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ANTHRACENE AND ANTHRAQUINONE 



ANTHRACENE AND 
ANTHRAQUINONE 



BY 

E. DE BARRY BARNETT, B.Sc.(LoND.), F.I.C 

LECTURER IN ORGANIC CHEMISTRY AT THE SIR JOHN CASS TECHNICAL INSTITUTE; 

FORMERLY RESEARCH CHEMIST TO LEVINSTEIN, LTD. ; AND WORKS 

MANAGER OF THE STOCKTON-ON-TEES CHEMICAL WORKS, LTD. 







LONDON 
BAILLIERE, TINDALL AND COX 

8, HENRIETTA STREET, COVENT GARDEN 
1921 

All rights reserved 



- 



PRINTED IN GREAT BRITAIN 



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 especially 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 
chemistry 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 will 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 

4G6645 



vi PREFACE 

anthraquinone ; but an account of naturally 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 since the war, and which at 
the time of going to press are not available in the Patent 
Office library. For such patents the author has been 
compelled to rely on the very inadequate abstracts pub- 
lished in journals such as the Chemisches Zentralblatt, 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 
PfafFs 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 BARNBTT. 

SIR JOHN CASS TECHNICAL INSTITUTE, 
JEWRY STREET, ALDGATE, E.G. 3, 
Jannary^ 1921. 



* 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, 10. 



CHAPTER IL 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 

.2-Anthraquinone, 73. i.4-Anthraquinone, 73. g.io-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. Hydroxyan throne and anthraquinol, 108. 
Dianthryl and its derivatives, 114. Tautomerism, 118. 



viii CONTENTS 



CHAPTER VI. ANTHRAQUINONE RING 
SYNTHESES 

PAGE 

I. From aromatic monocarboxylic acids . . .125 

II. From phthalic acid by the direct method ... .127 

III. Phthalic acid synthesis 13 



CHAPTER VII. THE BENZANTHRAQUINONES 

I. ang. -Benzanthraquinone (Naphthanthraquinone) . . .143 

II. tin. -Benzanthraquinone (Naphthacenquinone) .... 145 

III. /z#.-Benzanthradiquinone (Naphthacendiquinone) . . 152 

IV. tozwj-taw/^-.-Dibenzanthraquinone (Dinaphthanthraquinone) . 154 
V. /im.-Dibenzanthraquinone (Dinaphthanthraquinone) . . .156 



CHAPTER VIII. THE ALDEHYDES, KETONES, 
AND CARBOXYLIC ACIDS 

I. Aldehydes 159 

II. Ketones 160 

III. Carboxylic acids ......... 162 



CHAPTER IX. THE NITRO, NITROSO, AND 
HALOGEN ANTHRAQUINONES 

I. Nitro compounds ......... 167 

II. Nitroso compounds . . . . . . . . .169 

III. Halogen compounds . . . . . . . .170 



CHAPTER X. THE SULPHONIC ACIDS, 
MERCAPTANS AND SULPHIDES 

I. Sulphonic acids . . . . . . .176 

II. Sulphinic acids .180 

III. Sulphenic (Sulphoxylic) acids . .181 

IV. Mercaptans ..... .182 

V. Selenophenols . . . . . . . ' . .185 

VI. Sulphides . . 186 

VII. Bisulphides 187 

VIII. Diselenides 188 

IX. Thianthrenes . . . . . . - . . .188 



CONTENTS ix 



CHAPTER XL THE AMINOANTHRAQUINONES 
AND DIANTHRAQUINONYLAMINES 

Reduction of nitro 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 f 297 

IV, Pyranthridones 297 

V. Flavanthrones 300 



CHAPTER XIV. THE ACRIDONES, XANTHONES, 
AND THIOXANTHONES 

I. The Acridones 305 

II. The Xanthones 315 

III. The Thioxanthones . , , , , , , . 317 



CONTENTS 
CHAPTER XV. THE BENZANTHRONES 



PAGE 



I. Simple benzanthrones ........ 320 

II. Complex benzanthrones 327 

Violanthrones, 329. z^-Violanthrones, 331. Cyan thrones, 332. 
Helianthrones, 333. Pyranthrones, 335. 

CHAPTER XVI. THE CYCLIC AZINES AND 
HYDROAZINES 



I. Mixed azines and hydroazines ...... 
II. Simple azines and hydroazines ...... 


340 
342 


CHAPTER XVII. MISCELLANEOUS HETER( 


D- 


CYCLIC COMPOUNDS 




I. The Pyridazineanthrones ...... 


353 


II. The Pyrimidoneanthrones ....... 


354 


III. The Oxazines 


355 


IV. The Thiazines t . 


358 


V. TheCarbazols " . 


. 360 


VI. The Pyrrolanthrones ....... 


. 362 


VII. The Pyrrazols 


363 


VIII. The Indazols 


3 6 4 


IX. The Imidazols 


365 


X. The Oxazols 


. 368 


XI. Thelsoxazols 


369 


XII. The Thiophenes 


370 


XIII. TheThiazols . . ... 


37i 


XIV. The w0-Thiazolanthrones 


373 


XV. The Coeroxene derivatives . 


374 


XVI. The Coerthiiene derivatives 


378 


XVII. The Cceramidine derivatives 


379 


XVIII. Miscellaneous compounds . .... 


380 


CHAPTER XVIIL MISCELLANEOUS 




COMPOUNDS 




I. Arsenic compounds .... 


382 


II. Aceanthrenequinones ....... 


383 


III. Diazonium salts ....... 


385 


IV. Azo, azimino, and azoxy compounds .... 


387 


V. Hyclroxylamines, hydrazines and hydrazo compounds . 


389 


Addenda ..... . 


393 


Index to German Patents ... . . 


. 401 






Index to Subjects 


- 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. 

F.P. French Patent Specification. 

F.T. Zeitschrift f. Farben- u. Textil-Industrie. 

F.Z. Farbe-Zeitung. 

G. Gazetta chimica italiana. 

J. Jahresbericht der Chemie. 

J. pr. Journal fur 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 Gen6ral des Matieres Colorantes. 

Soc. Journal of the Chemical Society. 

Z. Zeitschrift fur Chemie. 

Z. ang. Zeitschrift ftir angewandte Chemie. 

FIRMS. 

Agfa. Aktien-Gesellschaft fur Anilin Fabrikation, Berlin-Treptow. 

B.A.S.F. Badische Anilin- 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/M. 

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. Briming, Hochst a/M. 

Wed. Wedekind u. Co. G.m.b.H., Uerdingen. 

W.t.M. Chemische Fabrik vorm. Weiler-ter-Meir, Uerdingen. 



ANTHRACENE 
AND ANTHRAQUINONE 

CHAPTER I 
INTRODUCTION 

HISTORICAL, SKETCH 

ANTHRACENE was first discovered in 1832 by Dumas and 
Laurent, who obtained it from the higher boiling 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 Fritzsche 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 Berthelot 
showed that anthracene is obtained by the pyrogenic de- 
composition of many simpler hydrocarbons. 

About this period some doubt was thrown on the belief 
that anthracene was really a single chemical compound, 
and P'ritzsche 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 
very little was known of the constituents of coal tar. 

i i 



AND ANTHRAQUINONE 

The first structural formula which was proposed for 
anthracene was due to Graebe and lyiebermann, who pro- 
posed both the formula 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 the 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 lyiebermann. 

Up to the year 1868 anthracene was regarded merely as 
a chemical curiosity, but in that year Graebe and lyiebermann 
made the discovery that alizarin yields 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 very great success that had recently attended other 
researches made with a view to obtaining synthetic dyes, 
naturally led to hopes that alizarin might also be made by 
an artificial process, and these expectations were fulfilled 

1 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 alizarin was prepared in 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 Webermann, 1 
and by Perkin. 2 

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 hydroxyl groups could 
be introduced into the molecule by direct oxidation. The 
immediate result of this discovery was the technical manu- 
facture of Alizarin Green X and Alizarin Indigo Blue, but 
simultaneously, although independently, R. E. Schmidt 
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 dyes 
which were discovered as a direct result of hydroxyanthra- 
quinones being made easily available may be mentioned 
Alizarin Cyanine Green and Alizarin Saphirol. Both of 
these discoveries were due to R. B. Schmidt, the former 
being obtained in 1894 and the latter in 1897. To 
R. B. Schmidt is also due the credit of the discovery in 1903 
that the presence of mercury during the sulphonation of 
anthraquinone leads almost exclusively to the formation 
of a-sulphonic acids, but Iljinsky seems to have made the 
same discovery independently and almost simultaneously. 
In a patent applied for in 1894 an insoluble product is 

1 Patent applied for on June 25, 1869. 

2 Patent applied for on June 26, 1869. 



4 ANTHRACENE AND ANTHRAQUINONE 

described as being obtained by heating anthrachrysazin 
with concentrated aqueous ammonia for fifteen hours at 
150-200, and it is claimed that this substance acts as a 
brownish black vat dye. 1 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 dyeing had been carried 
out since almost prehistoric times. The dyestuff 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 years. In 1901, however, Bohn discovered 
Indanthrene and Flavanthrene, and the great value of 
these dyestuffs led to an immediate search for other 
vat dyes containing the anthraquinone ring system. Success 
was soon achieved, as Anthraflavene was discovered by 
Isler in 1905, and Pyranthrene by Scholl in the same year, 
whereas the next year saw the discovery of Violanthrene 
by Bally. Since that time the discovery of new anthra- 
quinonoid vat dyes has been continuous, although during 
the last two or three years there has been a very remarkable 
falling off in the number of patents taken out. This falling 
off in the patent claims is not, however, confined to the 
anthraquinone series, but is very noticeable throughout the 
whole of the chemical industry. It does not denote any 
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 practically all competition, with the 
result that the firms interested prefer to preserve their dis- 
coveries as trade secrets, and thus avoid furnishing rival 
concerns in other countries with information. The de- 
preciated value of the mark rendering protection in foreign 
countries somewhat costly 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 dyes have applied for very few patents. This, how- 
ever, is not at all surprising, as they have naturally been fully 
engaged in reducing " known " processes to a workable form. 
The chief workers on anthraquinone have been I^ieber- 
mann, R. B. Schmidt, Bally, Bohn, TJllmann, and Scholl. 
lyiebermann worked almost continuously on the subject 
from 1868 right up to the time of his death in 1916. 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. Schmidt, 
Bally, 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 dyeing would be completely out of place in a volume of 
this description, but a few very 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- 
none series the most important acid dyes are Alizarin Cyanine 
Green and Alizarin Irisol, although several others are used. 
They are almost exclusively used for colouring wool and 
have little or no affinity 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 extremely 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 hydroxyl groups and, as will be 
seen later, the positions occupied by these groups is of 
great importance. Mordant dyes usually give different 
shades according to the mordant used, alizarin being a 
typical 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, whereas 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 dye is an insoluble 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 t 

too strongly alkaline to be used for wool. Vat dyeing is 
almost always carried out with the yarn, as with piece 
goods penetration is not sufficiently good to allow satis- 
factory results to be obtained. Vat d}^es, 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 dicharging the dye. 

Vat dyeing is somewhat expensive, but the shades ob- 
tained are usually very fast. Vat dyeing is largely used in 
the preparation of the best quality shirtings and upholstery 
materials. 

The commercial names 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 way 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 dyes 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 anthraquinone vat dyes, the following 
being a list of the chief registered names applying to 
this class of dye, together with the name of the firm 
registering. 1 

REGISTERED NAME. FIRM. 

Algol 2 'Bayer & Co. 

Caledon Scottish Byes, Ltd. 

Chloranthrene 3 British Dyestuffs Corporation, Ltd. 

Helindon Meister Lucius and Briinning. 

Hydranthrene L. B.- Holliday & Co., L,td. 

Indanthrene Badische Anilin u. Soda Fabrik. 

1 Some Cibanon colours (G.C.I. B.) are anthraquinonoid vat dyes con- 
taining sulphur. 

2 Also Leucol. 

3 Duranthrene was used by Levinstein, Ltd., before their amalgamation 
with British Dyes, Ltd. 



8 ANTHRACENE AND ANTHRAQUINONE 

COLOUR AND CONSTITUTION 

The 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 case 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 vety 
slight effect, although bromine atoms deepen the colour 
rather more than chlorine atoms. The entrance of a 
hydroxyl group, however, has a very considerable influence, 
although the auxochromic effect is almost completely 
destroyed 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 hydroxyl group. 

The influence of a primary amino group is much greater 
than that of a hydroxyl group, and in this case replacement 
of one aminohydrogen atom by an alkyl or aryl group 
increases its auxochromic character, the influence of an 
aryl group in this direction being considerably greater 
than that of an alkyl group. On the other hand, replacing 
one amino hydrogen by an acjljgrpup 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 : 



OH 



INTRODUCTION g 

NH 2 NHCH 3 NHPh NHCOCH a 



Yellow. 



Brick red. Bluish red. Violet red. 



Yellow. 



The influence of a group is always much greater when 
in the o-jxjsitioa than when in the j8-position. 

WHen two or more groups are present their effect is more 
or less additive, but when they are in the ^#;J3Osition 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 : 

NH 2 NH 2 NHCOPh NHCOPh 



Brick red. 



NH 



OH 

Bluish red. 



Yellow. 



NHCOPh 
Red. 



NHCH, NHPh NHPh 



NH 2 NH 2 

Violet. Bluish violet. 



\ 
/ 



NH 2 NHCH 3 NHPh C 

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. 



TO 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 j8, and the 9 and 10 positions 
by the prefix meso- or ms- : 

8orc< 9orms lorc< 




5oro( /Dorms 4orc< 

In the case of the more complex condensed derivatives 
this system is insufficient, and the following notation has 
been proposed by Scholl. 1 

Compounds^which when written in the ordinary way 
contain a straight line of rings are called linear (lin.), 
whereas those which when written in this way do not 
contain a straight line of rings are denoted as angular (ang.). 
When the line of rings is twice bent the terms as-bisangular 
and /raws-bisangular are employed. The following examples 
will make this clear : 





Linear. Angular. 





cis-Bisangular. tfraws-Bisangular. 

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 

1 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. 





5 CO 
i.2-Benzanthracene. i.g-Benzanthrone. 2.9 Naphthanthrone. 




5 CO 




2 . 3-Pyridinoanthra- 
quinone. 



3 (N ) . 4 Py r idino- 1 . 2 -ben zanthra- 
quinone. 



If two or more independent fused-on rings are present 
the simplest takes the lowest numbers, isocyclic 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. 





CO 4 



8-Nitro[5.6]Bz.-i-chlor- Bz.-i-chlor-Py-OC-hydroxy- 2.9-Naphthanthrone- 

i.2.5.6-dibenzanthra- 3(N)-4-pyridino-i.9-benz- Nt-2-sulphonic acid, 

quinone [1.2] Bz.-3~ anthrone - 6 - sulphonic 

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 by dashed figures : 





With more highly condensed systems any system of 
numbering becomes very 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 many years employed an adaptation of Pf affs 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 



6 3 

5 10 4 

Anthracene. 



8 



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 ^>0ra-quinone ring : 



i.4.9.io-Anthradi- 
quinone. 



2 .3-Benzanthraquinone. 



/iw-Dibenz-i.4.5.8 
anthradiquinone. 



INTRODUCTION 13 

This system 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-oii 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 any practical importance, the hydro- 
carbon being first isolated by Dumas J in 1832. Dumas 
named it " paranaphthalene," and observed that it was 
oxidised by nitric acid to a yellow crystalline substance. 
No synthesis of anthracene that is of any practical im- 
portance as a method of obtaining the hydrocarbon has 
yet been devised, but numerous syntheses have been de- 
scribed which have considerable interest from a theoretical 
standpoint, and the chief of these will be briefly 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 under somewhat similar conditions it was obtained 
by Letny 3 from Caucasian petroleum, by I/iebermann and 
Burg 4 from lignite tar oil, and by Atterberg 5 from wood 
tar oil. o-Benzyl toluene also gives it when passed through 
a red-hot tube, 6 or, in better yield, when passed over lead 
oxide below a red heat. 7 

Toluene, benzene, or styrene, when mixed with ethylene 
and passed through a red-hot tube, give anthracene, 8 and in 
connection with this it is interesting to notice that Kraemer 
and Spilker 9 have found that methylated benzenes will 

1 A. 5, 10. a B. 7, 113. Cf. Staudinger, B. 46, 2466. 

3 B. 10, iii2 ; 11, 1210. * B. 11, 723. 

6 B. 11, 1222. 6 Dorp, A. 169, 216. 

7 Behr and Dorp, B. 6, 754. 8 Berthelot, A. 142, 254. 
9 B. 23, 3169; 3269. 



ANTHRACENE AND ITS HOMOLOGUES 15 

combine quite readily with styrene in the presence of sulphuric 
acid to form phenyl aryl propanes, which when passed 
through a red-hot tube yield anthracene hydrocarbons, the 
yields 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 anhydrous 
aluminium chloride gives anthracene, and xylene 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 tetrabromide, 2 ethylidene 
bromide or chloride, 3 vinyl bromide, 4 perchlorethylene, 5 
methylene chloride 6 or chloroform, 7 anthracene hydro- 
carbons are obtained. In these syntheses it is probable that 
a ws-dihydroanthracene is first formed, which is then oxidised 
at the expense of part of the halogen compound, or that 
an ws-dichlordihydroanthracene is the first product, this 
then splitting off two atoms of chlorine. These are not 
evolved as such, but chlorinate part of the hydrocarbon or 
react with the carbon bisulphide which is usually used as 
a dilutant. 

Perkin and Hodgkinson 8 and Schramm 9 have shown 
that benzyl chloride itself gives anthracene under the 
influence of aluminium chloride, and lyimpricht 10 and 
Zincke u have found that benzyl chloride, when heated under 
pressure with water at 160, gives a mixture of benzyl 
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-bromberizyl bromide with metallic sodium 

* But compare R. Meyer, B. 45, 1609 ; 46, 3183, who has obtained 
anthracene by condensing naphthalene with acetylene. 
Anschiitz, A. 235, 157. a A. 235, 157. 

A. 235, 299 ; B. 17, 165. * A. 235, 323. 

Bl. [3] 19, 554- 6 A. Ch. [6] 11, 264 ; Bl. 41, 323. 

B. 18, 348. 8 Soc. 37, 726. 
B. 26, 1706. 10 A. 139, 308. 

11 B. 7, 276. 12 B. 12, 1965. 



16 ANTHRACENE AND ANTHRAQUINONE 

obtained a mixture of anthracene and dihydroanthracene. 
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, l 
but in spite of the good yield 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 noo 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 recrystallised 
from fatty acids such as oleic acid, 1 or it can be washed 
with acetone, 2 or liquid ammonia, 3 or sulphur dioxide. 4 By 
far the best method, however, is washing with pyridine or 
quinoline bases, 5 as this leaves a product containing 
90-98 per cent, of anthracene. Graebe 6 obtained anthra- 
cene free from carbazol by fusing with caustic potash, the 
carbazol forming its potassium salt and the anthracene 
being distilled off. This process has been the subject of 
several patents 7 but does not seem to have been a com- 
mercial success. Wirth 8 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 by washing 
with this solvent. 

When pure, anthracene is a colourless crystalline solid 
which melts at 216-5 and boils at 351. It has an intense 
violet fluorescence, but this is completely masked by small 
quantities of impurities. This fluorescence is shown by all 
anthracene derivatives in which each mesa-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 Reney and Erhart, D.R.P. 38,417. 
a By., D.R.P. 78,861. 

