Hc acid with j8-chloranthraquinone and then causing loss of water, and (2) by condensing 2-brom-3-benzylidene amino- anthraquinone with i-aminoanthraquinone-2-carboxylic acid and then removing the amino group by diazotising and
reducing :
1 B.A.S.F., D.R.P. 192,436.
" M. 35. 755.
A. 405, 95-
310 ANTHRACENE AND ANTHRAQUINONE
NH2 |
||||
COOH CI |
||||
1 |
+ |
' |
-> |
1 |
-NH- -COOH
-NHn \CO/
NH2 COOH
Br
+ PhCH : n]
I
->
^COOH PhCH : N
4-
PliCH : Ni
/NHn ^CO-
/NHn
\co/
They describe the substance as a bluish-violet vat dye, and are therefore at variance with the description of the substance given by the patentees and by Schaarschmidt. In Eckert and Halla's first synthesis the ring might close in two ways, giving either
I
/NH\
\co/
or
\
NH
CO
The second synthesis, however, leaves no doubt that the
THE AC RI DOMES
311
former structure is the correct one. In the patented method two alternatives are also possible :
1 |
|||||
/NH\ |
. /NH |
||||
\co/ |
<- |
^CH. |
|||
1 |
1 |
||||
-»
'NH—
but as the product is dijfferent from that obtained by Eckert and Halla the latter must be the correct one. This con- clusion is supported by the preparation of an acridone by Ullmann ^ by condensing i-chloranthraquinone-2-carboxylic acid with j8-aminoanthraquinone. Here again two alterna- tives are possible :
I
//NH-
\co-
<-
— NH— -COOH
/NH\
•CO/
/
but as the product formed is an orange vat dye it must be concluded that the former structure is correct. It is difhcult to see how Schaarschmidt's product could have any structure other than that which he assigns to it ; but the weight of evidence is against this, and consequently Schaar- schmidt's claims cannot be accepted.
Substituted acridones of the anthraquinone series are usually built from the substituted anthraquinones. Halogen atoms when present in the anthraquinone nucleus are readily replaced b}" arylamino or anthraquinonyl amino groups by heating with primar}^ aromatic amines or amino- anthraquinoues in the usual way, 2 and the same compounds
» B. 47, 553. « UUmann and Billig, A. 381. i. B. 43, 538.
312 ANTHRACENE AND ANTHRAQUINONE
can also be obtained by condensing an aminoacridone with a halogen compoimd.^ Very few sulphonic acids have been described, but in some of them the sulphonic acid group is extremely labile and is easily removed by heating with an organic solvent or by treatment with an acid, alkali; or reducing agent. 2
Tinctorial Properties. — The examination of the tinc- torial properties of the anthraquinone acridones has led to interesting results. In the case of the monophthaloyl acridones, i.e. those acridones in which the heterocyclic ring lies between one anthraquinone ring and one benzene ring, when the imino group is in the j3- position to one of the cyclic carbonyl groups of the anthraquinone nucleus the product is a yellow or orange vat dye, but the shades obtained are very loose to alkali, and there are no data available to say whether the fastness is improved by alkylating the cyclic imino group. When the cyclic imino group is in the a- position the product dyes in very bluish shades of red and the dyeings are fast to alkali. That this change in the tinctorial properties is due to the position of the imino group and not to the position of the carbonyl group was proved by Ullmann,^ who prepared all three isomeric monophthalojd acridones :
I
/NH\
\co/
C6H4
!
Bluish-red.
/CO-
Orange.
C6H4
I
-CO
yC6H4
Brownish-yellow.
Only the first of these (Indanthrene Red BN Extra ^) is fast to alkali, both the others being extremely loose. The formation of a second acridone ring with the imino group in the a- position shifts the colour still more towards the violet end of the spectrum ^ :
1 M.L.B., D.R.P. 239,543. 2 B.A.S.F.. D.R.P. 287.614-5.
8 A. 381. I ; B. 43, 538 ; 47, 553. 748. Cf. Schaarschmidt. A. 405, 95- By., D.R.P. 286,095.
* Caledon Red (Scottish Dyes, Ltd.). * B.A.S.F., D.R.P. 234,977.
THE ACRIDONES
313
CO
C«H
\,
6-^M
\co/
I
\nh/
C6H4
Indanthrene Violet RN Extra. ^
The entrance of halogen atoms into the molecule greatly increases the affinity for the fibre, and at the same time brightens the shade and shifts it towards the red end of the spectrum. 2 Amino and methoxy groups when in the para- position to the cyclic imino group shift the colour towards the violet end of the spectrum, but when in the para- position to the acridone carbonyl group they have the opposite effect, the anthraquinoue acridones thus behaving like the indigoid and thioindigoid dyes.^ The presence of an aryl- amino or anthraquinonyl amino group in the para- position to the cyclic imino group often gives rise to a green or greenish- grey vat dye, 4 and the same result is frequentty obtained by the introduction of an aryl mercapto group. ^
In the case of acridones in which the heterocyclic ring lies between two anthraquinoue ring systems (diphthaloyl acridones), the colour seems to depend very largely on con- stitution, as will be seen from the following formvilae :
/COn
Bluish-violet.*
1 |
\co/ |
1 |
1 |
CO NH |
1 |
Violet.
Orange.'
' Caledon Violet RN Extra (Scottish Dyes, Ltd.). ■ Schaarschmidt, A. 405, 95- B.A.S.F.', D.R.P. 242,063. 3 UUmann, B, 51, g-" Cf. Ullmann. B. 49, 2168. M.L.B.. D.R.P. 239.543 ; 243,586; 256,626.
« B.A.S.F., D.R.P. 263,078. « B.A.S.F., D.R.P. 248,996. • See p. 309, ' Eckert and Halla, M. 35, 755. * Ullmann, B. 47, 553, 562.
314 ANTHRACENE AND ANTHRAQUINONE
/COx.
CO
/NHs
\co/
/CO\
Reddish- brown, *
Reddish-brown. ^
Blue.i
Very little is known of the a7ithraquinone acridines, but Ullmann 2 by heating 2.2'-dihydroxy-i.i'-dianthr34- methane with ammonia obtained a dianthrylacridine which on oxidation passed into the anthraqninone acridine :
/OH H0\
^H?
\ch/ |
I
\ch/
I
This was fotmd to be a red vat dye, but the affinity is very poor.
More complex acridines are said to be obtained when a halogenated fluorenone or phenanthraquinone is con- densed with an aminoanthraquinone and the product then dehydrated. 3
Closelv related to the acridones and acridines are the
^ Schaarschmidt, A. 405, 109. " B. 45, 2259.
3 B.A.S.F., D.R.P. 269,194.
THE XANTHOMES
315
bluish-green vat dyes which are obtained by condensing two molecules of an aminoanthraquinone with one molecule of o-chlorbenzaldehyde.i
II. The Xanthones
The anthraquinone xanthones (phthaloylxanthones) are rather troublesome to prepare, as attempts to condense a halogen anthraquinone with salic34ic acid generally leads to loss of the carbox}d group. Salicylic aldehyde, however, will condense with a-chloranthraquinone and the resulting aldehyde can then be oxidised to the carboxylic acid, the xanthone ring being subsequently closed by treatment with phosphorus pentachloride 2 :
/OCfiH^CHO
O^
HOCO^
/CeHi
/0\
\co/
CfiH^
The method, however, is not a ver^- satisfactory one, as the aldehyde is extremely stable and ver^^ difficult to oxidise. In the above case, for example, the aldehj-de could only be oxidised by boiling it for five hours with chromic acid in a mixture of glacial acetic acid and sidphuric acid.
A more satisfactory method of preparing the xanthones is to condense an anthrol with formaldehyde and then to close the ring by treatment with phosphorus pentachloride. The xanthone is then obtained by subsequent oxidation : 2
/CH2 OH Hq/
1 Kalischer and F. Mayer, B. 49, 1994. F. Mayer and Stein, B. 50, 1306. F. Mayer and Lever, B. 52, 1641. Cas., D.R.P. 280,711.
2 UUmann and Urmenyi, B. 45, 2259.
3i6
ANTHRACENE AND ANTHRAQUINONE
\o/
I
I
The condensation of the anthrol with formaldeh^^de takes place quite readily at 70° in aqueous solution, or in a mixture of acetic acid and alcohol to which a little hydro- chloric acid has been added. Acetaldehyde can be substituted for formaldehyde, the condensation then being best effected in glacial acetic acid solution at 50° in the presence of a little hydrochloric acid. The methyl group is lost when the methyl xanthene is oxidised :
H\ /CH3
\o/
->
yCO^
Benzaldehyde also condenses with jS-anthrol, but in this case subsequent oxidation of the phen^d xanthene leads only to the anthraquinone phenyl xanthene (diphthaloyl phenyl xanthene) :
H
\„/c
6^5
H |
v/ |
CeH |
/^\ . |
||
\o/ |
||
1 |
1 |
The xanthones can also be obtained by condensing an o-chloranthraquinone carbox3-lic acid with a phenol, and then closing the xanthone ring by treatment with phosphorus pentachloride ^ :
1 UUmann, B. 47. 566. B.A.S.F., D.R.P. 251.696.
THE THIOXANTHONES
317
I
OCfiHs COOH
-O
—CO
y^e^H
>C«Ha
The xanthones are of no particular interest. They are usually yellow substances but are devoid of tinctorial properties.
III. The Thioxanthones
The anthraquinone thioxanthones (phthaloyl thioxan- thones) are always obtained from the corresponding sulphide in which a carbox}-! groujD is present in the ortho- position to the sulphur atom. This carbox}d group may be in the anthraquinone ring, in which case the sulphide is prepared either by condensing an o-mercapto anthraquinone carboxylic acid with a halogen compound, or by condensing an 0- halogen anthraquinone carboxylic acid with a mercaptan,i or the carbox}d group may be present in the ar>^l group. In this case the sulphide can be prepared by condensing an anthraquinone mercaptan with an o-halogen carboxylic acid ; but as a rule it is more convenient to condense the halo- gen anthraquinone with thiosalicylic acid. 2
The closing of the thioxanthone ring can usually be effected by heating with concentrated sulphuric acid, but as a rule much better results are obtained by the use of phosphorus pentachloride or toluene sulphochloride.3 Schaar- schmidt ^ has also prepared a number of thioxanthones from the corresponding nitrile by the action of sulphuric acid, and claims that the formation of the thioxan- thone is not preceded by the formation of the carboxylic acid. 5
1 B.A.S.F.. D.R.P. 243,750. Sanders, D.R.P. 253,983. » UUmann. B. 43, 539; 44, 3125. Frey, B. 45. 1361. By., D.R.P, 216,480. B.A.S.F., 234, g";. M.L.B,, D.R.P. 243,587.
3 Ullmann, B. 43, 539; 44, 3125. D.R.P. 238,983. B.A.S.F., D.R.P
243.750-
« A. 409, 59. D.R.P. 269,800.
5 Cf. p. 307.
3i8 ANTHRACENE AND ANTHRAQUINONE
Halogenated thioxanthones are usually best prepared by direct halogenation either before or after closing the thi- oxanthone ring.^ They can be converted into arylamino- and anthraquinonylamino-anthraquinone thioxanthones b}- treatment with a primar}^ aromatic amine or aminoanthra- qmnone.2 Primary amino compounds can be obtained by the nitration and subsequent reduction of the thio- xanthones themselves. 3
Tinctorial Properties. — The thioxanthones of the anthraquinone series are all vat dyes, but it is only those in which the cyclic sulphur atom is attached to the anthra- quinone ring system in the a- position which are of any value.
The relationship between the shades obtained and the constitution of the dye is of interest. It is well known that in the indigoid d5^es the replacement of the C5^clic imino group by a sulphur atom is accompanied b}^ a shifting of the colour towards the red end of the spectrum, and a preciseh^ similar effect is noticeable when the anthraquinone acridones are compared with the corresponding thioxan- thones. The thioxanthones are decidedly less highly coloured than the corresponding acridones and, as a rule, dye in yellow, orange, or red shades. Those compounds in which the siilphur atom is in the a- position are more highly coloured than the isomeric substances in which the sulphur atom is in the j8- position :
/C0\
•CoHj
Yellow.
N:o/
CoHj
Orange.
C.H,:
Vq/
\co/
C6H4
Red.
1 Ullmann, D.R.P. 242,386. B.A.S.F., 258,561. > Ullmann, D.R.P. 242,386. Cf. M.L.B., D.R.P. 231,854 ; 248,996. 3 Schaarschmidt, D.R.P. 250,271-2. Cf. M.L.B.. D.R.P. 243,587 ; 248,469.
THE THIOXANTHONES
319
/
CeHjx^
/COn
CO
/C«H4
\co^
.CO\
\co/
I
Red.
Yellowish-orange.
Reddish-orange.
The entrance of halogen atoms into the molecule renders the shades lighter :
Indanthrene Yellow GN.
Indanthrene Orange GN.
CHAPTER XV THE BENZANTHRONES
Benzanthrones are anthraquinone derivatives in which one carbonyl group has remained intact, whereas the carbon atom of the other carbonyl group forms part of a new benzene ring in which is also involved one of the a-carbon atoms :
CO 9 . 1 o-Benzanthrone.
The chemistry of the benzanthrones has become ex- tremely important during recent years, owing to the ver}- valuable tinctorial properties exhibited by some of the more complex members.
I. Simple Benzanthrones
The discovery of the benzanthrones originated in the observation ^ that only ver>' little anthraquinonequinoline (p3^ridinoanthraquinone) is obtained when j8-aminoanthra- quinone is treated with gtycerine, sulphuric acid and an oxidising agent (Skraup's quinoline synthesis), the main product of the reaction being a compoimd which melts at 251°, and which has the formula CooHnON. The same compound is obtained by treating anthraquinone quinoline with sulphuric acid and glycerine,^ and Bally and Scholl 3
1 B.A.S.F., D.R.P. 171,939- * BaUy, B. 38. 194-
» B. 44, 1656. 320
THE BENZANTHRONES 321
found that anthraquinone itself condenses readily with glycerine in the presence of sulphuric acid to produce a compound (benzanthrone) with the formula C17H10O. In all these cases it is obvious that one of the cyclic carbonyl groups has become involved in the condensation, and as benzanthrone itself on oxidation yields anthraquinone a- carboxy^lic acid, it follows that one of the a-carbon atoms has also become involved in the reaction. The formula given above is the only one which explains these facts.
The formation of benzanthrones by treating an anthra- quinone derivative with glycerine and a dehydrating agent is a very general one, and in addition to anthraquinone itself 1 is also shown by anthraquinone homologues,^ 1.2- benzanthraquinone,3 hydroxyanthraquinones,^ halogen anthraquinones,^ and other anthraquinone derivatives, provided alwa3's that there is a free a- position available. The best yields, however, are usually obtained by reducing the anthraquinone to the corresponding anthraquinol or anthranol.6 Anthracene itself will undergo benzanthrone formation, but in this case it is almost certain that con- densation is preceded by oxidation.' Benzanthrone forma- tion is not limited to the anthraquinone series as a similar type of compound, naphthindenon, is obtained when a- naphthol is treated with glycerine and an oxidising agent. ^ The mechanism of benzanthrone formation has been discussed b}' Bally and Scholl,^ who conclude that the first reaction consists in the formation of an aldol-like condensation product from one molecule of anthranol and one molecule of acrolein, that this then loses a molecule of water, and that the final closing of the ring is brought about by the loss of two atoms of hydrogen. This hydrogen is not, of course, evolved as such, but is utilised in reducing a further quantity of the anthraquinone to the anthranol. This view of the
1 Bally, B. 38. 194. Bally and SchoU, B. 44, 1656. B.A.S.F., D.R.P. 176,018.
2 B.A.S.F., D.R.P. 200.335. 3 B.A.S.F., D.R.P. 181,176. ^ B.A.S.F., D.R.P. 187,495. A. G. Perkin, See. 117, 697.
* B.A.S.F.. D.R.P. 205,294. « B.A.S.F., D.R.P. 176.018. etc.
' B.A.S.F., D.R.P. 176.01^. 8 B.A.S.F., D.R.P. 283.066.
B. 44. 1656.
21
322 AXTHRACEXE AXD ANTHRAQUTNONE
reaction is supported b\- the fact that it has been found impossible to induce benzanthrone formaticni to take place
with both carbonyl groups.
HOCH— CH : CH. HCT
I I
CH C ^ C
CoH^x /C^H^
COH
C^H,
COH
CO
(*
CO
In place of glycerine it is, of comse, possible to mono- or di-chlorhydrin, epichlorhydxin, triacetin,* etc, and Jacob Meyer - has prepared benzanthiones by condensing anthraquinone with ketones of the type R.COCHs.^
In the above method the benzanthr vr :> : :~":r>i by building the benzene ring on to the antli . :.. . . ^ns.
Benzanthrones, however, can also be fon„v i :.-. :.-:z .:p
the anthraqmnone residue, and estremely i: ._ . : ^ ? .-.:s
have been obtained by reactions of this type. Ilie n.r : :: : .i? used for achieving this resott fall broadly into tv : :...js;s viz. methods in which the anthiaqimione ring sys s
completed through the eyclic c..:: :.yl groo^. an.: : .: .is in which the anthraquinc: v : ,: > -: ^ : . is complete . 1:
the other central carbon ..
The first method ons-\.::cA ■.■:. :'::; r:cr.-r.i:: ;:\ ."f :. highly co:-,,". -\-.\i >c:-..- .-:■.:■■.: .--i' :.:::'.:: :/..::.: :v.^ by ios* <ii
two •.■.•.o'.oo'.i'.vS
.oaii.i -aiiiaj>ii:L^y iphthyi-a,8-dio -'- .x,c-yellow vat dye.
\-.
kaurbo^r M. add,* me
R A.S R.
ji^. -»f . i
^54. » DJLP, a47.
f «
c: •
♦
3B5E?
..» ^x
.r^. v^K
-I
•w -*c
irwx
V
•ZLJ^^aci
JsnTT n^A'^ B(^!:: Z3— D^ iy~ ^=l:r
iijLiwc±ii r^
— --rpti-i.rer
ri3F
t^Bif-
-__ i-rr
= «.
= X a za-
322 ANTHRACENE AND ANTHRAQUINONE
reaction is supported by the fact that it has been found impossible to induce benzanthrone formation to take place with both carbonyl groups.
yCH ; Cxi2 HOCH— CH : CH2 HC^
C,H,
CH C
C«H
6-^M
COH COH
In place of glycerine it is, of course, possible to use mono- or di-chlorh^'drin, epichlorhj-drin, triacetin,i etc., and Jacob Meyer 2 has prepared benzanthrones by condensing anthraquinone with ketones of the type R.COCHg.^
In the above method the benzanthrone is formed by building the benzene ring on to the anthraquinone nucleus. Benzanthrones, however, can also be formed by building up the anthraquinone residue, and extremely important results have been obtained by reactions of this type. The methods used for achieving this result fall broadly into two classes, viz. methods in which the anthraquinone ring system is completed through the cyclic carbonyl group, and methods in which the anthraquinone ring system is completed through the other central carbon atom.
The first method originated in the preparation of a highl}' condensed benzanthrone, anthranthrone, by loss of two molecvdes of water from i.i'-dinaphthyl-8.8'-dicarbox>-lic acid, or from i.i'-dinaphthyl-2.8-dicarbox}-lic acid,^ the product being an orange-yellow vat dye.
1 B.A.S.F., D.R.P. 204,354. 2 D.R.P. 247,187.
3 Kalb, B. 47, 1724. Cf. Weitzenbock, M. 39, 307.
THE BENZANTHRONES
323
Schaarschmidt ^ extended the method by showing that allochtysoketone (3.4-benzfluorenone) on fusion with caustic potash gives two monocarboxj^lic acids, one of these by loss of water passing back into allochrysoketone, whereas the other yields benzanthrone :
COOH
COOH
He also found that i-phen3'lnaphthalene-2.3-dicarboxylic acid b}' loss of water gave both allochr>'Soketone carboxylic acid 2 and benzanthrone carbox^-lic acid,^ the latter acid being obtained b}' heating for three hours with sidphuric acid of 91 per cent, strength. In this case the benzanthrone could only have been formed by the series of reactions shown below, i.e. by the opening of the fluorenone ring followed b}- loss of water in another direction :
COOH COOH
COOH
COOH
In confirmation of this vSchaarschmidt showed that the c^'clic imide of i-phenylnaplithalene-2.3-dicarbox}lic acid can be converted into the amide of allochr^-soketone car- box^'lic acid, and that this in turn gives the amide of the benzanthrone carboxylic acid. This method of preparing
1 B. 51, 1082. 2 B. 48. 1827. 3 j3 50, 294 ; 51, 1074.
324 ANTHRACENE AND ANTHRAQUINONE
benzanthrones is not invariabl}^ successful. Thus, starting with the fluorenone derivative (I) Schaarschmidt i en- deavoured to prepare the benzanthrone derivatives (II), but was not successful as the product obtained was the isomeric fluorenone (III) :
Schaarschmidt established the structure of his product by synthesising it by the action of copper powder on 2-ben- zoylanthraquinone-3-diazonium sulphate.
The second method of building up the anthraquinone ring system so as to produce a benzanthrone is due to Scholl,^ and is generally known as " Scholl's peri-method." It has proved of the utmost value in the study of the more complex benzanthrones, as will be seen later. The method is based on the fact that aromatic ketones in which there is at least one pair of free positions in the peri- position to one another evolve hydrogen when heated with anh3^drous aluminium chloride to about 140°, the two carbon atoms in the peri- position to one another becoming imited. Thus, phenyl-i-naphthyl ketone (a-benzoyl naphthalene) gives benzanthrone itself, 0- and _^-tolyl-i-naphthyl ketone give the corresponding methyl benzanthrones, the new bond being shown in the formulae as a dotted line :
CH=
CO CHs CO CO
In the case of m-tolyl-i-naphthyl ketone, two possible isomeis (A^and B) might be formed :
1 B. 51, 1230. • Scholl, A. 394, in ; B. 44. 1656 ; M. 33, i.
THE BENZANTHRONES
325
As the compound obtained is identical with that obtained from 2-methylanthrone by the glycerine method,^ formula A must be the correct one.
Benzanthrone on reduction 2 with sodium hydrosulphite yields dih3^drobenzanthrone (I), which is ver>^ sensitive to oxidation by atmospheric oxy-gen. Further reduction leads to benzanthrene (II or III), and then to dihydrobenzan- threne (IV or V) :
OH
Hp
H
K |
k. Jch |
CH\^CH |
\A CH. |
A/ \ Jch |
CH |
CH |
CH |
||
I |
n |
in |
This last compoimd is identical with the iso-chrysofluorene which Graebe ^ obtained by passing benzyl naphthalene over red-hot pumice.
When benzanthrone is halogenated * by means of molecular or nascent halogen either in aqueous suspension or in the presence of an organic solvent such as acetic acid or nitro- benzene, the halogen atoms first enter the Bz.-ring, the products giving unsubstituted anthraquinone-a-carboxylic acid on oxidation. Halogen atoms in this position are much more reactive than those attached to the anthra- quinone nucleus.
Bertram Meyer, F.P. 407,593 (G.C.I. B.).
- Ballv and Scholl, B. 44, 1656. ' B, 27 953.
' B.A.S.F.. D.R.P. 193.959-
326 ANTHRACENE AND ANTHRAQUINONE
The majority of the benzanthrone dyes are of compHcated structure and are treated elsewhere in this chapter, but orange and brown vat dyes have been claimed as being obtained b}- condensing halogen benzanthrones with primary aromatic amines, or by condensing aminobenzanthrones with halogen compoimds. ^ A black vat dye of uiiknown structure is said to be obtained when nitrobenzanthrone is fused with caustic potash. 2 It is probably a violanthrone derivative.
The benzanthrones yield highly coloured solutions when dissolved in concentrated sulphuric acid, although they are precipitated unchanged on the addition of water. From benzanthrone itself, however, a cr^^stalline ferrichloride, stannichloride and platinichloride can be obtained, and other benzanthrones form similar compoxmds.^ In these the metal chloride is probably loosely joined to the carbonyl ox3'gen atom, and their formation is not surprising as similar double compounds are formed by other ketones. Thus, benzophenone and fluorenone both form nitrates b}^ union with one molecule of nitric acid, and fluorenone also forms a trichloracetate. Both of them, and also acetophenone, form salts with metal halides such as stannic chloride and mercuric chloride, ^ and the union of ketones with aluminium chloride is well known. ^ Phenanthraquinone, benzil and other ketones exhibit the same tendency to form addition compounds with metal chlorides ^ and perchloric acid,"^ but in anthraquinone and its derivatives this tendenc}' is not so well marked. Thus, neither anthraquinone nor alizarin forms a perchlorate, although the former unites with two molecules of antimony pentachloride. It is not known whether the benzanthrones form perchlorates or not, but it is extremely probable that they would, and as the ketone perchlorates are usuallj- well crv^stallised and sparingly soluble substances, they would probably furnish a useful means of purifying the benzanthrones.
The hydroxybenzanthrones have been but little studied
1 By., D.R.P. 200,014. 2 G.C.I.B., D.R.P. 262,478.
■• A. G. Perkiu, See. 117, 696. « Kurt Meyer. B. 43, 157-
* See p. 130. « Kurt Meyer, B. 41, 2568.
' K. A. Hofmann and Metzler, B. 43, 178.
THE BENZANTHRONES 327
up to the present. The dihydroxybenzanthrone (beiizalizarin) obtained from alizarin has been prepared by Perkin.^ who finds that both hydroxys] groups can easily be methylated by treatment with methyl iodide and caustic potash. Con- sequently benzalizariu is probabl}' 7.8-dihydrox>^-i.9-benz- anthrone :
Curiously enough its tinctorial properties are very similar to those of alizarin, and a more detailed stud}^ of the hydroxy benzanthrones would probably lead to valuable information as regards the constitution of the hydroxy ketone dyestuffs.
II. The C0MPI.EX Benzanthrones
The complex benzanthrones can be broadly divided into two classes, viz. derivatives of per}dene and derivatives of pyrene. The former class comprises violanthrones, /so- violan- thrones, cyanthrones, and helianthrones, whereas the latter class comprises the p5^ranthrones. * In the following formulae the characteristic ring system is shown by heavy lines. 2
CO
Violanihrone \y iso-Violanihrone
» Soc. 117. 696.
* In the literature these compounds are almost invariably given names terminating in -ene, e.g. violanthrene, pyranthrene, etc. In the following pages the termination -one has been adopted to denote their ketonic structure the termination -ene being reserved for the parent hydrocarbon which can usually be obtained by reduction. This nomenclature is merely an extension of the system proposed by Scholl in connection with the helian- thrones, and in all cases where confusion seems likely to arise a footnote has been added. The same system has been adopted when deaHng with the indanthrones (indanthrenes), the change in this case being particularly advisable owng to Indanthrene being a registered trade name.
328 ANTHRACENE AND ANTHRAQUINONE CO co-
co
Heliani-hrone
CO Pyranihrone^
The hydrocarbons, per34ene and pyrene, themselves have been studied by SchoU. The former he obtained by heating naphthalene, or better i.i'-dinaphthyl, with anh5^drous aluminium chloride, i The latter has, of course, been known for many j^ears, but has also been investigated b}' Scholl, who has pointed out that in the case of condensed hydrocarbons which are readily oxidised to a quinone, the hydrogen atoms which are attacked during quinone formation are always those which are split out when the hydrocarbon undergoes a Friedel-Crafts reaction. On this basis, and with regard to the structure of the mono-, di-, and tri-benzoyl derivatives formed by the action of benzoyl chloride in the presence of aluminium chloride, ^ he concludes that pyrene quinone must have formula I or II, and not formula III, as proposed by Bamberger, ^ and as usually given in the literature :
By oxidising dibenzo3'l pyrene Scholl obtained what he thought was probably impure pyrene quinone, and there- fore he gives preference to formula I. Goldschmidt,* on the other hand, gives preference to formula II.
1 B. 43, 2202.
» A. 240, 158.
2 See p. 337. * A. 351, 230.
THE BENZANTHRONES 329
Vioi^ANTHRONES. — When benzanthrone is fused with caustic potash ^ a dark blue vat dye is obtained which was originally given the trade name of Violanthrene BS, this being subsequently altered to Indanthrene Dark Blue BO (Caledou Dark Blue B).2 The constitution of the dye was definitely proved by Scholl,^ who synthesised it by his peri- method by heating 4. 4'-dibenzoyl-i.i'-dinaphthyl with aluminium cliloride, three pairs of peri- positions becoming united as shown by the dotted lines in the following formula :
The formation of violanthrone by fusing benzanthrone obviously consists in the linking up of two molecules by the union of two pairs of carbon atoms as indicated by the dotted lines (formula I, page 330) . Such reactions are not un- common, and the appended formulae illustrate cases in which they have been observed, although several of the substances obtained have not 3'et been submitted to scientific examina- tion, so that the structure assigned to them is more or less guesswork. The substance represented by formula V is a green dye, whereas that represented by IV gives only bordeaux shades. From this it is probable that in V union has taken place at three points, the extra bond being denoted by the line of crosses. In VI it is probable that imion at either two or four points can take place, as when the fusion is carried out at 220-300° a reddish-brown dye (dotted bonds only) is obtained, whereas the dye obtained at higher temperatures is greyish-blue (dotted bonds and cross bonds).
1 B.A.S.F., D.R.P. 185,221; 188,193; 290,079. A. G. Perkin, E.P. 126,765 (1918).
- Scottish Dyes, Ltd. s B. 43, 2208.
330 ANTHRACENE AND ANTHRAQUINONE
BeMzonthrone,
cof\co
n
Naphihinolenon.
m
Naphihindandion. CO— c
IV
YI
A violantlirone is also obtained when the benzanthrone prepared from 1.2-beuzanthraquinone is fused with caustic alkali. It dyes in rather greener shades than violanthrone itself. Its structure, how^ever, is doubtful, as 1.2-benzanthra- quinone might form three isomeric benzanthrones.6
Nitration of violanthrone '^ yields a green vat dj-e, which was formerly known as Viridanthrene B, although the name was subsequentl}- altered to Indanthrene Green B (Caledon Green B).^ It is rather remarkable that a nitro compound should be capable of being used as a vat dye
1 Errera. G. (1911), 190- B.A.S.F., D.R.P. 283,066. - B.A.S.F., D.R.P. 283,365.
3 Karclos, D.R.P. 276,357-8; 276,956; 286,098. B.A.S.F., D.R.P. 280,880.
* Kardos, D.R.P. 275,220 ; 278,660; 280,8^9; 282,711; 284,210.
3 Kardos, D.R.P. 286,468. Cf. Graebe, A. 276, 17.
« B.A.S.F., D.R.P. 185,223.
' B.A.S.F., D.R.P. 1S5.222 ; 226,215.
« Scottish Dyes, Ltd.
THE BENZANTHRONES 331
without the nitro group being reduced. From nitroviolau- throne the corresponding amino- compound can be prepared, and this can be alkylated, arj^lated, or combined with alde- hydes. These amino compounds dye in rather greener shades than violanthrone itself, but are of no technical value. 1
When violanthrone is oxidised, e.g. with sulphuric acid and boric acid, a product is formed which has very feeble tinctorial properties. B}^ heating this with a condensing agent such as boric acid at 160°, however, it is converted into a powerful green dj^e, the tinctorial properties of which are improved by bromination, although the shade becomes somewhat yellower. 2 Violanthrone itself can be halogenated,^ the halogenated product being placed on the market as Indanthrene Violet RT.
zso-Vioi,ANTHRONES. — z'so- Violauthrouc is isomeric with violanthrone, and is obtained when brombenzanthrone is fused with caustic akali.* The patentees assigned to it formula I, but Scholl regards it as a per^-lene derivative and prefers formula II.