3 Welton, D.R.P. 113,291. 

4 By., D.R.P. 68,474. 

6 Chemische Fabriks-Actiengesellschaft in Hamburg, D.R.P. 42,053. 
Clark, J, Ind. Eng. Chem, 1919, 204. 

6 A. 202, 22. 

7 A. G. fiir Teer- u. Erd-olindustrie, D.R.P. 111,359; By., D.R.P. 
157,123 ; Agfa, D.R.P. 178,764. 

8 D.R.P, 122,852, 

9 B. 40, 4160. 

10 B. 47, 473. 

2 



i8 ANTHRACENE AND ANTHRAQUINONE 

the sodium atoms must be attached to the ws-carbon 
atoms, as treatment with carbon dioxide leads to the forma- 
tion of the sodium salt of dihydroanthracene dicarboxylic 
acid : 

H Na H COONa 



C C 

C 6 H 4 /\C 6 H 4 _^ C 6 H 4 /\C 6 H 4 

C C 

/\ /\ 

H Na H COONa 

Anthracene forms a well-crystallised picrate with one 
molecule of picric acid when treated with alcoholic solutions 
of picric acid. 1 

STRUCTURE. There is some doubt as to the disposition of 
the fourth valency of the m^so-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 

C 6 H 4 /j\C 6 H 4 C 6 H 4 ^\C 6 H 4 

CH CH 

Against the or^o-quinonoid formula it may 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 sufficiently 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, as Schlenk, 
Appenrodt, and Thai 3 have found that in the case of other 
hydrocarbons the formation of such compounds is closely 
allied with unsaturation. Auwers, 4 from a study of the 
optical anomality of ws-amylanthracene and ws-ainyl- 
g.io-dihydro-anthracene, also concludes in favour of the 

1 B. 7, 34; A. 139, 309. 

2 Absorption spectrum. Baly Soc. 93, 162. 

3 B. 47, 473. 4 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 

C 6 H 4 ^\C 6 H 3 C1 and C 6 H 3 ( 

CH CH 

The powerful fluorescence of anthracene and of all its 
derivatives in which the " bridge " remains intact points 
to double symmetrical tautomerism, so that on the whole the 
dynamic formula : 

CH CH CH 

C 6 H 4 ^>C 6 H 4 $ C 6 H 4 <^[)C 6 H 4 5> C 6 H 4 <Q>;C 6 H 4 

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 capacity 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 
pier ate. 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 hydroxyl 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 ANTHRAQUINONE 

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 l have shown that 
g-io-diphenylanthracene on oxidation does not give anthra- 
quinone, the chief oxidation product being o-dibenzoyl- 
benzene : 

C 6 H 5 



C 6 H 4 



| 
C 6 H 5 

and, curiously enough, i.2-dimethoxy-9-io-diphenylanthra- 
cene on oxidation gives dibenzoyl veratrol : 



/COC 6 H 5 



(MeO) 2 C 6 H 2 <( | >C 6 H 4 -> (MeO) 2 C 6 H 2 <; 

X C X COC 6 H 5 

C 6 H 5 

Anthraquinone is a very stable substance and resists the 
action to oxidising agents to a very marked extent. Hence 
although it is possible in some cases to rupture the centre 
ring with the production of an o-benzoyl 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 
usually almost completely destroyed. Of course, if only 
one of the benzene rings is weakened by 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. 

1 B. 48, 208. 



ANTHRACENE AND ITS HOMOLOGUES 21 

Although anthraquinone 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 l oxidised anthracene with lead dioxide in boiling 
glacial acetic acid solution and obtained anthraquinol, 
and Kurt Meyer 2 has shown that under these circum- 
stances the first product formed is acetoxyanthrone, which 
passes into anthraquinol by hydrolysis and subsequent 
isomerisation : 

H OCOCH, H OH OH 

\/ \/ I 

c c c 

C 6 H 4 /\C 6 H 4 - C 6 H 4 /\C 6 H 4 -> C 6 H 4 /\C 6 H 4 

C C C 

I! II I 

O O OH 

From ws-alkyl dihydroanthracenes lyiebermann 3 was 
able to obtain alkylhydroxyanthrones by careful oxidation 
with chromic acid : 

H R HO R 

\/ v 

C C 

x ^CeH 4 -> CeH 4 x ^CeH 4 

CH 2 C 

II 
O 

and Baeyer 4 obtained ws-phenyl hydroxyanthrone by 
the careful oxidation of ws-phenyl anthracene. In both 
cases more vigorous oxidation leads to anthraquinone. 
L,iebermann 5 also found that the moderated oxidation of 
the ws-alkyl hydroxydihydroanthracenes led to ws-alkyl 
hydroxyanthrones : 

B. 18, 3036. 

A. 379, 48. 

A. 212, 67 ; B. 13, 1596 ; 15, 452, 455, 462. 

A. 202, 54. 

A. 212, TOI. 



22 ANTHRACENE AND ANTHRAQUINONE 

HO R HO R 

\/ \/ 

C C 



H 4 -> C 6 H 4 /J>C 6 H 4 

CH 2 CO 



As will be seen later, the moderated oxidation of the 
anthranols readily leads to dianthrones : 

OH 

1 

C 6 H 4 /|\C 6 H 4 -> 

C CeH 4 C0H 4 

I 
H 

Kurt Meyer, 1 by oxidising anthracene with one molecule 
of lead dioxide in boiling glacial acetic acid, obtained a 
mixture of anthranol acetate and hydroxyanthrone acetate, 
this latter substance being the main product when two 
molecules of lead dioxide are used. 2 Similar results were 
obtained by using 

OCOCH 3 H OCOCH 3 



C CH C 

C 6 H 4 <j\C 6 H 4 <- C 6 H 4 /j\C 6 H 4 -> C 6 H 4 /\C 6 H 4 
CH CH C 

II 
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 : 

1 A. 397, 73. 2 C/. Schulze, B. 18, 3036. 



ANTHRACENE AND ITS HOMOLOGUES 23 



HC\~ -/CH 
C 6 H 4 



C 6 H 4 H H C 6 H 4 
^>C 
C 6 H 4 



The fact that Schulze l obtained anthraquinol 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 acetoxy- 
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 : 



H Br 

\/ 
C 



H OH 



C 6 H 4 /\C 6 H 4 




C 6 H 4 /\C 6 H 4 

C 

/\ 
H Br 



H OH 



H OH 



The further action of halogen brings about substitution 
of the ws-hydrogen atom in the hydroxyanthrone, subse- 
quent hydrolysis leading to anthraquinone : 



1 Loc. cit. 



z A. 379, 73, 1 66. 



24 ANTHRACENE AND ANTHRAQUINONE 

000 

I! II II 

c c c 

C 6 H 4 /\C 6 H 

C C C 

/\ 



Br OH HO OH O 

The action of nitric acid on anthracene is discussed on 
p. 50, but Dimroth, 1 by treating anthracene with nitric 
acid in glacial acetic acid solution, obtained dianthrone : 

C 6 H 4 C 6 H 4 H H C 6 H 4 



CeH 4 C 6 H 4 C 6 H 4 

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 very pure anthracene. 
The process, however, is a very inconvenient one to carry 
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 
hydrocarbon, 3 and, in fact, gave rise to the old name 
" photene." In more recent years the reaction has formed 
the subject of several investigations. L,inebarger, Orndorff, 
and Cameron 4 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. 

1 B. 34, 219. 

2 Elbs, J. pr. [2] 44, 267. 

3 Fritsche, Z. 1867, 290; Ernst Schmidt, J pr. [2] 9, 248; Graebe 
and Liebermann, A., Suppl. VII., 264. 

4 Am. 14, 599. 



ANTHRACENE AND ITS HOMOLOGUES 25 

Weigert l 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 by Fischer and Ziegler 3 and 
by Weigert and Kummerer. 4 The former investigators 
showed that a-methyl anthracene is much more rapidly 
polymerised than either anthracene itself or j8-methylanthra- 
cene. They also found that i-4-methylchlor anthracene, 
a-chlor anthracene, ws-monobromanthracene and a-chlor- 
ws-monobromanthracene all polymerise, whereas dihydro- 
anthracene, dihydromethylanthracene and ws-dibromanthra- 
cene do not. Weigert and Kummerer studied the action of 
light on the anthracene monocarboxylic acids and found that 
all three acids are polymerised, but the a-acid is only poly- 
merised slowly, whereas in the case of the j3-acid the action is 
rapid. The ws-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 by 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 hydrocarbons. In all probability their 
structure is represented by the formula : 

H \ / H 

x c cr 

C 6 H 4 /\C 6 H 4 C 6 H 4 /\C 6 H 4 

/C : Cv 

W X H 

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. 

2 B. 42, 1145 ; Z. f. physikal. Chemie, 62, 454. 

3 J. pr. [2] 86, 289. 4 B. 47, 898. 



26 ANTHRACENE AND ANTHRAQUINONE 

HOMOLOGOUS ANTHRACENES 

I-METHYI,ANTHRACENE. Very little information is avail- 
able with reference to this substance, although it has been 
described by two investigators. Birukoff l obtained it by 
condensing phthalic acid with ^>-cresol and then distilling 
the resulting i-methyl-4-hydroxyanthraquinone with zinc 
dust. He describes it as melting at 199-200 and giving a 
quinone which melts at 166-167. 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 recrystallisation 
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-methylanthracene by distilling i-methyl- 
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 3 by the alkaline reduc- 
tion of methylanthraquinones in which a methyl group is in 
the a-position to one of the carbonyl groups ; but Lavaux 4 
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 analogy with the correspond- 
ing naphthalene hydrocarbons. 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, 2068. 2 J. pr. [2] 83, 201. 

3 B. 20, 1365 ; J. pr. [2] 41, 12. 

4 C. r. 139, 976 ; 140, 44 ; 150, 1400 ; Bl. [4] 7, 539. 



ANTHRACENE AND ITS HOMOLOGUES 27 

2-METHYi,ANTHRACENE. This is a much more important 
compound than the isomeric i-methylanthracene and, as 
it is mnch 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 l obtained it from colophonium, and 
Iviebermann 2 and Jowett and Pother 3 from chrysarobin 
and eniodin. It is present in coal tar and has been isolated 
from this source by Schulz 4 and Bornstein, 5 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 hydrocarbons seems to be quite common, 
as Schulz 7 has obtained it by passing turpentine vapour 
through a red-hot tube, and O. Fischer, 8 Schulz, 9 and 
Weiler 10 have obtained it by similar means from ditolyl- 
methane and ditolylethane. 

Klbs n has obtained it by the prolonged boiling of the 
phenyl xylyl ketone obtained by condensing benzoyl chloride 
with ^-xylene, and Gresley 12 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, 13 who find that methyl benzenes, in 
this case w-xylene, condense with styrene in the presence of 
sulphuric acid to form diaryl propanes : 

C 6 H 5 CH : CH 2 -|-C 6 H 4 (CH 3 ) 2 -> C 6 H 5 C CH 2 C 6 H 4 CH 3 

l 

CH 3 

and these when passed through a red-hot tube apparently 
split off a carbon atom and yield an anthracene derivative. 

1 B. 11, 269. 2 A. 183, 162 ; 212, 34. 8 Soc. 81, 1581. 

B. 10, 1049. 5 B 15 Ig21 

6 B. 10, 1481. It must be remembered that this observation was pub- 
lished in 1877. It is highly improbable that any anthracene derivatives 
could be obtained from modern commercial aniline oil. 

7 B. 10, 118. s B. 7, 1195 ; J- pr. [2] 79, 555. 
9 B. 10, 118. 10 B> 7> ; ' 

11 J- pr- [2] 35, 471 ; 41, i, i ; B. 17, 2848. 

12 A. 234, 238. is 12 B. 23, 3169 ; 3269. 



28 ANTHRACENE AND ANTHRAQUINONE 

In 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 methyl anthracene in coal 
tar. 

2-Methylanthracene can, of course, be obtained by the 
distillation of methylhydroxyanthraquinones over zinc 
dust, 1 but this method is of theoretical rather than of 
practical importance. It is most readily obtained by the 
reduction of the corresponding quinone, 2 and as this is 
readily obtained from phthalic anrrydride and toluene, 
the hydrocarbon is easily available. 

The melting point of 2-methylanthracene given in the 
literature is very variable, most investigators giving it as 
198-204. Probably the figures given by O. Fischer, 3 
viz. 203 (uncor.) and 207 (cor.), are the most reliable. 
The latter figure is also given by I^impricht and Wiegand, 4 
Kraemer and Spilker, 5 and Scholl. 6 

OrndorfT and Megraw 7 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 j3-methyl- 
anthracene a third isomer has been described by Oudemas, 8 
who states that he obtained a hydrocarbon with the formula 
C 15 H 12 by distilling podocarpinic acid with zinc dust. He 
gives the melting point of the hydrocarbon as 117, and 
states that on oxidation it gives a quinone, C 15 H 10 O2, 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. 

DIMETHYI, 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, 181 ; Scholl, M. 39, 237. 

3 J- P^ [2] 79, 555. * A. 311, 181. 
5 B. 23, 3169 ; 3269. 6 M. 39, 237. 

7 Am. Soc., 22, 154. A> 170 , 243 ; J. pr. [2] 9, 416. 



ANTHRACENE AND ITS HOMOLOGUES 29 

forthcoming. As Lavaux l 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 extremely difficult to recognise 
as such, and which can only be separated into their con- 
stituents by special means. 

Several investigators have described a dimethyl anthra- 
cene melting at 225, and giving on oxidation a quinone 
melting at 156-160. Thus Waschendorff and Zincke 2 
obtained it from the heavy fractions of commercial aniline 
oil ; Anschiitz 3 obtained it by treating toluene with sym- 
tetrabrom-ethane and aluminium chloride, and also by 
treating toluene with aluminium chloride. 4 Friedel and 
Crafts 5 obtained it by the action of methylene chloride 
and aluminium chloride on toluene, and by the action of 
aluminium chloride on toluene also obtained a dimethyl 
anthracene. The melting point of this latter substance 
they give as 231, but find that it gives a quinone melting 
at 160. Elbs and Wittich 6 from toluene, chloroform, and 
aluminium chloride obtained a dimethyl anthracene melting 
at 215-216 and giving a quinone melting at 161-162 ; but 
I/avaux has shown that the melting point of their compound 
was too low owing to the presence of a little monomethyl 
anthracene. 

Lavaux 7 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 very 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. 

5 A. Ch. [6] 11, 265 ; Bl. 41, 323. e B. 18, 348. 

7 C. r. 139, 976 ; 140, 44 ; 152, 1400 ; Bl. [4] 7, 539. 



30 ANTHRACENE AND ANTHRAQUINONE 

The compound melting at 244-5 seems to be identical 
with the dimethyl anthracene obtained by Anschiitz and 
Romig l by distilling the condensation product 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 methyl anthraquinone carboxylic 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 Bibs 2 has shown 
that a-methyl anthraquinones do not give the corresponding 
anthracene derivative by reduction in alkaline solution. 
Further, L,avaux showed that the methyl anthracene 
carboxylic acid, by loss of carbon dioxide, gave j3-methyl- 
anthracene. 

lyavaux 3 found 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 L,avaux con- 
cluded that his acid was anthraquinone-2. 7 -dicarboxylic 
acid, and consequently that the dimethyl anthracene which 
melted at 244-5 was 2.7-dimethyl anthracene. 

Seer 4 by heating w-methyl benzoyl chloride with 
aluminium chloride to 140 obtained a mixture of three 
dimethyl anthraquinones, of which the main product 
melted at 235-236. By the action of w-methylbenzoyl 
chloride on w-xylene in the presence of aluminium chloride 
he obtained a tolyl xylyl ketone which when boiled 
(b.p. 315-320) for five days 5 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, 317 ; B. 18, 662. 

2 J- pr. [2] 15, i2i ; B. 20, 1365. 
8 C. r. 141, 354 ; 143, 687. 

* In the anthraquinone series these fusions are often very troublesome 
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. 

5 Cf. Elbs, J. pr. [2] 33, 185. 



ANTHRACENE AND ITS HOMOLOGUES 31 

identical with the products obtained by Lavaux. The fact 
that the tolyl xylyl ketone gave an anthracene derivative 
is proof that one methyl group is in the ortho- position 
to the carbonyl group, and if it is assumed that methyl 
groups have not wandered there are only two alternatives 
for the structure of the ketone and the dimethyl anthracene 
derived from it : 



CH 3 CO CO 







CH.5 



i.y-Dimethylanthracene. 2.6 Dimethylanthracene. 

L,avaux, 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-dimethyl anthracene. 

L,avaux 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 methyl- 
anthracene carboxylic, this latter by loss of carbon dioxide 
passing into j8-methyl anthracene. By further oxidation 
an anthraquinone dicarboxylic 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. I^avaux 
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- 
cene 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 by 
Dewar and Jones 1 as being obtained by heating toluene 
with nickel carbonyl and aluminium chloride is very doubt- 
ful. They describe it as 2.6-dimethyl anthracene and state 
that it melts at 215-216 and gives 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 3 by heating 
xylyl 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 xylene 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 4 and Heller 5 prepared i.4-dimethyl 
anthraquinone from ^-xylene and phthalic acid they do 
not seem to have reduced it to the anthracene com- 
pound. 

Klbs and Burich 6 condensed phthalic anhydride with 
o-xylene and obtained 3-4-dimethylbenzoylbenzoic acid, the 
position of the methyl groups being proved by F. Meyer, 7 
who, by fusion with caustic potash, obtained 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. z M. 33, 143. 3 A. 169, 207. 

* A. 240, 240. e B. 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-dimethyl- 
anthraquinone or 2-3-dimethylanthraquinone ; but since 
toluene yields exclusively j8-methylanthraquinone one is 
justified 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 by Bibs by oxidation melts at 340, whereas the di- 
carboxylic acid obtained by Scholl 1 by the oxidation 
of i.2-benzanthraquinone (naphthanthraquinone) melts at 
267-268. As Scholl's acid must be anthraquinone i.2-dicar- 
boxylic acid, it follows that Bib's acid must be the 2.3-dicar- 
boxylic acid. Both acids readily yield cyclic anhydrides, 
which shows that no wandering of the methyl groups can 
have taken place. Bibs and Burich reduced the dimethyl- 
anthraquinone by zinc dust and ammonia and obtained 
2.3-dimethylanthracene, m.p. 246. 

Several investigators have prepared i.3-dimethyl- 
anthracene, but their descriptions are so conflicting that it 
is very doubtful if the substance has ever been obtained 
pure. 

Bibs 2 found that benzoyl mesitylene on heating does not 
pass into a dimethyl anthracene ; but L,ouise, 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 mesitylene 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 
Ivavaux's i.6-dimethylanthraquinone (m.p. 169), as the 

* Limpricht, A. 312, 99, gives the melting point as 200, and Heller, B. 
43, 2891, as 205-206. 

1 B. 44, 2992 ; D.R.P. 241,624. 

2 J. pr. [2] 35, 487 ; 41, 12. 3 A. ch. [6] 187. 

3 



34 ANTHRACENE AND ANTHRAQUINONE 

latter investigator has done a mixed melting point deter- 
mination. The 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-methylanthracene, 
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 1 4-dimethylanthra- 
quinone l melts at 118. Louise considers that the hydro- 
carbon which melts at 71 is really i.3-dimethylanthracene, 
as he has prepared 2 i.3-dimethylanthraquinone from 
benzoyl mesitylenic acid, and finds that it melts at 157- 
158.* 

Totally different results have been described by other 
investigators. Gresly 3 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 4 condensed 
2.4-dimethyl benzoic acid with gallic acid in the presence of 
sulphuric acid and obtained i.3-dimethyl-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. BirukofT 
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 p condensed styrene with un- 
symmetrical trimethyl benzene (pseudocumene ?), and by 

Gresly, A. 234, 240. 