I II
Scholl 5 endeavoured to confirm his formula by effecting a synthesis of the dyestuff from dibenzoyl perjlene by his peri- method, thus :
» B.A.S.F., D.R.P. 267,418 ; 268,224 ; 284,700. - B.A.S.F., D.R.P. 259,370 ; 260.020 ; 280,710. =• B.A.S.F., D.R.P. 177.574. * B.A.S.F.. D.R.P. 194,252. ^ B. 43, 2208.
332 ANTHRACENE AND ANTHRAQUINONE
The synthesis, however, was not successful, and probably the carbonyl groups in dibenzoyl perylene are not in the positions in which they are shown in the above formula. iso-Violanthrone itself is a powerful vat dye, and was formerly known as Violanthrene R Extra, this being subse- quently changed to Indanthrene Violet R Extra (Caledon Brilliant Purple R).i Its dichlor derivative is Indanthrene Violet RR Extra (Caldeon Brilliant Purple RR) ^ and its dibrom derivative Indanthrene Violet R Extra. 2 Its nitro derivative is of no value. ^
Cyanthrones. — These are complex quinoline derivatives of benzanthrone, and have been but little investigated. Benzanthrone quinoline itself (3(N).4-pyridino-i.9-benzan- throne) is obtained from jS-aminoanthraquinone by Skraup's method, both quinoline and benzanthrone formation taking place simultaneously. 4 When fused with caustic potash it gives a vat dye, Indanthrene Dark Blue BT (formerly Cyanthrene). This has not been scientifically investigated, but is probably formed by the union of two molecules as shown by the dotted lines : ^
Its halosfen derivatives have also been described. ^
■'a
1 Scottish Dyes, Ltd. - B.A.S.F.. D.R.P. 217.570.
^ B.A.S.F., D.R.P. 234,749. * B.A.S.F., D.R.P. 171,939-
5 Baely, B. 38, 196. B.A.S.F.. 172,609. « B.A.S.F., D.R.P. 177.574-
THE BEN Z ANT H RONES 333
A much more simple benzanthrone quinoline is obtained by condensing i?2:.-chlorbenzanthrone with a-aminoanthra- quinone and then fusing the benzanthronyl-a-aminoanthra- quinone with caustic potash. Apparently the alkali causes closing of the quinoline ring as shown by the dotted line.i The product is a green vat dye, although it is not used commercially :
Hewanthrones. — When i.i'-dianthraquinonyl is re- duced, preferably by means of copper bronze and concen- trated sulphuric acid at 40-50°, ring formation takes place b}'- union of two ws-carbon atoms. The product is ms- benzdianthrone or helianthrone, a yellow vat dye, which, however, has not found technical application : 2
CO
Helianthrone.
By the same method Scholl has prepared dihydrox}- and tetrahydroxy derivatives. ^
It will be observed that in helianthrone there is a pair of carbon atoms in the peri- position to one another, so that a new ring, as indicated b}- the dotted line, should be fonned by heating with aluminium chloride :
1 B.A.S.F., D.R.P. 2i2,47T[.
2 Scholl. B. 43, 1734. D.R.P. 190,799; 197.933- Q- Eckert and Tomaschek, M. 39, 839.
' B. 44, io9i.'j'C>. Seer, M. 34, 631.
334 ANTHRACENE AND ANTHRAQUINONE
CO
JMS-Naphthadianthrone.
This Scholl has found to be the case, and he has also prepared the same compound by distilling dianthraquinonyl with zinc dust.i Meyer, Bondj^ and Eckert 2 claim that it is more readil}' obtained by exposing glacial acetic acid solutions of dianthrone to sunlight or iiltra-violet light, but their observa- tions require independent confirmation as they deduce the formula from four analyses in which values obtained for carbon var}^ from 87*8 to 887 per cent., and those for hydro- gen from 3*2 to 3*8 per cent. 3 In a later paper, however, Eckert and Tomaschek ^ describe several halogen derivatives which the}' have obtained by similar means. ws-Naph- thadianthrone acts as an orange vat dye, although reduction to the vat is very difficult.
The reduction products of helianthrone itself have been investigated b}^ Potschiwauscheg,^ who obtained three products :
H OH
H OH
H OH
H OH
The first of these he was only able to isolate in the form of its diacetate. He was unable to obtain the parent hydro- carbon.
Attention may here be drawn to a series of olive and brown vat dyes of miknown constitution which are obtained by
B. 52, 1829.
2 M. 33, 1451. M. 39. 839.
3 C.,,Hi Oj, requires C = 88 -4/11 = ' B. 43, 1746,
=3-16.
THE BEN Z ANT H RONES 335
the action of concentrated sulphuric acid and copper powder on anthraquinone derivatives. ^ The}- are probably helian- throne derivatives, although their structure has never been investigated. The brown and bronze vat dyes which are obtained from 1.2-benzanthraquinone, dianthrone and di- anthrol by heating with aluminium chloride are also probably helianthrones.2
Pyranthrones. — When 2.2'-dimethyl-i.i'-dianthraquin- onyl is heated alone at 380°, or with zinc chloride at 280°, or, better, with alcoholic caustic potash at 145°, a very fast orange vat dye is obtained, ^ which was formerly known as Pyranthrene, but was later named Indanthrene Golden Orange G. The dichlor derivative (Indanthrene Golden Orange R) and the dibrom derivative (Indanthrene Scarlet G) dye in redder shades and can be obtained either by halogen- ating pyranthrone, or, syntheticall}-, from the corresponding halogen dimethyldianthraquinony 1 . '
Pyranthrone formation also takes place when i.i'- dianthraquinonyl-2.2'-dialdehyde is reduced, e.g. with sodium h3'drosulpliite and the /gz<co-product thus formed then oxidised,^ and advantage has been taken of this reaction in printing, the pattern being printed on to the cloth with the aldehyde and the colour then developed in a h3-dro- sulphite bath followed by oxidation. The corresponding dianthraquinonyl diketones also yield pyranthrones on reduction, e.g. 2. 2 '-dibenzoyl-i.i '-dianthraquinonyl gives diphen3'lpyranthrone.6 These diar}-lpyranthrones are yeUow vat dyes, and Scholl has found that alkyl groups also decrease the colour.'^ The structure of p3-ranthrone was definitely established by Scholl b}' sj-nthesis by his peri- method, but as Scholl used the same methods for preparing some highly complex pyranthrones it will be best to postpone the discussion of the synthesis from pyrene, and first consider
1 B.A.S.F.. D.R.P. 190,656. By., D.R.P. 203.436; 205,442.
2 E., D.R.P. 237,751 ; 241,631.
^ SchoU, B. 43, 346, 5t2 ; 44, 1448, 1662 ; M. 32, 687. B.A.S.F.. D.R.P. 174.494; 175.067; 212,019; 287,270.
* Scholl, B. 43, 352; M. 39. 231. B.A.S.F., D.R.P. 186,596 ; 211,927 ; 218,162. ■ ' B.A.S.F.. D.R.P. 238.980.
« B.A.S.F.. D.R.P. 278.424. ^ M. 32, 687.
336 ANTHRACENE AND ANTHRAQUINONE
the mechanism of p^-ranthione formation from2.2'-dimeth3-l- i.i'-dianthraquinonyl.
At first sight it would seem probable that pyranthrone formation was preceded by a wandering of hydrogen atoms to the neighbouring cyclic carbonyl groups with the forma- tion of an aldol-like product, pyranthrone formation taking place by subsequent loss of water :
If this were the case, the corresponding diethyl and di-«- propyl dianthraquinonyls should behave in exactly the same way, giving rise to dimethyl and diethyl pyranthrone. In the case of di-zso-propyldianthraquinonyl there is no reason why the first of the above steps should not take place, but the aldol-like product could not pass into a pyran- throne b}" loss of water owing to the necessary hydrogen being absent. SchoU i has examined the behaviour of all three substances, and finds that diethyl and di-/so-propyl dianthraquinonyl both give pyranthrones, although not nearly so readily as dimethyldianthraquinonyl. In the case of 2.2'-di-iso-propyl-i.i'-dianthraquinonyl, however, no reaction whatsoever took place, although it was to be expected that the aldol-like substance would be obtained. It is therefore very probable that pyranthrone formation is a direct loss of water and is not preceded by a migration of hydrogen atoms. The dimethyl and diethyl pyranthrones which Scholl obtained are ven^ similar to pyranthrone itself in their tinctorial properties although they give paler shades.
The synthesis of pyranthrone and of many ver}- complex
pyranthrone derivatives has been achieved by Scholl 2
by means of his peri- method. Starting with pyrene he
first condensed it with benzoyl chloride in the presence of
1 M. 32, 687. = A. 394, III ; M. 33, I. D.R.P. 239,671.
THE BENZANTHRONES
337
aluminium cliloride, and in this wa}- obtained mono-, di-, and tribenzoyl pyrene. From dibenzoyl pyrene by heating with aluminium chloride he obtained pyranthrone (I), whereas the tribenzoyl derivative gave benzoyl pyran- throne (II) :
In benzoyl pyranthrone it will be noticed that there is still a pair of carbon atoms in the peri- position to one another. It was foimd impossible, however, to cause these to unite, and it seems to be a general rule that in the case of six-membered rings peri- condensation cannot take place twice at the same side of the p3'rene nucleus. This is probably to be attributed to steric influences, for, as will be seen below, in the case of five-membered rings such double peri- condensation is possible.
By condensing a-naphthoyl chloride and j3-naphthoyl chloride with pyrene Scholl obtained dinaphthoyl pyrenes, which when heated with aluminium chloride passed into complex pyranthrones (III and IV) :
in IV
In the case of di-a-naphthoyl pyrene, pyranthrone formation can only take place as indicated by formula III. In the case of di-/3-uaphtho}l pyrene, however, pyranthrone
22
338 ANTHRACENE AND ANTHRAQUINONE
formation might take place through the a-carbon atoms of the naphthalene nuclei, as indicated in formula IV, or it might possibly take place through the j8-carbon atoms. The a-carbon atoms, however, are always the most reactive, and it has been shown definitely in the case of phenyl naphthyl ketone that the a-carbon atom is capable of undergoing peri- condensation, 1 and also that in the case of jS-anthraquinonyl- a-naphthyl ketone it is the a-carbon atom which reacts. 2 Hence, in the absence of all evidence to the contrary, formula IV must be accepted as representing what actually takes place.
Scholl has also employed his peri- method for building up complex pyranthrones containing five-membered hetero- cyclic rings. He first showed that a-thienyl-i -naphthyl ketone gives a condensation product (V) when heated with aluminium chloride, and that a-furyl-i -naphthyl ketone behaves in the same way (VI), although in this latter case he was unable to isolate the product in the pure condition :
S CO 0 CO
V VJ
By condensing two molecules of a-thienylcarbonyl chloride with one molecule of pyrene, Scholl obtained two ketones, both of which when heated with aluminium chloride underwent condensation (VII and VIII) :
^ See p. 324. * See p. 156.
THE BENZANTHRONES
339
It will thus be seen that in the case of five-membered rings a double peri- condensation at the same side of the pyrene nucleus is possible.
As regards the tinctorial properties of these complex pyranthrones, the pyranthrones derived from both naphthoyl pyrenes dye in redder shades than pyranthrone itself, this being particularly noticeable in the case of the j3- compound (formula IV, page 337). Both thiophene pyranthrones are brown vat dyes, but the one represented by formtda VII is the most powerful.
Pyranthrone itself on reduction in alkaline solution gives onl}' a purple red vat, and in this way differs from many of the other complex anthraquinonoid vat dyes, such as indan- throne and flavanthrone, which are capable of giving two different vats. The pyranthrone vat is verj- unstable towards atmospheric 0X3'gen, and Scholl 1 was only able to isolate it in the form of its brombenzoyl derivative, which he found to correspond to formula IX. Further reduction leads to the parent h5-drocarbon, pyranthrene, which is represented by formula X :
X
Brown and green dyes can be obtained b}- the nitration and reduction of pyranthrone. 2
1 B. 43, 346. " Scholl, B. 43, 346. By., D.R.P. 220,580. B.A.S.F., D.R.P. 268,504.
CHAPTER XVI
THE CYCLIC AZINES AND-HYDRO-
AZINES
The C}'clic azines and hydroazines of the authraquinone series can be conveniently divided into two groups, viz. mixed compounds in which only one authraquinone ring S3^stem is present, and simple compounds in which the azine ring lies between two authraquinone residues. Of these two groups the latter has been studied most fully, as some extremely important vat dyes have been foimd to be simple authra- quinone h^'droazines.
I. The Mixed Azines and Hydroazines
Mixed azines are obtained by condensing an o-diamino- anthraquinone with an a-diketone. The simplest azine obtainable by this method is the pyrazino- compound (I), which is formed b}' condensing 1.2-diaminoanthraquinone with ethyl oxalate. ^ vSomewhat more complicated are the blue-black vat dyes which are obtained b}" condensing two molecules of an o-diamino authraquinone with one molecule of glyoxylic acid by boiling in glacial acetic acid solution, or in alcoholic solution in the presence of a little stdphuric acid. 2 Their structure probably corresponds to formula II ;
N N NH '
^COH N
1 Ertl. M. 35, 1427. Scholl, B, 44. 1729. Terres, B. 46, 1644. ^ G.E., D.R.P. 264.043.
340
THE CYCLIC AZINES AND HYDROAZINES 341
The first of these compounds is of some mterest, as it is also obtained by the oxidation of indanthrone.
Mixed azines have been obtained by condensing both i.2-dianiinoanthraquiiione and 2.3-diaminoanthraquinone with a large number of a-diketonic compounds such as benzil, phenanthraquinone, ^-naphthaquinone and isatin.^ With the latter substance under certain conditions 3-enow and red vat dyes are obtained the structure of which is quite uncertain, as, unlike other azines, they give almost colourless vats. 2
The azines obtahied from 1.2-diaminoanthraquinone are, of course, angular in structure, whereas those obtained from 2.3-diaminoanthraquinone must be linear. The former on reduction in alkaline solution give blue vats, whereas the latter give brown solutions. As the azines obtained from 1.2.3-triaminoanthraquinone give brown solutions on alkaline reduction it is probable that they are linear in structure and that the free amino group is in the a- position. ^
N-Substituted cyclic hydroazines are said to be obtained by condensing o-aminoar3'lamino anthraquinones with aldehydes and ketones, and it has been claimed that their sulphonic acids are blue wool dyes.^ o-Aminoazo- com- pounds are also said to yield cyclic azines under certain conditions. 5
Of greater importance is the cyclic azine sjmthesis devised by Ullmann.6 He found that when an o-nitrophenyl-i- amino-anthraquinone is reduced with sodium hydrosulphite the corresponding primar}- amino- compound is formed, but that if the reduction is brought about b}^ means of sodium sulphide an almost quantitative ^-ield of the C3'clic h3-dro- azine is obtained. The mechanism of this reaction consists, no doubt, primarily in the production of a hydrox^-lamine derivative, the azine ring being then closed b}' loss of a mole- cule of water :
» Scholl, M. 32. 1043. SchoU and Kacer. B. 37, 4531. Terres, B. 46, 1634. By., D.R.P. 170,565. » Bv., D.R.P. 251,956.
=» Scholl, M. 32, 1043. « By., D.R.P. 184,391 ; 252,529.
* M.L.B., D.R.P. 230,005 ; 232,526. « A. 380, 324.
342 ANTHRACENE AND ANTHRAQUINONE
NH
A somewhat similar synthesis has been devised by Ull- mann and Medenwald ^ who obtain azines by oxidising o- aminoatyl aminoanthraquinones with lead dioxide.
The hydroazines are blue substances which are capable of use as vat dyes although the mixed hydroazines are of no technical value. The imino hydrogen atoms cannot be replaced by acet}^ groups, ^ all attempts at acetylation lead- ing to the diacetate of the anthraquinol derivative owing to the cyclic carbonyl groups of one molecule becoming reduced at the expense of the imino hydrogen atoms of another molecule. On oxidation the hj'droazines pass into the corresponding azine. These are yellow compounds and are much more stable than the h3'droazines. As will be seen later, this is the reverse of what is found to be true in the case of the simple azines and hydroazines.
II. The Simple Azines and Hydroazines
Simple azines and hydroazines (indanthrones *) can be obtained by methods ver\^ similar to those employed for the production of the mixed compounds. Thus simple cyclic azines or hydroazines are obtained when o-diamino-
1 B. 46, 1809. 2 Ullmann, A. 380, 324.
* The first cyclic azine of the anthraquinone series to be prepared was trans, iz'sawg.-anthraquinonedihydro azine. This wa's placed on the market under the name Indanthrene Blue, and the name " indanthrene " has come into general use in the literature. The word " indanthrene," however, is a registered trade name (B.A.S.F.) and is applied to many vat dyes which are not azines. Indanthrene Blue is an anthraquinone deriva- tive and ketonic in structure, and in order to denote its ketonic nature the name should terminate in -one. In the following pages, therefore, the word " indanthrone" is used to denote the ketonic hydroazine, indanthrene (without a capital) being used for the parent, oxygen free hydroazine (trans. bisaiTg. -dihydroa.nthra.zine). Where " Indanthrene " is used as a registered trade name it is spelt with a capital. This system of nomen- clature should not lead to any confusion as the dihydroanthrazine is of very little importance. Where any confusion seems possible a footnote has been added.
THE CYCLIC AZINES AND HYDROAZINES 343
anthraquinones are condensed with o-dihydroxyanthra- quinones such as aHzarin, best by heating with boric acid and a solvent of high boiling point, 1 or with 1.2-anthra- quinone.2 In the latter case, of course, the product is an anthracene anthraquinone azine {trans, i^'saw^.-anthroanthra- quinone azine), but the anthracene residue is readily oxidised to the quinone. Cyclic azines are also obtained by oxidising o-aminodianthraquinonylamines by heating alone in the air, or by heating with a nitro- compound, oleum or sulphuric acid and manganese dioxide. -"^ The o-nitrodianthraquinonyl- amines also give C3^c]ic hydroazines on reduction with sodium sulphide, although in this case it is necessan,- to csiTTy out the reduction b}- fusion with cr3'Stallised sodium sulphide, as treatment with aqueous solution leads onl}- to brown substances of imknown constitution.* Better results are usually obtained b}' reducing 02-dinitrodianthraquinonyl- amines with stannous chloride and hydrochloric acid in acetic acid solution, one nitro group being split out.^ This method is of very general application for the preparation of azines and b}' it phenazine itself can be obtained in excellent yield from 02"dinitrodiphenylamine.<^
From a practical point of view by far the most important method of obtaining the indanthrones is by fusing the jS-aminoanthraquinones with caustic alkali, and this method has been ver>' widel}^ applied not only to ^-aminoanthra- quinone itself, '^ but also to diaminoanthraquinones ^ and j3-aminoanthraquinone sulphonic acids, ^ although in the latter case the sulphonic acid group is often lost. Even j8-anthramine is said to yield a cyclic hydroazine (anthr azine) when fused with caustic alkali, ^o The anthraquinonyl-j8- hydrox^'lamines, however, do not give cyclic azines. '^
1 By., D.R.P. 178,130. - Terres, B. 46, 1634.
' B.A.S.F., D.R.p! 186,465. By., D.R.P. 239,211. * By., D.R.P. 178,129; 213,501. •'• Eckcrt and Steiner, '^\. 35, 1120.
« Eckt-rt, M. 35, 1153. Cf. also B. 38, 2975 ; Soc. 95, 577- " Scholl, B. 36, 3427. B.A.S.F.. D.R.P. 129,845 ; 135,407-8; 287,270. » B.A.S.F., D.R.P. 157.685 9 B.A.S.F., D.R.P. 129.846. «» By., D.R.P. 172,684. Cf. B. 34. 3410. " M. 32. 1035
344 ANTHRACENE AND ANTHRAQUINONE
The mechanism of the conversion of j3-aminoauthra- quinone into indanthrone is not understood. At one time it was thought probable that the first product formed was a h3^drazo compound, and that this then underwent an ortho-sermdine rearrangement. This, however, can hardly be the case, as it has been found that no indanthrone is formed when j8-azox3^anthraquinone is reduced. It is possible that one molecule of the j3-aminoanthraquinone reacts in the ^-quinonoid form and then adds on another molecule reacting in the ordinarj^ form, the azine ring being completed by a second condensation of a similar nature :
K OH
H OH
Theories of this nature, however, are merely speculative and lack experimental verification.
In the alkali melt of jS-aminoanthraquinone the ind- anthrone is not present as such but as its reduction product (vat), from which, however, the indanthrone is readrl}- obtained by blowing air through the aqueous solution. Also in addition to indanthrone, flavanthrone (pages 300- 304) is formed, and when the melt is carried out with caustic alkali alone the reduction products of indanthrone and flavanthrone are produced in the ratio of about two to one. If a reducing agent is added to the alkali, indanthrone forma-
THE CYCLIC AZINES AND HYDROAZINES 345
tion is greatly hindered, and the reduction product (vat) of flavanthrone is then ahnost exclusively produced.^ If, on the other hand, the melt is carried out in the presence of an oxidising agent such as potassium nitrate or chlorate, 2 flavanthrone formation is prevented and only indanthrone is obtained. In this case, of course, it is the dye itself and not its vat which is produced. On this observation has been based a series of patents ^ claiming the production of indanthrone by oxidising ^-aminoanthraquinone with lead dioxide, manganese dioxide, chromic acid, nitric acid, etc., although these methods are of no practical importance.
Indanthrones can also be obtained from a-aminoanthra- quiuones by treatmg them with halogens,* or bj' fusing them with caustic alkali in the presence of a phenol or naphthol,5 or by heating them with acids or metallic salts such as chromium sulphate or copper sulphate. ^ The yields, however, are usuall}- ver^- poor although the last method has been extended to the preparation of complex indanthrones from aminobenzanthrones and amino- benzanthrone quinolines.'^
Another method of obtaining indanthrones, and one which has been of value in proving their structure and in preparing N-substituted indanthrones, consists in splitting out two molecules of halogen acid from two molecules of an o-amino halogen anthraquinone. Thus indanthrone itself is obtained when i-amino-2-bromanthraquinone is heated in some indifferent solvent of high boiling point with anhydrous sodium acetate and either cuprous chloride or copper powder ^ :
1 B.A.S.F., D.R.P. 135,408.
- Morton, Dandridgc, and Morton Sundour Fabrics, Ltd., E.P. 126,112 (1918). In spite of this A. G. Perkin claims in E.P. 126,764 (1918) that the \-ield and purity of the indanthrone is improved by carrying out the alkali hision in the presence of sucrose, glucose, lactose, or the like.
3 B.A.S.F., D.R.P. 139.633 ; 141.355 : 238,979.
* By., D.R.P. 161,923.
^ By.. D.R.P. 175,626.
« B.A.S.F., D.R.P. 186,636-7; 238,979.
' B.A.S.F., D.R.P. 198,507; 204,905; 210,565.
» By., D.R.P. I5«.287; 193.121.
346 ANTHRACENE AND ANTHRAQUINONE
CO CO
For the extension of this method to the preparation of indanthrone derivatives the reader is referred to the original literature.!
The cyclic hydroazines or indanthrones are blue com- pounds which act as powerful vat dyes. They are fairly easily oxidised to the yellow azines, but these are verj^ stable substances and strongh^ resist further oxidation although the}^ are readily reduced to the cyclic hydroazine. The most important member of the series is indanthrone itself (Indanthrene Blue R) , and as this has been uivestigated in detail it wUl be described at some length, as it serves as a general type.
In spite of the numerous methods which have been proposed for the manufacture of indanthrone, the onl}' one which is of any practical importance consists in fusing j3-aminoanthraquinone with caustic alkah.2 The dye itself forms an insoluble blue powder which usuallj' occurs in commerce in the form of a 20 per cent, paste.
Indanthrone is rather easily oxidised to the yellow azine, so that material dyed with Indanthrene Blue R is apt to become slightly 3^ellow on washing, although the original blue shade can be restored by treatment with a mild reducing agent. The oxidation to the azme is best carried out in the laborator^^ b}' means of nitric acid, a bimolecular product in which the two molecules are joined through the nitrogen atoms being formed as an intermediate product. ^ The azine itself is yellow and is much more stable than the hydroazine, the simple anthraquinone azines in this respect
1 Ullmann, A. 399, 341. By., D.R.P. 158,287; 158,474; 167,255; 193. 121.
" For laboratory details see SchoU, B. 36, 3427. 3 Scholl, B. 36. 3431 ; 40. 320.
THE CYCLIC AZINES AND HYDROAZINES 347
differing from the mixed azines. So stable in fact is the azine obtained from indanthrone that Scholl 1 was only- able to oxidise it by boiling it for forty hours with chromic acid in glacial acetic acid solution. Under these conditions it passes into the pyrazinoanthraquinone mentioned on
P- 340.
Indanthrone itself is a very feeble base and its salts even with strong acids are very readily decomposed. For a long time it was believed that the imino-hydrogen atoms could not be replaced by acyl groups, as treatment with acyl chlorides alwa3-s lead to the entrance of halogen atoms into the molecule with simultaneous reduction and ac^dation of the cyclic carbonyl groups. 2 In this way indanthrone resembles indigo,-^ benzoquinone,^ chloranil,^ and the oxazines and thiazines,^ but Scholl ^ succeeded in preparing a dibenzoyl indanthrone by boiling indanthrone for a few minutes with a great excess (70 parts) of benzoyl chloride. This derivative must have been N-dibenzoyl indanthrone, as on h3^drolysis indanthrone itself and not its reduction product was obtained. It was found to be a stable red substance, so that indanthrone, like indigo, changes from blue to red on acylation, both diacetyl indigo ^ and dibenzoyl indigo being red.
The behaviour of indanthrone on reduction has been carefully investigated by Scholl and his students. When the reduction is carried out b}^ means of sodium hydro- sulphite in alkaline solution, first a blue vat and then a brown vat is obtained, both being ver}- readil}' oxidised by the air and thereby being changed back to indanthrone. The blue vat consists of the sodium salt of anthraquinolanthra- quinone dihydroazine (formula I) and tmder the name Indanthrone Blue RS ^ has been used in printing. ^^ Scholl.
* B. 44, 1727.
- Scholl and Berblinger, B. 40, 395. B.A.S.F., D.R.P. 229,166. ^ Heller, B. 36, 2762.
* Buchka, B. 14, 1327. - Sarauw, A. 209, 129. ' Graebe, A. 146, 12.
* Scholl, B. 40, 399. Private communication from Bernthsen.
" B. 44, 1732. '^ Liebermann and Dickhuth, B. 24, 4133.
» Caledon Blue R (Scottish Dyes, Ltd.). i" B.A.S.F., D.R.P. 129,848.
348 ANTHRACENE AND ANTHRAQUINONE
Steinkopf and Kabacznik i have prepared the dibenzoyl derivative, and Scholl and Stegmuller 2 have shown that if the sodium salt is heated to 220°-230° with concentrated caustic soda, or if it is heated alone at 250° in an indifferent atmosphere, auto-oxidation and reduction takes place with the production of a mixture of anthraquinoneanthranol- dihj^droazine (formula II) and indanthrone :
OH
I CO NH C
2C6H4X /C6H2X xCgHoN^
CO NH C
CgH4 OH
OH
CO NH C
CcH4\ /CoH2< ^CgHoC I/C6H4
CO NH C
1 H
CO NH CO
+ C6H4<^C6H2<(^C6H2<0)C6H4+HoO
CO NH CO
II
The former compound, however, is much more readily obtained b}' reducing indanthrone with boiling alkaline sodium hydrosulphite solution and then oxidising the anthraquinol anthranol dihydroazine thus formed by exposure to the air. On oxidation with sodium hypo- chlorite it passes into the azine.
The brown vat obtained by the alkaline reduction of indanthrone consists of the sodium salt of anthraquinol- dihydroazine ^ and Scholl, Steinkopf, and Kabacznik * have prepared a tetrabenzoyl derivative.
1 B. 40, 390, ' B. 40, 924-
3 Scholl, B. 36, 3410. ^ B. 40, 390.
THE CYCLIC AZINES AND HYDROAZINES 349
Exhaustive reduction of iiidantlirone by means of zinc and caustic soda gives N-dihydroantlirazine. The dihydro- azine group in this is less stable than in indanthrone, so that heating alone suffices to split off two atoms of hydrogen, the product left being anthrazine. Both anthrazine and dihydroanthrazine on oxidation with chromic acid give anthraquinone azine. Anthrazine when boiled with nitric acid (D=i40o) gives a compound which is probably penta- nitrotetrahydrox}- anthrazine, although it has not been obtained in a state of purit}-.!
The reduction of indanthrone by hydriodic acid has been studied by SchoU ^ and by Kaufier,^ who find that three products are formed, viz, C28H16O2N2, CogHigOaNo and
CO NH CO CO N CO
:,K,<: )CoH2< >C6H2<^>C6H, -4" C6H4<^))C6H2^)>C6H2^\C6H,
yC\ NH CO , ^^.--^ CHo N CO
W ^OH
H\ /OH CO NH ^C-^ CO N CH2
:,H,<0>C6H2<^^C6H2<3>C6H4 ^-$ C6H4<^))C6H20C6H2<(^C6H4 CHo NH CO ^-^ CH2 N CO
0^ -' Anthronazine, CogHigOjN
CO NH CH2 CH N CH2
:eH,(()>C6H20C6H2<()>C6H4 '--^ Cen,(pC,li^^yCeli2(yCell, CHo NH CO ^^^ CH N CO
N-Dihydroanthronazine, CjjHjgOjNj *
CH NH CH2 CH N CH
CeH^v I /C6H2\ /C6H2\yC6H4 > CeH4\^j^C6H2\^^C6H2N^ y^6^4
CH NH CO CH N CH
Anthrazine, C^gHnNj
» Scholl. B. 40, 933. Cf. SchoU, B. 86, 3442. Bv.. D.R.P. 172,684. * B. 36, 3410. ' B. 36, 930.
350 ANTHRACENE AND ANTHRAQUINONE
C28H16N2. The last of these is anthrazine, and of the two former, the second is readily oxidised to the first either by loss of hydrogen when heated alone to 340°, or by boiling with nitrobenzene, and hence is probably a dih^-droazine. Neither compound is soluble in aqueous caustic alkali, but both are soluble in alcoholic alkali, and this points to an anthrone structure. If this be assumed' the reduction of indanthrone would appear to consist in an alternate adding on of hj'drogen and splitting off of water.
As stated on p. 346 fabric dyed with Indanthrene Blue R (indanthrone) tends to become yellow on washing owing to the oxidation of the dihj'droazine to the azine. Such oxidation is obviousl}' impossible if the iminohydrogen atoms are replaced by methyl groups, and N-dimethyl indanthrone, made from i-meth3-laniino-2-bromanthra- quinone by heating with sodium acetate and copper powder or cuprous chloride, 1 has been placed on the market under the name Algol Blue K. It is much faster to soap than Indanthrene Blue R, and has the further advantage that dyeings can be made from a cold vat, 2 whereas Indanthrene Blue R only gives satisfactory- results if used at a temperature of at least 50°.
Halogen indanthrones can be obtained from halogenated aminoanthraquinones,^ or by halogenating indanthrone itself by treatment with molecular or nascent chlorine, ^ or with sulphursd chloride, » thionyl chloride, ^ sulphur chloride or stannous chloride,'' antimon}^ pentachloride,^ or the chloride of an organic acid.^ The bromination of indan- throne, however, only takes place with great difficulty, and chlorindanthrones completely free from bromine are said
1 By., D.R.P. 158,287 ; 193.121 ; 234.294 ; B.A.S.F., D.R.P. 238,979-
- By., D.R.P. 240,265.
3 Ullmann, A. 399, 341. By., D.R.P. 158,474 ; 167,255.
* SchoU and BerbUnger, B. 40, 320. B.A.S.F., D.R.P. 138,167 ; 155,415. M.L.B., D.R.P. 296,841. G.C.I. B., E.P. 113,783 (1918). G.E., D.R.P. 292,127.