A. ch. [6] 6, 233. 

Elbs, J. pr. [2] 33, 319, obtained i.3-dimethylanthraquinone from 
w-xylene and phthalic anhydride, and gives the m.p. as 162. B. A. S. F. 
in D.R.P. 200,335 refer to i.3-dimethylanthraquinone, m.p. 159-163. 

A. 234, 240. 

B. 20, 870. 8 B. 23, 3169 ; 3269. 



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 Spilker give 
the melting point of their product as 298 uncor. 235 cor. 

TRIMETHYI<ANTHRACENES. Excluding ms - compounds 
there are sixteen possible trimethylanthracenes. Of these 
very few have been prepared, and in view of the very con- 
tradictory 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-trimethylbenzoyl benzoic 
acid with zinc dust obtained i.2.4-trimethylanthracene, m.p. 
243, the quinone melting at 161 ; and Bibs 2 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 3 by condensing durylic acid 
with gallic acid by means of sulphuric acid and then dis- 
tilling the trimethyltrihydroxy anthraquinone with zinc 
dust. By this means he obtained i.2.4-trimethylanthracene 
and from it the quinone by oxidation. He gives the melting 
points as 236 and 157-160. 

Bibs 4 has obtained 1.3.6- and i.4.7-trimethylanthracenes 
by heating 2.4.2'.4'- and 2.5.2'.5'-tetramethylbenzophenone. 
He finds that they 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 trie behaviour of the corresponding 
naphthalene derivatives, as very few trimethylnaphthalenes 
have been described, but i.4-dimethylnaphthalene is a 
liquid and melts at 18. 

TETRAMETHYI,ANTHRACENES. Friedel and Crafts 5 by 

1 A. 234, 238. * J. pr. [2] 41, 121. 3 B. 20, 867. 

4 J- pr. [2] 35, 482 ; 41, 141 ; B. 19, 408. 5 A. ch. [6] 11, 267. 



36 ANTHRACENE AND ANTHRAQUINONE 

treating w-xylene with methyl ene 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 l by the action 
of aluminium chloride on the chloride of mesitylenic acid : 



COCl CH CO CH 




CH 3 CH 3 CO 



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 m-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 3 
by heating w-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-tetramethylanthracene, 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 4 has repeated the work of Friedel and Crafts, and 

1 M. 33, 33. 2 A. 235, 173. 3 Soc. 85, 216. 4 M, 33, 33. 



ANTHRACENE AND ITS HOMOLOGUES 37 

by a slight variation in the experimental conditions has 
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 
i .3.6.8-tetramethylanthracene. 

OTHER ANTHRACENE HOMOLOGUES. There seem to be 
no records of attempts to prepare homologous anthracenes 
by the Friedel and Crafts' reaction, but I/ippmann, Pollok, 
and Fritsch, 1 by the prolonged boiling of anthracene with 
benzyl chloride 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 benzyl groups must be attached to the ws-carbon atoms. 
The dibenzyl 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 I^ippmann regards as dibenzalanthracene 
and fo's-dibenzalanthracene and assigns them the formulae : 

C CHC 6 H 5 C CHC 6 H 5 CHC 6 H 5 C 

C 6 H 4 /\C 6 H 4 and C 6 H 4 <J\C 6 H 4 C 6 H 4 /\C 6 H 4 

C- -CHC 6 H 5 C CHC 6 H 5 CHC 6 H 5 C 

Dibenzalanthracene, 6is-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 ms-homologues of anthracene have also been 
described, but they are invariably obtained by indirect 
1 M. 23, 672 ; 25, 793. 2 B. 23, 1570. 



38 ANTHRACENE AND ANTHRAQUINONE 

methods. Thus, Jiingermann 1 obtained ws-diamyl anthra- 
cene by reducing the product obtained by the action of 
amyl-magnesium bromide on amylhydroxy anthrone : 

HO C 5 H U C 5 H n 

\/ 

CO C C 

3 H 4 -> C 6 H 4 /\C 6 H 4 -> C 6 H 4 /\C 6 H 4 
C C C 



/\ 

HO C 5 H U HO C 5 H U C 5 H n 

It melts at 132-137. Other homologous anthracenes have 
been obtained by similar methods, and will be referred to 
elsewhere. ws-Diphenylanthracene has been obtained by 
Simonis and Remmert 2 by treating o-brombenzyltriphenyl 
carbinol with concentrated sulphuric acid : 

Ph Ph 

H \!/ Br 6 

C 6 H/ ,C 6 H 5 -> CeH/iNCeHd 



C \ C 

I X OH V 

Ph Ph 

and by a similar reaction the same investigators have pre- 
pared i .2-dimethoxy-ws-diphenylanthracene. 

1 B. 38, 2868. 2 B. 48, 208. 



CHAPTER III 

SIMPLE DERIVATIVES OF ANTHRA- 
CENE 

HYDROANTHRACKNES 

A CONSIDERABLE number of hydroanthracenes have been 
described, although none of them are of any particular 
interest. They are 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. 1 

The reduction of anthracene and its derivatives can be 
effected by various reducing agents. lyiebermann 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 
Q. 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 4 have found that j3-methyl- 
anthracene is quite unaffected by treatment in this way. 
Sodium amalgam 5 in conjunction with ethyl 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. 

2 A. Suppl. VII., 257 ; 212, 5 ; B. 1, 187 ; 9, 1202. 

3 J- pr. [2] 86, 289. 
* J. pr. [2] 92, 51. 

5 Bamberger and Lodter, B. 20, 3076 ; Padova, C. r. 148, 290 ; Wie^nd, 
B. 45, 492. 

39 



46 ANTHRACENE AND ANTHRAQUINONE 

hydriodic acid, seems to produce hydroanthracenes in which 
the ;ws-carbon atoms are affected, as the reduction products 
are non-fluorescent, do not form picrates, and, so far as any 
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, 2 
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 hydriodic acid melts 
at 101-103, is not fluorescent, and gives no picrate, whereas 
that obtained by reduction by hydrogenation in the presence 
of nickel melts at 89, shows a blue fluorescence, and gives 
a picrate. 

The hydroanthracenes as a rule are colourless solids 
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 
ws-carbon atoms. 

Of the individual members, only one dihydroanthracene, 
C 14 H 12 , is known. This melts at 108*5, an d is dehydro- 
genated when shaken in benzene solution with finely divided 
palladium. 4 Two tetrahydroanthracenes, C 14 H 14 , are 
known, which melt at 101-103 and at 89. The former 
is obtained by means of hydriodic acid, and the latter by 
catalytic reduction. As the latter is fluorescent and gives 
a picrate the ws-carbon atoms are probably intact. Two 
hexahydro compounds, C 14 H 16 , 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 5 and melts at 66-5, and 

1 A. ch. [8] 12, 468 ; Bl. [ 4 ] 1, 701 ; C. r. 139, 605 ; 141, 1029 ; 142, 

I2O2. 

2 B. 40, 1289; 41, 997. 3 Bl. [4] 1, 701. * Wieland, B. 45 492. 
5 Godchot, C. r. 142, 1203 ; A. Ch. [8] 12, 468. 



SIMPLE DERIVATIVES OF ANTHRACENE 41 

boils at 303-306. The method of formation renders it 
almost certain that the ws-carbon atoms are intact, and 
this is supported by the blue fluorescence of the compound. 
An octahydroanthracene, C 14 H 18 , has been prepared by 
catalytic reduction. It melts at 71, gives a picrate, and 
shows a green fluorescence. Hence, in all probability the 
ws-carbon atoms are intact, although Godchot 1 brings 
forward some arguments to the contrary, e.g. it gives hexa- 
hydroanthrone on oxidation with chromic acid. Deka- 
hydroanthracene, C 14 H 20 , melts at 73; dodekahydro- 
anthracene, C 14 H 22 , boils at 140-150 at 15 mm. ; and 
perhydroanthracene, C 14 H 2 4, 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 complicated, 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 meso- 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 exhibit 
geometrical isomerism of the cis-trans type. 

Diel 2 by passing chlorine gas over anthracene, first at 
the ordinary temperature and then at 230, obtained a 
dichloranthracene tetrachloride, Ci 4 H 8 Cl 2 .Cl 4 . 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 BI. r 4 ] 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 ws-carbon 
atoms, and, as the tetrachloranthraquinone is quite different 
from that synthesised from tetrachlor phthalic acid, the 
remaining four chlorine atoms must be heteronuclear. 
Their exact positions have not been 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 ws-dichloranthracene tetrachloride when heated de- 
composes into 2.3.9.io-tetrachloranthracene, so that the 
chief constituent of Diel's hexachlor compound was pro- 
bably 2.3.6.7.9.10 -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, Ci 4 H 10 Br 6 ) ; but Graebe and 
lyiebermann 3 have proved it to be dibromanthracene 
tetrabromide. When heated alone it gives tribromanthra- 
cene, and when treated with alcoholic potash tetrabrom- 
anthracene. Hammerschlag 4 found that the final product 
of the action of bromine vapour on anthracene at the ordinary 
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 two molecules of hydrobromic acid and 

1 Page 44. 2 A. 122, 304 

3 A. Suppl. VII, 304. 4 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 ms-dichloranthra- 
cene is treated with bromine vapour, 1 addition and substitu- 
tion products being formed, which when heated alone lose 
both bromine and hydrobromic acid, whereas only hydro- 
bromic 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 ms-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- 
anthracene, m.p. 298-300, 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 3 the first action is the formation 
of a very unstable addition compound, anthracene dihalide, 
which then splits off halogen acid and yields ws-halogen 
anthracene, the second ws-hydrogen atom being replaced in 
the same way. 4 The action of chlorine on anthracene in 
chloroform and benzene solution was first studied by 
Schwazer, 5 who obtained first ws-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 hydrochloric acid 
and gave trichloranthracene. More 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 dichloranthracene dichloride is really 

1 Schwazer, B. 10, 376; Hammerschlag, B. 19, 1106. 

2 B. 37, 4708. 

3 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. 

4 Meyer and Zahn, A. 396, 166. 

5 B. 10, 376. Cf. Radulescu, C. 1908 (2), 1032. 
8 D.R.P. 283,106. 



44 ANTHRACENE AND ANTHRAQUINONE 

a mixture of anthraquinone tetrachloride (m.p. 180) and 
dichloranthracene dichloride (m.p. 139-140) : 

Cl Cl 

\/ Cl 

C C 

C 6 H 4 /\C 6 H 4 C 6 H 4 /|\C 6 H 4 C1 2 

C C 

/\ Cl 

Cl Cl 

They find that low temperatures and the use of chloro- 
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 chlori- 
nating in benzene at 60. In a later patent l they claim 
that chlorination 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 3 have repeated Hammerschlag's work, 
and state that Hammerschlag'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 lyiebermann and L,inden- 
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. 4 B. 13, 1588. 



SIMPLE DERIVATIVES OF ANTHRACENE 45 

tetrachloranthracene. 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. lo-tetrachloranthracene, as on oxidation it yields 
2.3-dichloranthraquinone, the structure of which is known 
by its synthesis from 3.4-dichlorphthalic acid. 1 The iso- 
meric tetrachloranthracene obtained by the action of 
alcoholic caustic potash must be i^.g.io-tetrachloranthra- 
cene, as on oxidation it gives a dichloranthraquinone which 
is not identical with i.2-dichloranthraquinone obtained 
from 34-dichlorphthalic acid, nor with i.4-dichloranthra- 
quinone obtained from 3.6-dichlorphthalic acid. 2 

Cl Cl Cl C1 

KOH Heat 



Cl 



1 4 



Cl 



C 



Cl 



Cl 



By heating anthracene or ws-dibromanthracene in 
chloroform 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 lyieber- 
mann 4 obtained from their tetrabromide, but Meyer and 
Zahn's bromide (a-compound) differs widely in its physical 
properties from Graebe and L,iebermann's product (]8- 
compound). Thus Meyer and Zahn's tetrabromide melts 
at 134, whereas Graebe and I,iebermann's product melts 
at 182. The substances differ also in their crystalline 
form and solubility. The t 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, very slowly, in chloroform solution. 

1 Ullmann, A. 381, 27. 2 Ullmann, A., 381, 13, 26. 

8 A. 396, 166. * A. Suppl. VII., 304.' 



46 ANTHRACENE AND ANTHRAQUINONE 

Meyer 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 L,iebermann'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, 4 by heating anthraquinone with a large 
excess of phosphorus pentachloride, has obtained a hexachlor 
compound to which he ascribes the formula : 

Cl Cl 
\/ /H 



,H 



Cl Cl 

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 Meyer and Zahn 5 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 ms-dichloranthracene is 
produced. In alcoholic solution the action is very similar, 
alkoxyanthrone and anthraquinone being produced in 
dilute solutions, whereas from concentrated solutions ms- 

1 B. 10, 376. 2 B. 19, 1106. 

3 Stewart, " Stereochemistry " (1919), p. 107. 

4 Bull. Soc. Stii. Bucuresci, 17, 29; C. 1908 (2), 1032. 

5 A. 396, 166. 



SIMPLE DERIVATIVES OF ANTHRACENE 47 

dichloranthracene can be obtained. Ether has much the 
same effect as carbon bisulphide, anthracene dichloride and 
mono- and di-chloranthracene being produced. When 
glacial acetic acid is used as a solvent they find that the chief 
products are anthraquinone and dichloranthracene tetra- 
chloride. 

Iviebermann l and Schilling 2 have prepared numerous 
chloranthracenes by reducing the corresponding chloranthra- 
quinones with zinc dust and ammonia. 3 They find that, 
as in the case of the chloranthraquinones the a-chloranthra- 
cenes melt at considerably lower temperatures than the 
corresponding j8- compounds. 

Iviebermann finds that the a-chloranthracenes readily 
give addition products with chlorine, whereas the j8- com- 
pounds only give them with difficulty, as the chlorine atom 
in the j3-position seems to facilitate the substitution of the 
ws-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 




Br 



According to a patent 5 by Meister, Lucius, and B riming, 
although the ms-dichloranthracene 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. 

1 B. 47, ion. * B. 46, 1066. 

3 Cf. Fischer and Ziegler, J. pr. [2] 86, 291. 

4 J. pr. [2] 86, 291, 5 D.R.P. 282,818. 



48 ANTHRACENE AND ANTHRAQUINONE 

The chlorination of anthracene and of g.io-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 a.g.io-trichloranthracene. 

Very little work has been done on the halogenation of 
the homologous anthracenes, but O. Fischer and Reinkober 2 
have studied the action of bromine and chlorine on /3-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. 

Lippmann and Pollok 3 endeavoured to chlorinate 
anthracene by treating it with sulphur chloride in petroleum 
ether solution. They claim that prolonged action leads 
to ms-dichloranthracene, but that an intermediate com- 
pound, C 14 H 9 S 2 C1, 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 : 

Cl S : S Cl SH SH 



C C 



C 6 H 4 <J 



H 



\ 



CH CH 

but as they state themselves that the addition compound is 
unaffected 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 4 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, 5 who finds that 

1 M.L.B., D.R.P. 292,356. 2 J. pr. [2] 92, 49. 

8 B. 34, 2768. * A. 160, 126. 

& Bull. Soc. Stii. Bucuresci, 17, 29. C. 1908 (2), 1032. 



SIMPLE DERIVATIVES OF ANTHRACENE 49 

the first product is anthraquinone tetrachloride (red needles, 
m.p. 139, with decomposition), and that this on heating then 
passes into dichloranthracene dichloride and trichloranthra- 
cene : 

Cl Cl Cl Cl 

\/ I I 

c c c 

C 6 H 4 /\C 6 H 4 -> C 6 H 4 /|\C 6 H 4 C1 2 



Cl Cl Cl Cl 

As stated on p. 46, he finds that the use of larger 
quantities of phosphorus pentachloride leads to the forma- 
tion of two stereoisomeric hexachlor compounds. 

As already stated (p. 47), lyiebermann, vSchilling, and 
O. Fischer and Ziegler have prepared chloroanthracenes by 
reducing the corresponding chloroanthraquinones with zinc 
dust and ammonia. Kircher l endeavoured to obtain 
i.2.3.4-tetrachloranthracene in the same way from tetra- 
chloranthraquinone, 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- 
dichloranthracene ; but Ullmann and Billig 2 have since 
proved it to be 2.3-dichloranthracene, as its oxidation product 
is identical with the dichloranthraquinone 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 ws-dichloranthracene-j3-sulphonic acid is said to 
be obtained by sulphonating ws-dichloranthracene with 
chlorsulphonic acid, preferably in the presence of some 
neutral solvent such as chloroform, 3 or with oleum. 4 

1 A. 238, 346. * A. 381: 26. 

3 B.A S.F., D.R.P. 260,562. * M.L.B., D.R.P. 292,590. 

4 



50 ANTHRACENE AND ANTHRAQUINONE 

It has recently been found that g.io-dichloranthracene, 
when treated in the cold with nitric acid and an inert solvent, 
forms an addition compound with one molecule of the acid. 1 
This addition compound apparently has the formula : 

HO Cl 

\/ 
C 



v x 

C 

/\ 
N0 2 Cl 

and on heating to 90-95 is decomposed into anthraquinone. 
The formation of such addition compounds seems to be 
common to nearly all derivatives of 9.io-dichloranthracene. 

ACTION OF NITRIC ACID ON ANTHRACENE 

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 4 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 I^iebermann and A. O. 
Perkin, but has shown that their interpretations of the 
reactions involved were usually 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 ms- 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. 

4 B. 20, 974 ; 33, 3548 ; 34, 221. D.R.P. 127,399. 
6 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 first 
action is one of addition, Q-hydroxy-io-nitro-g.io-dihydro- 
anthracene being obtained (dihydro-nitro-anthranol) : 

H OH 

\/ 
C 



C 

/\ 
H N0 2 

L,iebermann and L,indemann l described this com- 
pound as being obtained by the action of nitrous oxides of 
anthracene, and named it " salpetersaiireanthracen ; " but 
Meisenlieinier failed to obtain it, and pointed out the pro- 
bable cause of the error on the part of L,iebermann (see p. 52) . 
The hydroxyl 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 3 



C 

/\ 

H N0 2 

If this compound is treated with hydrochloric acid the 
corresponding chloride 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 3 

\/ \/ 

C C 

<"-w./\c 6 H 4 -> 



H N0 2 H N0< 

1 B. 13, 1584. 



52 ANTHRACENE AND ANTHRAQUINONE 

It was probably this nitrite that L,iebermann and L,inde- 
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 analysed 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 
L,iebermann having generated his oxides of nitrogen from 
arsenious acid and nitric acid (0=1*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 ws-ethyl anthracene : 

H ^2^-5 ^2^-5 

\/ \ 

C C 

C 6 H 4 /\C 6 H 4 -> C6 

C C 

/\ I 

H H H 

This then adds on nitric acid to form ws-ethyl-nitro- 
anthranol, but the influence of the ethyl group has been to 
render the hydroxyl group much less reactive, so that the 
free hydroxy- compound is stable and can be isolated. 