5 B.A.S.F., D.R.P. 157,440. M.L.B., D.R.P. 293.971.
6 M.L.B., D.R.P. 287,590.
' M.L.B., D.R.P. 289,279. G.E., D.R.P. 296,192 ; 271,947. Cf. also M.L.B., D.R.P. 224,500 ; 240,792; 245,768; 246.867.
8 B.A.S.F., D.R.P. 168,042. » B.A.S.F., D.R.P. 229,166.
THE CYCLIC AZINES AND HYDROAZINES 351
to be obtained when indanthrone is suspended in bromine and then treated with chlorine. 1 Halogen indanthrones can also be obtained by boiling the corresponding azines with halogen acid. 2 The reaction in this case is merely the usual addition of a molecule of halogen acid to a quinonoid compoimd. The resulting monohalogen hydroazine can then be oxidised to the azine and a second atom of halogen introduced in the same way.
The halogen indanthrones are much less easily oxidised to the azine than is indanthrone itself, ^ and consequently the shades obtained by their use are fast to soap. Various halogenated indanthrones have been introduced as vat dyes, of which Indanthrene Blue GCD "^ and Indanthrene Blue GC ^ are the most important. The former consists chiefly of dichlorindanthrone, whereas the latter seems to be a mixture of dibromindanthrone and tribromindanthrone. They are both fast to soap and dye in somewhat greener shades than indanthrone itself.
Hydroxy indaiithrones can be synthesised from the corre- sponding aminohydrox}' halogen anthraquinone. Thus i- amino-4-hydrox>^-2-bromanthraquinone when heated with sodium acetate and a contact substance such as cuprous chloride or copper powder gives dihydrox>' indanthrone ^ (Algol Blue 3G). Hydrox}'l groups can also be introduced into the indanthrone molecule by direct oxidation with a mixtme of nitric and sulphuric acids, but nitroso and nitro groups enter at the same time. Thus from indanthrone SchoU and Mansfield ^ obtained a nitrodinitrosotiihydroxy derivative and also a tetranitrotetrahydroxy compound. Both, of course, were azines and on reduction yielded the corresponding triaminotrihydroxy - N - dihydroazine and tetraminotetrahydroxy - N - dihydroazine. Sulphonic acid groups when present in the indanthrone molecule also seem
I G.C.I.B., E.P. 113.783 {1918).
- Scholl, B. 86. 3436. Scholl and Berblinger, B. 40, 320. By., D.R.P. 147.872.
' Scholl and Berblinger, B. 40, 320,
*■ Caledon Blue GCD (Scottish Dyes, Ltd.).
'" Caledon Blue GC (Scottish Dyes, Ltd.).
« Bv., D.R.P. 193,121. ' B. 40, 326.
352 AXTHRACEXE AND AXTHRAQUIXOXE
capable of being replaced by liyd.rox\-l groups. Thus indanthrone sulphonic acid when heated with concentrated sulphuric acid gives a vat dye which d^-es in rather greener shades than indanthrone itself and is probably a h^-drox}* indanthrone. The same dye is obtained b\' heating indan- throne with sulphuric acid, with or without the addition of boric acid, at a temperature insufficient to' cause siilphona- tion.^
Ami-no indanthroiies can be built up from polyamino- anthraquinones by the usual methods, or the amino group can be introduced into the indanthrone molecule by taking advantage of the quinonoid character of the azine. Thus Scholl - fotmd that the azine obtained from indanthrone b}* oxidation reacts with aqueous ammonia at 200° or with boiling anihne and is converted into amino or phenylamino indanthrone. These are vat d3-es and dxe cotton in greenish shades of blue.
A few indanthrone sulphonic acids have been described. They can be obtained from aminoanthraquinone sulphonic acids 3 or by sulphonating indanthrone. -^ The}- are soluble in water and are acid dyes for wool or silk but are of no importance.
Brief reference may be made to two vat dyes of unknown constitution which have been obtained from indanthrone. One is a greenish-blue dye obtained by condensing indan- throne \^-ith formaldehyde in the presence of sulphiuric acid.^ The other is a green dye obtained by treating indanthrone with nitric acid in the presence of nitrobenzene. ^ Neither are of any technical value.
1 B.A.S.F., D.R.P. 227,790. 2 B 36^ .^38,
3 B.A.S.F., D.R.P. 129,846.
* B.A.S.F., D.R.P. 129,847; 216.891; 220,361.
^ By., D.R.P. 159,942. * By., D.R.P. 198,024.
I
CHAPTER XVII
MISCELLANEOUS HETEROCYCLIC COMPOUNDS
I. The Pyridazineanthrones
Pyridazoneanthrone is prepared by treating the ethyl ester or the chloride of anthraquinone-a-carboxylic acid with hydrazine * :
HOCO CO
CO
and N-phenylpyridazoneanthrone can be obtained by using phenylhydrazine in place of hydrazine itself. 2 By treating anthraquinone-a-ketones with hydrazine Schaarschmidt ^ has prepared C-arylpj^ridazineanthrones :
co°^''-
Pyridazineanthrones of more complicated structure are obtained by a similar reaction from the anthraquinone- i.2(N)-acridones,4 and the anthraquinone-i.2(S)-thioxan- thrones,5 the pyridazine ring being formed by bridging the two carbonyl groups, e.g.
1 Ullmann. A. 388. 211 ; B. 44, 129.
2 Ullmann, D.R.P. 230,454.
3 B. 48. 836.
* Ullmann and Sone. A. 380, 336"; B. 43. 537. B.A.S.F., D.R.P. 248,582.
' B.A.S.F., D.R.P. 254.097.
353 23
354 ANTHRACENE AND ANTHRAQUINONE
Derivatives of pyridazoneanthrone have been prepared by converting i-chloranthraquinone-4-carboxylic acid into the pyridazone and then replacing the chlorine atom by an amino, alkylamino, arylamino, or anthraquinonylamino group. 1 They are valueless yellow or brown vat dj^es. It is interesting to notice, however, that whereas the anthra- quinonylaminopyridazoneanthrone obtained by condensing the above chloro compound with ^-aminoanthraquinone is easily reduced to its vat, the isomeric compoimd obtained by combination with a-aminoanthraquinone is only reduced with the utmost difficulty.
Ullmann - by condensing pyridazoneanthrone with a- chloranthraquinone obtained N-a-anthraquinonylpyridazone- anthrone ; but it proved to be of no interest, and although a vat dye its tinctorial properties were extremel}^ feeble. The same remarks apply to the compounds obtained by condensing N-jfj-bromphenjdpyridazoneanthrone with amino- anthraquinone.
II. The Pyrimidoneanthrones
These are isomeric with the pyridazoneanthrones and can be obtained from the a-aminoanthraquinone or o- alkylamino-anthraquinone b}' treatment with a urethane ^ :
CO
NHg NrrNNH
CO i
EtOCONHj
CO CO
The reaction is a ver}^ general one and can be brought about
1 Ullmann, A. 388, 217 ; D.R.P. 248,998. Agfa, D.R.P. 271,902. - A. 388, 211. ^ M.L.B., D.R.P. 205,035.
HETEROCYCLIC COMPOUNDS 355
simply by boiling the amine with the urethane, although the condensation is more rapid in the presence of zinc chloride or other condensing agent. The method can be modilied by first converting the a-aminoanthraquinone into its urea chloride or urethane and then treating this with ammonia.' A somewhat similar method of preparation consists in heating the a-aminoanthraquinone with an acid amide in an indifferent solvent, pyrimidone ring formation then taking place very readily by loss of two molecules of water. 2 Urea itself acts as an acid amide, but in this case, of course, a molecule of ammonia is lost, the reaction taking place most readily in the presence of copper acetate. 3
A bipyrimidone compound has been obtained from 1.4-diammo anthraquinone. The pyrimidone derivatives have been ver>' little studied and do not seem to be of any particular interest.
III. The Oxazines
A few yellow vat dyes of ketomorpholine structure have been obtained by boiling o-hydroxy chloracetylamino- anthraquinones with dilute aqueous caustic soda solutions of 5 per cent, strength.'^ The formation of the morpholine ring is due to loss of hydrochloric acid, but the resulting compounds are of no particular interest :
The oxazines themselves are obtained when o-hydrox}-- ar}'lamino anthraquinones are oxidised by means of manganese dioxide, lead dioxide, chromic acid, oleum, or an organic nitro compound,-'' and consequently are often
» By., D.R.P. 225,982. 2 By., D.R.P. 220,314.
' M.L.B., D.R.P. 20S.014. •• M.L.B., D.R.P. 290,983.
^ By.. D.R.P. 141,575-
356 ANTHRACENE AND ANTHRAQUINONE
produced when reactions which should lead to o-hydroxy- arylamino compounds are carried out in the presence of an oxidising agent. Thus purpurin when boiled with a primary aromatic amine in the presence of boric acid and an oxidising agent such as mercuric oxide or nitrobenzene gives an oxazine.i This method can also be used for preparing oxazines in which the oxazine ring lies between two anthra- quinone groups. Thus 2-methoxy-i.i'-dianthraquinonyl- amine when heated with concentrated sulphuric acid at 170-180° in the presence of boric acid gives an oxazine, the sulphuric acid in this case acting as the oxidising agent. 2
A somewhat similar reaction also takes place when an a-amino anthraquinone is heated with a i-amino-2-halogen anthraquinone in nitrobenzene solution in the presence of a basic substance such as potassium acetate, and a contact substance such as copper acetate. ^ In this case the di- anthraquinonylamine is first formed and is then oxidised to the oxazine :
0
The oxidation is obviously brought about at the expense of the nitrobenzene, as the reaction does not take place if amyl alcohol is used as a solvent. The same oxazine is also obtained when 2-hydroxy-i-nitroanthraquinone is heated with copper powder in nitrobenzene solution. *
If the o-hydroxyarylaminoanthraquinone is obtained by heating an o-hydrox>mitroanthraquinone with a primary aromatic amine, oxazine formation often takes place without the use of an oxidising agent, the necessary ox}-gen being supplied at the expense of the nitrous acid liberated during the formation of the ar^-laminoanthraquinone. Thus an oxazine is obtained when 2-hydroxy-i-nitroanthraquinone
^ By., 153.770- - M.L.B., D.R.P. 273,444.
3 M.L.B.. D.R.P. 266,945- " M.L.B., D.R.P. 266,946.
HETEROCYCLIC COMPOUNDS
357
is boiled with a primar}- aromatic amiue, and 2.4-dili3'droxy- i-nitroanthraquinone undergoes oxazine formation particu- larly easily under similar conditions. ^
Alizarin might be expected to condense with o-amino- phenol to give an oxazine, but this is not found to be the case unless there is an amino or a hydroxyl group present in the anthraquinone molecule at 4. When such a group is present, however, oxazine formation takes place extremely readily, the reaction being brought about by heating under pressure with o-aminophenol in alcoholic solution in the presence of boric acid, or in aqueous solution when the aminoanthraquinone contains a sulphonic acid group. According to the patent - in which this reaction is described, purpurin gives a hydrox}'Oxazine which has one of the following formulae :
This statement, however, must be accepted with some reserve pending further confirmation, as it seems more probable that a dihydroxy^oxazine would be produced.
A ver>' curious case of oxazine formation has been described as taking place when i-ar3damino-2-hydroxy-3- halogen anthraqumones are heated alone or with basic substances. 3 The resulting oxazines contain no halogen, so that oxazine formation seems to be brought about by oxidation at the expense of the halogen atom : ci 0
' By., D.R.P. 141.575.
By., D.R.P. 153.517-
M.L.B., D.R.P. 156,477.
358 ANTHRACENE AND ANTHRAQUINONE
There is no need to isolate the arylamino compound, as oxazine formation takes place when 3-halogenalizarin is boiled with a primary aromatic amine.
lyittle or nothing is known of the substituted anthra- quinone oxazines, but sulphonic acids can be obtained by sulphonation.i •
IV. The Thiazines
Very little is known of the thiazines of the anthraquinone series although a few such compoimds have been described. SchoU 2 obtained what was probably /w-thiodianthra- quinonylamine
1
I
\s/
from thiazine (thiodiphenylamine) itself by the phthalic acid synthesis. He found that it was a greenish-blue dye, but that the affinity for the fibre was extremel)^ poor. The same was also found to be the case with the N-methyl derivative. Ullmann ^ found that a thiazine was formed when 2-amino-i.3-dibromanthraquinone was boiled with anthraquinone-a-mercaptan in nitrobenzene solution :
Br NH2
I
Br
Br
Br
In this reaction the oxygen necessary for closing the thiazine ring seems to be obtained from the carbonyl groups. The product is a violet-blue vat dye. Similar thiazine dyes have been obtained by condensing o-aminoanthra- quinone mercaptans with halogen anthraquinones, or by
1 By.. D.R.P. 141,982. 2 B. 44, 1241. =^ B. 45, S32.
HETEROCYCLIC COMPOUNDS
359
condensing o-aminohalogen anthraquinones with anthra- quinone mercaptans. In either case thiazine formation can be brought about by self-oxidation (heating alone or with a solvent of high boilmg point) or by heating with concentrated sulphuric acid and boric acid.^ Thiazines are also formed when an o-aminoanthraquinone mercaptan is condensed with a halogen anthraquinone in which the oytho- position with reference to the halogen atom is occupied b}^ an amino, metliox}^ or carbox}^ group, the group being split off during the condensation. 2
Thiazine formation takes place verj- readily, it merely being necessarj^ to heat the components together in some suitable solventsuch as nitrobenzene, pyridine or naphthalene, no catalj-st or condensing agent being required.
As would be expected a thiazine is also obtained when i.2-dicliloranthraquinone is condensed with i-aminoanthra- quinone-2-mercaptan.-'^
A few thiazines containing onl}- one anthraquinone residue have been prepared. Thus Laube and Libkind •* obtained a green vat dye by condensing i-chlor-2,4-dinitro- benzene with a-aminoanthraquinone, reducing the nitro groups and finally fusing the diaminophenj'lammoanthra- quinone with sulphur and sodium sulphide at 150° :
NHC6H3(NH2)2
\ S ^
It will be observed that thiazine formation takes place by loss of an amino group. From ^-aminoanthraquiuone a thiazine could not be obtained by this method.
Ullmann ^ has also obtained a thiazine containing only one anthraquinone residue b}'- condensing 2-amino-i.3-di- bromanthraquinone with thio-_/)-cresol and then treating
» B.A.S.F.. D.R.P. 248,169. 3 B.A.S.F.. D.R.P. 248,171.
■ B.A.S.F., D.R.P. 266,952.
* B. 43, 1730. ' B. 49, 2163, 2165.
360 ANTHRACENE AND ANTHRAQUINONE
the product with formaldehyde and concentrated sulphuric acid :
S S
^2 ^^HiCH^
I
I
NCH,
V. The Carbazols
Compounds in which a pyrrol ring lies between two authraquinone rings, or between one anthraquinone ring and one benzene ring, are best designated as phthaloyl carbazols. They can be obtained from carbazol by condensation with phthalic anhydride in the presence of aluminium chloride (phthalic acid synthesis, pp. 130-141), carbazol itself giving a diphthaloyl derivative which is probably linear in structure although this has not yet been definitely proved 1 :
CO
CO
CO
NH
CO
The N-alkyl derivatives of carbazol condense with phthalic anhydride more readily than carbazole itself, the condensation in many cases being effected simply by heating for five to ten hours with sulphuric acid of 80-90 per cent, strength. 2 The products are usually best purified by wash- ing with sodium hypochlorite solution.
Phthaloyl carbazols can also be obtained b}' building up the pyrrol ring. Thus, i.i'-diamino-2.2'-dianthraquin- onyl when heated with concentrated sulphuric acid loses a molecule of ammonia and passes into the diphthaloyl carbazol 3 ;
1 SchoU, B. 44, 1249.
« Ehrenreich, M. 32, 11 13. Cas., D.R.P. 261,495. B.A.S.F., D.R.P. 275,670.
3 M.L.B., D.R.P. 267,833.
HETEROCYCLIC COMPOUNDS
361
and the same compound is also obtained from i.i' dianthraquinonylamine by fusion with aluminium chloride, or by oxidation with sodium hypochlorite. ^ This latter method has also been applied to the preparation of mono- phthaloyl carbazols, as it has been found that these are obtained by the oxidation of those a-arylaminoanthraqui- nones in which the ortho- position in the arj-l group is unoccupied 2 :
As a rule, the oxidation is effected by means of chromic acid, ferric chloride, or hydrogen peroxide ; but if an acylammo group is present in the para- position in the anthraquinone nucleus the reaction takes place so easily that the carbazol is formed on heating in the air at 60-70°.
Monophthaloyl carbazols have also been synthesised by Ullmann ■^ by a somewhat different method. He found that the diazotisation of 2-amino-i-ar>damino anthra- quinones led to osotriazoles, similar compounds also being readily formed by condensing a-chloranthraquinones with aziminobenzene in the presence of potassium and copper acetates. These osotriazoles on heating, preferably in diphenylamine solution, split ojff nitrogen and pass into monophthalo3-l carbazols :
» M.L.B., D.R.P. 240,080; 251,021; 251,350. C/. also 267,522. These compounds were formerly ^vrongly regarded as complex indanthrones. - By., D.R.P. 288,824. 3 B. 47, 380.
362 ANTHRACENE AND ANTHRAQUINONE
iCl JfN 1 J
V
Both the monophthalo}-! carbazols and the diphthaloyl carbazols are yellow vat dyes, but the affinity is very poor and the shades are not fast to alkali. The tinctorial pro- perties of the N-alkyl derivatives, however, are said to be much more satisf actor3^ ^
VI. The Pyrrol anthrones
If an a-ar}-laminoanthraquinone is condensed with chloracetic acid, a glycine is obtained which passes into a pyrrolanthrone when boiled with acetic anhydride - ;
COOHCHt Nf
CO
NAr
CO CO
In this case the formation of the pyrrol ring is accom- panied by simultaneous loss of carbon dioxide. If the glycine is esterified and the ester then heated with an alkali and an indifferent solvent such as xylene, this loss of carbon dioxide is avoided and a pyrrolanthrone carboxydic acid obtained which can be used as an acid wool d^-e.^ If this carboxylic acid is heated with a dehydrating agent such as oleum or chlorsulphonic acid a further loss of water takes place with the formation of a second pyrrol ring :
» Cas.. D.R.P. 261,495. - M.L.B.. D.R.P. 270,789; 272,613.
3 M.L.B., D.R.P. 280,190.
HETEROCYCLIC COMPOUNDS
363
the resulting compound being a red vat dye.'
The C-aryl pyrrolanthrones can be obtained by condens- ing an atylchloracetic acid with an a-aminoanthraquinone and then boiling the product with acetic anhydride ^ ;
COOH CO
CO
An indolanthrone has been obtained by Scholl ^ by nitrating and reducing 3-methyl-i.2-benzanthraquinone, in this case reduction being accompanied by loss of water and formation of a pyrrol ring. The compound thus formed behaves as a true quinone and is readily reduced by sulphurous acid, phenylhydrazine and cold hydriodic acid :
CXa>H3 -
CO
The reduction product is soluble in alkali and is readily oxidised to the indolanthrone by atmospheric ox}-gen. The indolanthrone can, therefore, be used as a vat dye. It gives violet-brown shades, but the affinity is very poor.
VII. The Pyrrazols
The a-anthraquinomdhydrazines when boiled with water or glacial acetic acid readily lose water and pass into pyrazol compounds,* a monopyrazol being obtained
1 M.L.B.. D.R.P. 284,208. » B. 44, 2370 ; M. 32, looi.
- M.L.B., D.R.P. 279,198. * By., D.R.P. 171,293-
364 ANTHRACENE AND ANTHRAQUINONE
from anthraquinone-i -hydrazine and a dipyrazol from anthraquinone-i.s-dihydrazine :
In the case of i.S-dichloranthraquinone a pyrazol is formed by boiHng with hydrazine in pyridine solution, one chlorine atom being unaffected, but it is not certain if this is a general reaction. 1
Pyrazolanthrone when fused with caustic alkali undergoes a condensation which is very similar to indanthrone forma- tion from aminoanthraquinone. The product is a yellow vat dye which has the structure 2 :
VIII. The Indazols Anthraquinone indazols having the structure
or
are readily obtained from o-methylanthraquinone diazonium salts. The formation of the pyrazol ring takes place quite readily either by boiling the diazonium sulphate with water, or by heating it to 50° with sodium carbonate, or by treating
^ Mohlau, B. 45, 2233, 2244.
2 G.E.. D.R.P. 255,641 ; 301,554; 302,259; 302,260.
HETEROCYCLIC COMPOUNDS 365
it with cold pyridine. In some cases diazotisation and indazol formation can be combined in one operation, e.g. an indazol is formed when 2-methyl-i-aminoanthraquinone is treated with sodium nitrite in boiling glacial acetic acid solution. ^
The simple indazols have only extremely feeble tinctorial properties, but yellow vat dyes are said to be obtained when they are oxidised by treatment with halogens 2 or ferric chloride. 3 The structure of these oxidation products is unknown, but they are probably formed by the union of two molecules through the carbon atom of the pyrazol ring.
IX. The Imidazols
The imidazols are always obtained from o-diaminoanthra- quinones and are formed when the acyl derivatives of these substances are heated with deh3^drating agents such as sulphuric acid, zinc chloride, or the anhydride or chloride of an organic acid.* Imidazol formation therefore takes place when o-diamino anthraquinones are boiled for some time with acid chlorides or anhydrides, ^ or when the base is heated with a carboxydic acid in the presence of sulphuric acid. 6 As would be expected the nitrile can be used in place of the carboxylic acid, but it is not certain that in this case imidazol formation is due to the preliminary formation of the carboxylic acid, as according to Schaarschmidt imidazols are often formed imder conditions which are insufficient to bring about the hydrotysis of the nitrile.
A variation of the above method has been introduced by Ullmann and Medenwald,^ who find that 2-acetamino- i-nitroanthraquinone passes directly into the imidazol on reduction with sodium sulphide :
1 By., D.R.P. 269.842.
3 By., D.R.P. 268,505.
' By., D.R.P. 280,840.
' Schaarschmidt, A. 407, 176.
^ By., D.R.P. 238,981. Cf. Ullmann, A. 380, 322.
■^ Schaarschmidt, A. 407, 176. D.R.P. 251,480; 254,033.
" B. 46, 1807.
366 ANTHRACENE AND ANTHRAQUINONE
CCH3
C-Methylanthraquinone-i.2-imidazol.
Another variation consists in heating an o-acylamino halogen anthraquinone with a primary aromatic amine in the presence of copper powder. In this case an arylamino group first replaces the halogen atom, the imidazol being then formed by loss of water through the ac5damino group reacting in the enolic form ^ :
>CR
NHCOR |
-N^ |
||||
1 |
-> |
1 |
! -> |
1 |
|
CI |
NH OH Ar |
I |
N^ Ar |
A somewhat different method of preparing imidazols consists in condensing o-diaminoanthraquinone with an aliphatic or aromatic aldehyde or with an a>-dichlor com- pound such as benzalchloride, or, more particularly, a>- dichlor-j3-methyl anthraquinone. 2 In this reaction the primary product formed is a dihydroimidazol, but if sulphuric acid is used as a condensing agent this is at once oxidised to the imidazol itself. The dihydroimidazol can, however, be isolated if pyridine is used as a condensing agent. When the aldehyde used is chloral a much more complicated reaction takes place, and blue or black vat d3'es of unknowTi constitu- tion are obtained.^
If a ketone is substituted for an aldehyde in the above reaction compounds are obtained which, after sulphonation, can be used as acid wool dyes. The dyes obtained from acetone and acetophenone are red, whereas that obtained
1 M.L.B., D.R.P. 298,706.
2 Schaarschmidt, A. 407, 176. Ullmann, A. 399, 332. 238.982 ; 247,246. B.A.S.F., D.R.P. 261,737.
3 M.L.B., D.R.P. 284,207.
By., D.R.P.
HETEROCYCLIC COMPOUNDS
367
from anthrone is violet and that from benzophenone blue. Nothing is known of the structure of these d.3'es, and it is doubtful if they contain the imidazol ring system. ^
Schaarschmidt 2 has examined the tinctorial properties of a number of anthraquinone imidazols and finds that neither anthraquinone-i.2-imidazol nor anthraquinone-2.3-imidazol has any affinity for the fibre. Slight affinity, however, is shown by those imidazols in which a phenyl group is attached to the carbon atom of the imidazol ring, and the corresponding anthraquinonyl derivatives, the C-anthra- quinon}^ anthraquinone imidazols, have good affinity.
The majority of the imidazols are yellow, but Schaar- schmidt states that C-i3-anthraquinonyl-anthraquinone-i,2-
imidazol :
N
C(i3)CHH;02
which he prepared in three waj-s, viz. from 1.2-diamino- anthraquinone and anthraquinone-j3-carbox>dic acid, anthra- quinone-^-nitrile and co-dichlor-jS-methyl anthraquinone, is red, whereas in a patent specification ^ the same substance is described as being prepared from 1.2-diaminoanthraquinone and is stated to be a violet dye.
The onl}' imidazolon of the anthraquinone series which has been described up to the present was obtained by UU- mann '^ by treating i.2-diammo-3-bromanthraquinone with chloroformic ester. It has the formula :
Br
CO
» By., D.R.P. 264,290.
3 B.A.S.F,, D.R.P. 261,737.
= A. 407. 176. ^ A. 399, 332.
368 ANTHRACENE AND ANTHRAQUINONE
and is a yellow vat dye with good affinity although the shades are vety loose to alkali.
X. The OXAZOI.S
Oxazol formation takes place when o-hydroxyacylamino anthraquinones are heated with dehydrating agents, j3-amino- alizarin, for example, giving an oxazol when boiled with excess of benzoyl chloride i :
OH OH
OH NHCOCeHg
— Os
— N'
^
CCgHs
Oxazol formation is here obviously due to loss of water from the enolic form of the benzoylamino compound, and this view is supported by the formation of an oxazol by loss of nitrous acid when i-benzoylamino-2-nitroanthraquinone is boiled with sodium carbonate in naphthalene solution, 2 and also by the production of oxazols by the oxidation of acylamino-anthraquinones by lead dioxide in glacial acetic acid solution, or by nitric acid in nitrobenzene solution. ^
A somewhat similar reaction has been described by Ull- mann,* who finds that when 2-amino-i.3-dibromanthra- quinone is benzoylated very little of the benzoyl derivative is produced, the chief product being an oxazol. In this case it is the bromine atom in the a- position which is lost, the structure of the oxazol being proved by its decomposition into 2-amino-i-hydrox3'-3-bromanthraquinone when heated with sulphuric acid of 80 per cent, strength : /Ov OH
^N'
^
CCeHg
Br
iNHo
Br
» By., D.R.P. 252.839; 259,037. M.L.B., D.R.P. 284,181 ; 288,842. 2 M.L.B., D.R.P. 286,094. VMI-B., D.R.P. 286.093. * A. 339. 330.
HETEROCYCLIC COMPOUNDS 369
2.6-Diamino-i.3.5.7-tetrabromanthraquinone reacts in exactly the same way and gives a dibromanthraquinone dioxazol.
Oxazols and dihydro-oxazols are also formed by condensing o-aminohydroxyanthraqninones with aldehydes, ketones or the corresponding w-dichlor compounds. The reaction is brought about by heating the substances together with or without an indifferent solvent of high boiling point such as nitrobenzene. 1
XI. The Isoxazols
Isoxazols of the anthraquinone series in which one or both of the mcso- carbon atoms form part of an isoxazol ring have been prepared by Fremid and Achenbach - and by Schaarschniidt.3 The former investigators found that the oximes prepared from a-chloranthraquinones existed in two forms, one of which was unaffected by alkali whereas the other was converted into an isoxazol. By this means they prepared both a mono- and a di-isoxazol :
and
0' 'N
The isoxazols prepared by Schaarschmidt were isomeric with these, and were obtained by boiling anthraquinone- a-azides with water. B)^ this means one mono-isoxazol and two di-isoxazols were obtained :
Gattermann ^ also obtained these compounds from the azides but named them '• semi-azo " compounds, and sug- gested, with some reserve, that they contained monovalent
J By., D.R.P. 252.839. * B. 43, 3251.
» B. 49, 1632. ^ B. 49,2117.
24
370 ANTHRACENE AND ANTHRAQUINONE
nitrogen, although he has offered no evidence whatsoever in support of this view :
CO
XII. The Thiophenes
The i(S)-9-thiopheneanthrones have been prepared by Gattermann,! -^vj^o found that the anthraquinonyl-a-thio- glycoUic acids, obtained by condensing anthraquinone- a-mercaptans with chloracetic acid, lose water and carbon dioxide when boiled with acetic anh3^dride. This tendency to form a thiophene ring is greatly enhanced by the presence of a methyl group in the a- position to the mercaptan group, and in such cases it is usually impossible to isolate the anthra- quinon5'l thioglj-collic acid owing to the ease with which it passes into the thiopheneanthrone. In these cases, however, the loss of carbon dioxide only takes place slowly, so that the carboxylic acid can usually be isolated, e.g. :
COOH CO 1
CO
Friess and Schiirmann ^ also prepared thiopheneanthroncs. Their starting-out substance was anthraquinone-a-sulphur chloride, which they condensed with sodio-acetoacetic ester, the thiophene ring being formed on subsequent hj'drotysis :
COOEl
CHjCOCH-S CHjCOCi
CO ^ '
CO CO
They also found that a thiophene anthrone is produced
» A. 393, 122, 190. - B. 52, 2172.
HETEROCYCLIC COMPOUNDS 371
vvheu sodium authraquinone-a-mercaptide is condensed with /'-liydrox}--w-chloracetophenone :
HOC.H.C
CO
This reaction is by no means a general one, as no thio- phcne derivative is formed from either o-nitrobenzyl chloride or ^-nitrobenzylchloride.
XIII. The Thiazols
Anthraquinone thiazols are obtained from o-acylamino anthraquinone mercaptans by loss of water, the reaction being brought about by heating with a suitable dehydrating agent, such as acetic anh^-dride or, in many cases, merely by heating with an indifferent solvent of high boiling point, such as nitrobenzene. 1 There is no need to isolate the acylamino mercaptan, as acylation and thiazol formation take place simultaneously when the amino mercaptan is heated with a carboxylic acid or its chloride, anhydride, amide, ester, or nitrile.2 Even the isolation of the amino mercaptan can often be avoided, as in many cases thiazols are formed when o-amino or o-acylamino halogen anthra- quinones are treated with a sulphide, thiocyanate or other substance capable of replacing the halogen atom b}' a mer- captan group, the reaction being usually best carried out in pyridine solution. ^
In the above reactions carbon disulphide would seem to act to some extent as an acid anhydride, as it has been claimed -^ that i-aminoanthraquinone-2-mercaptan when heated with carbon disulphide m alcoholic solution at 95° is converted into a thiazol mercaptan in which the mercaptan group is attached to the carbon atom of the thiazol ring :
. * By., D.R.P. 250,090.
■ B.A.S.F., D.R.P. 260,905.
■' B.A.S.F., D.R.P. 260.905. M.L.B., D.R.P. 311,900.
^ By., D.R.P. 250,090.
372 ANTHRACENE AND ANTHRAQUINONE
/NH2
S : C : vS
^ vS
.N
C:S
or
C.vSH
Thiazol formation also takes place when o-aminoanthra- quinone mercaptans are condensed with an aldehyde or the corresponding w-dichlor compound. 1 The reaction is brought about by heating in a suitable solvent and is exactly analogous to the formation of oxazols from o-aminohydroxyanthra- quinones mentioned on p. 369, and to the formation ot imid- azols from o-diaminoanthraquinones (p. 366). As in the case of the oxazols, dihydro compounds (thiazolines) are often formed, this, of course, always being the case when a ketone is substituted for an aldeh3'de.2
Somewhat similar to the above methods is the formation of thiazols from o-aminohalogenanthraquinones by means of thiolbenzoic acid 3 :
NH..
Br
O
%
CPh ~>
HS'
-N
— S
\
CPh
The reaction takes place extremely easily, but the method has the disadvantage that the thiol acids are troublesome to prepare and are apt to react with other groups present in the molecule. Thus, 2-amino-i.3-dibrom anthraquinone gave the anthraquinone thiazol disulphide :
/^\
^N-
^
CPh PhC
/K
%
w
-s-
1 By., D.R.P. 252,839 ; 259,037.
- M.L.B., D.R.P. 253,089.
3 Ullmann, A. 399, 345. D.R.P.
B.A.S.F., D.R.P. 260,905.
254.743-
HETEROCYCLIC COMPOUNDS
373
Benzyl and benzylidene aminoantliraquinones in wliich an ortho- position, which is preferably also an a- position, with reference to the amino group is vacant pass into thiazols when fused with sulphur. ^ Here again there is no need to isolate the benzyl or benz^'lidene derivative as the reaction can be carried out bj- heating the amine with benzalchloride or benzo-trichloride, preferably in the presence of an in- different solvent such as naphthalene.-
6?s-Thiazolines in which the two molecules are j oined by the carbon atoms of the thiazoline rings can be obtained by fusing the o-acetamino chloranthraquinones with sulphur, ^ or by treating the o-amhioanthraquinone mercaptans with oxalyl chloride. "i They are vat dyes and have the structure
but have not been studied in detail.
A series of vat dyes giving red, bordeaux or violet shades has been described -'' as being obtained by heating 2-methyl- i-aminoanthraquinone with sulphur and an aromatic monamine or diamine. The patents give no information as to the structure of these substances, but it is quite possible that they are complex thiazols.
XIV. The «so-Thiazoi.anthrones
The jso-thiazolanthrones are formed when an anthra- quinone mercaptan is heated with ammonia and a poh- sulphide,^ and consequently can be obtained b}- heating any suitable a-substituted anthraquinone, such as an a- chloranthraquinone, an anthraquinone-a-sulphonic acid, or
> UUmann, A. 399, 345. Agfa, D.R.P. 229,165 ; 232,711-2 ; 233,072. ■' B.A.S.F., D.R.P. 264,943 ; 267,523.
» B.A.S.F., D.R.P. 280.882. « B.A.S.F., D.R.P. 280,88 s.
* Cas., D.R.P. 283,725 ; 287,005 ; 287,52 i. • By., D.R.P. 216,306.
374 ANTHRACENE AND ANTHRAQUINONE
au a-anthraquinonyl xanthate, with an alkali polysulphide and ammonia. The a-anthraquinonyl thiocyanates are particularly suitable as starting-out substances as they pass into the zso-thiazolanthrone on heating with ammonia at 140°, preferably in alcoholic solution, no polysulphide being required. 1 By their use Gattermann has prepared one mono and two isomeric dithiazols :
tso-Thiazolanthrones can also be prepared from the anthraquinone-a-sulphur chlorides by converting these into the sulphamide b}^ means of ammonia and then closing the iso-thiazol ring by treatment with mineral acids. 2 The a- sulphochlorides behave in a very similar wa}^ as the corre- sponding sulphonamides yield sulphone zso-thiazolanthrones by loss of water 3 :
HjN-SOg
CO
The tso-thiazols are pale yellow substances which are of no particular interest. The iso-selenazolanthrones have also been described. ^ They are obtained by treating the anthraquinone-a-selenocyanides ^ with ammonia.
XV. CcEROxENE Derivatives
When p3'rogallol is condensed with phthalic anh3-dride a pjTonine dye, gallein, is produced which forms a mono- methyl ester, isomeric colourless and coloured tetramethyl
» Gattermann, A. 393, 123, 192. By., D.R.P, 217,688. - Friess and Schijrmann, B. 52, 2172. 3 Ullmann, B. 52, 545. ^ By., D.R.P. 264,139. '■" By., D.R.P. 250,667.
HETEROCYCLIC COMPOUNDS 375
derivatives, a tetra-acetyl derivative, and a compound with three molecules of phenyl *so-cyanate.i There can be no doubt that this substance has the ordinary pyronine dye structure, the coloured tetramethyl compound being derived from the quinonoid form (I), and the colourless tetra-alkyl derivative from the lactone form (II) :
OH 0 OH HOrYV>OH
I II
When gallein is heated with concentrated sulphuric acid at 190-200° a molecule of water is lost and a new dye, ccerulei'n (Alizarin Green, Anthracene Green), is obtained. 2 This forms a triacetate, two monometh}^ ethers which are soluble in caustic alkali, and a trimethyl ether which is insoluble in caustic alkali. The carbox^d group present in gallein seems to have disappeared so that the new dye is no doubt represented by formula III ;
OH 0 OH
■OX"
in
This, it will be seen, contains the anthrone ring system, and the formation of similar compounds, coeroxenes, from other pyronine dyes has been recorded. ^
1 Orndorff and Brewer. Am. 23, 425 ; 26, 9G.
- Baeyer, B. 4, 595, 663. Buchka, A. 207, 272 ; B. 14. 1329. Most of Buchka's work has been contradicted by Orndorff and Brewer. Am. 23, 425 ; 26, 96.
» M.L.B., D.R.P. 86,225. Cf. By., D.R.P. 196,752.
376 ANTHRACENE AND ANTHRAQUINONE
Very similar to the above S3mtliesis is the preparation of the highly coloured coeroxonium sulphate (IV) by Decker * by heating fluorane with concentrated sulphuric acid :
OSO4H
In this case better yields are obtained by the use of oleum, as the reaction then takes place at a much lower temperature and sulphonation is avoided.
A third method 2 of preparing coeroxonium salts consists in heating the ar>d ethers of erythrohydroxy^anthraquinone with sulphuric acid of 70 per cent, strength, or with zinc chloride'at 160-180° :
o-so^H
Both the a-naphthyl and the jS-naphthyl ethers react in the same wa3^ as do also the aryl ethers of di-a-h5^droxyan- thraquinone. The products obtained from these dihydroxy- anthraquinones do not seem to have been studied in detail, and Decker does not state whether they contain one or two pyronine rings, neither is it clear whether he prepared them from quinizarin or anthrarufin or both.
The coeroxonium salts are highly coloured, but on neutralisation or when their solutions are sufficiently diluted
^ A.»348, 214, 223. f2 Laube, B. 39, 2245. 186.882.
Decker, A. 348, 232, 245. By., D.R.P.
HETEROCYCLIC COMPOUNDS
377
with water the colourless carbinol base, cceroxonol, formula V, is obtained :
These carbiuols are decomposed by light and atmo- spheric oxygen, but when boiled with alcohol, or when the coeroxonium sulphate is recrystallised from alcohol, ^ the corresponding ethyl ether is obtained, and this is much more stable.
On reduction 2 with zinc dust and acetic acid or am- monia, stannous chloride or cold h3^driodic acid, the carbinol base first passes into the coeroxenol, formula VI, These coeroxenols are soluble in caustic alkali, and do not form salts with acids. They are rapidly re-oxidised to the carbinol base by atmospheric ox}-gen, and hence are best isolated in the form of their stable acetyl derivatives. The}' can also be obtained direct from the phen}^ xanthene carboxylic acids by loss of water, the reaction being effected by concentrated sulphuric acid at the ordinarj' temperature or, more rapidh-, at 100° :
or
Further reduction of the coeroxenols by boiling with hydriodic acid and phosphorus leads to the parent com- pounds, the cceroxenes, formula VII :
1 Laube, B. 39, 2245.
- Laube. B. 39. 2245. Decker, A. 348, 217.
378 ANTHRACENE AND ANTHRAQUINONE
VII
These are yellow fluorescent substances which are readily- oxidised in acid solution and then pass into coeroxonium salts. By treating the ethyl-ether of coeroxonol with magnesium phenylbromide, lo-phenyl cceroxene, formula VIII, has been obtained, simultaneous reduction taking place. This is a very stable fluorescent yellow substance.
XVI. The Ccerthiene Derivatives
Coerthionium salts are obtained when a-anthraquinonyl aryl sulphides are heated for thirty hours at i6o° with sul- phuric acid of 70 per cent, strength. 1 The dianthraquinonyl sulphides also undergo a similar reaction although as a rule more vigorous treatment is required, e.g. heating to 150-180° with concentrated sulphuric acid. In some cases, however, the reaction takes place extremeh- easily and may take place with evolution of heat imder the influence of sulphuric acid monohydrate at the ordinary temperature, 2
The coerthionium salts are more highly coloured than the corresponding coeroxonium salts. The}' behave like the corresponding coeroxonium salts on reduction, but the parent substances, the coerthienes, have not ^-et been isolated :
S-Ac
NoOH
CO Coerthionium salt.
CO Coerthionol.
OH CcErthienol.
J Decker and Wursch, A. 348, 238. By., D.R.P. 186,882. - By., D.R.P. 252,530,
HETEROCYCLIC COMPOUNDS
379
XVII. The CacRAMiDiNE Derivatives Cceramidines can be obtained by treating a-ar>'lamino anthraquinones with suitable dehydrating agents, such as sulphuric acid of 60-80 per cent, strength at 150°, crystallised phosphoric acid at 200° or zinc chloride in glacial acetic acid, and when a 1.4- or 1.5 -diary lamino anthraquinone is used compounds can be obtained in which two acridine ring systems are present ^ :
From i-tolylamino
anthraquinone.
Yellowish-brown.
From 1 .4-ditoly lamino anthraquinone. Dark red.
From 1.5-ditolylamino anthraquinone. Dark blue.
i.i'-Dianthraquinonylamine and i.2'-dianthraquinonyl- amine also give cceramidine derivatives when treated with deh^'drating agents, the products being yeUow or orange vat dyes, 2 The reaction is a ver}'- general one and has been applied to the preparation of complex compounds from a- anthraquinon^^lamino acidrone and from a-anthraquinonyl- amino thioxanthone.^ It has also led to the preparation of cceramidine carboxy^lic acids from a-arylamino anthra- quinone carbox^lic acid, but when the carbox}4 group is in the oriho-position to the arj-lamino group acridone formation takes place simtdtaneously and, as would be expected, the acridone is usually the predominant product.*
The simplest cceramidine can also be prepared by condensing phthalic acid with diphenylamine in the presence of zinc chloride, 5 converting the resulting acridyl benzoic acid into its acid chloride, and linally treating this with aluminium chloride <* •,
1 By., D.R.P. 126,444. - By.. D.R.P. 239,544. ' Agfa, D.R.P. 258,808. ' By., D.R.P. 262,469. * Bernth.sen, A. 224, 45. " Dammann and Gattermann, F.T. 1, 325. Cf. Decker and Schenk, A. 348, 242.
38o ANTHRACENE AND ANTHRAQUINONE
When treated with dimethyl sulphate this gives the quaternary ammonium sulphate from which caustic alkali liberates the carbinol base, N-methylcoeramidonol i :
NCH,
XVIII. MiscEivLANEOUs Compounds
Anthraquinone-a-sulphochloride when treated with hydrazine yields a sulphohydrazine 2 :
NH
Anthrone condenses with true ^-quinones such as benzo- quinone or chloranil to give blue or green vat dyes.^ The reaction is brought about b}^ boiling in some indifferent solvent such as nitrobenzene or xylene, but it is doubtful if the dyes obtained are single substances. For the blue dye obtained from anthrone and^-benzoquinone the patentees suggest the formula
0
^ Decker and Shenk, A. 348. 242. 2 Ullmann, B. 52, 545.
=» M.L.B.,D.R.P. 251,020; 267,417.
HETEROCYCLIC COMPOUNDS
381
Oxazoneanthrones are obtained when anthraquinone- a-carboxylic acids are warmed with hydroxylamine in aqueous solution ^ : 0
An anthraquinonyl thioglycoUic acid can be obtained either by condensing i-alkyl (or ar>4) aniino-2-chloranthra- quinone with thioglycoUic acid or its ester, chloiide or amide, or by condensing I-alkyl (or aryl) amiuoanthraquinone-2-mer- captan with chloracetic acid. Such anthraquinonyl thio- glycoUic acids when heated alone or in an indifferent solvent, with or without the addition of a condensing agent such as phosphorus pentachloride, zinc chloride or thionyl chloride, pass into orange or brownish-red vat dyes 2 :
/NRH /NR— CO
^S.CHg.COOH
-CHs
When an anthraquinone mercaptan is condensed with a hydroxj-anthraquinone by treatment with concentrated sulphuric acid at 160°, compovmds are obtained which probably have the structure :
Instead of the mercaptan the disulphide, thiocyanate or xanthate can be used. The products are usuall}- red vat dves.3
1 Ullmann, A. 388, 211 ; 13. 44, 129. - Bv., D.R.P. 232.076.
' By., D.R.P. 235,094.
CHAPTER XVIII MISCELLANEOUS COMPOUNDS
I. Arsenic Compounds
Very little is known of the arsenic derivatives of anthra- quinone, although a few compounds have been described by Benda.i The aminoanthraquinones are not arsinated when heated with arsenic acid,^ but the anthraquinone arsinic acids can be readily obtained from the amino com- pounds b}^ Bart's method, ix. by treating the diaozonium salts with alkali arsenite. In many cases the ^delds are almost quantitative although in others the method fails completely, e.g. aminoalizariu gives no arsinic acid at all. The arsinic acids are usually fairh- stable, well-crystallised bodies which are onty decomposed when heated to a high temperature, and then split off arsenious oxide and form the h}drox>'anthraquinone. They differ from the arsinic acids of the benzene series by being precipitated in the cold both by magnesia mixture and by calcium chloride. They can be nitrated but with some difficulty, it being necessar}- to employ a large excess of nitrating acid.
The arsinic acids when reduced show a great tendency to split off their arsenic, and this is especially true of the anthra- quinone-a-arsinic acids. It is probably to this tendency to liberate inorganic arsenic compomids that the anthra- quinone arsinic acids owe their great toxidit}-. If the reduction is carried out with sodium hydrosulphite arseno- anthraquinols are formed. These in caustic alkali solution are very rapidly reoxidised by the air to the arsinic acids, and in this way differ from the arseno compounds of the benzene
' J. pr. [2] 95, 74. - Bechamp, C. r. 56, 1172.
382
MISCELLANEOUS COMPOUNDS
383
series which under similar conditions only form arsenoxides, the use of h^'drogen peroxide or iodine being necessary in order to convert an arseno benzene into the corresponding arsinic acid. The anthraquinone arsenoxides can, however, be obtained by oxidising the arsenoanthraquinols in sodium carbonate solution by atmospheric oxygen. Oxidation by hydrogen peroxide converts these into the arsinic acid, whereas when reduced with sodium hydrosulphite they revert to the arsenoanthraquinols.
II. ACEANTHRENEQUINONES
By the action of oxalyl chloride on anthracene in the presence of aluminium chloride lyiebermann and Zsuffa 1 obtained aceanthrenequinone (I), the structure being proved by the fact that oxidising agents convert it into anthraqui- none-a-carbox}'lic acid :
CO COOH
CO
At a later date the same investigators described several substituted aceanthrenequinones,^ and I^iebermann, Kardos and Miihle ^ by the action of oxalyl-chloride on dianthr}! obtained similar compounds, the diquinone (II) and the monoquinone dicarboxjdic acids (III) being the most interesting compounds obtained, although dianthr3-l tetra- carboxylic acid was also formed :
COi iCO COOH COOH
CO'-=r-'CO
ct^^co
1 B. 44, 202. » B. 44. 852, 1213 ; 45, 1187, 1213. ' B. 48, 1648.
384 ANTHRACENE AND ANTHRAQUINONE
The action of malonyl chlorine on anthracene ^ is very similar to that of oxal}-! chloride and leads to anthracene 1.9-indandion, but according to Freund and Fleisher 2 the reaction in the case of dimethyl malon3'l chloride takes a different course and leads to either IV or V, from which the corresponding anthraquinone can be obtained by oxidation :
CO
CO
CO
V
Aceanthrenequinone gives a monoxime 3 which is capable of dyeing wool 3'ellow from an acid bath. If this monoxime is treated with concentrated sulphuric acid, or with hydrochloric acid gas, glacial acetic acid and acetic anhydride, it is con- verted into anthracene-i.Q-dicarboxjdic acid audits monamide and cyclic imide.^ The amide and cyclic imide can also be obtained from anthracene-i.g-dicarboxj'Hc acid b5'the action of ammonia, and the imide is also formed when the monoxime of aceanthrene quinone undergoes the Beckmann rearrange- ment.^ When fused with caustic potash and the solution subsequently oxidised by exposure to the air a green vat dye is obtained which has been named aceanthrene green ^ and probably has the structure represented b}" formula VI :
CO
VI
Hydrolysis of aceanthrenequinone by caustic soda leads to a mixture of anthracene-i-aldehyde-9-carbox}-lic acid,
' Kardos, B. 46, 2090. D.R.P. 275,248.
- A. 373. 291 ; 399, 193.
3 Kardos, B. 46, 2086. D.R.P. 280,839.
' Kardos, D.R.P. 282,711.
5 Kardos, B. 46. 2086.
" Kardos, B. 46, 2086. D.R.P. 275,220; 278,660; 284,210.
MISCELLANEOUS COMPOUNDS
385
the anhydride of anthracene-i.9-dicarbox>'lic acid and anthracene hydroxy dion (VII or VIII). This latter gives a monoxime from which a cyclic imide (IX or X) can be obtained by the Beckmann rearrangement. The cyclic iraide on fusion with caustic potash gives a green vat dye (XI or XII) which has been named zso-aceanthrene green. ^
>coA^c
IX
III. DiAzoNiuM Salts
Primary amino-anthraquinones can usually be diazotised in suspension in dilute sulphuric acid by dissolving the amine in concentrated sulphuric acid and then precipitating by the addition of water. The majority of the acid is then removed by filtration and the precipitate, without drying or washing, suspended in water and treated with sodium nitrite. 2 In most cases, however, it is much better to carry out the diazotisation in concentrated sulphuric acid solution by slowly adding a solution of sodium nitrite in the same solvent. In some cases the reaction takes place rapidly, but in others it is rather slow, so that as a rule it is best to allow
1 Liebermann and Kardos, B. 47, 1203.
- Lauth, C. r. 137, 662. 25
386 ANTHRACENE AND ANTHRAQUINONE
the solution to stand in the ice chest overnight. Benda * finds that a large number of primary' aminoanthraquinones are most easil}- diazotised by dissolving in concentrated sulphuric acid and then rapidh" adding a large excess of nitrosyl sulphturic acid, no artificial cooling being used. By this means he claims that j3-aminoanthraquinone can be diazotized completely in a few minutes, whereas under other conditions the reaction requires 12 hours to become complete. 2
As already stated l-h3^drox}^-anthraquinone-4-diazonium sulphate can be obtained directly from anthraquinone by heating with nitrosyl sulphuric acid and boric acid in the presence of mercuric sulphate. ^
The anthraquinone diazonium salts are sometimes soluble in water, but more usually the}- are only sparingh- soluble, so that they are often easily isolated. Kacer and Scholl ^ find that the 6/s-diazonium sulphate derived from i.8-diamino- anthraquinone is readily soluble, whereas that derived from 1.5-diaminoanthraquinone is only sparingly soluble, and on this observation they base a method of preparing 1.5- and 1.8- derivatives of anthraquinone in a pure state from a crude mixture of the corresponding nitro compounds.
The anthraquinone diazonium salts are fairly stable bodies and are only decomposed by comparatively drastic treatment. Thus, i-hydrox>'anthraquinone-4-diazonium sul- phate is only converted into quinizarin when heated to 170-180® with concentrated sulphuric acid.^ Anthraquinone- I -diazonium sulphate chars if slowlj^ heated, and only explodes feebly if rapidly heated. ^ Even anthraquinone-i.5-&zs- diazonium sulphate only explodes when heated to 172°. The a-diazonium salts are somewhat more' stable than the corresponding j3- compounds. ^
1 J. pr. [2] 95, 76.
2 Detailed directions for diazotising a large number of aminoanthra- quinones will be found in the following papers and patents. Benda, J. pr. [2] 95, 76. Bottger and Petersen, A. 160, 151 ; 166, 149. Gattermann, A. 393, 132, 149. Kacer and Scholl, B. 37, 4185. Lauth, C. r. 137, 662. Schaarschmidt, A. 405, 115. B. 49, 2678. Scholl, M. 32, 708. Ullmann and Conzetti, B. 53, 828. By., D.R.P. 131,538.
3 By., D.R.P. 161,954. See also p. 261.
* B. 87, 4185. » Bv., D.R.P, 161,954.
« Kacer and Scholl, B. 87, 4185. ' Schaarschmidt, B. 49, 2678.
MISCELLANEOUS COMPOUNDS 387
The diazonium group can be replaced by other atoms or groups by the usual methods, the yields usually being satisfactory. It should be noted, however, that the action of cuprous salts sometimes has a tendenc}^ to produce dianthraquinonyls.i According to Schaarschmidt 2 i-chlor- anthraquinone-4-diazonium chloride when warmed gives a nitrogenous, chlorine free product. To this he gives the
formula Ci4H609^ , but further confirmation is necessary
before this can be accepted. When anthraquinone-2-di- azonium sulphate is heated with ammonia a product is obtained which contains 6*ii per cent, of nitrogen. Owing to the meagre information given in the patent 3 it is hardly possible to hazard a guess at the structure of this body, if indeed it is a single substance, but nitrogen content corre- sponds to that required by hydrox>^ azoanthraquinone. The diazonium sulphates also give nitrogenous condensation products with primary aromatic diamines * and with primary aminoanthraquinones.^ In the former case at least nitrogen is evolved during the condensation, and in the latter case the products are ^-ellow or orange vat dyes.
IV. AZO, AZIMINO, AND AZOXY COMPOUNDS
Hydroxy and amino azo compounds can be obtained by coupling anthraquinone diazonium salts with phenols or aromatic amines in the usual way but are of no interest. ^ Azo compounds are also formed when either a-amino anthra- quinone or j3-aminoanthraquinone is oxidised with bleaching powder. 7
The o-amino azo compounds when oxidised, especiall}- when oxidised with chromic acid, give triazols,^ e.g. :
» B.A.S.F., D.R.P. 215,006.
2 B. 46, 2678. » M.L.B., D.R.P. 253,238.
* M.L.B., D.R.P. 246,085. '^ M.L.B., D.R.P. 255,340.
" Lauth, C. r. 137. 662. Kauffler, F.T. 2. 469. Cf. also G.E., D.R.P. 245.973 I 250,274.
' M.L.B., D.R.P. 247,352.
8 G.E., D.R.P. 238,253 ; 245,191 ; 250,274 ; 253.088. M.L.B., D.R.P. 245,191-
388 ANTHRACENE AND ANTHRAQUINONE
N
N
Some of these have been claimed as vat d3'es, but they are of no practical importance. They are also fermed when the o-amino azo compounds are heated with a metallic catalyst, such as copper or iron, and a suitable solvent such as nitro benzene,! and when o-diamino anthraquinones are treated with nitrous acid.^
Azimino compounds (azides) are obtained when diazonium salts are treated with sodium azide,3 and Gattermann * has prepared a-aziminoanthraquinone by treating anthraquinone- a-diazonium sulphate with hydroxylamine and then causing loss of water from the resulting diazo-hydrox}^amino com- pound by treatment with acetic anhydride :
C14H7O2N2HSO4 -> C14H7O2N : N.NHOH -> Ci4H702N( j|
The /3-aziminoanthraquinones are more stable than the a-azimino compounds, these latter when heated losing a molecule of nitrogen and passing into oxazols,^ although Gattermann ^ has suggested that the product formed is a " semiazo " compound containing monovalent nitrogen :
CO N:
" Semiazo " compound.
There seems to be no justification for the " semiazo " formula which Gattermann has never developed since he proposed it in a " Preliminary Note."
Very little is known of the azoxy anthraquinones, although
1 G.E., D.R.P. 273.443- "" By.. D.R.P. 254,745.
^ Schaarschmidt, B. 49. 1632. * B. 49,2117.
* Schaarschmidt, B. 49, 1632. See also p. 369. « B. 49, 2117.
MISCELLANEOUS COMPOUNDS 389
Scholl 1 obtained j8-azoxyanthraquinone by reduciug /3- nitroanthraquinoue with glucose and caustic soda.
V. Hydroxyi^amines, Hydrazines, and Hydrazo
Compounds
Hydroxylamines can be obtained by the alkaline reduction of nitroanthraquinones either by sodium stannite 2 or by glucose and caustic soda, 3 although they are not easy sub- stances to prepare owing to the tendency of the reduction to go too far. Hydroxylamines are also formed by reducing nitro compounds with a solution of siilphur in oleum, but in this case they are extremely difhcult to isolate owing to the acid causing a ver}^ rapid rearrangement to the amino hydroxy compound.-* Phenyl hydrazine can also be used as a reducing agent, and by this means R. B. Schmidt and Gattermann ^ were able to confine the reduction to one nitro group in the case of 1.5-dinitroanthraquinone and 1.8- dinitroanthraquinone. The hydroxylamines are of very little interest. They are usually orange or red in colour, but give intensely green solutions in alkali. On oxida- tion with ferric}^ anide they give the nitroso- compound, and on reduction in alkaline solution the primary amine. Acids rapidly rearrange them into aminohydroxyanthra- quinones.
Hydrazines can be obtained by the reduction of the anthraquinone diazonium salts. The diazonium salts them- selves are not particularly easily reduced, so that it is best first to prepare the sulphonic acid by treating the diazonium sulphate with sodium sulphite, and then to reduce this to the hydrazine sulphonic acid by treatment with stannous chloride, sodium hydrosulphite or sulphurous acid.^ Use of sulphurous acid as a reducing agent, however, often leads to
1 M. 32, 1040.
2 R. E. Schmidt and Gattermann. B. 29, 2934. Cf. By., D.R.P. 100,137 ; M.L.B.. D.R.P. 135.409.
3 SchoU, M. 32, 1033. Wacker, B. 35, 666.
* By., D.R.P. 119,229. See also p. 244. 6 B. 29, 2934-
• Mohlau, B. 45, 2233, 2244. By., D.R.P. 163,^47
390 ANTHRACENE AND ANTHRAQUINONE
the entrance of a second sulplionic acid group, a hydraziue- a/3-disulphonic acid being produced, Tlie hydrazines them- selves are readily prepared from the sulphonic acids b}' hydrolysis with dilute h5'drochloric acid.
Hydrazines can also be prepared by condensing halogen anthraquinones with hydrazine, the reaction being best carried out in the presence of pyridine, i* As would be expected halogen atoms when in a- positions react most easily. Thus, 1.5-dichloranthraquinone when boiled with hydrazine in pyridine solution gives i-chloranthraquinone-5 -hydrazine, and when heated with h3?-drazine in pyridine solution at 145° it yields anthraquinone-i.5-dihydrazine. 2.6-Dichloranthra- quinone only reacts with hydrazine in pyridine solution at 170°, and then gives anthraquinone-2.6-dihydrazine. It should be noted that in the preparation of a-hydrazines by this method there is always a chance of the cyclic carbonyl group becoming involved in the reaction. Thus, i.8-dichlor- anthraquinone when boiled with hydrazine in pyridine solution gives a pyrazol.
The anthraquinone h3^drazines show much the same reactions as other aromatic hydrazines, and readily condense with aldehydes and ketones to form hydrazones. Many of these hydrazones when derived from aromatic aldehj'des or ketones have tinctorial properties, but vat dyes are only produced when there is at least one hydroxyl group present in the aryl group. 2 When this is the case the hydrazones are capable of dj-eing cotton either from a hydrosulphite vat or from their solution in sodium sulphite. The hy drazone formed from anthraquinone- 1. 5 -dihydrazine with _/)-hydrox>^benz- aldehyde gives greenish-blue shades, blueish-red shades being obtained with the hydrazone derived from w-hj^droxy benzaldehyde, and blue shades with that from 2.4-dihydroxy acetophenone. The corresponding hydrazones derived from anthraquinone-2.6-dihydrazine give brown shades.
Both a- and ^-anthraquinone hj'drazines form hydrazones when treated with acetoacetic ester. When heated with acetic anhydride the /S-hydrazone loses water and undergoes
I Mohlau, B. 45. 2245. a M.L.B.. D.R.P. 256,761
MISCELLANEOUS COMPOUNDS 391
pyrazalon formation in the normal way. The a- compound, on the other hand, does not, but when heated with a mixture of acetic anhydride and sulphuric acid is converted into a pyrazol, acetoacetic acid being split off.i
The hydrazine sulphonic acids have tinctorial properties and are capable of being used as acid wool dyes, although these are of no technical importance. Thus, anthraquinone-i.8- di-hydrazine-j8-sulphonic acid, Ci4H602[i.8](NH.NHS03H)2, gives scarlet shades. 2 The introduction of hydroxy 1 groups into the molecule tends to shift the colour towards the violet end of the spectrum.
Simple hydrazo- compounds in which the hydrazo group is joined to two anthraquinone residues, such as
C14H7O2.NHNH.C14H7O2,
do not seem to «have been prepared, although one or two mixed h5^drazo compounds have been described. Thus, dichloranthrachpv'sazin disulphonic acid condenses very readil}^ with phen5dhydrazine to produce a hydrazo com- pound 3 (di-phenylhydrazo-anthrachr>'sazin disulphonic acid ?), and a mixed hydrazo- compound is also formed by condensing phenylhydrazine, or phenylhydrazine sulphonic acid, with Imico- quinizarin.^
1 Mohlau, B. 45. 2233. See also p. 363. - Bv., D.R.P. 163,447
3 M.L.B., D.R.P. 99.078. * M.L.B., D.R.P. 204,411.
ADDENDA
Page 38. Cf. also pp. 31-32. — Ray 1 has stated that anthra- cene derivatives are obtained from aromatic hydrocarbons and chloroform, beuzal chloride, or carbon tetrachloride by a modification of the Friedel and Crafts reaction in which the catalyst is prepared from aluminium and mer- curic chloride by a special process. From benzene and chloroform or benzal chloride he states that he prepared g.io-diphenyl-g.io-dihydroanthracene, but gives its melting point as 159° as compared with i64"2° found by lyinebarger,^ who prepared it from benzal chloride and benzene by means of aluminium chloride. Haller and Guyot 3 have also prepared the compound by reducing 9.10-diphenyl anthra- cene, but give the melting point as 218°. Their product evolved hydrogen when heated, whereas that obtained by Linebarger does not appear to have done so. Ray's product prepared from chloroform appears to have been impure (found : C=93"2, YL=6j. C26H20 requires C=94'o, H=6-o), although the analysis of that obtained from benzal chloride agrees closely with the theoretical. Ray states that his product on oxidation with chromic acid gave anthraquinone, whereas Simonis and Remmert ^ found that 9.10-diphenyl- anthracene itself does not give anthraquinone on oxidation. Ray also states that his product when treated with acetic an- hydride and pyridine gave a diacetj-l derivative. It is difficult to see how a diacetyl derivative could be obtained from a h^^drocarbon by the method employed, and in any case such a diacetjd compound would contain thirty carbon atoms and not twenty-eight as Ray states. (Found: 0=85*3, H =7*4.
^ Soc. 117, 1335- ' Am. 13, 554.
* C. r. 138, 1252. * Page 20.
393
394 ANTHRACENE AND ANTHRAQUINONE
C28H24O2 requires €=857, H=6-8; C30H24O2 requires C=86-5, H=5-8.)
From benzene and carbon tetrachloride or benzotri- chloride Ray obtained a hydrocarbon which melted at 159° and which he designates as 9.9.10.10-tetraphenyl- dihydroanthracene. It should be noted that the melting point is the same as that of the product obtained from chloroform or benzal chloride. Ray does not give any facts serving to differentiate them, and analytical data for carbon and hydrogen are insufficient. (Found : C=94'0, 94-0; H=6-8, 5-1. CggHgg requires C=94-2, H=5-8 ; C26H20 requires C==94*o, H=6-o.)