HO C 2 H 5 






H NO 2 



SIMPLE DERIVATIVES OF ANTHRACENE 53 

If nitric acid is added to nitroanthranol 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 6 H 4 /\C 6 H 4 -> C 6 H 4 /f>C 6 H 4 

C C 



H NO 2 NO 2 

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 undoubtedly formed by the action of the 
alcohol on the nitro.anthranol nitrate or nitrite first formed : 
H ONO H OCH 3 

\/ \/ 

C C 

C 6 H 4 /\C 6 H 4 C 6 H 4 /\C 6 H 4 

C C 

/\ /\ 

H NO 2 H NO 2 

They are very readily hydrolysed by alkali and simulta- 
neously lose water, the product being ws-nitroanthracene. 
If anthracene in glacial acetic acid is treated with 2\ 
1 P.R.P. 127,399. 2 Soc. 59, 648 ; 61, 866, 



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 * by the action of nitric 
acid on anthracene in the presence of iso-butyl alcohol 
under certain conditions, and more lately and in good yield 
by Kurt Meyer 2 by nitrating anthrone in acetic acid : 

O 



C G H 4 /\C 6 H 4 
C 



H NO 2 

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 NO 2 



C 

C 6 H 4 /\C 6 H 4 
C 



N0 2 N0 2 

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 ws-dinitroanthracene. This is a stable compound 
melting at 294, which has also been obtained by Perkin, 3 
together with the mononitro compound, by nitrating anthra- 
cene in nitrobenzene solution. He did not recognise it, 

1 Soc. 61, 868. a A. 396, 150. ' Soc. 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 lyieber- 
mann and lyandshoff. 1 

The composition of the above trinitro- compound 
receives support from the investigation of the action of nitric 
acid on ethyl-dihydroanthracene carried out by Meisen- 
heimer. As stated previously, the first product formed is 
ethyl nitroanthranol : 

HO C 2 H 5 

\/ 
C 

C 6 H 4 /\C 6 H 4 

C 

/\ 
H N0 2 

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 : 

C 2 H 5 

C 



N0 2 
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 

C 6 H 4 <Q>C 6 H 4 
C 



C 2 H 5 N0 2 

i 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 : 

C 2 H 5 N0 2 

\/ 
C 



C 

/\ 
N0 2 N0 2 

This corresponds exactly 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. 

Iviebermann and I,andshoff l nitrated dihydroanthracene 
and obtained a substance which they named hydroanthracene 
nitrite, and to which they ascribed the formula : 

H H H H 



C C 

C 6 H 4 /\C 6 H 4 or C 6 H 4 /\C 6 H 4 

C C 

/\ /\ 

ONO ONO ONO NO 2 

It seemed very improbable that dihydroanthracene would 
react differently towards nitric acid than anthracene itself, 
especially as ethyl dihydroanthracene reacts in the same way 
as anthracene, and Meisenheimer therefore re-examined the 
point and found that lyiebermann's and L,andshofFs " hydro- 
anthracene nitrite" is really nothing but a mixture of 
nitroanthrone and trinitrodihydroanthracene. 

It was mentioned on p. 51 that lyiebermann and 

Lindemann 2 studied the action of nitrous acid on anthracene 

and obtained a substance which they named " salpetersaure- 

anthracen." Under somewhat different conditions and by 

1 B. 14, 467. 8 B. 13, 1585 ; 14, 484 ; 33, 3547. 



SIMPLE DERIVATIVES OF 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 lyiebermann 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 syw-dinitro- 
dihydroanthracene, and that it is formed by the addition 
of two (single) molecules of nitrogen dioxide : 

H N0 2 

\/ 
C 

C 6 H 4 /\C 6 H 4 

C 

/\ 
H N0 2 

With reference to this it should be noted that a similar 
reaction takes place between stilbene and nitrogen dioxide : 1 

H H 

C 6 H 5 CH=CHC 6 H 5 -> C 6 H 6 C- - 



N0 2 N0 2 

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 by this method, but which, curiously enough, he 
did not identify, although he prepared an acetyl derivative : 3 
H OH O 

I 1 II 

C C C 

C 6 H 4 /\C 6 H 4 -> C 6 H 4 /\C6H 4 or C 6 H 4 /\C 6 H 4 

C C C 

1 I II 

NO 2 NO NOH 

1 B. 34, 3540. * A. 323, 232. Soc. 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 : l 

S N0 2 S NO 



S 



S 
OH 



and dinitro-, trinitro-, and tetranitronaphthalene also give 
nitronitroso- compounds under the influence of alkali. 2 
sym-Trimtrobenzene and sym-trinitrotoluene behave in a 
somewhat similar manner. 

Meisenheimer 8 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 OCH 3 



C 
/ 



O 



By the action of potassium hypobromite on this compound 
he obtained : 

H OCH 3 



C 

/\ 
Br N0 



> B. 28, 1535. * B. 32, 2876, 3528 ; D.R.P. 127,295. A. 323, 205. 



SIMPLE DERIVATIVES OF ANTHRACENE 59 

which by loss of hydrobromic acid gave methoxynitro- 
anthracene. By treating this with potassium methoxide 
and then with sodium hypobromite he got : 



CH 3 OCH 3 

\/ 
C 



and 



\)K 



CH 3 OCH 3 

v 

c 

C 6 H 4 /\C 6 H 4 
C 

Br NO 2 



This last compound he oxidised to dimethoxyanthrone. 
On treating it with mineral acids, however, it was instan- 
taneously hydrolysed to anthraquinone oxime. 

Trinitrodihydroanthracene under the influence of alkali 
loses a nitro group and passes quantitatively into dinitro- 
anthracene : 



H N0 2 

v 

c 

C 6 H 4 /\C 6 H 4 -> 
C 

NO 2 NO 2 


H NO 2 

\/ 
C 

CeH 4 /\C 6 H 4 
C 

HO NO 2 


N0 2 

-> C 6 H 4 /^C 6 H 4 

C 

1 
NO 2 



and dinitrodihydroanthracene by a very similar reaction 
gives mononitroanthracene : 



H NO 2 


H OH "" 


H 


C 


\/ 
C 


< 


i 


C 6 H 4 /\C 6 H 4 -> 


C 6 H 4 /\C 6 H 4 


-> C 6 H 4 <^ 


> 


C 


C 


C 


/\ 


/\ 




i 


H N0 2 


H NO 2 - 


NO 



Nitroanthrone dissolves in alkali to form a coloured 
solution from which it is reprecipitated by acetic acid in 



60 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 

II II 

c c 

C 6 H 4 /\C 6 H 4 C 6 H 4 /\C 6 H 4 

C C 



H NO 2 ] 

X OH 

Colourless. Red. 

and Hantzsch l 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 



C 6 H 4 <J\C 6 H 4 



NO 2 

This compound was described by Perkin, 2 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, 1216. 2 Soc. 61, 868. 

3 A. 330, 153. * A. 396, 137. 



SIMPLE DERIVATIVES OF ANTHRACENE 61 

O OH 

II I 

c c 

C 6 H 4 <f>C 6 H 4 C 6 H 4 < / | N >C 6 H 4 



C C 

/\ I 

H N0 2 N0 2 

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 anthr one- anthranol isomerism will be 
found more fully discussed on p. 119. 

vSui,PHONic 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. lyinke, 1 by sulphonating anthracene 
claimed to have obtained two different monosulphonic 
acids, each of which gave a different hydroxyanthracene when 
fused with caustic potash. L,iebermann, 2 however, repeated 
L,inke's work and failed to obtain any monosulphonic acid 
the conditions specified by lyinke always leading to disul- 
phonic acids. Graebe and lyiebermann, 2 and L,iebermann 
and Rath, 3 however, obtained a monosulphonic acid by 
1 J. pr. [2] 11, 227. 2 A. 212, 43 ; B. 11, 1613. 3 B. 8, 246. 



62 ANTHRACENE AND ANTHRAQUINONE 

sulphonation. These latter observers distilled the sodium 
salt of their acid with potassium f errocyanide and saponified 
the resulting nit rile. 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. They 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 Anonyme des Matieres 
Colorantes 1 sulphonate anthracene at a temperature 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 the 
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 sulphonic 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-i -sulphonic acid and 30 per cent, of anthracene- 
2-sulphonic acid. Heifter 4 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 sulphochloride 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; 73,961 ; 76,280. 2 D.R.P. 77,311. 

8 D.R.P. 251,695. * 4 B. 28, 2258. 



SIMPLE DERIVATIVES OF ANTHRACENE 63 

four hours at 150 with alcoholic ammonia. By reduction 
with zinc and ammonia or with sodium sulphite he obtained 
the sulphinic acid. 

lyiebermann l by sulphonating anthracene obtained two 
disulphonic acids which he separated by taking advantage 
of the different solubilities of their lead and sodium salts. 
These on fusion with caustic alkali gave two different 
hydroxyanthracenes, the acetyl derivatives of which lyieber- 
mann oxidised and then hydrolysed, and thus obtained 
anthrarufin and chrysazin. 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. 2 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 lyampe 3 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 lyiebermann ; 
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 - 
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 j8- isomer predominates, and on heating 
with sulphuric acid the a- acid is converted into the jS- acid 
by the wandering of the sulphonic acid group. This 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, 1613. * B. 12, 182. 3 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, 1 or with 
zinc and ammonia. 2 Reduction must, however, not be more 
vigorous than is necessary, as otherwise the sulphonic acid 
group may be split off. This is particularly likely to happen in 
the case of the a-sulphonic acid. lyiebermann and Hermann, 3 
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 L,iebermann and Bischoff 4 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-carboxylic acid. It was accompanied by a small quantity 
of an isomeric acid which gave a soluble barium salt and 
which I/iebermann 5 has since recognised as anthracene- 
a-carboxylic 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 j8- acid. 

HYDROXYANTHRACENBS 

Hydroxyanthracenes, in which the hydroxyl groups are 
attached to the ws-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. 18,47- 6 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 ws-compounds 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 hydroxyl 
group is attached to one of the ws-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 hydroxyl 
groups is very apt to take place, so that the anthrol obtained 
often contains fewer hydroxyl groups than the anthra- 
quinone derivative from which it was made. 1 A much 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 by 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 anthraquinone 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 i.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. 3 

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 Hermann, 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 1 with nitrous acid, 
and in alkaline solution couple with diazo- solutions to produce 
hydroxy azo compounds. 2 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 alkylated anthrol is usually obtained in 
almost quantitative yield, whereas the phenols of the 
benzene series are almost unaffected. The naphthols can 
be alkylated by saturating their alcoholic solutions with 
hydrogen chloride, but the reaction takes place with some 
difficulty and the yields are poor. 

The following anthrols have been described : 



Position 
of OH. 


Name. 


M.p. 


Acetyl derivative, 
m.p. 


Methyl 
ether, m.p. 


Ethyl 
ether, m.p. 


I 


_ 


152 decomp. 128-130 decomp. 


70 


69 


2. 





Decomp. at 200 198 


175-178 


I45-I46 


1.2 





131 decomp. 145 







Z.4 


. . 


169 








1-5 


Rufol 


265 decomp. 196-198 


22 4 


I 7 9 


1.8 


Chrysol 


225 decomp. 184 


198 


139 


2.3 





Decomp. 180 155-160 204 




? ? 


Flavol 


260-270 


254-255 




i 229 

1 



Flavol was described by Schtiler, 4 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-dihydroxy 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, 5 by reducing anthracene-j3-sulphinic acid with zinc 
and hydrochloric acid, obtained anthracene-jS-mercaptan. 
Kehrmann and Sava, 6 by treating its lead salt with dimethyl 
sulphate, obtained dimethyl-j3-anthraquinonyl sulphonium 
salts. 

1 Dienel, B. 39, 930. Lagodzinski, A. 342, 59. 

2 Lagodzinski, B. 39, 1717. Agfa, D.R.P. 21,178. 

3 Liebermann and Hagen, B. 15, 1427 ; B. 21, 2057. Dienel, B. 38, 
2863. Lampe, B. 42, 1413. 

4 B. 15, 1807. 6 B. 28, 2263. 6 B. 45, 2898. 



SIMPLE DERIVATIVES OF ANTHRACENE 67 



O ANTHR ACENES 

Methods involving 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. 

ms-Anthramine (ms-aminoanthracene) was first prepared 
by Goldmann x by heating anthranol with concentrated 
aqueous ammonia at 200, and later was prepared by 
Meisenheimer 2 and Dimroth 3 by the reduction of ws-nitro- 
anthracene with tin and hydrochloric 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 4 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, 5 calcium chloride am- 
monia, 6 or acetamide, 7 but o- and p-ammo anthrols and 
o- and ^-diamino anthracenes are more readily obtained by 
the reduction of the corresponding nitrosoanthrol, 8 or the 
hydroxy or amino azo- compound. 9 

Anthramines can also sometimes be obtained by reducing 
the corresponding aminoanthraquinone, e.g. Romer 10 
obtained 0-anthramine by heating jS-aminoanthraquinone 
with hydriodic acid and phosphorus ; but the method is not 

1 B. 23, 2522; A. 330, 165; By. D.R.P. 127,399. 

2 B. 33, 3548. 

3 B. 34, 220. 

4 C. r. 149, 217. 

5 Liebermann and Bollert, B. 15, 816. 

6 Pisovschi, B. 41, 1434. Liebermann, loc. cit. (footnote). 

7 Liebermann and Bollert, B. 15, 226; A. 212, 56. Dienel, B. 38, 
2863. Liebermann, B. 41, 1434 (footnote). 

8 Dienel, B. 38, 930. Lagodzinski, A. 342, 73. 

9 Pisovschi, B. 41, 1434. Lagodzinski, B. 39, 1717. A. 342, 75. 
10 B. 15, 223. 



68 ANTHRACENE AND ANTHRAQUINONE 

a satisfactory one, and Graebe and Blumenfeld * failed to 
reduce a-aminoanthraquinone to a-anthramine. 

The anthramines 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 Bz-anthramines dijfer from ws-anthramine, 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. 3 The primary anthramines react 
very readily with methyl iodide and pass directly into 
quaternary ammonium salts, Ci 4 H 9 N(CH 3 ) 3 I, 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 5 states that he obtained aminoazo 
anthracene by treating a-anthramine with amyl nitrite in 
alcoholic solution. Bollert, 6 on the other hand, states that 
j3-anthramine when treated in alcoholic solution either with 
nitrous acid or amyl nitrite yields (Ci4H 9 NH) 2 NO. In 
Bollert's compound, however, it is not improbable that one 
of the ms-hydrogen atoms had been affected. 

The following simple anthramines have been described : 



Position of NH 2 . 

I 

2 



M.p. 



Acetyl derivative, m.p. 
198 



240 



About TT^ i / Monoacetyl, 273-274 
! \ Diacetyl, 115 

1 B. 30, ii 18. 2 Liebermann and Bollert, B. 15, 226; A. 212, 56. 

3 Bollert, B. 16, 1634. Dienel, B. 38, 2863. * Bollert, B. 16, 
5 B. 41, 1434. 6 B. 16, 1634. 



SIMPLE DERIVATIVES OF ANTHRACENE 69 

NITRIDES AND CARBOXYUC ACIDS 

The ws-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 lyiebermann 2 by heating anthra- 
cene under pressure with carbonyl chloride at 180, and at 
a later date Behla 3 and lyiebermann and ZsufTa 4 showed 
that if the temperature is raised simultaneous chlorination 
takes place, the product being ws-chloranthroic acid. The 
yields of anthroic acid obtained by this method are very poor, 
but more recently lyiebermann and ZsufTa 5 have obtained 
it in eighty per cent, yield by heating anthracene with 
oxalyl chloride to 160-170. If oxalyl chloride is used in 
conjunction with aluminium chloride the yield of anthroic 
acid falls to about thirty per cent., but aceanthrene quinone 
is simultaneously formed in sixty per cent, yield : 



co, ,co 




and this, on careful oxidation in neutral or alkaline solution, 
gives anthracene-i.Q-dicarboxylic acid. 6 The behaviour of 
anthracene homologues and halogen substitution products 
towards oxalyl chloride is very similar. 7 

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 ms- 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. 

2 A. 160, 137; B. 2, 678. * R 18> 3l69; 20. 704. 
4 B. 44, 202. 5 B. 44, 202. 

6 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 ester ified with the utmost difficulty, 
prolonged heating of the silver salt with the alkyl iodide 
under pressure usually being necessary. 

The nuclear carboxylic acids cannot be obtained directly 
by the oxidation of the methyl anthracenes, as simultaneous 
oxidation of the ms-carbon atoms always takes place, the 
product invariably 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 carboxylic acids. 1 The 
acids can also be obtained by the hydrolysis of the nitriles, 
and this method has been applied in several instances by 
lyiebermann and his students. 

The following nuclear carboxylic acids have been 
described : 



Position of COOH. 


M.p. of acid. 


I 


245 


2 





1-3 


Above 330 


1.4 

2-3 


320 approx. 
345 


1.2.4 







- 



ALDEHYDES AND KETONES 

No aldehydes of the anthracene series have been described, 
and very little is known of the ketones. Perrier 2 condensed 
anthracene with benzoyl chloride in the presence of alumi- 
nium chloride, and obtained three compounds, having melting 
points of 75, 143, and 203. L,ippmann and Fleisser, 8 and 
lyippmann and Keppich 4 also obtained three compounds, 
viz. a monobenzoyl derivative melting at 148, a dibenzoyl 

1 Elbs, B. 20, 1363; J. pr. [2] 41, 6, 121. Graebe and Blumenfeld, 
B. 30, 1118. Lavaux, C. r. 143, 687. 

2 B. 33, 816. 3 B. 32, 2249. 4 B. 33, 3086. 



SIMPLE DERIVATIVES OF ANTHRACENE 71 

derivative melting at 158, and a tribenzoyl derivative 
melting over 300. All three compounds gave anthra- 
quinone on oxidation, and hence it would appear that in all 
of them the benzoyl groups are attached to the ws-carbon 
atoms. It is somewhat difficult, however, to account for 
three benzoyl groups. In a later paper L,ippmann and 
Pollok ! claim that better yields 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 B. 34, 2766. 



CHAPTER IV 



THE ANTHRAQUINONES AND 
DIANTHRAQUINONYLS 

THEORETICALLY six monoquinones might be derived from 
anthracene, viz. four homonuclear quinones : 

O O O 

:O 



:O 



i.2-Anthra 
quinone. 



O 

1 4-Anthra- 
quinone. 



2.3-Anthra- 
quinone. 



O 

9.io-Antlira- 
quinone. 



and two heteronuclear quinones : 



O 



O: 



:0 



O 



i .5-Anthraquinone. 2 .6- Anthraquinone. 

Of these Q.io-anthraquinone is by far the most important 
and is what is ordinarily understood by the term " anthra- 
quinone." Of the other isomers i.2-anthraquinone and 1.4- 
anthraquinone have both been prepared, but 2-3 anthra- 
quinone is unknown, and the same applies to the heteronuclear 
quinones. 



ANTHRAQ UINONESDIA NTHRA Q UINON YLS 73 

In addition to the monoquinones there is a possibility 
of the existence of numerous diquinones, some of which are 
known, and a triquinone has also been described. 



i . 2 - ANTHR AQUINONH 

This was obtained by Dienel l 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. lyike 
all a-diketonic compounds it condenses with o-phenylene 
diamine to form an azine. I,agodzinski 3 endeavoured to 
obtain 2.3-anthraquinone by oxidising 2*3-dihydroxy anthra- 
cene, but without success. 