Page 68. — ms-N-Methyl anthramine cannot be obtained by methylating ws-anthramine either by treatment with methyl iodide or dimethyl sulphate. It is, however, readily obtained by heating anthrone with aqueous methylamine solution at 220°. It forms sulphur-yellow needles which sinter at 85° and melt at 90°. It is very easily oxidised and its solutions exhibit an intense green fluorescence.
Page 81. — When anthraquinone is reduced by heating at 230° with glucose, sucrose, lactose, or other sugar in the presence of aqueous, caustic soda of 30 per cent, strength, anthranol is produced. ^
Page 99. — When anthranol is treated with a cold con- centrated solution of formaldehyde, it passes readily into methylene anthrone (methylene anthraquinone) 2 :
CO
^6^4^ yC6H4 C CH2
This forms pale yellow prisms which melt at 148°. It unites instantaneously with one molecule of bromine to form brom-methylbromanthrone, also obtained by the action of bromine on methylanthranol methyl ether. ^
1 A. G. Perkin, E.P. 151,70718. Cf. M.L.B., D.B.P. 249,124.
2 K. Meyer, A. 420, 134. ^ k. Meyer and Schlosser, A. 420, 131.
ADDENDA 395
Page 112. — The alkylation of antliranol has been further studied by Kurt Meyer and Schlosser.i They find that alkylation with dimethyl sulphate or diethyl sulphate leads to the formation of 0-alk3'l compounds (anthranol methyl and ethyl ethers), whereas alkylation with alkyl iodides leads to the production of C-alkyl derivatives. From anthranol and methyl iodide the chief product was methylanthranol methyl ether (I) together with dimethyl anthrone (II) :
OCH3
I
C CO
c c
I /\
CHg CH3 Crl3
I II
Similar products were obtained by means of ethyl iodide.
Page 118. — Kurt Meyer 2 has extended his investigations on the tautomerism of the anthraquinone reduction products to the corresponding compounds obtained from some hydroxy anthraquinones. The reduction of erythrohydroxy anthraquinone by sodium hydrosulphite and alkali or by tin and hydrochloric acid ^ leads to a product which must be regarded as the anthrone, as the equilibrium mixture in alcohol (•I--2 gram in 100 c.c.) contains only 3 to 4 per cent. of the enole (anthranol). Reduction of erythrohydroxy- anthraquinone with zinc dust and caustic soda leads to I -hydroxy anthraquinol. The corresponding enole, i(?4).9- dihydrox}^ anthrone can be obtained by brominating i-hydrox}' anthrone and then replacing the bromine atom by the h^'droxjd group by treatment with aqueous acetone. In alcoholic solution the equilibrium mixture contains only about 10 per cent, of the enole (anthraquinol). The reduc- tion products of quinizarin show an even more marked tendency to become ketonised. Reduction of quinizarin with tin and hydrochloric acid in glacial acetic acid solution
1 A. 420, 126. « K. Meyer and Sander, A. 420, 113.
» M.L.B., D.R.P. 242,053.
396 ANTHRACENE AND ANTHRAQUINONE
leads to 1.4.9-triiiyd.roxy anthrone, whereas reduction with zinc and caustic soda leads to the isomeric dihydroxy anthraquinol. This latter substance, however, is extremely unstable and is ketonised merely by recrystallisation. The anthranol obtained by the reduction of jS-hydroxj-anthra- quinone was also examined, but quantitative results as to the state of the equilibrium mixtm'e coulH not be obtained, as even excess of bromine did not cause the disappearance of the fluorescence. The substance, however, was probably chiefly enolic, so that the ketonising influence of h^^droxyl groups would seem to be confined to those occupying a- positions. In connection with this it is interesting to notice that Willstatter and Wheeler 1 have found that hydro- juglone exists in two forms. One of these is probably the true phenol (1.4.5-trihydroxynaphthalene), whereas the other is probably i.4-dihydrox^^-5-keto-5.8-dihydronaphthalene :
H H OH \/ OH
HO OH
O
OH
the presence of the two hydroxyl groups in a- positions rendering the ketonic form stable.
Page 136. — Phthalic anhydride will condense with hydrindene 2 to give a ketonic acid which on treatment with ten parts of 15 per cent, oleum at 60-70° yields a mixture of two isomeric phthaloyl hydrindenes (I and II) :
CO
CO
CHg
CHg CHz
n
M.p. 108-110°. M.p. 181°.
^ B. 47, 2796. - Braun, Kirschbaum and Schuhmann, B. 53, 1165.
ADDENDA 397
The second of these substances on reduction with zinc dust and ammonia passes into the corresponding anthracene derivative (m.p. 242-243°), whereas the former yields a product which melts at about 150° but which could not be obtained pure. It therefore behaves on reduction in the same way as the a-methyl anthraquinones.
Page 140. — 3-Nitrophthalic acid, 4-nitrophthalic acid, and the corresponding acetyl aminophthalic acids will condense with benzene under the influence of aluminium chloride to form ketonic acids. ^ It is not stated whether or not dehydrating agents will convert these into anthraquinone derivatives.
Page 159. — i-Chlor-2-dichlormethyl anthraquinone is converted into i-chloranthraquinone-2-aldehyde by heating with concentrated sulphuric acid and boric acid. 2
Page 160. — 2-Methyl-i-aminoanthraquinone when heated with an aromatic nitro compound and an alkali, with or without the addition of a primary aromatic amine, gives an azomethine derivative from which i-aminoanthraquinone- 2-aldehyde can be obtained by hydrolysis with an acid. 3
Page 163. — i-Chloranthraquinone-2-aldehyde is readily oxidised to the carboxylic acid by chromic acid.*
Page 168. — By nitrating anthraquinone to the dinitro compound Dhar ^ obtained 1.5-dinitroanthraquinone (m.p. 360°), 1.3-dinitroanthraquinone (m.p. 240°) and two other isomers w^hich he was unable to identify. For the analysis of the 1.3-dinitro compoimd he gives the figures : found N=4'2 ; calculated, N=9-39.
Page 171. — 2-Methyl-i-chloranthiaquinone when chlori- nated gives 2-dichlormethyl-i-chloranthraquinone.<5
^ Lawrence, Am. Soc. 42, 1871.
- Schaarschmidt and Herzenberg, B. 53, 1809.
=" Cas. E.P. 148,339 (1915).
* Schaarschmidt and Herzenberg, B. 53, 1809. ^ Soc. 117, looi. •
* Schaarschmidt and Herzenberg, B. 53, 1809.
398 ANTHRACENE AND ANTHRAQVINONE
Page 173. — i-Amino-2-meth3-lanthraquinone can be con- verted, into 2-meth3-l-i-cli]oranthraqmnone by Sandmeyer's method, but the reaction must be carried out in the cold in order to avoid the formation of anthraquinone-i.2-indazol.i
Page 208. — Both a-aminoanthraquinone and jS-amino- anthraquinone can be methylated b}* boiiing with dimethyl sulphate and a mild alkali such as sodium carbonate, in the presence of an inert solvent of high boiling point such as nitrobenzene or tetrachlorethane.2
Pages 265-266. — Kurt Meyer and Sander have examined leuco-qumizarin. I and /^wco-quinizarin II. The former can also be obtained from /^wco-purpurin by warming with glacial acetic acid, but will not give purpurin by oxidation. Its conversion into quinizarin is not brought about by oxidation but by loss of water, and can be effected by alkali even in the absence of atmospheric ox}-gen. In view of these facts Meyer and vSander consider that leuco-quini- zarin I must be 2-hydroxy-i.4-diketo-i.2.3.4-tetrahydro- anthraquinol (I). Loss of a molecule of water from this substance would give rise to 9.io-dihydrosy--i.4-anthra- quinone (II), which would pass into the i.4-dih3-drox3'-9.io- anthraquinone (quinizarin, formula III) b\- ketonisation of the hydrox\-l groups and simultaneous enoHsation of the qiuno- noid carbonyl groups :
OH p OH P . CO 5"
'^"iHOH
Hz OH 5 ^ OH 5 CO 0"
I II . ffl
Page 324. — By condensing the chloride of i-chloranthra- quinone-2-carbox}-lic acid with /)-x}-lene, Schaarschmidt and Herzenberg ^ obtained the xylyl chloranthraquinonyl ketone, from which they were able to prepare the corre- sponding amino ketone (I) by heating with ammonia. This when diazotised and then treated with copper powder
^ Loc. cit. * Atack and Haworth, E.P. 147,964.
9 B. 53, 1807. Cf. also B. 53, 1388.
ADDENDA
399
gave four products, viz. {a) traces of xylyl hydroxyanthra- quinonyl ketone ; (b) about 20 per cent, of X}- lyl anthraquinony 1 ketone itself, also obtained by condensing the chloride of anthraquinone-2-carbox}'lic acid with _^-xylene ; (c) a fluore- none derivative (formula II) in about 25 per cent, yield ; and (d) a benzanthrone derivative (formida III) in about 50 per cent, yield :
The phthaloyl fluorenone (II) passed into the benzanthrone derivative (III) when heated with zinc chloride. Both II and III yielded the carbox}-lic acid (IV) when fused with caustic alkaU, the carboxyl being formed by the opening of the fluorenone ring.
Page 328. — An investigation of perylene and its aeriva- tives has been commenced.^
1 Hansgirg and A. Zinke, M. 40. 403. A. Zinke and Unterkreuter, M. 40, 405.
400 ANTHRACENE AND ANTHRAQUINONE
Page 370. — Compotinds wldch are probably isoxazols of the type :
N
I
CR
are obtained by treating i-nitro-2-alkylantliraqtiinones with oleum. 1 Compotinds which may or may not be isoxazols of the above structure are obtained by treating 2-methyl- i-aminoanthraquinone with alkali alcoholates.^
Phthaloyl acenaphthene.^ — Phthalic anhydride will con- dense fairly readily with acenaphthene to give a ketonic acid in which the carbonyl group occupies one of the a-positicns of the naphthalene ring. This substance, how- ever, differs from the corresponding naphthalene derivative in showing great resistance to the action of dehydrating agents. Neither concentrated sulphuric acid nor phosphorus pentoxide will convert it into phthaloyl acenaphthene, but the anthraquinone ring can be closed by heating to 200'' with phosphorus pentachloride. The yields, however, are poor.
1 M.L.B., E.P. 147.00T (1918). 2 M.L.B., D.R.P. 293,576.
^ Groebe, A. 327, 99-
INDEX TO GERMAN PATENTS
D.R.P.
3.565
6,526
17,627
695 21,178 23,008 26,197 38,417 42.053 46,654 47.252 50.164 50,708 54.624 56,951 56,952 58,480 60,855 61,919 62,018 62,019 62,504 62,505 62,506
62,531 62,703
63,693 64,418 65.182 65,375 65-453 65,650
66,153 65,811 66,917 67,061 67,063 67.470 68,113 68,114 68,123 68,474 68,775 69,013 69.835
Patentee. Pryzibram
M.L.B. B.A.S.F. Agfa B.A.S.F. Majert Reney and Chem. Fab B.A.S.F.
By.
MX.B. By.
Ort and M By.
M.L.B. By.
M.L.B. By.
Erhart A.G.
.B.
Date. |
Page |
1S78 |
278 |
1878 |
192, 198 |
1881^ |
255 |
1881^ |
296 |
1882 |
64. 65, 66 |
1882 |
296 |
1883 |
293 |
1886 |
17 |
1887 |
17 |
1888 |
296 |
1888 |
296 |
1888 |
254, 281, 295 |
1888 |
254, 281, 295 |
1890 |
295 |
1890 |
179. 278 |
1890 |
278 |
1890 |
295 |
1890 |
260, 277 |
1890 |
200 |
1890 |
264 |
1890 |
284 |
1890 |
264 |
1890 |
264 |
1890 |
264 |
1890 |
260 |
189I |
294 |
1890 |
260 |
1890 |
260 |
1890 |
260 |
1891 |
260 |
189I |
260 |
1890 |
200 |
1891 |
92, 264 |
1892 |
281, 284 |
1891 |
200 |
1890 |
260 |
1891 |
260 |
1892 |
294 |
189I |
92. 264 |
189I |
92, 264 |
189I |
92 |
1892 |
17 |
1890 |
258 |
189I |
260 |
189I |
258 |
401
26
402
D.R.P. 69.842 ^'9.933 69.934 70.515 7o.«^5 70,78a
7i.9<'4 72,220
72.552 73.605 73.684
73,860
73.942 73.961 74.212
74.353 74.431 74.562 74.508 75.054 75.2SS 74.400 76,262 76,280 76,941 77.179
77.3" 77.720
77.721
77.818
7»."42 78.772 78,861 79,768 80.407 81,244 81.245 81.481 8l.6g4 81.741 81,742
81.959 Ri,o(Hi
81.Q0-' 83.035 8 vo<>8 83.0S5
84. s>' >
84.--
84.774
86.^>97 86.150 86.ii5 80.530 86.6 nO
S7.6JO 87.7?o
IXDEX TO
Pauotee
By.
M.L.B.
By"
Soc. Anon M.L.B.
By.
Soc. Anon
M.L.B.
By.
M.L.B.
By.
m!l.b.
B.A.S.F. Soc. Anon B A.S.F. M.L.B. Soc. Anon M.L.B. B.A.S.F. M.L.B.
M.L.B. By.
m!l.b.
By.
M.L.B. By.
M.L.B. Bv.
M.L.B.
Nietxki
Bv.
M.L,B.
B>-.
Bv K. B \.SF
GERMAN PATENTS |
||||
Dale. |
Page. |
|||
. 1892 |
92. : |
264 |
||
1892 |
264 |
|||
1S92 |
264 |
|||
1892 |
281 |
|||
. 1892 |
295 |
|||
1 891 |
263 |
|||
. 1893 |
179. |
258 |
||
. 1893 |
62 |
|||
. 1893 |
193 |
|||
. 1892 |
282 |
|||
• 1893 |
193 |
|||
I ^13 |
242 |
|||
l-'ji |
264 |
|||
1893 |
62 |
|||
1 8.) 3 |
281 |
|||
IS.)2 |
264 |
|||
IS02 |
281 |
|||
. 1^93 |
281 |
|||
. 1893 |
281 |
|||
. 1893 |
242, |
287 |
||
. 1893 |
136 |
|||
1893 |
249. |
250. 25 |
||
1892 |
246 |
|||
, 1893 |
62 |
|||
. 1892 |
243 |
|||
• 1893 |
173 |
|||
1893 |
62 |
|||
. 1894 |
179. |
193 |
||
1892 |
206 |
|||
. 1893 |
242. |
287 |
||
1894 |
173 |
|||
1894 |
193 |
|||
• 1894 |
17 |
|||
• 1893 |
258 |
|||
■ 1894 |
140 |
|||
1803 |
258 |
|||
• 1893 |
262 |
|||
. 1893 |
259. |
260 |
||
• 1893 |
246. |
282 |
||
1895 |
193 |
|||
• 1895 |
249 |
|||
. i8q^. |
260 |
|||
1893 |
260 |
|||
1894 |
258 |
|||
1S03 |
258 |
|||
1S04 |
4 |
|||
1S94 |
258 |
|||
. i'>95 |
261 |
|||
1894 |
203 |
|||
I S03 |
263 |
|||
• i>95 |
194 |
|||
1S04 |
200. |
203 |
||
1895 |
375 |
|||
1S05 |
202, |
203 |
||
!- -5 |
262 |
|||
»^95 |
s6o |
|||
1894 |
1x6 |
|||
iSoi |
246 |
I
I
INDEX TO
D.R'. |
Patentee |
88.03 |
B.A.S.R .. |
89,07 |
By. |
89,14 |
B.A.S.F. .. |
89,82 |
By. |
90,01 |
it ' ' |
90,70 |
B.A.S.F. .. |
91.19 |
By. |
91,10 |
»» • • |
91,12 |
i> • • |
91,58 |
B.A.S.F. .. |
92,51 |
By. |
92,80 |
B.A.S.F. .. |
92,98 |
>» • • |
93.23 |
By. |
93.30 |
>» • * |
94.36 |
»» • • |
95.^5 |
it ' ' |
96,17 |
t* • • |
96,34 |
»» ' • |
97,27 |
M.L.B. . . |
97.64 |
Bv. |
97,^ |
m'.l.b. . . |
98,69 |
By. |
99,c8 |
M.L.B. . . |
99, ?4 |
By. |
99,ei |
M.L.B. . . |
99.^ |
>> • • |
99,84 |
t» • • |
100,16 |
By. |
100,17 |
I> ' • |
ioo,i8 |
>> • • |
101,20 |
By. |
ioi,j6 |
»» |
ioi,i>5 |
»> • • |
ioi,>6 |
f$ • • |
101,09 |
tt ' ' |
102, =2 |
i» ' * |
102, f.8 |
ft • • |
1 03, .-.5 |
»» • • |
1 03, -.6 |
»> • * |
103,66 |
i> • " |
I03.i28 |
it • • |
I03,c8 |
tt • • |
104,14 |
M.L.B. . . |
I04,d2 |
By. |
io4,'7 |
>» • • |
I04,?7 |
M.L.B. . . |
104,01 |
By. |
105, n |
>9 • • |
io5,?7 |
i» ' ' |
io6,H |
»> • ' |
106,27 |
B.A.S.F. .. |
106,55 |
M.L.B. |
io7,-?8 |
»> • ■ |
107,31 |
By. |
i07,;;o |
y» • " |
108,74 |
B.A.S.F. .. |
108,52 |
By. |
GERMAN PATENTS |
|||
Date. Page, |
|||
• • • |
. 1893 246 |
||
. 1895 265 |
|||
1892 246 |
|||
. 1895 203 |
|||
. 1895 261 |
|||
1892 206 |
|||
. 1895 201, 203 |
|||
1896 201, 203 |
|||
. 1896 203 |
|||
. 1895 188 |
|||
1896 203 |
|||
. 1896 246 |
|||
1896 246 |
|||
. 1896 203 |
|||
. 1896 203 |
|||
. 1896 203 |
|||
. 1897 204 |
|||
1892 246 |
|||
. 1897 277, 283 |
|||
. 1897 173 |
|||
, 1897 258, 260 |
|||
. 1897 249 |
|||
. 1897 280 |
|||
. 1897 196, 391 |
|||
. 1897 25S |
|||
. 1897 277, 2S4 |
|||
. 1897 277, 2S4 |
|||
. 1897 277, 284 |
|||
. 1897 277, 283 |
|||
. 1897 283, 3S9 |
|||
. 1899 192 |
|||
. 1897 259 |
|||
, 1892 247 |
|||
. 1897 196 |
|||
. 1898 196 |
|||
. 1898 204 |
|||
. 1898 283 |
|||
. 189S 263, 264 |
|||
» |
. 1897 194, 283 . 1898 196 i8g8 240 . 1897 180 |
||
. 1898 238, 239. 240, |
277 |
||
. 1897 263, 264 |
|||
. 1898 169, 244 |
|||
. 1898 277 |
|||
. 1898 249 |
|||
. 1898 228 |
|||
. 1898 283 |
|||
. 1897 244, 246 |
|||
. 1898 282, 283 |
|||
. 1898 196 |
|||
. 1898 241 |
|||
. 1899 263, 264 |
|||
, 1898 170 |
|||
, 1898 196 |
|||
. 1898 196, 199 |
|||
. 1899 246, 283 |
403
400
Page the type
^'•^^ c
♦^ >*.
'-»■
are obt oleum, i] of the i-aniiiM Phtl dense acid il a-posil ever, in sh( agents |)ento^ the phosj)]
•^
J
.•»
wm.m
A7
a
TS
405
y
I Of^
1897 1898 1897 189S 1898 1898
24':
1898 228 1898 28.
[897
1898 282
1898 IgC
244. 2^'
'iC-
1898
1899 263, .04
241
1898
70
1898 196 ^^98 196,199
1899 246, 283
404 |
INDEX TO GERMAN PATENTS |
||||
D.R.P. |
Patentee. Date. Page. |
||||
108,420 |
M.L.B. .. |
. 1898 196 |
|||
108,459 |
B.A.S.F. .. |
. 1897 249 |
|||
108,578 |
By. ... |
. 1899 283 |
|||
108,837 |
Soc. Anon. |
. 1898 140 |
|||
109,613 |
B.A.S.F. .. |
. 1897 246 |
|||
"1,359 |
A. G. fur Teer . |
. 1899 17 |
|||
111,866 |
B.A.S.F. |
1899 196, 226 |
|||
111,919 |
M.L.B. . . |
1898 263, 264 |
|||
112,179 |
J» • • |
1899 a8o |
|||
112,297 |
Soc. Anon. |
. 1898 140 |
|||
112,913 |
tt • |
. 1898 140 |
|||
113. on |
B.A.S.F. |
. 1899 196 |
|||
113,291 |
Wilton . . |
. 1899 17 |
|||
113,292 |
B.A.S.F. . |
. 1899 231 |
|||
113.724 |
By. |
. 1899 246, 283 |
|||
113.934 |
B.A.S.F. |
. |
. 1899 196 |
||
114,197 |
Soc. Anon. |
. 1898 140 |
|||
114,198 |
J J |
. 1898 140 |
|||
114,199 |
By. |
. 1899 200, 205, 274 |
|||
114,263 |
it • |
. 1899 272 |
|||
114,840 |
B.A.S.F. . |
. 1899 231 |
|||
115,002 |
By. |
. 1897 246 |
|||
115,048 |
tt • |
. 1899 228 |
|||
116,746 |
tt • |
. 1899 246, 283 |
|||
116,867 |
j» ' |
. 1900 196 |
|||
116,951 |
It • |
. 1899 187 |
|||
117.923 |
tt • |
. 1899 276 |
|||
119,228 |
tt " |
. 1899 283 |
|||
119,229 |
II |
. 1900 246. 247, 389 |
|||
II9.755 |
Simon |
. 1899 250, 280 |
|||
119.959 |
B.A.S.F. . |
. 1899 284 |
|||
121,155 |
It |
. 1900 196, 226 |
|||
121,315 |
II * |
. 1898 246 |
|||
121,684 |
»» • |
. 1898 198 |
|||
125,094 |
»» |
. 1899 228, 229, 251 |
|||
125,578 |
By. |
. 1900 196, 198 |
|||
125,579 |
l» • |
. 1900 243, 277 |
|||
125,666 |
It • |
. 1900 196 |
|||
125,698 |
II • |
. 1900 203 |
|||
126,015 |
H |
. 1899 251 |
|||
126,392 |
It • |
. 1899 228 |
|||
126,393 |
#» • |
. 1899 228 |
|||
126,444 |
It |
• 1900 379 |
|||
126,542 |
»» |
. 1900 196 |
|||
126,603 |
B.A.S.F. . |
1900 251 |
|||
126,803 |
By. |
. 1900 198, 203 |
|||
126,804 |
M.L.B. . |
. 1901 194 |
|||
127,295 |
It • |
1900 58 |
|||
127,399 |
By. |
• 1901 50, 53, 67 |
|||
127,458 |
tt • |
1900 196 |
|||
127.459 |
It • |
1900 196 |
|||
127,532 |
It • |
. 1900 196 |
|||
127,699 |
It • |
. 1901 273, 274 |
|||
128,196 |
B.A.S.F. . |
. 1899 231 |
|||
128,753 |
,, • |
1900 203 |
|||
128,845 |
>> |
. 1900 173 |
|||
129,845 |
,, • |
. 1901 194, 343 |
|||
129,846 |
II • |
■ |
• 1901 343. 352 |
INDEX TO GERMAN PATENTS
405
D.R.P.
129,847 129,848
131.403 131.538 133,686
134.985 135.407 135.408
135.409
135.634 136,015
136.777 136,778 136,872
137.074 137.078 137.495 137.566 137.782 137,783 I38.II9
138.134 138,166 138,167 138.324 138,325 139.425 139.581 139.633
139.634 141,296
141,355 141.575 141,982 142,052
142.154 143,804
143.858 144,111
144.634 145,188
145.237 145.238 145.239 146,223 146,691 146,848 147,277
147.851 147,872 148,079 148,109 148,306 148,767 148,792
148,875 149,780 149,781
Patentee. B.A.S.F
By. „
b.'a.s.f. '.'.
Deichler and Weizmann . B.A.S.F
m.l'.'b.
By.
B.A.S.F
By
B.A.S.F. ..
By.
Sadler & Co
B.A.S.F. ..
By.
B.A.S.F. ..
Deichler and Weizmann .
M.L.B. ..
By
B.A.S.F
By.
M.L.B.
f f
By. M.L.B.
By'.
BA.S.F. By.
B.A.S.F.
By. M.L.B.
Date, |
Page. |
1 901 |
352 |
1901 |
347 |
I901 |
273 |
1900 |
173, 286 |
1901 |
300 |
1900 |
148 |
I901 |
343 |
1901 |
300, 343. 345 |
1901 |
389 |
I901 |
206 |
1901 |
300 |
1900 |
197, 198 |
1900 |
197. 198 |
190I |
79. 201 |
1901 |
229, 251 |
1901 |
196 |
1901 |
74 |
1900 |
203 |
1900 |
175 |
1898 |
229 |
1902 |
300 |
1900 |
231 |
1 901 |
231 |
1902 |
350 |
1900 |
149 |
1900 |
149 |
1902 |
277 |
1900 |
198 |
1900 |
300. 345 |
1901 |
302 |
1902 |
277 |
190I |
300. 345 |
1902 |
355. 356 |
1902 |
358 |
1899 |
196 |
1902 |
206 |
1900 |
277 |
1902 |
277 |
1901 |
196 |
1900 |
198 |
1902 |
241,287 |
1902 |
193 |
1902 |
242 |
1902 |
196 |
1902 |
91, 269, 287 |
1900 |
228 |
1900 |
224, 226 |
1902 |
79. 201 |
1902 |
194 |
1902 |
351 |
1902 |
79. 201 |
1901 |
227 |
1902 |
203 |
1903 |
196, 198 |
1903 |
250 |
1903 |
241 |
1903 |
196 |
1903 |
24c, 295 |
4o6
D.R.P.
149,801 150.322 151,018 151.384 I5I0II 151. 512
^51.513 152,013
152,175 153.129 153.194 153.517 153,770 154.337 154.353 155.045 ^55,415 155.440 155.572 156,477 156,759 156,762 156,803 156,960 157.123
157,449 157.685 158,076 15S.257
15S.277 158,278 158,287
158.413 158,474 158,531 158,891
158.951 159.129
159,942 160,104 160,169 161,026 161,923
161,954 162,035
162,792 162,824 163,041 163,042
163.447 163,646 163,647 164,129 164,292 164,791 165,140 165,728 165,860
INDEX TO
Paten lee
By.
M.L.B.
B.A.S.F.
I f
By.
Wed. B.A.S.F. Wed. By.
B.A.S.F.
By.
B.A.S.F.
M.L.B.
By.
m.'l.b.
By.
B.A.S.F.
M.L.B.
By.
M.L.B. By.
B.A.S.F. By.
GERMAN PATENTS |
|||
Date. |
Page. |
||
• • |
1902 |
177 |
|
. . |
• • 1903 |
198, 200, 263, 281. |
282 |
1902 |
203 |
||
. . |
1900 |
203 |
|
1902 |
196 |
||
• . 1903 |
198 |
||
• • 1903 |
198 |
||
1900 |
1^4 |
||
1902 |
275, 276 |
||
• • 1903 |
261, 262 |
||
• ■ 1903 |
275. 276 |
||
■ • 1903 |
357 |
||
. . |
1902 |
356 |
|
. . |
• • 1903 |
261, 262, 263 |
|
• • 1903 |
258 |
||
■ ■ 1903 |
259 |
||
. . |
■ • 1903 |
350 |
|
1903 |
258 |
||
• • 1903 |
203 |
||
■ • 1903 |
357 |
||
I901 |
224 |
||
• • 1903 |
287 |
||
. . |
. . 1904 |
227 |
|
• • 1903 |
260 |
||
. . |
• . 1903 |
17 |
|
• • 1903 |
350 |
||
. . 1904 |
343 |
||
1900 |
224, 226 |
||
. . |
. . 1904 |
196 |
|
. . |
. . I904 |
285 |
|
• . 1905 |
287 |
||
• • 1903 |
345, 346, 350 |
||
.. 1903 |
259 |
||
. . |
• ■ 1903 |
346. 350 |
|
• • 1903 |
287 |
||
. . |
• ■ 1903 |
242 |
|
. . |
• ■ 1903 |
228 |
|
I901 |
196 |
||
. . 1904 |
352 |
||
• • 1903 |
179, 278 |
||
. . 1904 |
229 |
||
. . 1904 |
238, 260 |
||
. . |
. . 1904 |
345 |
|
. . 1904 |
261, 262, 386 |
||
. . 1904 |
258 |
||
. . 1904 |
262 |
||
• • 1903 |
232 |
||
. . |
. . 1904 |
238, 262 |
|
. . 1904 |
280 |
||
. . 1904 |
389. 391 |
||
. . |
. . I901 |
196 |
|
. . |
. . 1904 |
283, 284 |
|
. . 1904 |
288 |
||
• . 1903 |
178, 194 |
||
. . |
. . I901 |
229 |
|
. . 1904 |
196 |
||
• • 1903 |
202 |
||
. . 1904 |
278 |
INDEX TO GERMAN
D.R.P, |
Patentee |
166,433 |
By. |
166,748 |
t } |
167.169 |
>> • |
167,255 |
1* • * |
167,410 |
>» • • |
167,461 |
11 ■ * |
167,699 |
M.L.B. . . |
167,743 |
Wed. |
168,042 |
B.A.S.F. . |
I70.II3 |
By. |
170,329 |
Wed. |
170,562 |
By. |
171.293 |
II |
171.588 |
>t |
171,836 |
ft |
171,939 |
B.A.S.F. .. |
172,105 |
M.L.B. . . |
172,300 |
Wed. |
172,464 |
M.L.B. |
172,575 |
By. |
172,609 |
B.A.S.F. .. |
172,642 |
By. |
172,684 |
>i ' ' |
172,688 |
>t ' ' |
172,733 |
it ' • |
174,131 |
M.L.B. .. |
174.494 |
B.A.S.F. .. |
174,699 |
By. |
174.984 |
B.A.S.F. .. |
175,024 |
By. |
175,067 |
B.A.S.F. .. |
175,069 |
By. |
175,626 |
tt |
175,629 |
,, . . |
175,663 |
Wed. |
176,018 |
B.A.S.F. .. |
176,019 |
*» • • |
176,641 |
By. |
176,955 |
»> • ' |
176,956 |
II * * |
177,574 |
B.A.S.F. .. |
178,129 |
By. |
178,130 |
II • * |
178,631 |
II |
178,764 |
Agfa. |
178,840 |
By. |
179.608 |
) 1 • • |
179,671 |
i» • • |
179,893 |
B.A.S.F. .. |
179,916 |
Wed. |
180,016 |
By. |
180,157 |
B.A.S.F. .. |
181,176 |
»i • • |
181,659 |
Wed. |
181,722 |
By. |
181,879 |
M.L.B. . . |
183,332 |
• » ' " |
183,395 |
»* • • |
PATENTS |
407 |
Date. Page. |
|
1904 196 |
|
1904 287 |
|
1903 178. 194 |
|
1904 346, 350 |
|
1904 219. 225 |
|
1904 91, 269 |
|
1904 168. 242, 287 |
|
1904 274 |
|
1903 350 |
|
1904 204 |
|
1903 178. 241 |
|
1904 341 |
|
1904 363 |
|
1904 219. 225 |
|
1905 296 |
|
1904 294. 320, 332 |
|
1904 128 |
|
1905 274 |
|
1903 203 |
|
1905 188 |
|
1904 332 |
|
1903 240, 241 |
|
1905 343, 349 |
|
1904 179. 258, 259, 260. |
278 |
1904 302 |
|
1905 208 |
|
1905 335 |
|
1905 232 |
|
1905 159 |
|
1902 206 |
|
1905 335 |
|
1905 210 |
|
1905 345 |
|
1905 188 |
|
1901 274 |
|
1904 275, 321 |
|
1904 321 |
|
1905 188 |
|
1905 188 |
|
1905 232 |
|
1905 331. 332 |
|
1905 233. 343 |
|
1905 343 |
|
1904 240 |
|
1906 17 |
|
1905 188 |
|
1905 188 |
|
1905 188 |
|
1905 94 |
|
1905 275 |
|
1905 188 |
|
1905 92 |
|
1904 321 |
|
1905 275 |
|
1903 206 |
|
1903 203 |
|
1906 250 |
|
1903 196 |
4o8 INDEX TO |
GERMAN PATENTS |
||
D.R.P. Patentee. |
Date. |
Page. |
|
184,391 By. |
. . 1905 |
341 |
|
184,495 B.A.S.F |
. . 1905 |
91 |
|
184,768 M.L.B |
. . 1906 |
270 |
|
184,807 |
. . 1906 |
270 |
|
184,808 M.L.B |
1906 |
270 |
|
184,905 B.A.S.F |
. . 1906 |
232 |
|
185,221 |
. . 1904 |
329 |
|
185,222 |
. . 1904 |
3JO |
|
185,223 |
. . 1904 |
330 |
|
185,546 M.L.B |
1906 |
196 |
|
185,548 By |
. . 1906 |
290, 292 |
|
186,465 B.A.S.F |
. . 1906 |
233. 343 |
|
186,526 |
. . 1904 |
255 |
|
186,596 |
. . 1906 |
335 |
|
186,636 |
. . 1906 |
345 |
|
186,637 |
1906 |
345 „ |
|
186,882 By. |
1906 |
376. 378 |
|
186,990 B.A.S.F |
. . 1906 |
188 |
|
187,495 |
. . 1904 |
321 |
|
187,685 Wed |
• • 1903 |
274 |
|
188,189 M.L.B |
. . 1906 |
270 |
|
188,193 B.A.S.F |
. . 1905 |
329 |
|
188,596 M.L.B |
1906 |
270 |
|
188,597 |
. . 1906 |
270 |
|
189,234 |
. . 1905 |
294. 295 |
|
189,937 Wed |
. . 1903 |
276 |
|
190,476 By. |
. . 1906 |
179 |
|
190,656 B.A.S.F |
1906 |
96. 335 |
|
190,799 Scholl. |
. . 1906 |
333 |
|
191,111 B.A.S.F |
. . 1906 |
290 |
|
191,731 M.L.B. |
. . 1903 |
196 |
|
192,201 By. |
1906 |
290 |
|
192,436 B.A.S.F |
. . 1906 |
306, 309 |
|
192,484 |
. . 1906 |
270 |
|
192,970 |
. . 1906 |
290 |
|
193,104 M.L.B. |
. . 1906 |
280 |
|
193,121 By. |
. . 1907 |
345, 346, 347. |
351 |
193,272 K |
. . 1907 |
100 |
|
193.959 B.A.S.F |
1906 |
325 |
|
193.961 Heller. |
. . 1906 |
134. 143 |
|
194,252 B.A.S.F |
. . 1906 |
293. 331 |
|
194.253 By. |
. . 1906 |
232, 235, 293 |
|
194,328 M.L.B. |
. . 1906 |
132. 135 |
|
194.955 Wed. |
. . 1906 |
253 |
|
195,028 M.L.B. |
. . 1906 |
253 |
|
195.139 By. |
. . 1907 |
196 |
|
195,874 Wed. |
. . 1903 |
241. 283 |
|
196,752 By. |
. . 1907 |
375 |
|
196,980 M.L.B. |
. . 1907 |
253 |
|
197,082 By. |
. . 1907 |
273, 274 |
|
197,554 B.A.S.F. .. |
1907 |
232 |
|
197,607 By. |
1904 |
241 |
|
197.649 .. .. . |
. . 1904 |
240 |
|
197.933 Scholl |
. . 1906 |
333 |
|
198,024 By. |
1907 |
352 |
|
198,025 B.A.S.F. . . |
1907 |
291, 292 |
|
198,048 |
1907 |
291 |
|
198.507 |
1907 |
345 |
D.R.P.
199,713 199.756 199.758 200,014 200,015 200,335 201,327 201,542 201,904 201,905 202,398 202,770 203,083 203,436 203,752 204,354 204,411 204,772 204,905 204,958 205,035 205,095 205,096 205,097 205,149
205,195 205,212 205,217 205,218 205,294 205,442 205,551 205,881 205,913 205,914 205,965 206,054 206,464 206.536 206,645 206,717 207,668 208,162 208,559 208,640 208,969 209,033 209,231 209,232 209,233 209,321 209,331 209,351 210,019 210,565 210,863
211.383 211.927
INDEX TO
Patentee By. B.A.S.F.
By. B.A.S.F.
m.l!b.
By.
MX.B. Wed.
By.
B.A.S.F.
M.L.B.
By.
B.A.S.F.
G.C.I.B.
M.L.B.
B.A.S.F.
M.L.B.
By.
M.L.B.
By.
G.C.I.B.
B.A.S.F. By. M.L.B. By.
M.L.B.
Wed.
By.
B.A.S.F.
By.
B.A.S.F.
M.L.B.
By.
G.C.LB.
By.
M.L.B.
By.
G.C.LB.
M.L.B. G.C.I.B.
By.
B.A.S.F. Wed. B.A.S.F.
GERMAN PATENTS |
|||
Date. Page. |
|||
1907 290 |
|||
• 1905 95 |
|||
1907 229. 230 |
|||
. 1907 326 |
|||
. 1907 291. 292 |
|||
• 1905 34. 321 |
|||
• 1907 231 |
|||
. 1907 96 |
|||
• 1907 293 |
|||
1907 201, 203 |
|||
• 1903 178. 239. 241 |
|||
• 1907 273 |
|||
. 1906 248 |
|||
• 1906 335 |
|||
1907 290 |
|||
. 1905 322 |
|||
• 1907 391 |
|||
. 1907 183. 187 |
|||
■ 1907 345 |
|||
. 1907 188 |
|||
• 1907 354 |
|||
• 1907 293 |
|||
. 1907 201 |
|||
• 1907 253 |
|||
. 1907 201 |
|||
• 1907 173 |
|||
. 1907 188 |
|||
. 1907 188 |
|||
. 1907 188 |
|||
• 1905 321 |
|||
• 1906 335 |
|||
1907 201 |
|||
1903 202 |
|||
• 1907 173 |
|||
• 1907 355 |
|||
• 1903 238, 278 |
|||
. 1907 183 |
|||
• 1907 300 |
|||
. 1908 183, 187 |
|||
. 1907 196 |
|||
. 1908 232, 235 |
|||
. 1908 250 |
|||
1908 232, 235 |
|||
. 1908 188 |
|||
. 1907 183 |
|||
. 1908 234 |
|||
1907 290, 291 |
|||
1907 188 |
|||
1908 188 |
|||
1908 188 |
|||
. 1908 196 |
|||
1907 188 |
|||
1908 188 |
|||
1908 213. 214 |
|||
1908 345 |
|||
1908 179, 238, 241, |
278 |
||
1908 300 |
|||
• 1908 335 |
409
410 |
INDEX TO Gl |
IRMAN PATENTS |
|||
D.R.P. |
Patentee, Date. |
Page |
|||
211,958 |
B.A.S.F |
. 1908 |
213 |
||
211,967 |
G.C.I.B. . . |
• 1907 |
188 |
||
212,019 |
B.A.S.F. .. |
. 1908 |
335 |
||
212,204 |
ft |
• 1907 |
290 |
||
212,436 |
By. |
1908 |
213, 214 |
||
212,470 |
B.A.S.F. .. |
. 1908 |
232. 235 |
||
212,471 |
»* • • |
. 1908 |
333 |
||
212,697 |
M.L.B, . . |
■ 1907 |
265, |
||
212,857 |
By. |
1908 |
183 |
||
213,501 |
»> • • |
. 1908 |
233. 343 |
||
213,506 |
G.C.I.B. . . |
• 1907 |
188 |
||
213,960 |
By. |
1908 |
186 |
||
214,150 |
i# • • |
. 1908 |
173 |
||
214.156 |
Thiimmler |
. 1909 |
178 |
||
214,714 |
B.A.S.F. .. |
1908 |
174 |
||
215,006 |
>$ • • |
1908 |
91, 173.387 |
||
215,182 |
»» • ' |
. 1908 |
214 |
||
215.294 |
By. |
• 1907 |
211 |
||
216,071 |
B.A.S.F. .. |
• 1907 |
174 |
||
216,083 |
M.L.B. . . |
• 1907 |
231 |
||
216,268 |
>> • ' |
. 1908 |
286 |
||
216,280 |
B.A.S.F. .. |
1908 |
232. 235 |
||
216,306 |
By. |
1908 |
373 |
||
216,480 |
»> ' ' |
. 1908 |
317 |
||
216,597 |
B.A.S.F. .. |
. 1908 |
290 |
||
216,668 |
By. ... |
1908 |
232. 235 |
||
216,715 |
B.A.S.F. .. |
• 1905 |
171, 172 |
||
216,772 |
By. |
. 1908 |
213 |
||
216,773 |
»> • • |
. 1908 |
196 |
||
216,891 |
B.A.S.F. .. |
190S |
352 |
||
216,980 |
By. |
1908 |
213, 214 |
||
217.395 |
B.A.S.F. .. |
• 1907 |
232. 293 |
||
217,396 |
tt |
• 1907 |
232, 293 |
||
217.552 |
By. |
1908 |
178 |
||
217,570 |
B.A.S.F. .. |
. 1909 |
332 |
||
217,688 |
By. |
. 1908 |
374 |
||
218,161 |
B.A.S.F. .. |
• 1907 |
232, 293 |
||
218,162 |
/» • • |
. 1909 |
335 |
||
218,476 |
It • • |
1908 |
294 |
||
218,571 |
By. |
. 1908 |
208 |
||
220,032 |
>» • • |
. 1909 |
227 |
||
220,314 |
,, |
1908 |
355 |
||
220,361 |
B.A.S.F. .. |
. 1909 |
352 |
||
220,579 |
ft |
. 1909 |
211 |
||
220,580 |
By. |
. 1909 |
339 |
||
220,581 |
l> • • |
• 1909 |
232, 234, 235 |
||
220,627 |
»» • • |
. 1909 |
208 |
||
221,853 |
Ullmann |
. 1909 |
306 |
||
222,205 |
B.A.S.F. .. |
. 1909 |
210 |
||
222,206 |
l> • • |
. 1909 |
211 |
||
223,069 |
By. |
. 1909 |
213, 214, 219 |
||
223,103 |
>t • • |
1908 |
253 |
||
223,176 |
G.C.I.B. . . |
1901 |
188 |
||
223,210 |
Kinzlberger & Co |
1908 |
115 |
||
223,510 |
By. |
. 1908 |
213. 214 |
||
223.642 |
Ullmann . . |
. 1909 |
178 |
||
224,019 |
M.L.B. . . |
. 1908 |
180 |
||
224,490 |
*t • • |
. 1909 |
219 |
INDEX TO GERMAN PATENTS
411
D.R.P. 224,500 224,589 224,808 224,982 225,232 225,982 226,215 226,230 226,879 226,940 226,957 227,104 227,324 227,398 227,790 228,876 228,901 229,110 229,111 229,165 229,166 229,316
■229.394 229,408 229,465 230,005 230.052 230,399 230,400 230,407 230,409 230,411
230,454 230.455 231,091
231.853 231.854 232,076 232,127
232.135 232,262 232.526 232,711 232,712
232.739 232,791 232,792 233.072 233,126 234,289
234.294 234.518
234.749 234,922
234.977 235.094 235,312
235.776
Patentee. M.L.B. By.
Ullmann By.
b'.'a.s.f.
Geigy. By.
Ullmann
By.
B.A.S.F.
By."
Agfa.
M.L.B.
Agfa.
B.A.S.F.
By.
B.A.S.F.
M.L.B.
Agfa.
M.L.B.
By.
B.A.S.F.
By."
B.A.S.F. Ullmann G.C.I. B. M.L.B.
By. M.L.B
By. M.L.B.
Agfa.
M.L.B.
Agfa.
By.
Griinau, Landshoff, and
By.
B.A.S.F.
By. Wed.
Meyer
Date. |
Page |
1909 |
350 |
1908 |
187 |
1908 |
213. 214 |
1909 |
197 |
1908 |
213, 218 |
1908 |
355 |
1910 |
330 |
1909 |
149 |
1909 |
188 |
1908 |
213, 214 |
1909 |
188 |
1908 |
213 |
1909 |
197 |
1909 |
213 |
1909 |
352 |
1910 |
174 |
1909 |
170 |
1909 |
188 |
1909 |
220, 222 |
1910 |
373 |
1909 |
347. 350 |
1909 |
287 |
1909 |
163 |
1909 |
220 |
1909 |
188 |
1910 |
341 |
1910 |
232 |
1909 |
211 |
1909 |
211 |
1909 |
234 |
1909 |
211 |
1909 |
211 |
1909 |
353 |
1910 |
144. 304 |
1909 |
196 |
1909 |
220 |
1909 |
318 |
1909 |
381 |
1909 |
208 |
1909 |
221 |
1909 |
233 |
1910 |
341 |
1910 |
373 |
1910 |
373 |
1909 |
219 |
1909 |
221 |
1909 |
221 |
1910 |
373 |
1909 |
293 |
1908 |
76 |
1909 |
350 |
1910 |
212 |
1910 |
332 |
1910 |
222 |
1909 |
312. 317 |
1910 |
381 |
1910 |
208 |
1909 |
199 |
412
INDEX TO GERMAN PATENTS
D.R.P.
236,375 236,442 236,769 236.857 236,978
236,979 236,980
236,981 236,982 236,983 236,984
237,751 237.946 238,158 238,253 238,488 238,550 238,551 238,552 238,553 238,979 238,980 238,981 238,982
238,983 239,211
239,543 239,544 239,671 239,762 240,002 240,079 240,080 240,192 240,265 240,276 240,327 240,520 240,792 241,472 241,624 240,631 241,786 241,805 241,806 241,822 241,837 241,838 241,985 242,029 242,063 242,291 242,292
242,379 242,386 242,621
243,077 243-489
Patentee M.L.B. B.A.S.F. M.L.B. B.A.S.F. M.L.B.
G.E.
Wed.
B.A.S.F.
G.E.
By.
M.L.B.
B.A.S.F.
m.l!b.
By.
Ullmann
By.
M.L.B.
By.
SchoU
M.L.B.
B.A.S.F.
M.L.B.
By.
m!l.b.
B.A.S.F.
Agfa.
B.A.S.F.
Scholl
G.E.
B.A.S.F.
By. M.L.B.
Casella
B.A.S.F.
M.L.B.
Ullmann B.A.S.F. Scholl Agfa.
Date. |
Page. |
1909 |
220 |
1910 |
214 |
1910 |
209 |
1910 |
297 |
1909 |
220 |
1909 |
220 |
1909 |
220 |
1909 |
220 |
1909 |
221 |
1909 |
220 |
1909 |
220 |
1910 |
335 |
1909 |
188 |
I910 |
297 |
19IO |
387 |
1910 |
235 |
1909 |
219, 220 |
1909 |
220 |
1909 |
220 |
1909 |
220 |
1910 |
345. 350 |
1910 |
335 |
19IO |
220, 365 |
1910 |
366 |
1910 |
317 |
1910 |
343 |
1909 |
312, 313 |
19IO |
379 |
1910 |
336 |
1909 |
183 |
1910 |
306 |
1909 |
218 |
1910 |
234. 361 |
1909 |
220 |
1909 |
350 |
19IO |
232 |
1909 |
306 |
1910 |
160 |
1910 |
188. 350 |
1910 |
92, 159 |
1910 |
33. 143. 164 |
1910 |
335 |
1911 |
160 |
1911 |
223 |
1911 |
255 |
1909 |
219 |
I910 |
212 |
I910 |
212 |
1908 |
183 |
1910 |
188 |
I911 |
313 |
1909 |
221 |
1909 |
219, 221 |
1910 |
285 |
1910 |
318 |
1911 |
188 |
1911 |
164 |
1909 |
210, 211 |
INDEX TO GERMAN PATENTS
413
D.R.P. 243.586 243.587 243.649 243.750 243.751 243.788
244.372 245,014
245.191 245,768
245.875 245.973 245.987 246,079 246,085 246,086 246,477 246,867 246,966 247,187
247.245 247,246
247.352 247,411 247,412 247,416 248,169 248,170 248,171 248,289 248,469 248,582 248,655 248,656 248,838 248,996 248,997 248,998 248,999 249,225 249.368 249,721 249.938 250,075 250,090 250,271 250,272 250,273 250,274 250,742 250,885 251,020 251,021
251. 115 251.234
251.235 251.236 251.350
Patentee M.L.B.
B.A.S.F. G.C.I.B.
Ullmann Wed.
M.L.B.
G.E.
By.
m!l.b.
B.A.S.F.
Agfa.
B.A.S.F.
J. Meyer
Wed.
By.
M.L.B.
B.A.S.F.
Casella
By.
B.A.S.F.
By.
M.L.B.
B.A.S.F.
By.
B.A.S.F.
Agfa.
B.A.S.F.
Ullmann
m.l!b.
By.
m!l.b.
K. Meyer
By.
Schaarschmidt
B.A.S.F. G.E. B.A.S.F. M.L.B.
B.A.S.F. M.L.B.
If
By. M.L.B.
Date. |
Page. |
1909 |
306, 308, 313 |
1910 |
317.318 |
1910 |
286 |
1911 |
317 |
1911 |
188 |
1909 |
162 |
1910 |
199 |
1910 |
199 |
1910 |
387 |
1910 |
350 |
1910 |
306 |
1910 |
387 |
1911 |
255 |
1911 |
266 |
1910 |
387 |
1911 |
222 |
1911 |
223 |
1909 |
188, 350 |
1911 |
306 |
1911 |
322 |
1911 |
199 |
1911 |
366 |
1909 |
387 |
1911 |
196, 199 |
1911 |
184 |
1911 |
188 |
1911 |
359 |
1911 |
306 |
1913 |
189, 35 |
1908 |
213 |
1910 |
318 |
1911 |
353 |
1910 |
211 |
1911 |
223 |
1911 |
194 |
1911 |
313. 318 |
1911 |
214 |
1911 |
354 |
1911 |
92, 297, 302 |
1908 |
186 |
1911 |
255 |
1911 |
175 |
1910 |
233 |
1910 |
23.46 |
1911 |
371 |
1910 |
318 |
1910 |
319 |
1911 |
187 |
1911 |
387 |
1911 |
163 |
1911 |
291 |
1911 |
380 |
1911 |
234. 361 |
1911 |
187 |
1911 |
188 |
1911 |
188 |
1911 |
255 |
1911 |
234. 361 |
414
INDEX TO GERMAN PATENTS
D.R.P. |
Patentee. |
251,480 |
Schaarschmidt |
251,695 |
By |
251,696 |
B.A.S.F |
251,709 |
>» • • • • |
251,845 |
W.t.M |
251,956 |
By. |
252,529 |
I> • • • • |
252,530 |
f, • • • • |
252,578 |
B.A.S.F |
252,759 |
By |
252,839 |
»> • • • • |
253,088 |
G.E |
253.089 |
By |
253.090 |
B.A.S.F |
253.238 |
M.L.B |
253,507 |
tl • • • • |
253,683 |
1* • • " • |
253,983 |
Sanders . . |
254,033 |
Schaarschmidt |
254,091 |
Agfa |
254,097 |
B.A.S.F |
254,098 |
G.C.I.B |
254.185 |
M.L.B |
254,186 |
t > • • • • |
254.450 |
B.A.S.F |
254.475 |
M.L.B |
254.561 |
By |
254.710 |
Griinau, Landshoff, and |
254.743 |
UUmann . . |
254.744 |
M.L.B |
254,745 |
By |
255,031 |
»» • • • ' |
255,121 |
f* |
255.340 |
M.L.B |
255.591 |
Ullmann and Goldberg |
255.641 |
G.E |
255.821 |
M.L.B |
255.822 |
f> • • • • |
256.297 |
>> • ' • • |
256,344 |
B.A.S.F |
256,515 |
,, |
256,623 |
M.L.B |
256,626 |
tP • * • • |
256,667 |
By |
256,761 |
M.L.B |
256,900 |
By |
257,811 |
M.L.B |
257,832 |
Wed |
258,343 |
Agfa |
258,556 |
M.L.B |
258,561 |
B.A.S.F |
258,808 |
Agfa. |
259,037 |
By |
259,365 |
B.A.S.F |
259.370 |
,, |
259,432 |
G.E |
259,881 |
M.L.B |
260,020 |
B.A.S.F |
Meyer
Date, |
Page, |
I910 |
365 |
I9II |
62 |
I9II |
316 |
I9II |
187 |
19II |
211 |
I911 |
341 |
I9II |
341 |
I91I |
378 |
I9II |
173 |
I9II |
74 |
I9II |
368, 369, 372 |
19II |
387 |
I91I |
372 |
1911 |
308 |
I910 |
387 |
1908 |
186 |
1909 |
179, 230, 231 |
1911 |
317 |
19II |
365 |
I9II |
136 |
I912 |
353 |
I9II |
188 |
I911 |
225 |
I9II |
233 |
I9II |
173 |
I9II |
305 |
I912 |
186 |
1910 |
76 |
I9II |
372 |
19IX |
220 |
I912 |
388 |
I912 |
129, 138 |
1912 |
165 |
I910 |
387 |
I910 |
186 |
I912 |
364 |
I9II |
210 |
1911 |
233 |
1911 |
292, 293 |
I912 |
196 |
1911 |
206 |
I9II |
76 |
I9II |
306, 313 |
I912 |
374 |
I912 |
390 |
I9II |
222 |
1909 |
232 |
I912 |
286 |
I912 |
194 |
I9II |
93 |
I910 |
318 |
I910 |
379 |
I9II |
368, 372 |
I912 |
163 |
I912 |
331 |
I912 |
227 |
I912 |
95 |
1912 |
331 |
INDEX TO GERMAN PATENTS
415
D.R.P.
260,562 260,662 260,765 260,899 260,905 261,270 261,271 261,495 261,557 261,737 261,885 262,076 262,469 262,477 262,478 262,788 263,078 263,340 263,395 263,423 263,424 263,621 264,010 264,043 264,139 264,290 264,940 264,941 264,943 265,194 265,647 265,725 265,727 266,521 266,563 266,945 266,946 266,952 267,081 267,212 267,414 267,415 267,416 267,417 267,418 267,445 267,522 267,523
267,544 267,546 267,833 268,049 268,219 268,224 268,454 268,504 268,505 268,646
Patentee. |
Date. |
Page |
|||
B.A.S.F. . |
. 1912 |
49 |
|||
M.L.13. . |
. 1911 |
95 |
|||
By. |
1911 |
264 |
|||
Agfa. |
. 1912 |
194 |
|||
B.A.S.F. . |
1911 |
371. 372 |
|||
»» • |
1911 |
230 |
|||
j» |
. 1911 |
230 |
|||
Casella |
1911 |
360, 362 |
|||
G.C.I.B. . |
. 1912 |
188 |
|||
B.A.S.F. . |
. 191 1 |
366, 367 |
|||
Agfa. |
1912 |
196 |
|||
G.E. |
. 1912 |
227 |
|||
By. |
. 1912 |
379 |
|||
M.L.B. . |
1911 |
186 |
|||
G.C.I.B. . |
. 1912 |
326 |
|||
M.L.B. . |
. 1911 |
234 |
|||
B.A.S.F. . |
1912 |
313 |
|||
M.L.B. . |
. 1912 |
180 |
|||
B.A.S.F. . |
. 1911 |
179. 231 |
|||
By. |
1911 igii |
287 196 |
|||
Wed. |
. 1911 |
286 |
|||
By. |
igi2 |
292 |
|||
G.E. |
. 1912 |
340 |
|||
By. |
. 1912 |
374 |
|||
»» • |
1912 |
367 |
|||
»» |
1912 |
185 |
|||
ft |
. 1912 |
185, 188 |
|||
B.A.S.F. . |
1912 |
373 |
|||
G.C.I.B. . |
. 1912 |
188 |
|||
Wed. |
. 1912 |
286 |
|||
M.L.B. . |
1912 |
196 |
|||
B.A.S.F. . |
. 1911 |
179, 231 |
|||
M.L.B. . |
. 1912 |
180 |
|||
B.A.S.F. . |
1911 1912 |
179. 231 356 |
|||
J» |
. 1912 |
356 |
|||
B.A.S.F. . |
. 1911 |
359 |
|||
Afga. |
1912 |
159 |
|||
M.L.B. |
1912 |
206 |
|||
Casella |
. 1912 |
210 |
|||
n |
1912 |
210 |
|||
it |
. 1912 |
210 |
|||
M.L.B. . |
. 1912 |
380 |
|||
B.A.S.F. . |
1912 |
331 |
|||
By. |
. 1912 |
225 |
|||
M.L.B. . |
. 1912 |
234. 361 |
|||
B.A.S.F. . |
1912 |
373 |
|||
M.L.B. . |
. 1911 |
173 |
|||
»» |
• 1909 |
95 |
|||
M |
1912 |
234. 360 |
|||
B.A.S.F. . |
. 1909 |
76 |
|||
»i • |
. 1912 |
306 |
|||
»f |
• 1913 |
331 |
|||
M.L.B. . |
. •- |
1912 |
196 |
||
B.A.S.F. . |
1912 |
339 |
|||
By. |
• 1913 |
365 |
|||
Brass |
. 1912 |
306 |
4i6 INDEX TO GERMAN PATENTS
D.R.P. Patentee. Date. Page. ,|
268,793 By. 1912 293 ]!
268,984 „ 1912 225
269.194 B.A.S.F 1911 314
269,215 Wed 1912 286
269,249 Agfa 1913 171
269,749 M.L.B 1913 196
269.800 Schaarschmidt 1912 307,317
269.801 Cassella 1912 210
269,842 By. 1913 365
269,850 B.A.S.F 1912 306
270,579 By. .. .. .*. .. 1912 213
270.789 M.L.B 1912 362
270.790 „ 1912 196
271,475 By. 1911 222
271,681 M.L.B 1911 173
271,790 „ 1913 165
271,902 Agfa 1912 354 '
271,947 G.E 1913 350
272.296 B.A.S.F 1913 307
272.297 „ 1913 308
272.298 By. 1911 186
272.299 „ 1912 280
272.300 „ . . . . . . 1912 186
272.301 „ 1913 264
272.613 M.L.B 1912 362
272.614 „ 1912 196
273.318 M.L.B 1912 76
273.319 ,. 1912 76
273,341 By 1913 163
273.443 G.E 1913 388
273.444 M.L.B 1913 356
273,809 Junghaus . . . . . . . . 1911 230
274,357 By. 19" 186
274.783 SchoU 1913 286
274.784 .. 1913 91
275,220 Kardos 1913 330. 384
275,248 „ 1913 384
275,299 By. 1912 231
275,517 M.L.B 1913 165
275.670 B.A.S.F 1912 360
275.671 .. 1913 307
276.357 Kardos 1913 33°
276.358 „ 1913 330
276,956 „ 1913 330
277.393 G.E 1913 179
277,439 M.L.B 1912 181, 186
277.733 Hofmann 1913 75
278,424 B.A.S.F 1913 335
278,660 Kardos 1913 33°. 384
279,198 M.L.B 1914 363
279.866 B.A.S.F 1913 226
279.867 „ 1913 232
280,092 „ 1913 69
280,190 M.L.B 1913 290, 362
280,646 Agfa 1913 196
280.710 B.A.S.F. .. 1913 331
280.711 Cassella . . 1913 315
280.712 „ 1913 307
INDEX TO GERMAN PATENTS
417
o
2 O
5
3
D. ?.
280 39
280 4^0
280 io
280^1
280,52
280,53
280, 5
281
281,
281,
282,:
282,.
282,41
282,€:
282,7:
282,8;
282,9 '
283,0
283,1.
283,2
283.31
283,4^
283,7^
283,72
284,08
284,08
284,17
284,18
284,20
284,20;
284,20c
284,21c
284,70c
284,790
284,976
286,092
286,093
286,094
286,095
286,096
286,098
286,468
287,005
287,270
287,523
287,590
287,614
287,615
287,867
288,464
288,474
288.665
288,824
288,825
288,842
288,878
289,112
289,279
Patentee Kardos By. B.A.S.F.
M.L.B.
Agfa.
By.
UUmann
By.
UUmann
M.L.B.
Kardos
M.L.B.
Agfa.
B.A.S.F.
M.L.B.
G.E.
B.A.S.F.
Agfa.
B.A.S.F.
Cassella
G.E.
M.L.B.
Kardos
B.A.S.F.
M.L.B.
By. •Cardos
"assella
J.A.S.F.
assella
[.L.B.
.A.S.F.
y-
.A.S.F.
y-
?fa.
:l.b.
l^L.B.
Date; |
Page. |
[913 |
330. 384 |
913 |
365 |
[913 |
330 |
f9l3 |
210 |
C913 |
373 |
[913 |
373 |
[913 |
285 |
[913 |
220 |
[913 |
183 |
914 |
167 |
913 |
164 |
914 |
127, 138 |
[914 |
276 |
^913 |
196 |
913 |
330. 384 |
t9i3 |
47 |
[913 |
222 |
913 |
321. 330 |
[912 |
43 |
[913 |
75 |
[913 |
330 |
914 |
288 |
913 |
307 |
^913 |
373 |
914 |
75 |
914 |
75 |
914 |
75 |
913 |
368 |
913 |
366 |
913 |
363 |
913 |
291 |
913 |
330. 384 |
913 |
331 |
913 |
44 |
913 |
173 |
913 |
1 96 |
913 |
368 |
913 |
368 |
914 |
312 |
914 |
307 |
914 |
330 |
914 |
330 |
914 |
373 |
913 |
254. 335. 343 |
914 |
373 |
913 |
350 |
914 |
306, 312 |
914 |
312 |
914 |
179, 279 |
914 |
206 |
914 |
179, 279 |
914 |
196 |
914 |
361 |
914 |
208 |
913 |
368 |
914 |
178 |
914 |
179, 279 |
914 |
35*5 |
27
4i8
INDEX TO GERMAN PATENTS
D.R.P.
290,079
290,084
290,814
290,879
290,983
290,984
291,984 _
292,066
292,127
292,247
292,356
292.395
292,457 292,590
292,681
293,100
293,156
293.567
293.970
293.971 295,624 296,019 296,091 296,192 296,207 296,841 297,079 297,080 297,261
297.567 298,182 298,183
298,345 298,706 299,510 301.452
301,554 302,259 302,260 305,886
307,399 308,666 311,906
Patentee B.A.S.F. G.E.
Agfa.
M.L.B.
By.
G.E.
Ullmann
G.E.
M.L.B.
B.A.S.F.
Agfa.
M.L.B.
Wed.
M.L.B.
By.
M.L.B.
By.
G.E.
Wed.
M.L.B.
Wed.
By.
M.L.B.
Wed.
By.
G.E.
By.
Scholl.
M.L.B.