1 .4-ANTHRAQUINONE 

This was first described almost simultaneously by 
Dienel 4 and L,agodzinski, 5 both of whom obtained it by 
oxidising 4-amino-i-anthrol with ferric chloride, and shortly 
after Pisovschi 6 obtained it by oxidising i.4-diamino 
anthracene. It forms yellow needles which, according to 
Dienel, melt at 206, whereas Pisovschi states that the com- 
pound darkens at 210 and melts with decomposition at 
218. I^ike 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. 7 

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. 2 B< 27, 1438; 28, 1422; A. 342, 59. 

3 B. 28, 1533. * B. 39, 931- 5 B. 39, 1717. 
6 B. 41, 1436. 7 Pienel, B. 39, 931. Haslinger, B. 39, 3537. 



74 ANTHRACENE AND ANTHRAQUINONE 

a,n excess of chromic acid in boiling glacial acetic acid 
solution, 1 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 necessary 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 purity of which 
depends, of course, on the grade of anthracene used, is 
filtered off, washed, dried, and then dissolved in concentrated 
sulphuric acid at 130. This 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. 3 

1 Kopp, Monit. Sci. [3] 8, 1159. Graebe and Liebermann, ibid. [3] 
9, 421. 

2 By. D.R.P. 252,759. This patent describes a continuous electrical 
recovery process. 3 Sadler & Co., D.R.P. 137,495. 



ANTHRAQUINONESDIANTHRAQUINONYLS 75 

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 oxygen. On a technical scale 
it is stated that the reduction can be effected with finely 
divided iron and alkali. 1 

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 chlorate 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 4 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 loo per cent., have been claimed by carry ing out 
the oxidation in 20 per cent, sulphuric acid suspension in 
the presence of a little eerie sulphate as a catalyst. 6 

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- 
Blektron, and good results claimed. 7 Probably ms-nitro- 

1 Lewis and Gibbs, A.P. 1,293,610 (1918). 

2 B. 45, 3334 ; 46, 1669. 

3 B. 47, 1991. Hofmann, D.R.P. 277,733. 

4 B. 47, 2238. 

5 B. 48, 821. 

6 E.P. I9,i78 02 . 

7 D.R.P. 283,213 ; 284,083-4; 284,179. Cf. A.P. 1,119,546. 



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 ready 
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, 1 and the Aktien Gesellschaft Griinau, lyandshoff 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, L,ucius, and Briinning 
have developed the use of chlorates, and in two patents 4 
claim the use of the chlorates of iron, nickel, cobalt, man- 
ganese, and chromium. 

Attempts have been made to carry 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. 5 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) 6 
claiming oxidation by air or oxygen by passing anthracene 
vapour over a vanadium catalyst at 300-500. 

The use of ozone has also been claimed. 7 

Anthraquinone is a yellow crystalline solid 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. 

2 D.R.P. 234,289 ; 254,710. 

3 M.L.B., D.R.P. 256,623 (taken over from Akt. Ges. Griinau, Lands- 
hoff u. Meyer). 

4 D.R.P. 273,318-9. 

6 M.L.B., D.R.P. 292,681. 

6 E.P. I34.522 18 . 

7 Heinemann, E.P. 55I4 15 . 

8 Phillipi, M. 33, 373. Kempf, J. pr. [2] 78, 257. The melting point 
usually given in the literature, viz. 278*, is too low. 



A NTHRA Q UINONESDIA NTHRA Q UINON YLS 77 

sharply from the isomeric i.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, 1 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 
hydroxylamine 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 
Freund and Achenbach 4 have found that i-chlor anthra- 
quinone gives a monoxime quite easily, and that i.5-dichlor- 
anthraquinone readily forms both monoximes and dioximes. 
The monoximes of i-chloranthraquinone and of i.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 

1 Goldschmidt, B. 16, 2179. Cf. Schunck and Marchlewski, B. 27, 2125. 
~ Kurt Meyer, A. 396, 165. 

3 Kaufler and Suchanek, B. 40, 518. 

4 B. 43, 3251- 



78 ANTHRACENE AND ANTHRAQUINONE 

probably geometrical, although in the case of the oxime of 
i-chloranthraquinone positional isomerism is not impossible : 



HON NOH 

ii ii 

C Cl C Cl 






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 l 
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 erythrohydroxy anthraquinone will give no oxime, 
whereas its alkyl and aryl ethers give monoximes with 
difficulty, and anthrarufin dimethyl ether will give a mon- 
oxime. No oxime could be obtained from i.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 difficulty, and analysis and 
molecular weight determinations point to the formula : 

Ph C Ph 

II 
C 



C 

II 

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. 

1 B. 25, 1498 ; 3293- 2 B. 41, 1362. 



A NTHRA Q UINONESDIA NTHRA Q UINON YLS 79 

Gosch ! has found that anthraqtdnone condenses with 
aldehyde ammonia if heated with it for six hours at 220. 
The product melts at 28 1, and he ascribes to it the formula : 

H C CHO 

II 
C 

C 6 H/\C 6 H 4 

C 

II 
H C CHO 

Bayer & Co. 2 state that if anthraquinone is boiled with 
primary aromatic amines and a condensing agent such as 
boric acid, products are obtained in which both the carbonyl 
oxygen atoms have been replaced by 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. Very similar 
products seem to be obtained from anthraquinone-j8-sul- 
phonic acid, 3 but as these are practically insoluble in dilute 
caustic soda, it would seem that the sulphonic 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 C 3 5H33O2N 3 S. 

Anthraquinone, when fused with caustic potash, yields 
benzoic acid, 4 and caustic fusion has been applied in some 
cases for determining the constitution of anthraquinone 
derivatives. Owing to the stability of the anthraquinone 
ring, however, the method is rather tedious to carry out, 
and in the case of dimethyl anthraquinone I^avaux found it 
necessary to heat to 260 for three hundred consecutive hours. 

HOMOLOGOUS ANTHRAQUINONES 

The alkyl anthraquinones are of no great importance, 
and have not been studied in detail. Most of the methyl 

1 Soc. Ill, 610. z D.R.P. 148,079. 3 By. D.R.P. 136,872 ; 147,277. 
4 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 j8- 
methyl 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. f$- Ethyl 
anthraquinone and fi-propyl anthraquinone were prepared 
by Scholl ! 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 L,iebermann 5 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. By working 
1 M. 32, 687. 

* 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 " hydrosulfit " as " hydrogen sulphite." 

3 For example see pp. 179, 265. 

4 C. r. 79, 764. 

5 A. 212, 5. B. 9, 1202; 10, 607; 11, 1610; etc. 



I 
OH 



ANTHRAQUINONESDIANTHRAQUINONYLS 81 

in sealed tubes, however, they were able to obtain more highly 
hydrogenated substances. 1 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 

I V V 

C C C 

C 6 H /|\C 6 H 4 - C 6 H/\C 6 H 4 -> C 64 

C CO C 

/\ 
HO H 

Anthraquinol, Anthrone. Hydroxydihydro- 

anthracene. 

Compounds of this last type are somewhat unstable, and 
very readily lose a molecule of water. 

lyiebermann 3 has more recently studied the mechanism 
of the reduction of anthraquinone compounds with hydriodic 
acid, and has isolated several addition compounds containing 
iodine and hydriodic acid. 

Much more interesting results have been obtained with 
other reducing agents. Thus lyiebermann, 4 by reducing 
anthraquinone with tin and hydrochloric acid, obtained 
anthrone in good yield ; and more recently 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 employed by a very large number 
of investigators, 6 and if the reaction is carried sufficiently 
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, 

1 See Chapter III. 

3 Liebermann and Pleus, B. 35, 2923. 

8 B. 87. 3341; 88,1784. 

4 B. 20, 1854. 
A. 397. 55- 

6 E.g. Elbs, J. pr. [2] 41, 6, 121 ; B. 20, 1365. Lampc, B. 42, 1414, etc. 
R. E. Schmidt, B. 37, 70. 



82 ANTHRACENE AND ANTHRAQUINONE 

however, to anthraquinone derivatives in which there is 
a methyl group in the a- position, as Elbs 1 has found that 
these on alkaline reduction pass into hydrocarbons 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-hydroxyl group of 
the anthranol, e.g. 

CH, 





Moderated reduction with zinc dust and an alkali leads 
first to the anthraquinol, 2 and Perger 3 has found that 
further reduction leads to the ms-hydroxydihydroanthracene, 
which by 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 : 

C 6 H 4 OH OH C 6 H 4 



C 6 H 4 

which by loss of water passes into dianthryl : 

C 6 H 4 C 6 H 4 



C 6 H 4 

This lyiebermann and Gimbel 5 managed to obtain direct 
from anthraquinone by reduction with tin and hydrochloric 
acid ; and more recently Eckert and Hofmann 6 have repeated 
L,iebermann's work and find that much better yields are 

1 J- pr- [2] 41, 6, 121 ; B. 20, 1365. 

2 Graebe and Liebermann, A. 160, 126. Liebermann, A. 212, 65. 
Romer and Schwazer, B. 15, 1040. 

3 J- pr- [2] 23, 127. * B. 18, 3034. 5 B. 20, 1854. 6 M. 36, 497- 



ANTHRAQUINONES-DIANTHRAQUINONYLS 83 

obtained if the reduction is carried out in the presence of 
a trace of a platinum salt. 

Hans Meyer, 1 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 : 

C 6 H 4 C 6 H 4 HCi C 6 H 4 H H c 6 H 4 




HO-C^C C^-AC OH NaOH 

C 6 H 4 C 6 H 4 C 6 H 4 CgH 4 

Dianthrol. Dianthrone. 

This latter on reduction in glacial acetic acid with tin 
and hydrochloric acid gives tetrahydrodianthrol, which 
passes into dianthryl very readily by loss of water : 2 

pj- ^6^4 H [ C 6 H 4 ^ C 6 H 4 C 6 H, 

SCr^ 

HO p TT 
L 6 M, 

From a commercial point of view alkaline sodium hydro- 
sulphite (Na 2 S 2 O 4 ) is the most important reducing agent for 
anthraquinone derivatives, as it readily converts them into 
the soluble vats, these being readily oxidised to the original 
substance on exposure to the air. The reaction has been 
examined by Grandmougin, 3 who has found that the reduction 
product is the anthraquinol : 

OH 

C 
C 6 H 4 /|\C 6 H 4 



As will be seen later, the anthraquinone vat dyes often 

i B. 42, 143- M. 30, 165. 

M. 36, 497. 

8 J- pr. [2] 76, 138; R.G.M.C. 12, 44. 



84 ANTHRACENE AND ANTHRAQUINONE 



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 1 has shown 
that none of the following compounds will give " vats " : 



CH. 



CH, 



CH. 



CH 



NHCH 2 C 6 H 5 



C 6 H 5 CO, 



I 

1 


/COC 6 H 5 

K 

\fATT f^ TJ 

V^-TL 2 Vx gXl g 



CH. 



>N 



C 6 H 4 [/>]CH 



In the case of this last compound it is curious to notice that 
the dicarboxylic acid obtained by oxidation : 

COOH 



C 6 H 4 [/>]COOH 

can be reduced in alkaline solution. 

The use of amalgamated zinc and hydrochloric acid has 
been advocated by Clemmensen, 2 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 
found discussed in the chapter dealing with the anthrones 
and dianthryl 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. 

2 B. 47, 684. Cf. By., D.R.P. 296,091 ; 301,452 ; 305,886. 



ANTHRAQUINONESDIANTHRAOUINONYLS 85 

proved of the utmost value in the study of naturally occurring 
anthraquinone compounds. 

ACTION OF GRIGNARD'S SOLUTION. 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 

v \/ 

C C 

C 6 H 4 /\C 6 H 4 C 6 H 4 /\C 6 H 4 

CO C 

/\ 
R OH 

With magnesium aryl halides the reaction is similar, 
anthraquinone, for example, reacting with two molecules of 
phenyl magnesium bromide to form : * 

HO Ph 



C 

C 6 H 4 /\C 6 H 4 
C 

HO Ph 

In these compounds in which an aryl and a hydroxyl 
group are attached to each ws-carbon atom, the hydroxyl 
groups are very reactive and are readily 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 very stable, and on 
treatment with potassium iodide readily split off their 
chlorine and pass into sym-diaryl anthracenes. By starting 
with a diaryl anthrone and treating this with an aryl mag- 
nesium bromide, a compound containing three aryl groups 

1 C.r. 138, 327, 1251 ; 139, 9; 150, 1290; Bl. [3] 33, 1104. Clarke, 
K 41, 935. Am. Soc. 33, 1966. 

2 Loc. cit. 



86 ANTHRACENE AND ANTHRAQUINONE 

and a hydroxyl group attached to the two ws-carbons is 
obtained, 1 e.g. 

Ph Ph 



C 6 H 4 /\C 6 H 4 

C 

/\ 

Ph OH 

In these the hydroxyl group is very easily etherified by 
alcohol and hydrochloric acid, but a fourth aryl group 
cannot be attached to the ms~ carbon atom unless this aryl 
group contains an amino group or a phenolic hydroxyl 
group 2 (see p. 89). 

By treating anthraquinone with a molecule of magnesium 
benzyl chloride, Haller 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 by condensing anthrone with benzaldehyde : 




CO 

o 

Benzylidene anthrone was also obtained by I^evi 4 and 
by Bach 5 by benzylating alkaline solutions of anthraquinol 
with benzyl bromide and subsequently treating the benzyl 
hydroxy anthrone with concentrated sulphuric acid, and 
their description of the substance is in close agreement with 
that given by Haller and Padova. Tschilikin, 6 however, 
has recently prepared the substance by treating anthraquinol 
with dimethylphenylbenzyl ammonium chloride (leuco- 

1 C. r. 139, 9. 2 C. r. 140, 283, 343. 3 C. r. 141. 857. 

B. 18, 2152. 5 B. 23, 1567. 6 B. 47, 1055. 



ANTHRAQUINONESDIANTHRAQUINONYLS 87 

trope D) and gives the melting point as 117 in place of the 
126-127 found by I^evi, Bach and Haller, and Padova. 
Tschilikin obtained benzylhydroxy anthrone simultaneously. 
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 : 

CH 3 OH CH 3 OCH 3 

\/ V 

C C 

C 6 H 4 <^>C 6 H 4 -> 

C C 

/\ /\ 

CH 3 OH CH 3 OCH 3 

* I 

CH 2 CH 2 

C C 

C 6 H 4 /\C 6 H 4 C 6 H 4 <Q>C 6 H 4 

C C 

/\ /\ 

CH 3 OH CH 3 OCH 3 

the reaction being exactly similar to that undergone by the 
benzyl derivative described on the previous page. 

Similar compounds were obtained by treating phenyl 
methoxy anthrone with an alkyl magnesium iodide and then 
boiling the resulting substance with glacial acetic acid : 

CgHs OCH 3 CfiEIs OCH 3 

Y Y 

C 6 H /^>C 6 H 4 -> C 6 H/\C 6 H 4 

C C 

CH 3 OH 

1 Bl. [3] 33, 1144. Cf. Clarke, B. 41, 935; Am. Soc. 33, 1966 (corre- 
sponding ethyl compounds). 



88 ANTHRACENE AND ANTHKAQUINONE 

Haller and Guyot * have studied the action of Grignard's 
solutions on other anthrones. Starting with diphen}-!- 
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 

C 6 H 4 /\C 6 H 4 -> C 6 H 4 /\C 6 H 4 -> C 6 H 4 /\C 6 H 4 
CO C C 



Ph OH Ph H 

This latter compound they were also able to synthesise by 
treating the methyl ester of triphenylmethane-o-carboxylic 
acid with magnesium phenyl bromide : 

Ph Ph Ph Ph 

Q \/ \/ 

C.OCH 3 C OCH 3 C 

CeH^/CeH, -> C^^/C^ -> C 6 H 4 /\C 6 H 4 
C C C 

/\ /\ /\ 

Ph H Ph H Ph H 

This latter synthesis closely resembles the synthesis of 
ms-diphenylanthracene by Simonis and Remmert. 2 These 
investigators found that 0-brombenzyl triphenyl carbinol 
loses hydrobromic acid very readily when treated with 
sulphuric acid and passes into ws-diphenylanthracene : 

H Ph Br Ph 

\l/ I 

C C 



6 H 4 <( 



c c 

/\ I 

Ph OH Ph 



)>C 6 H< 



1 C. r. 139, 9. 2 B. 48, 208. Cf. C. r. 138, 1252 ; 140, 1461, 



A NTHRA Q UINONESDIA NTHRA Q UINON YLS 89 

and i.2-dimethoxy-ws-diphenylanthracene can be obtained 
in a very similar manner : 

HO Ph H Ph 

Y ';' l 

(CH 3 0) 2 C 6 H 2 <^ / C 6 H 5 -> (CH 3 0) 2 C 6 H 2 <(J>C 6 H 4 
C C 

/\ I 

Ph OH Ph 

As stated on p. 86, the hydroxyl group in triphenyl 
hydroxy dihydroanthracene cannot be replaced by an aryl 
group, but these compounds react readily with compounds 
of the type ArX when Ar is an aryl group and X an hydroxyl 
or primary, 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 

V 

c 

C 6 H 4 /\C 6 H 4 
C 

A 

Ph ArN(CH 3 ) 2 

The diphenyl dihydroxy dihydroanthracene which is 
obtained by the action of magnesium phenyl bromide on 
anthraquinone will . also condense with tertiary amines. 
The products are compounds of the type : 

Ph CeHiNMeo 

\/ 
C 

C 6 H 4 /\C 6 H 4 

C 

/\ 
Ph C 6 H 4 NMe 2 

and exhibit geometrical isomerism. 2 

1 Haller and Guyot, C. r. 140, 283. 2 C. r. 140, 283, 343. 



90 ANTHRACENE AND ANTHRAQUINONE 

The dihydroxy compound can also be converted into 
the dichlor- compound by means of alcoholic hydrochloric 
acid, and from this the chlorine is readily split off by potassium 
iodide, the product being ws-diphenyl anthracene : 

Ph OH Ph Cl 



Ph 



\/ 

C 

/ 



\, 



Ph OH 



C 6 H 4 <J>C 6 H 4 

C 

/\ 

Ph Cl 



C 6 H 4 



C 
Ph 



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. 1 

THE DlANTHRAQUINONYLS 

The dianthraquinonyls are the anthraquinone analogues 
of diphenyl and are not to be confused with the dianthra- 
quinones (p. 116). 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 '-Dianthraquinonyl. 

The dianthraquinonyls can, of course, be built up from 
diphenyl by the phthalic acid synthesis, and this method is 
discussed on p. 135. The results, however, are not satis- 
factory, and the dianthraquinonyls are much more readily 
1 Bl. [3] 25, 315; Bull. Soc. ind. Mulhaus, 72, 268. 



ANTHRAQUINONESDIANTHRAQUINONYLS 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 hydroxyl groups are present in 
the molecule. Thus erythrohydroxy anthraquinone on 
fusion with caustic potash gives i.i'-dihydroxy-2.2'-dianthra- 
quinonyl, 1 the structure being proved by its giving a fur- 
furane derivative by loss of water, and by its giving 2.2'- 
dianthryl on distillation with zinc dust. 2 In the case of 
quinizarin, dianthraquinonyl formation takes place more 
readily, heating 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'-tetrahydroxy-2.2 / -dianthraquinonyl. 4 
The oxidation of hydroxyanthraquinones by hypochlorites 
usually leads either to halogenation or to complete rupture 
of the ring system, but Scholl 5 has found that alizarin can 
be oxidised to i.2.i'.2 / -tetrahydroxy-3.3 / -dianthraquinonyl 
by treatment under suitable conditions with potassium 
hypochlorite 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'-dianthryl by distillation 
with zinc dust. 