Date. |
Page |
1914 |
329 |
1914 |
184 |
I914 |
224 |
1914 |
173 |
1913 |
355 |
1914 |
291 |
1914 |
222 |
19I4 |
13S |
1915 |
350 |
I913 |
2B7 |
1914 |
48 |
1914 |
224 |
1914 |
183 |
1914 |
49 |
1914 |
76 |
1914 |
197 |
1913 |
171 |
1913 |
393 |
1913 |
88 |
1914 |
350 |
1912 |
196 |
1915 |
50 |
1915 |
84, 271 |
I915 |
350 |
1912 |
188 |
I914 |
350 |
1912 |
188 |
1912 |
188 |
1915 |
271 |
I913 |
188 |
1973 |
188 |
I913 |
188 |
1916 |
130, 157 |
1913 |
366 |
1913 |
188 |
1916 |
84, 271 |
1914 |
364 |
1914 |
364 |
1916 |
364 |
1917 |
84, 271 |
1916 |
297 |
1916 |
232 |
1913 |
188. 371 |
INDEX TO AUTHORS
AcHENBACH, 77, 78, 369
Aders, 285
Akt. Ges. f. Anilinl? Fabrikation (Agfa), 17, 64-66. 136, 159, 173, 188, 194, 196, 210, 211. 220, 222. 288, 354, 373. 379
Akt. Ges. f. Teer u. Erdfil Indus- trie, 17
Akt. Ges. Griinau, Landshoff u. Meyer, 76
Anderson. 1, 2, 42, 43
Anschutz, 15, 29, 30. 36, 37
Appenrodt, 17, 18
Atack, 398
Athenberg, 14
Auerbach, 126, 294
Auffenberg, 229
Auwers, 18
Bach, 37, 86, 87
Badische Anilin u. Soda Fabrik (B.A.S.F.). 7. 34, 49, 69, 76, 91, 92, 94. 159, 160. 163, 172-174, 179, 184. 187-189. 194, 196-199. 203, 206, 210. 211, 213, 214, 222-224. 226-235, 243, 246, 249, 251, 254, 255. 261-263, 270, 284, 290-297, 300, 306-309, 312-318, 320-322, 329-333, 335, 339, 343, 345, 347. 350-353. 359, 360, 366, 367, 371-373, 387
Baeyer, 21, 96. 98. 104. 109. 123. 127. 128
Bally, 4, 294, 320, 321, 325, 332
Baly. 18. 149, 268
Bamberger, 39, 269, 328
Barret Co., 76
Bayer u. Co. (By.), 7, 17, 62, 67. 74. 79. 84. 91. 92. 96, 130. 157, 163- 165, 169, 170, 173, 175, 177-180, 183, 186-188, 192, 194, 196-198. 200-214, 218, 219, 222, 224, 225, 227-229, 231-235, 238-244. 246- 248, 251, 253, 254, 258-266, 269- 274, 276-284, 287. 288, 290-293, 295, 296, 307, 312. 313, 31-7, 326, 335, 339, 341, 343, 345, 346, 349-352. 355, 357, 358. 361. 363, 365-376. 378-381. 388, 389, 391
Bechamp, 383
Behla, 69
Behr, 14, 125, 132
Benda, 382, 386
Benesh, 92, 301
Bentley, 132, 148, 149, 151, 152,
239 Berblinger, 228, 229, 247, 350, 351 Bernthsen, 347, 379 Berthelot, 1. 14 Billig, 49, 137, 306, 308, 311 Binder, 273
Birnkoff. 26, 34, 126, 128. 163 Bischoff, 64, 69 Bistrzycki, 97, 133, 139 Bliss, 116 Blumenfeld, 68, 70, 140, 165, 167,
207 Boeck, 65, 237, 266 Bohn, 3, 4, 5. 94 Bollert, 67, 68. 176 Bondy, 117, 334 Bornstein, 27, 164 Bottger, 167, 168, 192, 244, 249,
386 Brass, 211, 306 Braun, 396 Brewer. 375 British Dyes, Ltd., 7 British Dyestuffs Corporation, Ltd.,
7 Brunck, 296 Bucherer, 251 Buchka, 347, 375 Burchker, 133 Burg. 14 Butescu. 162 Byk. 25
Cameron. 24
Caro, 3, 127. 128, 176, 281
Cassella u. Co. (Cas.), 188, 210, 307,
315, 360, 362. 373. 397 Chem. Fabrik. Akt. Ges. Hamburg,
17 Chojnacki, 238 Ciamician, 27, 164 Clark, 17. 85, 87 Clans, 180, 192, 193. 244
419
420
INDEX TO AUTHORS
Clemmensen, 84
Colman, 134, 143
Conzetti, 138, 173, 248, 249, 274,
306, 386 Crafts, 29, 35-37, 133, 134 Crossley. 129, 176, 238
Dammann, 379
Dandridge, 345
Davis, 186
Decker, 187, 247, 275, 376-380
Dehnst, 176
Deichler, 139, 147-152
Delacre, 16
Dewar, 32, 36, 37
Dhar, 392
Dickhuth, 347
Diehl, 41, 42, 170, 238
Dienel, 65-69, 73, 162,105,237,266
Dimroth, 24. 50, 67, 92, 93, 116,
129, 139, 237, 238, 261, 263, 266,
269, 274 Dootson, 306 Doralle, 269
van Dorp, 14. 32, 125, 132 Drewson, 127 Dumas, 1, 14 Diinschmann, 177
Eberle, 168, 224, 226
Eckert, 82, 92, 95, 96, 98, 114-117, 160, 164, 165, 168, 170-172, 174, 175, 192, 207, 224, 232-234. 242, 249, 273, 280, 309-311, 313, 333, 334, 343
Ehrenreich, 360
Ehrhart, 17, 75
Elbs, 24, 26, 27, 29, 30, 32-35, 70, 81, 82, 132, 133-135. 143, 162, 164
Errera, 330
Ertl, 340
Eurich, 32, 33
FiCK, 129, 139, 238. 261, 263, 266 Fischer, O., 25-28, 39, 43, 47-49,
162-164, 168, 247, 248, 267, 268,
282, 285, 288 Fleisher. 70. 384 Freund. 77. 78, 369, 384 Ere}', 139, 196, 232, 248, 287, 317 Friedel, 29, 35, 36, 133, 134 Friedemann, 237 Friedl, 148, 149. 151. 152 Friedlander, 100 Friess, 181-183, 186, 187, 229, 273,
370, 374 Fritsch, 37
Fritzsche, 1, 24, 168, 195 Frobenius, 180, 238, 240, 241
Gabriel, 134, 143, 145-147, 150-
152 Gardner, 132 Gattermann, 183. 186. 187, 238,
239, 246, 309, 370, 374, 379, 386,
388, 389 Geigy & Co., 149, 206 Georgievics. 239, 258, 260, 271, 272 Ges. f. Chem. Ind. in Basel
(G.C.I.B.). J44, 188, 206, 326,
335, 350, 351 Gibbs, 75
Gimbel, 82, 114, 124 Girard, 281 Glock, 164, 165 Godchot, 39, 40, 41 Goldberg, 186 Goldmann, 67, 98, 105, 106 Goldschmidt, 77, 328 Gosch, 79 Graebe, 2, 3, 17, 24, 42, 43, 45, 46,
48, 61, 68-70, 74, 79, 82, 113,
133, 140, 143, 144, 165, 167, 168,
176, 178. 207, 239. 243. 247, 278,
285, 294. 296. 325. 330. 347 Grandmougin, 83, 113, 265 Grawitz, 281 Gresly, 27, 32, 34, 35, 132-134, 140.
163 Griesheim Elektron (G.E.), 75, 184,
222, 224, 227, 267, 304, 340, 350.
364, 387, 388 Grimm, 128 Gross, 285 Guyot. 87. 88. 97, 101, 103, 113.
133. 140, 393
Hagen. 66, 244
Halla, 306, 309-311, 313
Haller, 86-88, 90, 97, 101. 103. 113,
140, 393 Hallgarten, 107 Hammerschlag, 42-44, 46, 164 Hansgirg, 399 Hantzsch, 60, 168 Harrop, 132, 148, 149, 151, 175, 187,
197 Hartenstein, 157 Haslinger, 65, 173 Haworth, 398 Heffter, 62, 66 Heinemann, 76 Heller, 32, 33, 130, 132, 134, 137,
140, 143, 144, 150, 162. 164, 173.
175, 198, 200, 347 Hepp, 94, 172, 174, 180, 238, 240,
241 Herzenberg, 397
INDEX TO AUTHORS
421
Hinsberg, 181
Hodgkinson, 15
Hofmann, 75, 76, 82, 114-116, 138,
326 Holdermann, 168 HoUiday (L.B.) & Co.. Ltd., 7, 272,
276 Hormann, 64, 65, 237, 26() Hovermann, 139, 248 Hutchison, 186
Iljinsky, 3, 5, 177 Imhoff, 43 I pat jew, 40 Isler. 4, 5
Jackson, 15 Jacowlew, 40 Jones, 33, 36, 37 Jowett, 27 Jnngermann, 38 Junghaus, 330
Kabacznik, 348
Kacer, 192, 341, 386
Kaiser, 135
Kalb, 322
Kalischer, 160, 315
Kalle & Co. (K.), 100, 126
Kardos, 330, 383-385
Kauffler, 43, 77, US, 121, 168, 173,
199, 209, 242, 349, 387 Kauffmann, 146 Kammerer, 237 Kehrmann, 66 Kempf, 76 Keppich, 70 Kinzlberger & Co., 117 Kircher, 49, 138, 172 Kirschbaum, 396
Klingenberg, 94, 159, 160, 172, 175 Klinger, 154 Klobukowski, 263 Knoevenagel, 91 Knuppel, 294 Konig, 210 Kopp, 74
Kraemer, 14, 27, 28, 34, 35 Kummerer, 25
Lagodzinski, 65-67, 73, 139 Lampe, 63, 65, 66, 81 Landshoflf, 55, 56 Laube, 173, 210, 247, 275, 287, 359,
376, 377 Laurent, 1,2
Lauth, 167, 192, 193. 385-387 Lavaux, 26, 29-33, 70, 79, 164 Law, 272, 276
Lawrence, 397
Le Royer, 137
Leonhardt, 140
Lesser, 92
Letny, 14
Leupold, 145-147, 150-152
Lever, 315
Levi, 86, 87
Levinstein, Ltd., 7
Lewis, 75
Libkind, 359
Liebermann, 2, 3, 5. 14, 21, 24, 27, 39, 42-52, 55-57, 61, 63-70, 74, 79-82, 96, 98, 99, 102, 104, 106, 108, 109, 113, 114, 118, 127, 128, 133, 147, 164, 165, 168. 176-178. 202, 237-239, 243, 244, 247, 265. 266, 278. 280, 347, 383, 385
Liebig, 116
Lifschiitz. 180, 192, 240, 244. 249
Limpricht, 1, 15, 28, 33. 133. 134, 141, 164
Lindemann. 51, 52, 57
Lindenbaum, 44. 104
Linebarger, 24, 393
Linke. 61. 65
Lippmann, 37, 48. 70. 71
Lodter, 39
Louise, 33, 34, 141
Maffelzzoli. 164, 165, 207
Majert, 293
Mamlock, 101
Mansfield, 351
Marchlewski, 77
Mayer, 315
Medenwald. 211, 224-226. 231. 342. 365
Meek. 267, 271
Meerwein, 100, 101
Megraw, 28
Meisenheimer. 50-54. 56-58, 60, 61, 67
Meister. Lucius u. Briinning (M.L.B.). 4, 43, 47-50, 76. 93. 95, 128, 132, 135, 136, 138, 140, 165, 168, 173, 179-181. 183, 186, 188, 193, 194, 196. 198, 201, 203. 206, 208, 210. 212. 218-222, 224-227. 230-234. 240-242. 249, 250, 253, 258, 259, 263, 265, 270, 277, 280- 282, 284-287. 290-295. 306, 309. 312. 317. 318. 341, 350, 354-357, 360-363, 366. 368, 371, 372, 375, 380. 387, 390, 391. 400
Mettler. 132, 136, 249
Metzler. 326
Meyer. B., 324
Meyer. F., 32, 134
422
INDEX TO AUTHORS
Meyer, H., 83, 115, 117, 124, 334 '
Mever. J., 322
Mever, K., 21-23, 42-46, 54, 60, 61, 77, 81, 96, 98, 101, 107, 111, 117-120, 123, 124, 326, 394-398
Meyer, R., 15, 267, 268
Mej-er, V., 78 ■
Michael, 145
Mills, 156, 157 !
Mohlau, 273, 364, 389-391 '
Molinari, 17 j
Morton, 345 I
Miihle. 383
Nathanson, 146
Neovious, 141
Niementowski, 28, 295
Nienhaus, 242, 266
Nietzki, 28, 128, 164. 194
Noah, 239
Noelting, 192, 194, 195, 224
Norris, 132, 148, 149. 151, 175. 187,
197 Nourrison, 139
Orchardson, 148-152 Orndorf, 24, 28, 116. 375 Ort, 294 Oudemas, 28
Paar, 270 Pabst, 281 Padova, 39, 67, 86, 87, 98-100,
116-118 Parthey, 202 Pechmann, 133
Perger, 82, 110, 176, 201, 202, 278 Parkin, A. G., 50, 53, 54, 57, 60,
103, 164, 321, 326, 327, 329. 345, Parkin, W. H., 3, 15, 43, 176, 178,
281 Perrier, 70 Peter, 144 Petersen, 167, 168. 192, 244, 249,
386 PhiUppi, 76, 156, 157 PhiUips, 296 Pisovschi, 65, 67, 68, 73 Plath, 265, 276, 282, 285 Pleus, 69, 81, 177, 265 Pollok, 37, 48, 71, 96 Pother, 27
Potschiwauscheg, 302, 334 Praetorius, 269 Prescott, 186 Prud'homme, 3, 202. 294 Przibram & Co., 192, 198, 278 Pschorr, 155
Qua, 133 Quoos, 75
Radulescu, 43, 46, 48
Rakitin, 40
Rath, 61, 69, 164
Ray, 393
Rebsamen, 248
Ree, 137
Reinkober, 39,*48, 164
Remmert, 20, 38, 88, 393
Remy, 17
Ritter, 75
Robiquet, 126
Romer, 67, 82, 94, 126, 167, 168.
172, 174, 176, 192, 193, 229, 240,
249, 253, 280, 281 Romig, 30
Rosentiel, 80, 126, 281 Roser, 145 Roux, 137 Russig. 157 Rubidge, 133
Sachs, 206
Sadler & Co., 74
Sander, 395
Sanders, 317
Sandmeyer, 168
Sapper, 163, 247
Sarauw, 347
Sava, 66
Schaarschmidt, 134, 140, 160, 161. 166, 168, 187, 192, 193, 196-198, 207, 295, 307-309, 312-314. 317, 318. 323, 324, 353, 365, 367. 369, 386-388, 397, 398
Schardinger, 280
Schenk, 379, 380
Schapper, 133, 139
SchifE, 126
Schilhng, 47, 49, 174
Schlank, 17, 18, 102
Schlossar, 394, 395
Schmidt, E., 24, 195
Schmidt, R. E., 3, 5, 65, 81, 177, 178, 180, 192. 206, 238, 239, 287, 241. 259, 389
Schmidt. W.. 138
Schneider, 75
Schoeller. 128
SchoU, 4, 5, 10, 28, 33, 80, 91, 92, 94, 95, 116, 133-136, 141. 143- 145, 156, 157, 164, 168, 173, 188, 192. 195, 202, 207, 224, 226, 228- 230. 269, 273, 286, 297. 300-303, 320, 321, 325. 328, 329, 331, 333- 336, 339-341, 343, 346-352, 358, 360, 363, 386, 389
INDEX TO AUTHORS
423
Schramm, 15
Schrobsdorf. 201, 238. 247. 266,
273, 275, 277. 280 Schuhmann, 396 Schiller, 65, 66 Schiilke, 130, 132-134, 137. 140,
143, 162 Schiiltz, 14, 27, 164 Schulze, 21-23, 82, 93, 114, 269. 274 Schumpelt, 75
Schunck, 77, 126. 176, 240. 253, 281 Schurmann, 181-183, 186, 187, 273.
370, 374 Schwazer, 43, 46, 82, 280 Scottish Dyes, Ltd., 7 Seer, 30, 32, 36, 84, 92, 133, 136,
141, 164, 165, 169, 184, 192, 207,
213, 214. 232. 233 Seuberlich, 126 Simon, 239. 250, 280 Simonis, 20. 38, 88, 393 Smiles, 186
Societe Anon, des Mat. Col., 62. 140 Sone, 353 Sonn. 220
Spilker, 14, 27, 28, 34. 35 StahUng. 87 Stahlschmidt, 192, 295 Staudinger, 14, 78 Strecker, 2 Stein, 315 Steiner, 170, 171, 175, 224, 232. 234,
273, 280, 343 StegmuUer. 348 Steinkopf. 348 Stewart, 268 Strobel, 281 Suchannek, 77, 118, 121
Terres, 163, 166, 193, 207. 340.
341, 343 Thai, 17, 18
Thomas, 148, 149, 151, 152 Thorner, 98 Thiimmler, 178
Tomaschek, 92, 98, 117, 333, 334 Troschke, 202 TschiUkin, 86, 87 Tuck, 149
Uffers, 97 Uhlenhuth, 94. 172, 174
Ullmann. 5. 49, 92, 94, 95, 127. 132. 133, 137, 138, 159. 160. 162, 163, 165-167, 171-173, 175, 178. 180. 183, 186, 187. 192, 193, 196. 197, 200, 211, 224-226, 229, 231. 232. 248, 249, 274, 276, 287. 297, 302, 305-308. 311-318, 341, 342. 346. 350, 353, 354, 358, 359, 361, 365- 368, 372-374, 380, 381, 386
Unterkreuter, 399
tirmenyi, 315
VoswiNCKEL, 147, 152-154
W.^CKER, 192, 209, 389
Walker, 169
Walsch. 132, 175, 178, 192
Waschendorf, 27, 29, 164
Watson, 267, 271
Wedekind & Co. (Wed.), 178, 179.
188, 199, 238, 241. 253, 271, 273-
276, 278, 286 Weigert, 25 Weiler, 27, 164 Weiler ter Mer (W.t.M.). 211 Weitz. 99, 133 Weitzenbock, 154, 184, 207, 213,
214 322 Weizmann, 132. 147-153, 178, 187,
192, 197, 239 Welton, 17 Wende, 35, 126 Wheeler, 396 White, 15
Wiegand, 28, 134, 164 Wieiand, 39, 273 Willgerodt, 164, 165, 207 Willstatter, 396 Wirth, 17 Wislicenus, 146 Wittich, 29
WolbUng, 173, 238, 240. 248, 277 Wolfenstein, 270 Wortmann, 192, 194, 195. 224 Wiirsch, 187, 378
Zahn, 42-46
Ziegler. 25, 39. 43, 47, 49, 162, 168,
282, 285, 288 Zincke, 15, 29, 98, 152, 164, 181 Zinke. 273. 399 Zsuffa. 69, 383
INDEX TO SUBJECTS
For index purposes the prefix "mono" is not used. Where two or more substituents are present they are usually arranged in ascending order of mass, substituted amino groups being treated as amino groups, alkoxy groups as hydroxy], and all alkyl groups as methyl. Both bromine and iodine are treated as equivalent to chlorine.
ACEANTHRENE GrEEN, 384
zso-aceanthrene green, 385 quinone, 69, 162. 383 monoxime, 384 Acetamino anthracene, 68
anthraquinone, 224, 228, 230, 290 benzophenone carboxylic acid,
136 bromanthraquinone, 301 chloranthraquinone, 230, 373 nitroanthraquinone, 365 phthalic acid, 392 Acetchloramino anthraquinone, 228 Acetophenone, 133 Acetoxyanthracene, 66
anthrone, 21, 23 Acetyl nitroanthranol, 61 Acetylene, 15
tetrabromide, 15, 29, 36 Acid Alizarin Blue BB, 246, 279 Acid Dyes, 5 Aldehyde ammonia, 79 Algol, 7
Blue, 3G, K, 351 Brilhant Orange FR, 218 Violet 2B, 215, 218 R, 214 Orange R, 235 Pink R, 215, 216 Red B, 235
FF, 5G, 215 Scarlet G, 215, 216 Violet B, 215, 218 Yellow 3G, 191, 214 R, 215
WG, 191. 215, 216 Alizarin, 2, 16, 49, 91, 93, 128, 180, 202, 238-240, 252-255, 257, 260, 263. 260-269. 272. 276, 278-280, 285. 287, 343. 357
Alizarin Astrol, 204 Black, 295 Blue Black, 205
Blue, A, ABl. F, GW, R. RR, WA, 295
S, 296
X, 3, 294-296 Bordeaux, 205, 238, 257, 259,
260, 264, 276, 277, 282 Brilliant Green G, 203, 204 carboxylic acid, 264 Cardinal, 284 Cyanine B. BS, 246. 279
G, 284
Green, 3, 5, 199, 203, 204
R, 239, 264, 284
2R, 264
3R, 260
RA Extra, 264
3RS, 246, 279
WRS, 246, 279 Cyanol Violet R, 203 dimethyl ether, 247 Direct Green G, 203, 204
Violet R, 203 disulphonic acid, 278 GD, 254 GI, 254 Garnet R, 284 Green, 295, 375
S, 296
X, 3, 296 Indigo Blue, 3, 296 Irisol, 5, 203 Maroon, 284 methyl ethyl ether, 247 mit Blaustich, 254 monomethyl ether, 247 No. 1, 254 Orange A, Cy, SW, W, 282
424
INDEX TO SUBJECTS
425
Alizarin Pure Blue, 198, 204 RA, RG, RR, RX, V. 254 Red S, 278, 279 SSS. 279 3WS. 279 SDG, SX, 254 Saphirol, 3, 190, 283, 284 sulphonic acid, 254, 259, 263,
278, 279 Viridine, 205 AUochrysoketone, 323 carboxylic acid, 323 Amino alizarin, 251, 284. 294, 295, 368 382 anthracene, 53, 67, 68, 294, 343 anthrapurpurin, 295 anthraquinone, 67, 68, 140, 190- 231, 258, 290-294, 300, 305, 307, 311, 320, 332, 343-346, 354-356, 359, 363, 382, 385- 387 393 aldehyde, 160, 392 carboxylic acid, 196, 197, 20"^,
305, 306, 309 raercaptan, 358, 359, 371 nitrile, 198
sulphonic acid. 193, 209. 241. 343. 352 anthrol, 67, 73 anthrone, 103, 117. 123 azoanthracene, 68 benzanthraquinone, 152 benzanthrone, 345
quinoline, 345 bromalizarin, 251
anthraquinone, 229-231. 301, 345 sulphonic acid, 231 chloranthraquinone, 78, 136, 166.
229 dianthraquinonylamine, 292, 343 dibromanthraquinone, 172, 198,
229, 230, 258, 259, 368. 372 dichloranthraquinone. 229 dihydroxyd ianthraquinonyl-
amine, 234 dinitroanthraquinone, 225, 226 e r V t h rohydroxvanthraquinonc,
' 93. 209. 241,"250. 279 flavopurpurin, 294 hydroxyanthraquinone, 93, 202, 209. 236, 241, 250, 266. 279. 294 benzanthraquinone. 151 bromanthraquinone, 351, 368 indanthrone, 292, 352 methyl anthraquinone, 160, 166, 365, 373, 392, 397 benzanthraquinone, 144
Amino nitroanthraquinone, 168, 193, 224, 225, 227 phthahc acid, 129 pyridanthrone, 293 quinizarin, 129, 295 violanthrone, 331 Amyl anthracene, 18 dihydroanthracene, 18 hydroxyanthrone, 38. 110 Angular structure, 10 Anihdo anthrone, 120 Anisol. 139
Anthracene, Action of nitric acid on, 50 listimation of, 74 Halogenation of, 41-50 Oxidation of, 14, 16, 46, 50, 73-
76, 116 Purification of, 16, 17, 24 Sulphonation of, 61-64 Synthesis of, 1,2, 14, 15, 16 Structure of, 18, 19 aldehydes, 70 Blue SWX, 246. 279 WB, WG. 247
WR. 239, 247. 257. 260. 279 carboxylic acid. 25, 62. 64. 69, 162. See also Anthroic acid, dibromide, 43
dicarboxylic acid. 69. 384. 385 dichloride. 43. 47 disulphonic acid, 61-63, 66 Green, 375 hexabromide, 42 homologues, 26-28 indandion, 384 ketones, 70 mercaptans, 66 methyl nitrate, 53 nitrile, 62, 64. 69, 165 oil, 16 ozonide, 17 sulphinic acid, 63, 66 sulphamide, 62 sulphochloride, 62 sulphonic acid, 61-65, 69, 174 Anthrachrysazin, 4, 238. 257, 270.
282 Anthradiquinones, 73. 92-94, 274 Anthraflavene, 4
Anthrafiavic acid, 126, 238, 240, 253. 255, 268. 270, 271, 274- 277, 280, 284 ISO- Anthrafiavic acid, 126, 195, 238, 240, 253. 268. 276, 277, 280, 284 Anthraflavone G, 94 Anthraflavones, 80, 94
426
INDEX TO SUBJECTS
Antliragallic acid. See Anthra-
gallol. Anthragallol, 126, 238, 250, 251,
260, 264, 269, 280 Anthramine. See Aminoanthra-
cene. Anthranilic acid, 195 Anthranol, 22, 67, 77, 96, 98, 105, 115, 321, 394. See also Anthrone. Tautomerism of, 118-124 acetate, 22
anthraquinone dihydroazine, 348 ethyl ether, 105, 395 methyl ether, 107, 395 Anthranthrone, 322 Anthraphenone, 70, 71 Anthrapinacone, 82, 114 Anthrapurpurin, 202, 238, 253-255,
260-263, 271, 275, 282 Anthraquinol, 21, 23, 46, 75, 81-83, 86, 96, 99, 103, 108, 113, 122. See also Hydroxvanthrone. Tautomerism of, 121, 124 anthraquinone dihydroazine, 347 diethyl ether. 111 dihydroazine, 348 dimethyl ether. 111 ethyl ether, HI methyl ether. 111, 122 AnthraquinoUne. See Pyridino-
anthracene. Anthraquinone (1.2) 65, 72, 73, 343
(1.4) 65, 72, 73
(1.5) 72 (2.3) 72
(2.6) 72
(9.10) 2, 16, 23, 46, 47, 50. 69, 71,
73 et seq., 133. 201, 267, 268 Oxidation of, 20, 77, 254-256,
259, 261, 262 Preparation of, 73-76 Reduction of, 75, 80 et seq., 114,
115, 124 Synthesis of, 2 acid amides, 165, 206, 207
chlorides, 165 acridine, 314 acridone, 137, 205, 353
sulphonic acid, 312 aldehyde, 159, 164 arsinic acid, 382 azine, 340-352 Blue SR Extra, 198 carbazol, 360-362 carboxylic acid, 62, 70, 94, 140,
156, 160, 162-166, 206, 321,
353, 367, 381, 383 diazonium salts, 91. 227, 232, 249,
385, 386, 389
Anthraquinone dicarboxylic acid, 30, 31, 33, 143, 144, 150, 164 dichloride. See Dichloranthrone. dihydrazine, 364 dimercaptan, 183, 189 dicelenide, 188
disulphide, 181, 183, 184, 187, 381 disulphonic acid, 66, 176-1 '5 8,
183, 240, 241, 254, 278 disulphoxide, 181 ethers, 284 fluoresceine, 164 glycine, 207, 208 isatin, 307 imidazol, 365-368 imidazolon, 367 indazol, 364, 365 ketones, 160, 308, 353 monoxime, 57, 59, 77, 101 nitrile, 162, 165, 307, 365, 367 osotriazol, 361 oxazin, 355
sulphonic acid, 358 oxazol, 368, 388 phenanthridone, 297 phenylhydrazone, 77 pinacones, 161 pyrazols, 363 quinoUne. See Pyridinoanthra-
quinone. ring syntheses, 125-141 selenophenol, 185 sulphamide, 181, 374 sulphenic acid, 180-182, 186 sulphinic acid, 180-182 sulphochloride, 180, 183, 370, 380 sulphonic acid, 63, 64, 79, 133, 176-180, 183, 201, 231, 239- 241, 252-254, 259, 263, 373 sulphoxylic acid. See sulphenic
acid, sulphurbromide, 181
chloride, 181, 182, 374 tetrachloride, 44, 49 thiazine, 358 thiazol, 371
disulphide, 372 thiazoline, 372 thioxanthone, 317-319, 363 trisulphonic acid, 177 violet, 199 xanthones, 315-317 Anthraquinonvl acrylic acid, 160. 164, 165 aminoacridone, 379
anthraquinone. See Dianthra- quinonylamine .
dianthraquinonylamine, 233 et seq.
INDEX TO SUBJECTS
427
Authraquinonyl aininoacridone, 379 thioxanthone, 379 pyridanthrone, 293 anthraquinone imidazol, 367 arsenoxide, 383 azide, 369, 388 iso-cyanate, 219 glycylaminoanthraquinone, 214 hydrazine, 340-352, 363, 364. 389
sulphonic acid, 389, 390 hvdroxylamine, 343, 389 mercaptan, 181-187, 358, 359,
370, 371, 373, 381 oxaminic acid, 226 piperidine, 195 pyridazoneanthrone, 354 selenocj^anide, 185, 374 sulphide, 186, 187 thiocyanate, 183, 374, 381 »50-thiocyanate, 222 thioglycollic acid, 370, 381 thiourea, 221
chloride, 222 urea, 191. 219-221
chloride, 219, 220, 221. 355 urethane, 219, 220, 225, 355 xanthate, 183, 374, 381 Anthrarufin. 63, 126, 209, 238, 243, 244, 253, 257. 259, 260, 267, 270, 273, 274, 277. 280, 376 dimethyl ether, 78 disulphbnic acid. 243, 277, 283 Anthratriquinone, 73 Anthrazine. 343, 349, 350 Anthrimide. See Dianthraquinonyl-
amine. Anthroanthraquinone azine. 343 Anthroic acid. 69 Anthrol, 64-67. 140. 315, 316 Anthrone, 54, 81, 86. 96-105. 367, 380. See also Anthroiie. tautomerism of, 118-124 azine, 349 dihydroazine, 349 Anthrylamine. See Aminoanthra-
cene. Arsenic compounds, 383, 384 Arsenoanthraquinol, 382, 383 Aziminoanthraquinone, 388 Azoanthraquinone, 387 Azoxyanthraquinone, 344, 388, 389
Barnett's notation, 12
Basic dyes. 5
Benzal acetoacetic ester. 100
acetophenone, 101
malonic ester, 100 Benzalizarin. 327 ang. Benzanthracene. 143
lin. Benzanthracene, 147 anthradiquinone. 152-154 anthraquinone (1.2). 33, 80. 134, 142-145. 164. 321, 330, 335 (2.3). 142. 145-152 anthrene, 325
anthrone. 101. 164. 320-339 carboxylic acid. 323 quinohne. 332 anthronjdaminoanthraquinone,
333 dianthrone, 333 fluorenone, 323 Benzoic acid, 125
Benzoyl aminoanthraquinone, 191. 215 chloranthraquinone. 297 dianthraquinonylamine, 235 hydroxyanthraquinone,2 1 5, 2 1 7 nitroanthraquinone. 216. 217.