. Dianthraquinonyls can be obtained from the anthra- 
quinone diazonium salts by 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 readily into the dianthra- 
quinonyl, provided that no very considerable quantity of 
halogen acid is present, 6 and diazonium sulphates can also 
be converted into the dianthraquinonyl by treating them with 
copper in the presence of acetic anhydride. 7 

By., D.R.P. 167,461. 
Scholl, B. 52, 2254. 
By., D.R.P. 146,223. 
Scholl, B. 52, 2254. 

B. 52, 1829; D.R.P. 274,784. B.A.S.F., D.R.P. 215,006. 

Scholl, B. 40, 1696. B.A.S.F., D.R.P. 184,495. Cf. Knrevenagel, 
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. 1 Both a- 
and j8- 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 cases 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 benzylidene derivative. 2 

The dianthraquinonyls themselves are of no great im- 
portance, their chief interest lying in their relation to the 
helianthrones (p. 333) and flavanthrones (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. 4 

THE ANTHRADIQUINONES 

Polyhydroxy anthraquinones in which two hydroxyl 
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. 5 I^esser, 6 and Dimroth and 

1 Scholl, 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. 
Ullmann, 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 Scholl, B. 51, 452. Ullmann, A. 399, 332. D.R.P. 248,999. 

3 Scholl, B. 43, 355, 1738. 

4 Scholl, B. 40, 1696. 

5 By., D.R.P. 66,153 ; 68,113; 68,114; 68,123; 69,842 

6 B. 47, 2526. 



ANTHRAQUINONESDIANTHRAQUINONYLS 93 

Schultze 1 obtained i.^g.io-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 
i.4-anthraquinone, show the usual quinone reactions. Thus, 
i.4.9.io-anthradiquinone is rapidly reduced to quinizarin 
by sulphurous acid, it adds on a molecule of hydrochloric 
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 ^-hydroxyamino- 
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 1.2.9.10- 
anthradiquinone has not been isolated, but Dimroth and 
Schultze have obtained a straw-yellow solution by 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 undoubtedly consists of a solution 
1 A. 411, 345. 2 M.L B., D.R.P. 258,556. 



94 ANTHRACENE AND ANTHRAQUINONE 

of i.a.g.io-anthradiquinone, but the quinone is so unstable 
that it was found impossible to isolate it. 



ANTHRAP%AVONES 

If j8-methyl 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 Anthraflavone G, and was originally believed 
to have the structure : 




although Scholl 2 showed that neither /3-ethylanthraquinone 
nor j3-propylanthraquinone gave any trace of an anthra- 
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 only of anthraquinone-j8-car- 
boxylic acid. Further, they pointed out that anthraflavone 
adds on a molecule of bromine without any evolution of 
hydrobromic acid, and that the dibromo- product thus 
obtained is quantitatively changed back to anthraflavone by 
treatment with diethylaniline. These facts all point to 
anthraflavone being really dianthraquinonyl ethylene, and 
this is in agreement with the observation of Ullmann and 
Klingenberg, 4 that anthraflavone is obtained when co- 
dibrom-j8-methyl anthraquinone is heated with dimethyl- 
aniline, or better with diethylaniline. 

The stilbene structure has been fully 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. 
8 M. 32, 690. 8 B. 46, 712. 4 Loc. cit. 



ANTHRAQUINONESDIANTHRAQUINONYLS 95 

Romer 1 obtained anthraflavone by heating o>-dibrommethyl 
anthraquinone with sodium iodide in acetone solution, or by 
treating it with copper powder; 2 and Ullmann 8 has employed 
this method for preparing dichloranthraflavone from 2-chlor- 
3-dibrommethyl anthraquinone. 

Scholl 4 condensed phthalic acid with j8-methyl naphtha- 
lene, and from the 3-methyl-i.2-benzanthraquinone thus 
obtained he got an anthraflavone which no doubt had the 
structure 



co I I \ co 





CO 



although Scholl gave it cyclic formula in conformity with the 
then belief that anthraflavone contained a seventh ring. 
ScholTs product was a vat dye, and gave reddish shades of 
yellow. A vat dye which gives orange shades is said to be 
obtained by adding bromine to a boiling solution of i-chlor- 
4-methyl anthraquinone in nitrobenzene. 5 The constitution 
of the dye is unknown, but it may be a stilbene derivative. 

1 B. 46, 709. M.L.B., D.R.P. 260,662 ; 267,546. 

2 Cf. Eckert, M. 35, 300. 3 B. 47, 560. 

4 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 ANTHRANOI, 

Anthrone itself was first obtained by Liebermann l by 
the moderated reduction of anthraquinone with hydriodic 
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 3 and concentrated sulphuric acid at 
30-40. This last process has been investigated by Eckert 
and Pollak, 4 who find that the first product formed is the 
anthraquinol (hydroxyanthrone ?), the anthrone then being 
formed by further reduction. 

Baeyers obtained ws-phenyl anthrone by heating tri- 
phenylmethane-o-carboxylic acid with dehydrating agents : 




COOH 




CO 



1 A. 212, 5; B. 20, 1854. 2 A. 397, 55. 

3 B.A.S.F., D.R.P. 190,656 ; By., D.R.P. 201,542. 

4 M. 38, ii ; 39, 839. 6 A. 202, 54. 

96 



ANTHRONE AND ANTHRANOL 97 

and Bistrzycki and Ulffers 1 have prepared hydroxy- 
anthrone and one or two other anthrone derivatives by this 
method, although the reaction is often complicated 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 : 



C0 Q 6 H*NM e 




COOH 




The phthalide thus formed they reduced to the corre- 
sponding triphenylmethane carboxylic acid, which, on boiling 
with phosphorus oxychloride in dimethylaniline solution, lost 
a molecule of water and passed into an anthrone derivative : 





COOH v CO 

The same investigators 3 obtained ms-diphenylanthrone 
by condensing phthalyl tetrachloride with benzene in the 
presence of aluminium chloride : 

COC1 CO 



C 6 H 4 / 



A 

Ph Ph 



and also by condensing dichloranthrone or phenylchlor- 
anthrone with benzene 

CO CO 

C 6 H 4 /\C G H 4 ~> C 6 H 4 /\C 6 H 4 

C C 

/\ /\ 



Cl Ph Ph Ph 

B. 31, 2799. 2 Bl. [3] 25, 315. 9 C. T. 121, 102. 

7 



98 ANTHRACENE AND ANTHRAQUINONE 

Baeyer l had previously obtained the same compound by 
heating phenyl hydroxyanthrone 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 forms 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 united to a 
mesa-carbon atom, as both give anthraquinone on oxidation. 
As was to be expected, chlorine reacts similarly, but much 
more vigorously, so that only the dichlor compound could be 
isolated. The same dichloranthrone (m.p. 132-134) had 
previously been obtained by Thorner and Zincke 4 by 
treating 0-methylbenzophenone with chlorine : 

CO CO 

5 - C 6 H 4 /\C 6 H 4 
CH 3 CC1 2 

Nuclear chloranthrones have been obtained by Eckert 
and Tomaschek 6 by reducing chloranthraquinones with 
copper powder and concentrated sulphuric acid. Padova 6 
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. 4 B. 10, 1478. 

5 M. 39, 839. C. r. 149, 217. 



ANTHRONE AND ANTHRANOL 99 

alkyl chloranthrones are obtained by the action of phos- 
phorus pentachloride on the products obtained by alkylating 
hydroxyanthranol (anthraquinol), 1 and lyiebermann 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 
extremely reactive, so that monobromanthrone is converted 
into hydroxyanthrone by aqueous solvents, 3 and into 
methoxyanthrone by methyl alcohol. 4 Ammonia does not 
convert it into an amino compound, but into bromdianthrone, 
but arylamino anthrones are obtained by treatment with 
primary aromatic amines. 5 Copper powder converts it into 
dianthrone. 6 

Anthrone reacts normally with nitroso dimethyl aniline, 7 
and Padova 8 has found that with benzaldehyde it gives 
phenylmethylene anthrone, and with benzophenone chloride 9 
it yields diphenylmethylene anthrone : 

CHPh CPh 2 

C C 



vxC 




It does not, however, react with aniline, dimethyl- 
aniline or with benzophenone itself. With benzo-trichloride, 
however, it gives phenyldichlormethyl anthrone, 9 which 
when heated with pyridine splits off a molecule of hydro- 
chloric acid and passes into phenylchlormethylene anthrone : 

1 A. 212, 67. B. 13, 1596; 15/452, 455, 462. C. r. 121, 102. 

2 B. 37, 3337. 

3 A. 379, 45. 

4 A. 323, 236 ; 379, 45. Cf. also B. 38, 2868. 

5 A. 396, 133, 145. 

6 A. 396, 143. 

7 B. 40, 525. Cf. B. 32, 2341 ; 33, 959 ; 34, 118, 3047. 

8 C. r. 141, 857. Cf. Weitz, A. 418, 29. 

* C. r. 143, 121. In the abstract of this paper published by the Chemical 
Society (Soc. 90, (i) 741), " chlorure de benzophenone " is mistranslated 
as " chlorobenzophenone." 



ioo ANTHRACENE AND ANTHRAQUINONE 

H cci 2 ph cicph 

c c 

CG^X xC 6 H 4 C 6 H 4 <T/C 6 H 4 

c c 

6 6 

Padova l also found that anthrone reacts with chloro- 
form in alcoholic solutions of caustic potash to form a com- 
pound : 

C 6 H 4 C 6 H 4 

O = 

C 6 H 4 

and Friedlander 2 and Kalle & Co. 3 have obtained vat dyes 
by condensing it with isatine dichloride and dibromoxy- 
thionaphthene : 

C 6 H 4 NH C 6 H 4 S 




C 6 H 4 CO C 6 H 4 CO 

Meerwein 4 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 very readily : 

yCOCHg 

C 6 H 5 CHCH(COOBt) 2 C 6 H 5 CHCH<( 

| | x COOEt 

CH CH 

H 4 C 6 H 4 <f>C 6 H 4 



CO CO 

Attempts to hydrolyse such compounds usually lead to 
the formation of anthrone, but in the case of the addition 
compound with benzalmalonic ester the hydrolysis could be 
effected by means of sulphuric acid in glacial acetic acid 
solution and lead to : 

1 C. r. 140, 290. 2 B. 42, 1060. 

3 D.R.P. 193*272. 4 J. pr. [2] 97, 284. 



ANTHRONE AND ANTHRANOL 101 

C 6 H 5 CHCH 2 COOH 
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 * 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 dimethylaniline in the presence of 
anhydrous aluminium chloride to form a compound 
Me 2 NC 6 H 4 C 6 H 4 NMe 2 

V 

c 

C 6 H 4 /\C 6 H 4 

CO 

Liebermann and Mamlock 3 found that bromanthrone reacts 
very readily with resorcinol by simply boiling in benzene 
solution, no condensing agent being required. Under these 
conditions one would rather expect the hydroxyl 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 C 6 H 3 (OH) 2 C 6 H 3 (OH) 2 

Y i I 

C 6 H 4 /\C 6 H 4 , or C 6 H 4 /|\C 6 H 4 

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. 2 c> r> 136> 535> 3 B< 3 



102 ANTHRACENE AND ANTHRAQUINONE 

which must correspond to the second formula, is strongly 
fluorescent. 

In phenylchloranthrone the reactivity of halogen atom 
is, as would be expected, greater than it is in the case of 
brom-anthrone. With resorcinol condensation takes place 
in exactly the same way as with bromanthrone, but in the 
case of the simpler phenols, such as phenol and cresol, 
the reaction is different, the hydroxyl group reacting with the 
halogen atom and at the same time condensation taking 
place with the carbonyl group ; products of the structure : 

Ph OR 



RO OH 
being obtained. 1 

In the case of alcohols the hydroxyl group reacts with 
the halogen atom, but simultaneous condensation with the 
carbonyl group does not take place, so that the products are 
alkoxyanthrones. 

The structure of phenylchloranthrone is very similar to 
that of triphenylmethyl 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 similar to triphenyl methyl. lyiebermaiin 2 and 
his co-workers have found evidence that this is actually the 
case, and Schlenk, 3 by boiling phenyl chloranthrone in 
petroleum ether solution with copper bronze, obtained a 
yellow 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^ per cent, of 
C 2 oH 13 O and 66| per cent, of C4oH 2 6O 2 . Schlenk has pointed 
out that if the bridge formula for anthracene is correct 
ws-diphenyl anthracene is really a derivative of the unknown 
hexaphenylethane : 

1 B. 38. 1800. 2 B. 37, 3337 ; 38, 1799- 3 A. 394, 3340. 



ANTHRONE AND ANTHRANOL 103 



C 6 H 4 C 6 H 5 C 6 H 5 

Diphenylanthracene. Hexaphenyl ethane. 

and consequently might readily form a compound containing 
two trivalent carbon atoms. He was unable, however, to 
bring about this change. 

ws-Nitroanthrone is formed when anthracene is treated 
with nitric acid under certain conditions, 1 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 4 obtained an 
impure substance which lost ammonia very readily and 
formed anthraquinol. This was probably amino anthrone, 
but owing to its instability it could not be purified sufficiently 
for analysis. 

The chlorine atoms in dichlor anthrone are capable of 
reacting with nuclear hydrogen atoms under the influence of 
aluminium chloride, and by this means Haller and Guyot 5 
have prepared tetramethyl and tetraethyl diaminodiphenyl 
anthrone from dichloranthrone (anthraquinone dichloride) 
and dimethyl and diethyl aniline : 

Cl Cl Me 2 NC 6 H 4 C 6 H 4 NMe 2 

\/ \/ 

C C 

C 6 H 4 <^>C 6 H 4 +2C 6 H 5 NMe 2 - C 6 H 4 <(^>C 6 H 4 
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 in the presence of aluminium 
chloride diphenyl anthrone is produced, a compound 

1 Perkin, Soc. 59, 648 ; 61, 866. * Kurt Meyer, A. 396, 150. 

A. 396, 133. * LOG. cit. 6 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, 1 and by Baeyer by condensing phenyl hydroxy 
anthranol with benzene in the presence of sulphuric acid : 2 

Ph Ph Cl Ph 



CC1 2 C 

C 6 H 4 <Q>0-|-C 6 H G -> C 6 H 4 <^>C 6 H 4 - 

CC1 2 CO CO 

f Ph OH 

\/ 

C 



CO 

Starting with this substance several interesting syntheses 
have been carried out. 

Iviebermann and L/indenbaum * found that it was very 
readily reduced by zinc and acetic acid to the corresponding 
hydrocarbon, and that by treating this latter with bromine 
one, and only one, of the hydrogen atoms attached to the 
ws-carbon atom could be replaced : 

Ph Ph Ph Ph 

\/ \/ 

C C 

C 6 H 4 <f>C 6 H 4 - C 6 H 4 <f>C 6 H 4 
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 C 52 H 3e and show 
two extra hydrogen atoms. Such a compound would only be formed by 
loss of bromine and not by loss of hydrobromic 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 crystals 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 usually attacked by atmo- 
spheric oxygen. Anthranol itself on moderated oxidation 
passes into dianthrone, but the arylamino-anthranols pass 
into the corresponding anil : l 

T <? 

c . c 

C 6 H 4 <J>C 6 H 4 -> C 6 H 4 <Q>C 6 H 4 



NHPh . 

Goldmann 2 has studied the behaviour of anthranol 
when heated in alkaline solution with ethyl iodide and has 
isolated three products. The first of these is anthranol 
ethyl ether (ws-ethoxy anthracene). It reacts violently 
with bromine, but at 20 forms an unstable addition 
1 A. 396, 147. B. 21, 1178, 2505. 



io6 ANTHRACENE AND ANTHRAQUINONE 

compound which evolves hydrobr online acid at o, and 
passes into a more stable dibrom compound. This on 
oxidation yields, first, the monoethyl 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 by Goldmann is a very 
stable substance melting at 136. It is unaffected by 
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 unsym-diethyl 
dihydroanthracene, and must, therefore, be diethylanthrone : 
Et Et Et Et 

\/ \/ 

C C 

C 6 H 4 <Q>C 6 H 4 - C 6 H 4 /\C 6 H 4 

CO CH 2 

It is interesting to observe the difficulty with which this 
reduction is effected in view of the fact that the correspond- 
ing diary 1 compounds, e.g. diphenylanthrone, are very 
readily reduced to the wwsym-diaryldihydroanthracenes by 
boiling with zinc and glacial acetic acid. 1 

The third compound isolated by Goldmann melted at 
77, and on moderated oxidation yielded C-ethyl hydroxy 
anthrone, a compound previously obtained by Liebermann 2 
by the ethylation of hydroxy anthrone. It must, therefore, 
be the ethyl ether of ethyl anthranol : 

C 2 H 5 



C 



OC 2 H 5 

1 B. 38, 1799- 2 A. 212, 70. 



ANTHRONE AND ANTHRANOL 107 

Hallgarten 1 has carried out similar experiments with 
methyl iodide, zso-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 interesting experiments on the action of diazonium 
salts on the anthranol ethers. They find that, contrary to 
the belief usually held, diazonium salts often couple quite 
readily with phenolic ethers and even with unsaturated 
aliphatic hydrocarbons. 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 in 
the phenolic ether. Positive groups, especially alkoxy 
groups, in the phenolic ether greatly facilitate the coupling 
when in the meta position. In the case of the phenolic 
ethers derived from phenols and naphthols, dealkylation 
does not take place, the product being an alkoxyazo com- 
pound. When anthranol methyl ether is used, however, 
dealkylation 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 

V - 

c c 

C 6 H/\C 6 H 4 -> C 6 H/\C 6 H 4 

C C 

/\:NAr <; s> N.NHAr 

Methylanthranol methyl ether also couples with dizaonium 
salts, and it is probable that the mechanism of the reaction 
is somewhat similar : 

1 B. 21, 2508. 

1 B. 47, 1741. Cf. A. 398, 74 '. B. 52, 1468. 



io8 ANTHRACENE AND ANTHRAQUINONE 

OCH 3 CH 3 OH 

I \/ 

c c c 

C 6 H 4 /\C 6 H 4 - C 6 H 4 /\C 6 H 4 -> C 6 H 4 /\C 6 H. 4 

C C C 

I /\ /\ 

CH 3 CH 3 NiNAr CH 3 N : NAr 



HYDROXYANTHRONE AND ANTHRAQUINOI, 

Hydroxyanthrone is to be considered as the tautomeric 
(ketonic) form of anthraquinol, 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 l obtained hydroxyanthrone 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 by 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 only 
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 4 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. 3 A. 323, 236. 

4 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 ws-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 dihydro- 
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. 


Butyl dihydro 
anthracene. 


Amyl dihydro 
anthracene. 


Tetra hydro 
anthracene. 


Hexa hydro 
anthracene. 


Carbon 
Hydrogen . 


92-3 
7'7 


91 '5 

8'5 


91-2 
8-8 


92-3 
77 


91-3 

87 



I/iebermann, 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 very readily by cold hydro- 
chloric or hydrobromic acid. 1 

(3) Although the hydroxyl group cannot be acetylated 
in the ordinary way, I/iebermann 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 readily split off 
water and pass into ws- alkyl anthracenes : 



1 B. 37, 3337- 



2 A. 202, 54- 



no ANTHRACENE AND ANTHRAQUINONE 
HO R HO R R 

V \/ I 

c c c 

C 6 H 4 /\C 6 H 4 ^ C 6 H 4 /\C 6 H 4 l5 C 6 H 4 /|\C 6 H 4 

c c c 

6 /\ I 

H H H 

The reaction here is exactly analogous to the reduction of 
anthraquinone to anthracene carried out by Perger. 1 It 
has received confirmation by I,iebermann, 2 who alkylated 
Perger's hydroxy dihydro anthracene and obtained sub- 
stances which readily passed into ws-alkyl anthracenes by 
loss of water, and which on moderated oxidation yielded 
alkyl hydroxy anthrones : 

R 




H H 



O 

The above reactions were all obtained with the ethyl, 
propyl, zso-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- 

i j. pr . [2] 23, 137. * A. 212, 67. B. 13, 1596 ; 15, 452, 455. 4 62 



ANTHRONE AND ANTHRANOL in 

logues. Obviously this is an O-methyl compound (methoxy 
anthrone) : 

H OMe 

\/ 

C 



CO 

On one occasion, however, lyiebermann 1 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 

Y i 



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-ethyl ether and also 
I^iebermann's C-ethyl hydroxy anthrone. 

The formation of C-alkyl compounds by the alkylation 
of hydroxy anthranol is very 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 
equilibrium 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, 1175. a A. 379, 47. 



H2 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 compounds : 

ONa NaO R NaO R 

! \/ V 

C C C 

C 6 H 4 /[>C 6 H 4 -> C 6 H 4 /\C 6 H 4 -> C 6 H 4 /\C 6 H 4 

C C C 

I /\ II 

ONa NaO Br O 

The production of the O-methyl compound is to be 
ascribed to the predominance of the " normal " reaction in 
this case : 

OiNa~"l|CH 3 OCH 3 



I 
C 



C C 

I I 

ONa ONa 

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 hydroxyl group of the aryl hydroxy anthrones is 
very reactive and, as is pointed out elsewhere (p. 85), is 
readily replaced by chlorine or bromine by treatment with 
halogen acid. The carbonyl group is also reactive and 



ANTHRONE AND ANTHRANOL 113 

Haller and Guyot 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 : 

Me 2 NC 6 H 4 OH Me 2 NC 6 H 4 OH 

V V 

c c 

C 6 H 4 0C 6 H 4 - C 6 H 4 /\C 6 H 4 

CO C 

/\ 
Ph OH 

The anthraquinols are the enolic forms of the hydroxy 
Enthrones and are of great importance, as they are readily 
soluble in dilute alkali and the alkaline solutions are very 
rapidly oxidised by the air or by weak solutions of hydrogen 
peroxide with the formation of the corresponding anthra- 
quinone. The insoluble vat dyes are always applied to tfte 
fibre in the form of their anthraquinol derivative (" vat " or 
" leuco- compound "), the insoluble dyestuif being subse- 
quently 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 
L,iebermann 2 by the reduction of anthraquinone with zinc 
dust and caustic soda, and more recently Grandmougin 3 
has shown that the reduction is better effected with sodium 
hydrosulphite in alkaline solution, the reducing agent always 
used in vat dyeing. Owing to the ease with which the 
anthraquinols are oxidised by the air their isolation is a 
matter of some difficulty, and for this reason I/iebermann 4 
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 
acetyl derivatives are quite stable they can easily be purified. 
They can be hydrolysed by alkali, but owing to the sensitive- 
ness of the free hydroxy compounds it is necessary to work 

1 C. r. 137, 606. 2 A. 160, 126, 

s J. pr. [2] 76, 138; B. 39, 3963. 4 B. 21, 436, 1172. 

8 



H4 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 diethyl sulphate has 
already been described (p. in). 



DlANTHRYI, AND ITS DERIVATIVES 

Dianthryl is the hydrocarbon formed by the union of 
two anthracene residues by their ws-carbon atoms, and corre- 
sponds to anthracene in much the same way that diphenyl 
corresponds to benzene : 

C 6 H 4 



C 6 H 4 

Theoretically five other dianthryls are possible which 
may be represented as A[g][i]A, A[g][2]A, A[i][i]A, 
A[i][2]A and A [2] [2] A, where A indicates an anthry (C 14 H 9 ) 
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 : 

C 6 H 4 OH OH C 6 H 4 C 6 H 4 C 6 H 4 



C 6 H 4 C 6 H 4 C 6 H 4 C 6 H 4 

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 Kckert and Hofmann 3 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. 3 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, 1 and as this on oxidation gives 
anthraquinone, the nitro groups must be attached to the 
ws-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 dianthryl in the same way 
that anthranol corresponds to anthracene : 

C 6 H 4 C 6 H 4 



It was first prepared by Hans Meyer 2 by the reduction 
of anthraquinone with zinc and caustic soda under pressure 
at a high temperature, and more recently Eckert and Hof- 
mann 3 have obtained it by the alkaline hydrolysis of the 
diacetate obtained by oxidising dianthryl with lead dioxide 
in glacial acetic acid solution : 



C 6 H 4 C 6 H 4 C 6 H 4 C 6 H 4 

* 

C 6 H 4 C 6 H 4 



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 : 4 

1 B. 20, 2433. 2 B. 42, 143 ; M. 30, 165 ; Kinzlberger & Co., D.R.P. 223,210. 
3 M. 36, 497. 4 B - 42, 143. 



n6 ANTHRACENE AND ANTHRAQUINONE 



O : C<C=CC : O 
C 6 H 4 



It has been stated that w^so-ethers of hydroxylated 
dianthranols are formed when mandelic acid is heated with 
pyrocatechol or hydroquinone at 200-300, although in the 
case of resorcinol the product is dihydroxydiphenyl methane 
carboxylic acid. 1 The course of the reaction is not clear, 
and the results claimed cannot be unreservedly accepted 
without further confirmation. 

Dianthrone is the tautomeric form of dianthranol, just 
as anthrone is the ketonic form of anthranol, and the two 
isomers are interconvertible by the action of acids and 
alkalis (see p. 124). It is obtained by the action of copper on 
bromanthrone, 2 and Dimroth 3 has obtained it in quantitative 
yield by the action of ferric chloride on anthranol, and in 
smaller yield by the action of nitric acid on anthracene : 

H H 



2 O : C C -> O : C C C C : O 

"Br 
C 6 H 4 C 6 H 4 C 6 H 4 

Padova 4 has also claimed that it is obtained in good 
yield when dianthranol is oxidised with phenanthraquinone. 

Orndorff and Bliss 5 have described a compound which 
they obtained by the action of sunlight on benzene solutions 
of anthranol, and by boiling benzene solutions of the same 
substance. This they regarded as a bimolecular polymer 
of anthranol, and named it dianthranol, but there is little 
doubt that their substance was really dianthrone. 

Dianthrone melts rather indefinitely at 245-255, and is 
insoluble in cold alkali. 

Dianthraquinone is readily obtained by the oxidation of 
dianthranol, Eckert and Hofmann 6 finding that it is 
produced by the sulphuric acid hydrolysis of dianthranol 

i H. von Licbig, J. pr. [2] 78, 95- * A. 379, 44. 

3 B. 34, 219. Cf. Scholl, B. 44, 1075. 4 C. r. 149, 217. 

a Am. 18, 453. 6 M. 36, 497, 



AN THRONE AND ANTHRANOL 117 

diacetate, although more readily obtained by oxidising 
dianthranol in alkaline solution with potassium persulphate 
or hydrogen peroxide, 1 or, according to Kinzlberger & Co., 
by potassium permanganate : 2 



-> O : C<Q>C=C^>C : O 
C 6 H 4 C 6 H 4 C 6 H 4 C 6 H 4 

Padova 3 has stated that it is also obtained when di- 
anthranol is oxidised by amyl nitrite in pyridine solution ; 
but according to Meyer, Bondy and Bckert 4 the substance 
obtained by Padova was really only a mixture of anthra- 
quinone and unchanged dianthranol. Bckert and Toma- 
schek 5 have studied the chlordianthraquinones. These 
they obtained by oxidising the chlordianthranols with 
potassium persulphate, and found that they are oxidised by 
atmospheric oxygen under the influence of light to more 
highly condensed compounds, e.g. 



co ci 




CO Cl 



Kurt Meyer 6 endeavoured to prepare aminoanthrone 
by the action of ammonia on bromanthrone, but always 
obtained brom-dianthrone, which by treatment with copper 
powder or when heated alone lost hydrobromic acid and 
passed into dianthraquinone : 

C 6 H 4 Br H C 6 H 4 C 6 H 4 C 6 H 4 

0:C<Q>C-- C<^>C:0 ~> O : C<Q>C : C<^>C : O 
C 6 H 4 C 6 H 4 



1 M. 33, 1447. 2 D.R.P. 223,210. 

3 C. r. 148, 290. * M. 33, 1447. 

5 M. 39, 839. 6 A. 396, 133. 



n8 ANTHRACENE AND ANTHRAQUINONE 

TAUTOMERISM 

Kurt Meyer l has studied the question as to what extent 
anthranol and anthrone compounds can be considered to 
be tautomeric : 

OH O 

I II 

C C 

C 6 H 4 /\C 6 H 4 ^ 



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 insolubilhy 
in cold alkali points to the ketonic formula. Also Padova 2 
has prepared condensation products with aldehydes and 
ketones (see p. 99), and Kaufler and Suchannek 3 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 Meyer found that if an alkaline solution of L,ieber- 
mann'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 crystalline. It is readily soluble 
in most media, giving yellow solutions with a strong blue 
fluorescence, but these fairly rapidly lose their colour and 

1 A. 379, 37. 

2 C. r. 141, 857 ; 143, 121. 

3 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 C 



C 6 H/\C 6 H 

6 4N x^ 6 



H 4 v I x 



CH 2 C 

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 * has done by 
using the disappearance of fluorescence to determine the 
end point, as this is very, 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. 

Equilibrium is also set up on fusion, and if anthrone is 

* A. 396, 140. 



120 ANTHRACENE AND ANTHRAQUINONE 

melted and then suddenly cooled it is found to be partially 
soluble in cold alkali. 

Compound. Per cent enole. 

Anthrone . . . . . . n 

Nitroanthrone . . . . . . . . 3 

Phenylanthrone . . . . . . 30 

Anilidoanthrone . . . . . . 80 

Hydroxyanthrone . . . . . . 96 

In pyridine solution all the above seemed to be completely 
enolised. 

Kurt Meyer * has noted the following differences between 
the reactions of anthranol and anthrone : 

(1) Anthranol is readily attacked by mild oxidising agents 
such as ferric chloride, bromine, amyl nitrite, etc., whereas 
anthrone is not attacked in the cold and only with difficulty 
on heating. As anthrone is most readily oxidised in those 
solvents which favour the change to the enolic form, it is 
probable that oxidation only 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 enolic 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 - phenyl 
hydrazine. He obtained two isomeric benzoyl derivatives, 
however, one of which must be ketonic, as he obtained it by 
condensing dibromanthrone with benzoyl phenyl hydrazine. 
The other isomer he obtained by coupling diazotised aniline 
with anthranol, and then benzoylating the azo dye. This 
latter must be enolic, and by comparing the properties of the 
two benzoyl derivatives Meyer formed the opinion that the 

1 A. 379, 37. a A. 396, 152. 



ANTHRONE AND ANTHRANOL 121 

parent azo- dye was probably enolic. Kauffler and Such- 
annek, 1 and more recently Charrier, 2 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. 4 

Kurt Meyer 5 has also examined the isomerism of anthra- 
quinol : 

OH 
I O 

c c 

C 6 H 4 /|\C 6 H 4 $ C 6 H 4 /\C 6 H 4 
C C 



OH H OH 

Anthraquinol. Hydroxyanthrone. 

which is obviously enolic, as it is soluble in cold aqueous 
alkali, is fluorescent and is very 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 unable 
to convert it into hydroxyanthrone, but succeeded in 
preparing this latter substance by treating bromanthrone 
with water : 

H Br H OH 

Y Y 

C 6 H 4 /\C 6 H 4 -> C 6 H 4 /\C 6 H 4 
CO CO 

He found it to be colourless, non-fluorescent and stable 
to atmospheric oxygen. 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 alcoholic 
alkali. The interconversion of the isomers in this case is much 

1 B. 40, 518. 2 G. 45, 502. 

3 For absorption spectrum see Sircar, Soc. 109, 762. 

4 B. 40, 525. 6 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 until 
after being submitted to prolonged boiling, unless a catalyst 
such as hydrochloric 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 180, and hydroxy anthrone at 167, and 
on further heating both decompose into anthrone, anthra- 
quinone and water, without apparently first undergoing 
any interconversion. An exactly similar isomerism is 
exhibited by methoxy anthrone and anthraquinol mono- 
methyl ether. Here the ketonic form is obtained by the 
action of methyl alcohol on bromanthrone, 1 and is enolised 
by warm dilute alkali, the enolic form being obtained 
direct by the action of metltyl iodide or dimethyl sulphate 
on anthraquinol. 2 This on oxidation gives dimethoxy- 
dianthrone, which cannot form an enolic isomer as it has no 
labile hydrogen atom : ~TT 

i 
CO C 



L4 \/ 

C 



H Br \* OH if/ 

CO 
C 6 H/\C 6 H 4 



C C 

H OMe OMe 



C 6 H 4 OMe OMe C a H 4 

oc<>c - cco 




A. 323, 235. a A. 376, 47. 



ANTHRONE AND ANTHRANOL 123 

Baeyer l obtained phenyl anthrone by heating tri- 
phenyl methane-o-carboxylic acid with sulphuric acid. 
Ph H Ph H 

\/ \/ 

C C 

C 6 H 4 /\C 6 H 5 C 6 H 4 <^>C 6 H 4 

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 strongly fluorescent, 
soluble in cold alkali, and is readily oxidised by bromine, 
or by air when in alkaline solution. It is much less stable 
than anthranol itself, and on keeping rapidly reverts to the 
ketonic form. 

Kurt Meyer 3 endeavoured to prepare amino anthrone, 
but was unable to obtain it in a pure state. However, he 
was able to prepare arylamino 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 bromine. 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 yields the anil, 
and it is curious to note that whereas the monoanil is deep 
red, the dianil is only yellow : 

O NPh 

C C 

C 6 H/)>C 6 H 4 C 6 H/\C 6 H 4 

C C 

NPh NPh 

Deep red. Yellow. 

1 A. 202, 54. 2 A. 396. 133. Loc. cit. 



124 ANTHRACENE AND ANTHRAQUINONE 

Dianthranol and dianthrone exhibit the same form of 
isomerism as anthranol and anthranone. Thus, Hans 
Meyer * prepared dianthranol by reducing anthraquinone 
with zinc and caustic soda under pressure, and found that it 
was ketonised by prolonged boiling with alcoholic hydro- 
chloric acid, the reverse change being brought about by 
caustic potash : 



C 6 H 4 C 6 H 4 HCI C 6 H 4 H H C 6 H 4 

C C^COH KOH O : C<^^>CC<^>C : O 
C 6 H 4 C 6 H 4 C 6 H 4 C 6 H 4 

and Kurt Meyer 2 has found that ws-anthramine when oxidised 
by amyl nitrite, 3 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 : 

C 6 H 4 H H C 6 H 4 C 6 H 4 C 6 H 4 

HN : C<>C C< C : NH -> 



C 6 H 4 C 6 H 4 C 6 H 4 C 6 H 4 

This latter compound melts rather indefinitely at 324- 
334, and was obtained by Gimbel 3 by nitrating and reducing 
dianthryl. So far the reverse change has not been brought 
about. 

i B. 4-2, 143. z B. 46, 29. 3 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. FROM AROMATIC MONOCARBOXYUC ACIDS 

When aromatic monocarboxylic 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 : 

co 






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 yields are 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 Schunck and Romer 1 found that when w-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 formed anthraflavic 
acid is the most plentiful (82 per cent.), the remainder con- 
sisting chiefly of anthrarufin and a little i.y-dihydroxy 
anthraquinone. They contradict Rosentiel's statement 2 
that fc'so-anthraflavic acid is also formed. Other Irydroxy 
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 anthraflavic acid, 3 and gallic acid gives rufigallol. 4 

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 trimethyl 
anthragallol by Wende 6 from durylic acid and gallic acid, 
and of anthragallol itself from benzoic acid and gallic acid. 7 
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-hydroxy-i -benzoic acid and with 2-methyl-5- 
hydroxy-i-benzoic acid gives respectively 5-methy 1-1.2.3. 6- 
tetrahydroxy anthraquinone and 5-methyl-i.2.3.8-tetra- 
hydroxy anthraquinone. 8 

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. 

4 Robiquet, A. 19, 204 (18*6). Schiff, A. 163, 218. 

5 B. 20, 870. 6 B. 20, 867. 
7 Seuberlich, B. 10, 38. Auerbach, Ztg. 1882, 910. 

8 K., D.R.P. 87,620. 



ANTHRAQUINONE RING SYNTHESES 127 

method of forming the anthraquinone ring could be carried 
out by a catalytic method, e.g. by passing the vapour of the 
aromatic monocarboxylic acid over a suitable catalyst, such 
as precipitated silica or aluminium or calcium phosphate, 
although no such method has been recorded. 



II. FROM PHTHAUC 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-benzoyl 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 under the heading " Phthalic Acid Synthesis," 
and in the present section only 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 hydroxyanthraquinones. 

In some cases phthalic acid will condense with a phenol 
to form a hydroxy anthraquinone simply under the in- 
fluence of heat, no dehydrating agent or catalyst being used. 
Thus, Baeyer and Drewson A obtained 4-methylerythro- 
hydroxy anthraquinone by heating phthalic anhydride with 
^>-cresol for two days at 160-200, and more recently Ull- 
mann 2 has found that when phthalic anhydride is heated 
with ^>-chlorphenol a mixture of 4-chlorerythrohydroxy 
anthraquinone and of o-hydroxychlorbenzoyl benzoic acid 
is obtained. As a rule, however, the condensation only 
takes place in the presence of a condensing agent such as 
sulphuric acid, although, as will be seen, boric acid or alu- 
minium chloride are often effective. 

When sulphuric acid is used as a condensing agent 
phthalein formation takes place simultaneously, so that 
the yields obtained are often extremely poor. Baeyer and 
Caro, and lyiebermann and his students have studied the 
condensation of phthalic 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 hydroxy anthraquinones, such as erythro- 
hydroxyanthraquinone mixed with a little j3-hydroxyanthra- 
quinone from phenol itself, 1 alizarin and hystazarin from 
pyrocatechol, 2 and quinizarin from hydroquinone. 3 The 
yields, however, never exceeded 5 per cent, of the theoreti- 
cally possible, and Birukoff 4 states that the condensation of 
phthalic anhydride with _/>-cresol gives a yield of only ij per 
cent, of 4-methylerythrohydroxyanthraquinone. It should 
be noted that during the condensation of phthalic anhydride 
with ^>-chlorphenol simultaneous replacement of the chlorine 
atom by hydroxyl 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. 5 

The condensation of phthalic anhydride with phenols 
under the influence of concentrated sulphuric acid has been 
extended to the preparation of 3-methyl quinizarin from 
phthalic anhydride and methylhydroquinone by Nietzki, 6 
and to the preparation of various heteronuclear methyl- 
dihydroxy anthraquinones from 5-methyl phthalic acid and 
pyrocatechol and hydroquinone by Niementowski, 7 but the 
yields are unsatisfactory. 