368 trihydroxyanthraquinone. 215. 218 anthracene, 70. 71 authraquinonyl mercaptan, 184,
187 benzoic acid, 20. 130, 131 chloride, 70
diaminoanthraquinone, 216 mesitylene. 33 mesitylenic acid, 34 methylaminoanthraquinone, 216,
217 naphthalene. 324 nitroanthranol. 61 propionic acid, 133 pyranthrone, 337 pyrene, 328, 337 Benzyl anthracene, 37 chloride, 15, 37 hydroxyanthrone. 86, 87 toluene, 14 trichloracetate, 16 Benzylidene aminoanthraquinone. 210 bromanthraquinone, 301. 309 chloranthraquinone, 297 anthrone. 86 mesitylene. 33 Bisangular structure. 10 Bisdiketohydrindene, 145, 146 Bisthiazoliiies, 373 Bromalizarin, 276
aminoanthraquinone, 228 anthracene, 25, 43 anthraquinol ethyl ether. 106 anthraquinone, 43, 106, 137, 187, 210 nitrile. 197
428
INDEX TO SUBJECTS
Bromalizarin anthrone, 98, 99, 101, 102, 108, 116, 117, 121-123
benzanthrone, 331 benzylbromide, 15
triphenyl carbinol, 38, 88 dianthrone, 99, 117 dibenzylanthracene, 37 erythrohydroxyanthraceiie, 273 methylanthraquinone, 172
bromanthrone, 395 quinizarin, 200, 205 thiodianthraquinonylamine, 358 toluene, 137 Butyl hydroxyanthr one, 110
Caledon, 7
Blue, GC, GCD, 351
R, 347 Brilliant Purple R, RR, 332 Dark Blue, 329 Green, 330 Red, 312
5G, 215 Violet RN Extra, 313 Yellow G, 302 Carbazol, 141, 360 Carbonyl chloride, 69 Carboxyphenyl anthraquinone car-
boxylic acid, 84 Carminic acid, 148, 269 Chloracetamino anthraquinone, 291 carboxylic acid, 207 hydroxyanthraquinone, 355 aUzarin, 175, 276 anthracene, 25, 43, 47 anthraquinone, 47, 49, 77, 98, 137, 170, 173, 175, 183, 186- 188, 197,, 210, 306, 309, 315, 354, 369, 373 aldehyde, 397 carboxylic acid, 140, 160, 196,
311, 316, 354, 392, 398 diazonium chloride, 387 monoxime, 77, 78, 369 nitrile, 166 anthraquinonyl hydrazine, 390 Chloranthrene, 7 Chlor anthroic acid, 67
benzanthraquinone, 144, 150, 304 benzanthrone, 333 benzene, 136 benzophenone, 78 benzoylchloranthraquinone, 308 brom anthracene, 25
benzanthraquinone, 150 dianthranol, 117 dianthraquinone, 117 dibrommethyl anthraquinone, 94, 95, 172, 175
Chlor dichlormethylanthraquinone 397
dihydroxyanthraquinone, 276
erythrohydroxyanthraquinone, 127, 248, 274, 276
flavopurpurin, 275
naphthalene, 144, 150, 304
nitro alizarin, 175, 200 anthraquinone, 175, 203 Chloroform, iS, 29, 31 Chlor phenol, 127-129, 138
phthalic acid, 128
purpurin, 249
pyridanthrone, 292
quinizarin, 93, 248, 274
toluene, 26, 137, 140
tolyl methane, 15 Chrysarobin, 27
Chrysazin, 63. 209, 238, 242, 253, 257, 260, 262, 266, 273, 274, 277, 280, 282
disulphonic acid, 277
dimethyl ether, 280 zso-Chrysofluorenone, 325 Chrysol, 66 Cibanon, 7
Coccinic acid, 129, 140 Coeramidine, 379
carboxylic acid, 379 Cceroxene, 374—378 Coeroxenol, 377 Cceroxonol, 377 Coeroxonium salts, 376 Coerthiene, 378 Coerthienol, 378 Ccerthionol, 378 Coerthionium salts, 378 Ccerulein, 375 Colophonium, 27 Cresol, 26, 127, 128, 139, 140 Cyanthrene, 332 Cyanthrone, 327, 332
Deckahydroanthracene, 41 Diacetamino anthracene, 68
anthraquinone, 224 Diacetoxy anthracene, 66, 73 Diamino anthracene, 67, 73
anthrachrysazin disulphonic acid,
246 anthraiiavic acid disulphonic acid,
284 zso-anthraflavic acid disulphonic
acid, 284 anthraquinone, 78, 93, 193-195, 202, 207, 209, 226, 228-230, 250, 279, 282, 294, 308, 340- 343, 355, 365-367, 386, 388 per bromide, 228
INDEX TO SUBJECTS
429
Diamino anthrarulin, 93, 282 disulphonic acid, 283, 284 bromanthraquinonc, 367 chrysazin disulphonic acid, 284 dianthraquinonylaminc, 233, 234 dianthraquinonyl, 300, 301, 300 dianthryl, 115, 124 dihydroxy dianthraquinonyl-
amine, 233 dinitroanthraqiiinone, 194 indanthrone, 234 nitroanthraquinone, 225 phenylamino anthraquinone, 359 tetra brom anthraquinone, 198, 226, 229, 369 nitro anthraquinone, 224, 226 Diamyl anthracene, 38 Dianilido benzanthraquinone, 147 Dianthramines, 68 Dianthranol, 115-117, 120, 124 diacetate, 115, 117 dimethyl ether, 115 Dianthraquinone, 115-117 Dianthraquinonyl, 90-92, 135, 301. 333, 334 acetylene, 175 Dianthraquinonyl amine, 190, 191, 231-235, 305, 306, 361, 379 aminoanthraquinone, 190, 232
et seq. carboxylic acid, 92 dialdehyde, 159, 335 dibromethylene, 175 dicarboxylic acid, 300 disulphide, 187 ether, 286 ethylene. See Anthraflavone.
diamine, 211 sulphide, 186, 178. urea, 220 Dianthrene, 24, 25 Dianthrol, 83, 335 Dianthrone, 22, 24, 83, 99, 105, 116,
120, 124, 334, 335 Dianthryl, 82, 83, 91, 98, 114, 115, 124, 383 acridine, 314 Dibenzalanthracene, 37 iJs-Dibenzalanthracene, 37 Dibenz anthracene, 158 anthradiquinone, 156 anthraquinone, 135, 142, 143,
154-158 anthratriquinone, 157 Dibenzovl amino anthraquinone, 215, 216 anthrarufin, 215, 218 dianthraquinonyl, 218 hydroxj'anthraquinone, 215
Dibenzoyl anthracene, 70 benzene, 20 dianthraquinonyl, 335 dibenzylamino anthraquinone, 84 dinaphthyl, 329 indanthrone, 347 '
pyrene, 328, 331, 337 veratrol, 20 Dibenzyl amino anthracene, 37 anthraquinone, 84, 207 anthracene, 37 Dibenzylideneaminodianthra-
quinonyl, 301 Dibrom anthracene, 25, 43, 45 tetrabromide, 42, 43, 45 anthraflavone, 94 anthraquinone, 43, 170, 172, 247 anthrarufin disulphonic acid, 197,
283 anthrone, 77, 78, 101, 120 chrysazin, 247, 277 dinitro anthrarufin, 283
chrysazin, 284 erythrohydroxy anthraquinone,
273 ethoxy anthracene, 106 flavanthrone, 302 hystazarin, 275 indanthrone, 351 methyl anthraquinone, 95, 1 72, 1 75
chloranthraquinone, 172 oxythionaphthene, 100 purpuroxanthin, 276 pyranthrone, 335 iso-violanthrone, 332 Dichlor anthracene, 43, 44, 46-50, 172 dichloride, 43, 44, 49 hexachloride, 44 octachloride, 44 sulphonic acid, 49 tetrabromide, 46 tetrachloride, 41, 42, 44, 47 anthrachrvsazin disulphonic acid, 391. Dichlor anthradiquinone, 93, 248 anthraflavic acid, 274, 275 anthraflavone, 95 anthraquinone, 44, 45, 49, 77, 170, 172, 173, 175, 189, 197, 203, 308, 359, 364, 390 carboxylic acid, 165 dioxime, 77 monoxime, 77 anthrarufin, 276 anthrone, 97, 98, 101. 103 benzanthrone, 147, 150 benzanthraquinone. 150 sulphonic acid, 144
430
INDEX TO SUBJECTS
Dichlor dihydroanthracene, 15, 31 erythrohydroxyanthraquinone,
248, 274 indanthrone, 351 method anthraquinone, 164, 171,
366, 367 nitroanthraquinone, 175 phthalic acid. 45, 49, 128, 137-
139, 144, 148 pyranthrone, 335 quinizarin, 248 Jso- violanthrone, 332 Diethoxy anthracene, 66 Diethyl amino anthroquinone sul- phonic acid, 209 aniline, 141 anthrone, 106 dianthraquinonyl, 336 dihydroanthracene, 106 pjrranthrone, 336 Dihydro anthracene, 15, 16, 25, 31, 39, 40, 56, 80. 84 anthrazine, 342, 349 benzanthradiquinone. See Di- hydroxy - lin - benzanthraqui- none benzanthrene, 325 benzanthrone, 325 flavanthranol, 303 flavanthraquinol. 304
hydrate. 303 flavanthrene hydrate, 302 methyl anthracene, 25 chloranthracene, 39 naphthacene. See Dihydrobenz-
anthracene. nitroanthranol, 51, 52 pyranthridene, 299 Dih^'droxy anthracene, 66, 73 anthraquinol, 265 anthraquinone. 126, 238. 270, 276. See also special names such as Alizarin. Quinizarin, etc. 1.4-anthradiquinone, 398 benzanthraquinone, 147, 149, 150,
152. 153 benzanthrone. 327 benzoylbenzoic acid. 136 dianthraquinonyl, 91
amine, 233, 234 dianthr^'lmethane, 314 dibenzanthradiquinone. 157 dichlor anthraquinone, 136 benzoyl benzoic acid. 249 dinitrosodinitroflavanthrone, 302 dipyridinoanthraquinone, 295 hehanthrone, 333 hexachloranthraquinone, 229
Dihydroxy indanthrone, 351
methyl dianthryl methane, 316
naphthalene, 148 carboxylic acid, 157
nitroanthraquinone, 357
phenyl dianthryl methane, 316
trinitrobenzoic acid, 270 Diketohydrindine. 146 Dimethoxy anthracene. 66
anthraquinqjie, 78
anthrone, 59
dianthraquinonyl, 301
dianthrone. 122
diphenyl anthracene, 20. 38, 89 Dimethyl amino benzophenone car- boxylic acid. 197
aniline. 141
anthracene. 15, 26, 28-35
anthraflavic acid, 126
anthragaUol, 126
anthramine, 68
anthraquinone, 29-34, 79, 134. 141. 168 carboxyhc acid. 132, 140
anthraquinonyl sulphonium salts, 66
anthrone, 395
benzaldehyde. 36
benzoic acid, 32, 34. See also Mesitylenic acid.
benzoyl benzoic acid, 32
dianthraquinonyl. 136, 254, 298, 300. 335, 336
dibenzanthraquinonyl. 145
dichlor anthraquinone. 175 dinitroanthraquinone, 175
dihydroxy dihydroanthracene, 87
dimethoxydihydroanthracene, 87
dinitroanthraquinone, 169
diphthaloyl thianthrene, 189
indanthrone, 350
malonyl chloride, 384
nitroanthraquinone, 169
pyranthrone, 336
tetrahydroxybenzanthraquinone, 147
trihydroxyanthraquinone, 34 Dinaphthanthradiquinone, 156 Dinaphthanthraquinone. See Di-
benzanthraquinone . Dinaphthoyl p^Tene. 337 Dinaphthyl dicarboxylic acid, 322 Dinitramino tetrabromanthraqui- none, 227
tetranitroanthraquinone, 226 Dinitro anthracene. 50. 64, 59
anthrachrysazin, 194
anthraflavic acid, 280
fso-anthraflavic, 280
INDEX TO SUBJECTS
43T
Dinitro anthraflavic acid disulphonic acid, 199
anthraquinone, 167-169, 178, 193-195. 199, 242, 244-246, 261, 282, 389, 397
anthrarufin, 194, 243, 247 disulphonic acid, 243, 283
chrysazin, 283
dianthraquinonyl, 301 amine, 233, 243
dianthryl, 116, 124
dihydroanthracene, 57, 59
diphenj-lamine, 343
hystazarin, 280
naphthalene, 58
purpuroxanthin, 282 Diphenyl, 135
aminobenzanthraquinone, 147
anthracene, 20, 38, 88. 90, 102, 103, 106
anthrone, 88, 97, 103, 106
dichlordihydroanthracene, 90
dihydroanthracene, 393
dihydroxy dihydroanthracene, 85, 89, 90
ketene, 78
methylene anthrone, 99
pyranthrone, 335 Diphthaloyl acridone, 309, 313, 314
carbazol, 360-362
oxazine, 356-358
phenylxanthene, 316
thianthrene, 189
thiazine, 358-360 Diprop5'l dianthraquinonyl, 336 Dip\aidinoanthraquinone, 294 Disodioanthracene, 17, 18 Disulphonaminoanthraquinone, 225 Ditolyl, 136
aminoanthraquinone, 201, 379 hydroxyanthraquinone, 204
ethane, 27
methane, 27
propane, 27 Dixylyl, 136
Dodekahydroanthracene, 41 Duranthrene, 7 Dur>'lic acid, 35, 126 Dyeing, 5
Emodin, 27
Ervveco Acid Alizarin Blue R, 199
Alizarin Acid Red BS, 279 Erythrohydroxy anthraquinone, 78, 91, 128.238, 240, 244, 257. 260, 262, 265-268, 273, 274, 280, 395 sulphonic acid, 180 Ethoxy anthracene, 66, 105
Ethoxyanthrone, 395 Ethine diphthalidc, 145 iso-Ethine diphthalidc. See Dihy-
droxybenzanthraquinone. Ethyl anthracene. 52
anthranol ethyl ether, 106
anthraquinone, 80, 94, 134
benzene, 80, 134
benzyl aniline, 141
dihydroanthracene, 62, 55
ethoxy anthracene, 106
hydrox}^ anthrone, 106, 110, 111
nitro anthracene, 55, 56 anthranol, 52, 55
trinitrodihydroanthracene, 56 Ethylidene bromide, 15, 30
chloride, 15
Flavanthranol hydrate, 302 Flavanthraquinol hydrate, 303 Flavanthrene, 4, 290, 302, 304
hydrate, 303, 304 Flavanthrenol hydrate, 303 Flavanthrine, 304
hydrate, 303 Flavanthrinol hydrate, 303 Flavanthrone, 92, 290, 298-304,
344, 345 Flavol, 66
Flavopurpurin, 238, 253-255, 260- 263, 271, 275, 281, 282
sulphonic acid, 279 Fluorane, 376 Furjd naphthyl ketone, 338
Gallein, 374, 375 Gallic acid, 34, 35, 126 Green oil, 16 Grignard's solution, 85-90
Halogen anthracenes, 41-50
anthraquinones, 136-138, 170- 175, 247 HeUanthrone, 92, 327, 328, 333-
335 Helindon, 7
Brown 3 GN, 221 Orange GKN, 221 Yellow 3 GX, 220, 221 Helio Fast Yellow, 215 Hemimellitic acid, 140, 162 Hemipinic acid. 139, 148, 238 Hepta bromanthracene, 42 anthraquinone, 170 chloranthracene. 42
anthraquinone. 170, 171 hydroxyanthraquinone, 239
432
INDEX TO SUBJECTS
Hexa brorn anthracene, 42, 43 chlor anthracene, 42, 47 anthraquinone, 170 anthrarufin, 251 chrysazin, 251 hydro anthracene, 39, 40, 84 anthrone, 41 flavanthrene, 304 hydrate, 303 hydroxyanthraquinone, 180, 239, 246, 247, 257. See also special names such as Anthracene Blue WR, etc. disulphonic acid, 245, 279 methj-l anthracene, 36 phenyl ethane, 102 Hydranthrene, 7 Hydrindene, 396 Hydroanthracene nitrite, 56 Hydroanthracenes, 39-41, 265 Hydro] uglone, 396 Hydroquinone, 128, 129, 140. 263 diacetate, 129 dimethyl ether, 139 Hydroxy acetyl naphthaquinone, 270 anthracene, 61, 63, 64 anthragallol, 239 anthrapurpurin, 238, 262, 266 anthraquinol, 265, 395 ^-Hydroxy anthraquinone, 78, 139, 266, 268, 271, 274. 280, 381, 396 diazonium sulphate, 261, 262,
386 sulphonic acid, 241 anthraquinonyl carbinol, 270 anthrarufin, 238, 241, 253, 257,
260 anthrone. 23, 46, 96, 97, 99, 106, 108-113, 120-124. See also Anthraquinol. Tautomerism of, 120-124 acetate, 22, 108 benzanthraquinone, 144, 147-150 benzoic acid, 126. See also
SalicyUc acid, brom anthraquinone, 273 chlor anthraquinone, 127, 128, 138, 248, 274-276, 286 benzanthraquinone, 149 chrysazin, 238, 241, 253, 260 dianthraquinonj-lamine, 233 dibromanthraquinone, 273 dichloranthraquinone, 248, 274 dihydroanthracene, 81, 82, 110,
140 diketo hexahydroanthraquinol, 398
^-Hydroxy dinitroanthraquinone, 250, 280 diphenylamino anthraquinone,
205 ethyl aminoanthraquinone, 208 flavopurpurin, 238, 262, 266 hydroquinone triacetate, 129,
140 naphthoquinonyl acetic acid, 269
acryhc acid. 269 naphthoyl • benzoic acid, 139,
148 nitroanthraquinone, 250, 356 benzanthraquinone, 150 dihydroanthracene, 51 nitroso nitroanthraquinone. 169.
244 phthaUc acid. 129. 139, 140. 148,
263 purpurin, 238 pyridanthrone. See P5n4done-
anthrone. pyridinoanthraquinone, 294-296 pyxidone anthrone, 291 toluic acid. 126 Hydroxy lamino anthraquinone, 1 69.
192 Hystazarin. 128. 130, 139. 238. 272. 275. 280
Indanthrene, 4, 7, 342 Blue GC. GCD, 351 R, 346, 350 RS. 347 Bordeaux B. 190, 235
R Extra, 235 Dark Blue BO, 329
BT, 332 Golden Orange G. R, 335 Green B, 330 Orange GN, 319 Red BN Extra, 312
G. 235 Scarlet G. 335
Violet R Extra, RR Extra. 332 RN Extra. 313 RT, 331 Yellow G. 290. 302 GN. 319 Indanthrone. 254. 300. 301. 341- 352 sulphonic acid, 352 Indenigo, 147 Indolanthrone, 363 lodoanthraquinone, 210 Isatin dichloride, 100 Isoxazols. 77, 78. 369, 370, 400
Kymric Green, 190. 203
INDEX TO SUBJECTS
433
Leucol, 7 Lignite tar oil, 14 Linear structure, 10
Malonyl chloride, 384 Mesitylene, 141 Mesitylenic acid, 36 Methanthrene, 28 Methoxy anthracene, 66 anthraquinone, 161, 168 anthrone, 99, 108, 111, 122 benzoyl aminoanthraquinone, 215 chloranthraquinone, 247 dianthraquinonylamine, 356 nitroanthracene, 59 phthaiic acid, 148 Methyl amino anthracene, 394 anthraquinone nitrile, 197
sulphonic acid, 209 bromanthraquinone, 350 anthracene, 16, 25-28, 30, 31, 39, 80, 162, 173 carboxylic acid, 30, 31 anthranol methyl ether, 107, 108,
395 anthraquinone, 26, 28, 79, 80, 94, 134, 159, 162, 163, 166, 168, 171 carboxylic acid, 30, 31 imidazol, 366 anthraquinonyl sulphoxide, 182 anthrone, 325
benzanthraquinone, 95, 145, 363 benzanthronc, 324 benzophenone, 98 benzoyl chloride, 30 bromanthraquinone, 137 chloranthracene dibromide, 47 cceramidonol, 380 dianthraquinonyl, 92 dianthraquinonylamine, 309 dihydroxy anthraquinone, 128
nitro anthraquinone, 249 dinitro anthraquinone, 168 erythrohydroxyanthr a q u in o n e,
127, 128 hydroxy anthraquinone, 26, 28 anthrone. 111 benzanthraquinone, 144 benzene tricarboxylic acid, 147 benzoic acid, 126 chloranthraquinone, 200, 248 nitroanthraquinone, 249, 282 methoxy anthracene, 108 anthraquinone, 282 naphthalene, 1 14 naphthalene, 143 nitroanthraquinone, 195, 247 pentabrom anthracene, 48
Methyl phenyl hydroxy methoxy dihydroanthracene, 87 phthahc acid, 128 P5a'idanthrone, 292
anthraquinone, 298, 299 quinizarin, 128, 163, 248 tetrahydroxy anthraquinone, 126 thianthrene, 189 thiodianthraquinonylamine, 358 tolylanthraquinone, 84, 136 trihydroxyanthraquinone, 129 Methylene amino anthraquinone, 226 anthraquinone, 394 anthrone, 394 chloride, 15, 29, 31. 36 methyl hydroxy dihydroanthra- cene, 87 methoxy dihydroanthracene, 87 phenyl methoxy dihydroanthra- cene, 87 Mordant dyes, 5
Naphthacendiquinone. See Benz-
anthradiquinone . Naphthacene. See Benzanthracene Naphthacenquinone. See Benz- anthraquinone. Naphthadianthrone, 334 Naphthalene, 15, 134, 143, 144. 156 Naphthylanthraquinonyl ketone,
156 Naphthalene sulphonic acid, 63 Naphthanthraquinone. See Benz- anthraquinone. Naphthindandion, 330 Naphthindenon, 321, 330 Naphthol, 139, 148
sulphonic acid, 148 Naphthoquinol, 157 Naphthoquinone carboxylic acid,
307 Naphthoyl benzoic acid, 131, 134 Naphthylanthraquinonyl ketone,
338 New Anthracene Blue WR, 284 Nickel carbonyl, 32. 36 Nitramines. 226, 227 Nitramino anthraquinone, 227 dinitroanthraquinone, 226 nitroanthroquinone, 226, 227 tetrabromanthraquinone, 227 Nitro alizarin, 200, 247, 263, 281, 282, 284 anthracene, 50, 53, 57-59, 67 anthrapurpurin, 247, 282 anthraquinone. 167-169, 178, 192, 100, 231, 242. 243
28
434
INDEX TO SUBJECTS
Nitro alizarin aldehyde, 160 carboxylic acid, 165, 198 nitramine, 224
sulphonic acid, 169, 180, 193, 244 anthraquinonyl hydroxylamine,
389 anthrone, 52-54, 56, 59, 60, 103,
120, 267 anthrapurpurin, 282 benzanthraquinone, 145, 150, 389 chrv'sazin, 280
d'imethyl ether, 280 dianthraquinonyl, 92
amine, 343 erythrohvdroxyanthraquinone, 243, 250 disulphonic acid, 343 flavopurpurin, 247, 282 h\'stazarin, 280 naphthalene disulphonic acid,
58 phenj-laminoanthraquinone, 341 phthalic acid, 148, 397 purpurin, 263, 279, 281 pyridinoanthraquinone, 294 quinizarin, 261. 280, 282 toluene, 195 violanthrone, 330, 331 Nitroso anthraquinone, 169 sulphonic acid, 169 anthranol, 67 anthrone, 44
naphthol disulphonic acid, 58 nitro anthracene, 55 Nomenclature, 10
OCTABROMANTHRACENE, 42
Octachloranthracene, 42 anthraquinone, 229, 251 diaminoanthraquinone, 228, 229
Octahydro anthracene, 40 sulphonic acid, 40, 41 anthranol, 40
Octahydroxy anthraquinone, 239, 260,272
Opianic acid, 238
Oxalyl chloride, 69, 162, 383
Oxanthracene, 2
Oxazone anthrone, 381
Paranaphthalene, 1, 14 Paranaphthalose, 2 Paranthrene. See Dinathrene. Pentabrom anthracene, 42
anthraquinone, 42, 170 Pentachlor anthracene, 47
anthraquinone, 170
benzophenone, 229
Pentahydroxy anthraquinone, 239,
247, 264. See also special
names _.j^ such as Ahzarin
Cyanine R.
Pentanitro dianthraquinonylamine,
233 Perchlorethylene, 15 Perhydroanthracene, 41 Peryiene, 327, S28, 399 Petroleum, 14 Pfaff's notation, 1 Phenanthrene, 135 Phenanthroyl benzoic acid, 135 Phenazine, 343 Phenol, 128
Phenyl amino anthraquinone, 199 indanthrone, 352 quinizarin, 200 anthracene, 21, 109 anthraquinone, 135
xantiaone, 316 anthrone, 96, 120, 123, 135 azo anthranol, 103 benzoylbenzoic acid, 135 chloranthraquinonj^ ketone, 160 chlor anthrone, 97, 102, 103
methylene anthrone, 99 coeroxene, 378 dichlormethyl anthrone, 99 diphenylmethane carboxyhc acid,
135 hydroxy anthranol, 104, 109
anthrone, 21, 98 methoxy anthrone, 87 methylene anthrone, 99 naphthalene dicarboxylic acid,
323 naphthyl ketone, 324, 338 pyridazone anthrone, 353 xylyl ketone, 27 Phosene, 1 Photene, 1, 24
Phthahc acid, 20, 28, 32, 34, 80, 127 et seq., 145 et seq. synthesis, 130-141, 392 Phthaloyl acridone, 305-314 carbazol, 360-362 fluorenone, 399 hydrindene, 396 oxazine, 356-358 thiazine, 358-360 thioxanthone, 317-319 xanthone, 315 Piperidine, 195, 196 Propyl anthraquinone, 80, 94, 134 iso-Propyl anthraquinone, 134 Propyl benzene, 80 t50-Propyl benzene, 134 Propyl hydroxyanthrone, 110
INDEX TO SUBJECTS
435
Pseudocumene, 34, 30, 132, 134
Pseudopurpurin, 264 Purpurin, 93, 238, 239, 254, 259, 2G0, 2(52, 263, 265, 266, 268-270, 278, 281, 356, 357 carboxylic acid, 264 disulphonic acid, 278 sulphonic acid, 259, 263, 278 tso-Purpurin. See Anthrapurpurin. Purpuroxanthin, 238, 244, 265, 272,
276, 282, 285 Pyranthrene, 4, 335, 339. See also
Pyran throne. Pyranthridene, 299 Pyranthridone, 290, 297, 299 Pvranthrone, 254, 299, 327, 328,
335-337 Pyrazinoanthraquinone, 347 Pjnrazolanthrone, 363, 364 Pyrene, 327, 328, 336 Pyrenequinone, 328 PjTidanthrene, 289 Pyridanthrone, 289, 290-293 Pyridazineanthrone, 353-355 Pyridazoneanthrone, 353 Pyridine anthracene, 289, 294 anthradiquinone, 296 anthraquinone, 289, 293, 294,
32U benzanthrone, 332 Pyridone anthrone carboxylic acid, 291 pyridinium chloride, 291, 292 P>T:imidone anthrone, 354 P>Trocatechol, 128, 130 Pyrrol anthrone, 362, 363
carboxyUc acid, 362 Pyromellitic acid, 156
QuiNALiZARiN. See Alizarin Bor- deaux. Quinizarin, 73, 91-93, 128, 129. 138, 139, 157, 184, 201, 203, 204, 209, 238. 248, 250, 259, 261. 262, 265, 267-269, 272, 274, 280, 287. 376, 395. 396 /fiMco-Quinizarin I. 265. 266, 396
II, 265, 266, 296 Quinizarin carboxylic acid, 163, 261 disulphonic acid, 259 Green. See AUzarin Cyanine
Green, sulphonic acid, 204, 259
RuFiGALLic acid. See Rufigallol. Rufigallol, 126, 239, 260, 263, 272 Rufiopin, 238 Rufol, (J6
Salicylamino antiiraquinone, 214 SalpetersaiJreanthracen, 51, 52, 56 Scholl's Peri synthesis, 324 iso-Sclenazolantlironc, 374 Semiazo compounds, 369, 388 Silver salt, 177 Sirius Yellow G, 143 Solway Blue, 190, 283
Blue-Black, 205
Purple, 203 Stilbene, 57 Styrene. 14. 15, 27. 34 Succinyl aminoanthraquinone, 191, 214, 216. 217
diaminoanthrarufin, 214 Sulphohydrazines, 380 Sulphonamide process, 197, 211
Tetraacetdiamino dibromanthra- quinone, 229 tetrabromanthraquinone, 229 Tetrabenzoylamino anthraquinone,
218 Tetrabrom anthracene, 42, 43, 45 tetrabromide, 42 anthraquinone, 42, 43, 170 ethane. See Acetylene tetra- bromide. Tetrachlor anthracene, 41-45, 48, 49 anthraquinone, 42, 49, 138, 170-
173 anthratriquinone, 93 benzoylbenzoic acid, 49 phthahc acid, 42, 128, 138, 139.
148, 171 quinizarin, 248 Tetraethyl diamine diphenyl-
anthrone. 103 Tetrahydro anthracene, 39, 40 dianthrol, 83 flavanthrene, 303 hydrate, 303 Tetrahydroxv anthraquinone, 238, 239, 247, 248, 260, 262, 272, 277. See also special names such as Alizarin Bordeaux, etc. dianthraquinonyl, 91, 269 dibenzanthraquinone, 157 dichloranthraquinone, 248 dinitroanthraquinone disulphonic
acid, 179 helianthrone, 333 Tetramethyl anthracene. 35-37 anthraquinone. 36. 84. 169 benzophenone, 35 diaminodiphenylanthrone, 103 dianthraquinonyl. 136
436
INDEX TO SUBJECTS
Tetramethyl diiiitroanthraquinone , 169 tetranitroantliraquinone, 169 azine, 351 Tetramino dianthraquinoiiylamine, 234 dihydroxy flavanthrone, 302 tetrahydroxy indanthrone, 351 Tetranitro anthraflavic acid, 280 t50-anthraflavic acid, 280 anthraquinone dinitramine, 224 anthrapurpiirin, 263 chrysazin, 247, 282 dianthraquinonylamine, 233 flavopurpurin, 263 naphthalene, 58 Tetraphenyl dihydroanthracene,394 Thianthrene, 141, 188 Thiazine, 358
iso-Thiazolanthrone, 373, 374 Thiazols, 181, 371 ThiazoUnes, 372 Thienyl naphthj'l ketone, 338 Thiodianthxaquinonylamine, 358 Thiodiphenylamine, 141, 358 Thiopheneanthrone, 370, 371 Thiophenes, 182, 186, 370, 371 Toluene, 14, 15, 27-30, 32, 80, 133,
134, 156 Tolyl amino anthraquinone, 199, 379 naphthyl ketone, 324 xylyl ketone, 30, 31 Triamino anthraquinone, 341
trihj'droxy indanthrone, 351 Triazols, 387, 388 Tribenzoyl aminoanthraquinone, 218 anthracene, 70 pyrene, 328, 337 Tribrom anthracene, 42, 43, 45 anthraquinone, 350 indanthrone, 350 methylanthraquinone, 172, 174 Trichlor anthracene, 46, 48, 49 anthraflavic acid, 275 anthraquinone, 170 benzene, 171
trihydroxyanthraquinol, 265 Trihydroxy anthraquinone, 129, 238, 257, 260, 262, 266, 278. See also special names such as Purpurin. sulphonic acid, 278
Trihydroxy benzanthraquinone, 148
dinitroso nitroanthraquinone azine, 351
naphthalene, 395 Trimethyl anthracene, 35
anthragallol, 126
anthraquinone, 35, 134
benzoyl benzoic acid, 35, 132
trihydroxy»nthraquinone, 35 Trinitro benzene, 58
dianthraquinonylamine, 233
dihydroanthracene, 54, 56, 59, 267
naphthalene, 58
toluene, 58 Triphenyl dihydroanthracene, 88
hydroxy dihydroanthracene, 86, 88, 89
methane carboxylic acid, 88, 96, 123
methyl, 102 Turpentine, 14
Urethanes, 219, 220, 225 Untersalpetersaiireanthracen, 57
Vat dyes, 4, 6 Veratrol, 139 Vinyl bromide, 15 Violanthiene, 4. See also Viol- anthrone.
BS, 329
R Extra, 332 Violanthrone, 327, 329, 330 jso- Violanthrone, 327, 331, 332 Viridanthrene B, 330
Wood tar oil, 14
Xanthopurpurin. See Purpuro-
xanthin. Xylene, 15, 27, 30, 32, 34, 36. 133,
134, 138, 141, 393 Xyloyl benzoic acid, 34 Xylyl aminoanthraquinonyl ketone, 399 anthraquinonyl ketone, 399 chloranthraquinonyl ketone, 398,
399 chloride, 32 hydroxyanthraquinonyl ketone,
399 mesityl ketone, 36
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