By using chlorphthalic acid in place of phthalic acid, 
heteronuclear chlorhydroxy anthraquinones can be obtained, 
and it has been claimed 8 that hydroquinone condenses readily 
under the influence of concentrated sulphuric acid with 
chlorinated phthalic acids, in which not more than one 
chlorine atom is in the ortho- position to a Irydroxyl 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 completely in the case 
of 3.6-dichlorphthalic acid and tetrachlorphthalic acid. 

Baeyer and Caro, B. 7, 972 ; 8, 152. 

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. 

Liebermann, B. 10, 608 ; A. 212, 10. 
B. 10, 201 1. 7 B. 33, 1631, 

8 M.L.B., D.R.P. 172,105. 



ANTHRAQUINONE RING SYNTHESES 129 

Crossley * has investigated the condensation of 4-amino- 
phthalic acid with hydroquinone in the presence of sulphuric 
acid at 170-190, and finds that the main product is 1.4.6- 
trihydroxyanthraquinone, 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 i.4.6-trihydroxy 
compound did not melt at 300, whereas Dimroth and Kick 2 
give its melting point as 256. 

In some cases the yield of hydroxyanthraquinone is 
greatly improved by carrying out the condensation with 
concentrated sulphuric acid in the presence of boric acid, 
and by this means it has been claimed 3 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 phthalei'n 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 Kick 4 obtained i.2.4-6-tetrahydroxyanthra- 
quinone by heating ^-hydroxyphthalic acid with hydroxy- 
quinol triacetate and boric acid in benzoic acid solution. 
In the same way they obtained i.4.6-trihydroxybenzoic acid 
from hydroxyphthalic acid and quinol, and i-methyl- 
3.5.8-trihydroxyanthraquinone 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 anlrydride with phenols, 
naphthols, anthrols or hydroxyanthranols at 180-250 in 

1 Am. Soc. 40, 404. * A. 411, 330. 

8 By., D.R.P. 255,031 < A. 411. 325. 

9 



130 ANTHRACENE AND ANTHRAQUINONE 

the presence of anhydrous aluminium chloride. 1 The 
reaction is best carried out by using a great excess of phthalic 
anhydride as a solvent. By this means hystazarin is ob- 
tained from pyrocatechol, no alizarin being formed. 

III. PHTHAUC 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 

C 6 H 4 /\0+C 6 H 6 -> C 6 H 4 /\C 6 H 5 -> C 6 H 4 <^>C 6 H 4 
CO COOH CO 

As the method is of very general application, and as the 
yields are often almost theoretical, it has met with very 
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- 
perature, although as a rule is only completed by heating on 
the water bath for 6-12 hours, viz. until the evolution of 
hydrochloric acid gas ceases. In carrying 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 gives 
more satisfactory results. These will be discussed when deal- 
ing with the various classes of substance which have been 

1 By., D.K.P. 298,345. * Heller and Schulke, B. 41, 3627. 



ANTHRAQUINONE RING SYNTHESES 131 

found to undergo the condensation. As a rule, the best pro- 
cedure is to add i part of powdered aluminium chloride to 
i J-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 ordinary temperature or on gently warm- 
ing and is completed by boiling under a reflux condenser 
nnt.il 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 anthraquinone derivative, but if desired to do so it 
will often be found that the most satisfactory results are 
obtained by crystallising the ammonium salt. 

In carrying 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 
the molecule before closing the anthraquinone ring. 

For closing the anthraquinone ring concentrated sulphuric 
acid (six to ten parts) is usually employed, but the ease with 
which water is lost varies very much with the individual 
compounds. Thus, naphthoyl benzoic acid loses water at 
45-50, whereas benzoyl benzoic acid requires a temperature 
of about 120, and in other cases the reaction only takes place 
at temperatures of 150 or above. When this is the case 
sulphonation frequently takes place simultaneously. If the 
ketonic acid becomes sulphonated it is usually impossible to 
close the ring at all, whereas if ring formation precedes 
sulphonation 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 be 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 hydroly tic action of the aluminium 
chloride, and also in some cases brings about simultaneous 
oxidation. Thus, Gresly 2 condensed phthalic anhydride 
with pseudo-cumene and obtained a trimethyl benzoyl 
benzoic acid which, when heated with oleum, gave dimethyl- 
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, 3 and Elbs 4 has 
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 often 
proved of value in obstinate cases consists in reducing the 
ketonic group and thus obtaining the diphenyl methane 
derivative. The ring can then often be closed by means of 
sulphuric acid or oleum, zinc chloride or sodamide, and the 

1 Bentley, Gardner and Weizmann, Soc. 91, 1630. Bentley and Weiz- 
mann, Soc. 93, 435. Harrop, Norris and Weizmann, Soc. 95, 1212. Walsch 
and Weizmann, Soc. 97, 687. Bentley and Weizmann, Soc. 105, 2748. 
Heller and Schiilke, B. 41, 3627. Mettler, B. 45, 800. Gresly, A. 234, 241. 

* A. 234, 238. Cf. also Ullmann, A. 388, 217. 

* Behr and van Dorp, B. 7, 578. Bentley and Weizmann, Soc. 93, 435. 
M.L.B., D.R.P. 194,328. 

* j. pr. [2] 41, 122, 



ANTHRAQUINONE RING SYNTHESES 133 

resulting anthrone then oxidised to the anthraquinone. 
This method has often proved useful in the S3 r 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. 1 

HOMOLOGOUS ANTHRAQUINONES. 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 
chloride 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 anhydride and 
benzene giving acetophenone when treated with aluminium 
chloride. Previous to this Biircker 4 had shown that 
succinic anhydride will condense with benzene in the presence 
of aluminium chloride to give /3-benzoyl propionic acid. 

The preparation of anthraquinone 5 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 difficulty in closing the anthra- 
quinone ring by heating the benzoyl benzoic acid with 
ordinary concentrated sulphuric acid at 125-150. If oleum 
is used instead of concentrated sulphuric acid, simultaneous 
sulphonation takes place with production of anthraquinone- 
j8-sulphonic acid. 7 The condensation of the phthalic 

1 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. 

2 Bl. 41, 323- 

3 A. ch. [6] 14, 446. 
* A. ch. [5] 26, 435. 

5 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, i. Heller, Z. ang. 19, 669. Heller 
and Schiilke, B. 41, 3627. Rubidge and Qua. Am. Soc. 36, 732. 

6 Heller, Z. ang. 19, 669. 

7 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 methyl anthraquinones are being prepared 
from toluene or the xylenes. 

From toluene * the main product obtained is j3-methyl- 
anthraquinone, from oxylene 2 2.3-dimethylanthraquinone, 
from w-xylene 3 i.3-dimethylanthraquinone and from p- 
xylene 4 i.4-dimethylanthraquinone. Pseudo-cumene gives 
i.2.3-trimethylanthraquinone, 5 although, as has already 
been pointed out, the final closing of the ring by means of 
sulphuric acid is apt to be accompanied by simultaneous 
oxidation of one methyl group to carboxyl. Scholl 6 has 
prepared ethyl, propyl and zso-propyl anthraquinone from 
phthalic anhydride and ethyl, propyl, and ^'so-propyl benzene. 
Condensation between phthalic anhydride and naphthalene 7 
takes place with great ease, and the resulting naphthoyl 
benzoic acid loses water very readily when warmed to 
45-50 with concentrated sulphuric acid, the product being 
i.2-benzanthraquinone. This compound and its derivatives 
are treated in greater detail in Chapter VII., but here it may 
be pointed out that so easily does naphthalene condense with 
phthalic anhydride that the reaction may be carried out in 
benzene, toluene or xylene solution without the solvent being 
attacked, provided no excess of phthalic anhydride is used. 
Benzene, in fact, is the best solvent to employ. 

Anthracene 8 also condenses readily with phthalic 
anhydride, 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 Schiilke, B. 41, 3627. 
Elbs, J. pr. [2] 41, 4. 

2 F. Meyer, B. 15, 636. Limpricht, A. 312, 99- Elbs, J. pr. [2] 41, 6 ; 
B. 20, 1361. Heller, 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. 

5 Gresly, A. 234, 238. Elbs, J. pr. [2] 41, 122. 

6 M. 32, 687, 

7 Elbs, B. 19, 2209. Gabriel and Colman, B. 33, 448. Heller and 
Schiilke, B. 41, 3627. Heller, D.R.P. 193,961. 

8 Heller and Schiilke, B. 41, 3627 ; 45, 669. Heller, D.R.P. 193,961. 
Cf also Schaarschmidt, B. 49, 381. 



ANTHRAQUINONE RING SYNTHESES 135 

Treatment of the product with dehydrating agents, however, 
does not lead to an anthraquinone, but to rupture of the mole- 
cule with formation of anthracene and phthalic acid, so that 
the phthaloyl group is probably attached to the ws-carbon. 

Phthalic anhydride will also condense with phenanthrene, 1 
and the phenanthroyl benzoic acid, when treated with phos- 
phorus pentoxide, gives an anthraquinone derivative which is 
probably i.2.34-dibenzanthraquinone and has the structure 
C 6 H 4 C C(X 

| || yC 6 H 4 , although this has never been proved. 

C 6 H 4 C CO X 

Elbs 2 and Kaiser 3 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 anthraquinone 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 yields were very poor. 
Benzoyl benzoic acid itself is readily and quantitatively 
reduced to the diphenyl methane derivative by ammonia 
and zinc dust in the presence of copper sulphate, but in the 
case of phenyl benzoyl benzoic acid the yield 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 carboxylic acid, although 
the reaction was slow- and required 144 hours. From this 
compound he was unable to split out water by means of 
sulphuric acid, owing to sulphonation taking place, but by 
heating with zinc chloride or sodamide at 190 he obtained 
phenyl anthrone, from which j3-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. 194,3^8. J. pr. [2] 41, 145. 

3 A. 257, 95- 4 B. 44, 1075. B. 44, 1086. 



136 ANTHRACENE AND ANTHRAQUINONE 

Scholl found that o-ditolyl l will also condense with two 
molecules of phthalic anhydride, but a dimethyl dianthra- 
quinonyl can only be obtained from the product with the 
utmost difficulty. As it gives no pyranthrone it must be 
3.3'-dimethyl-2.2'-dianthraquinonyl. p-Ditolyl, on the con- 
trary, will only condense with one molecule of phthalic 
anhydride, 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. 3 

0s-Dixylyl (2.4.2'4'-tetramethyl s diphenyl) condenses 
with two molecules of phthalic anhydride to produce a 
mixture of phthaloylic acids. From these 2.4.2'. 4'-tetra- 
methyl-i-i'-dianthraquinonyl 4 can be obtained by treat- 
ment with concentrated sulphuric acid at 100. 

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 by condensing a halogenated phthalic 
acid with an aromatic hydrocarbon. 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 5 obtained a dichlor- 
dihydroxy anthraquinone by chlorinating the dihydroxy 
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 / -carboxylic acid and then treating 
with dehydrating agents. 6 The method, however, has been 
very little developed. 

The formation of homonuclear halogen anthraquinones 
from phthalic anhydride and aromatic halogen compounds 
has been fairly fully investigated. Chlorobenzene 7 and 

1 B. 44, 1091. 2 Scholl, B. 44, 1091. 

3 Seer, M. 33, 540. Scholl, B. 43. 512. 

8 B. 35, 800. " 6 Agfa, D.R.P. 254,091. 

7 M.L.B., D.R.P. 75,288. 



ANTHRAQUINONE RING SYNTHESES 137 

bromobenzene 1 lead to the corresponding j3-halogen 
anthraquinones, and ^-chlortoluene leads, of course, to i- 
methyl-4-chloranthraquinone. 2 From o-chlortoluene Heller 
and Schulke 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-chlorar:tliraquinone. Ullmann 4 proved the latter of these 
to be correct by oxidising it to the corresponding carboxylic 
acid and then condensing with aniline. The resulting 
anilidoanthraquinone carboxylic acid by loss of water 
passed into an acridone which was neither anthraquinone- 
i.2-acridone nor anthraquinone-2.i-acridone, and hence 
must have been anthraquinone-2.3-acridone. 

The condensation of phthalic anhydride with o-, m-, and 
p-biom toluene has been studied by Heller, 5 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 
^>-bromtoluene 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, 6 for example, having 
shown that aluminium chloride is capable of converting 
a-brornnaphthalene into jS-bromnaphthalene. 

The condensation of 3.6-dichlorphthalic acid and 2.4- 
dichlorphthalic acid with aromatic hydrocarbons has been 
studied by several investigators, 7 without any results of 

Ullmann, A. 380, 337. 

Heller and Schulke, B. 41, 3627. Heller, B. 45, 792. 
Heller and Schulke, B. 41, 3627. Heller, B. 45, 792. 
B. 47, 553- 

B. 47, 792. 6 A. ch. [6] 12, 334. 

7 Harrop, Norris and Weizmann, Soc. 95, 1212. Ullmann and Biliig, 
A. 381, i. Le Royer, A. 238, 356. Ree, A. 234, 239. 



138 ANTHRACENE AND ANTHRAQUINONE 

particular interest being recorded, although 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 has also been em- 
ployed for preparing homonuclear tetrachlor anthraquinone. 2 

A large number of heteronuclear chloranthraquinones 
have been obtained by Hofmann 3 by condensing various 
chlorphthalic acids with aromatic halogen compounds, but 
they are of no particular interest. 

HYDROXYANTHRAQUINONKS. Phthalic acid as a rule 
will not condense with free phenols under the influence of 
aluminium chloride to produce a hydroxybenzoyl benzoic 
acid, as a phthalein is usually the sole product, although 
recently Ullmann and Schmidt 4 have found that in many 
cases a good yield of the hydroxybenzoyl 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 ^-chlorhydroxybenzoyl benzoic acid and 
i.4-hydroxychloranthraquinone, the conversion of the former 
into the latter being completed by warming with concen- 
trated sulphuric acid, 5 whereas as already stated the direct 
condensation of phthalic anhydride with ^-chlorphenol by 
sulphuric acid leads only to quinizarin. 6 

1 Harrop, Norris and Weizmann, Soc. 95, 1212. 

2 Kircher, A. 238, 344. 3 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, TO; B. 10, 608. By., D.R.P. 255,031. See 
also pp. 128, 129. 



ANTHRAQUINONE RING SYNTHESES 139 

The condensation of phthalic anhydride with phenols 
can often be brought about with satisfactory results by 
first methylating the hydroxyl groups, as this hinders 
phthalein formation. During the condensation, however, 
the aluminium chloride usually 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 lyagodzinski, 1 who obtained quinizarin from quinol 
dimethyl ether, and hystazarin from veratrol, but Nourri- 
son 2 had previously shown that jS-hydroxyanthraquinone 
could be obtained from anisol. It has also been used to a 
considerable extent by Weizmann 3 and his students, who 
have obtained various hydroxyanthraquinone derivatives 
by condensing phthalic acid or a methoxy phthalic acid, 
such as hemipinic acid with aromatic hydrocarbons or 
phenolic ethers. 

The preparation of hydroxyanthraquinones 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 by Deichler and Weiz- 
mann, 4 who obtained hydroxynaphthoyl benzoic acid by 
heating a-naphthol with phthalic anhydride and boric acid 
at 190, and has been extended by Weizmann and his 
students, 5 who have prepared numerous hydroxyanthra- 
quinone derivatives from phthalic 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 7 has condensed 
tetrachlorphthalic acid with hydroquinone, and Dimroth 
and Kick 8 have condensed phthalic acid, 4-hydroxyphthalic 

1 B. 28, 117; A. 342, 90. 
8 B. 19, 2105. 

3 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. 

4 Deichler and Weizmann, B. 36, 547. 

5 Bentley, Gardner and Weizmann, Soc. 91, 1630. 
B. 45, 1358. 

7 B. 47, 1210. A. 411, 315 



140 ANTHRACENE AND ANTHRAQUINONE 

acid and coccinic acid (6-methyl-4-hydroxyphthalic acid) 
with, hydroquinone and hydroxyhydroquinone. In the case 
of hydroxylrydroquinone 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 
cannot be altogether avoided, a phthalein, for example, 
being the sole product formed when 4-hydroxy phthalic acid 
is condensed with o-cresol. 

Schaarschmidt l condensed phthalic acid with a-anthrol 
by the use of boric acid, but was unable to close the ring. 

MISCELLANEOUS SUBSTANCES. Carboxylic acids can 
sometimes be obtained by 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-/3-carboxylic acid by oxidising tohryl 
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, 4 and Graebe and I^eonhardt, 5 
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 6 condensed 
phthalic acid with ^-chlortoluene and then oxidised the 
methyl group to carboxyl, but were unable to close the ring 
although before oxidation the ring closed quite easily, and 
they experienced no difficulty in oxidising i-methyl-4-chlor- 
anthraquinone to the corresponding carboxylic acid. 

One or two tertiary amino anthraquinones have been 
obtained by the phthalic acid synthesis, as Haller and 
Guyot 7 have found that phthalic anhydride will condense 
with tertiary aromatic amines which have a free para- 

1 B. 49, 381. 2 seep. 132. 

3 M.L.B., D.R.P. 80,407. * B. 30, 1116. 

5 A. 290, 231. B. 41, 3627. 

7 Bl. [3] 25, 166; C. r. 119, 139. Cf. Societe anonyme des Matieres 
Colorantes, D.R.P. 108,837; 112,913; 112,297; 114,197-8, Also 
Weitz, A. 418, 29. 



ANTHRAQUINONE RING SYNTHESES 141 

position such as dimethyl aniline, diethyl aniline and ethyl 
benzyl aniline, and Scholl and Neovious l have condensed 
two molecules of phthalic anhydride with one molecule of 
carbazol. 

Thianthrene and thiodiphenylamine will also condense 
with either one or two molecules of phthalic anhydride, and 
the rings can be closed by means of zinc chloride 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 resulting trimethyl benzophenone to carboxyl. 
The monocarboxylic acid thus obtained when treated with 
dehydrating agents passed into i.3-dimethylanthraquinone. 

L,impricht 4 endeavoured to carry out a somewhat 
similar synthesis. He condensed phthalic acid with o- 
xylene and then oxidised both methyl groups to carboxyl. 
He then condensed the resulting benzophenone tricarbpxylic 
acid with 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. 

1 B. 44, 1249. 2 Scholl and Seer, B. 44, 1233. 

3 A. ch. [6] 6, 233. * A. 312, 99. 



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 CO 

I fl 

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 i.2-benzanthraquinone or 
flwg.-benzanthraquinone (I) and 2.3-benzanthraquinone or 
tin. -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 Scholl's system of nomenclature 
and designate it as /m.-dibenzanthraquinone or 2.3.6.7- 
dibenzanthraquinone 

CO 





iff TV 

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. 

tfraws-fo'sflwg.-Dibenzanthraquinone or i.2.5-6-dibenz- 
anthraquinone (IV) has also been synthesised, but its 
derivatives have not been studied. 

I. flWg.-BENZANTHRAQUINONE (NAPHTHANTHRAQUINONE) 

awg.-Benzanthraquinone is extremely easily obtained 
from naphthalene by the phthalic acid synthesis, 1 either 
by using carbon disulphide as a solvent, 2 or, preferably, 
by carrying out the reaction in benzene or toluene solution, 
as the phthalic anhydride condenses with the naphthalene 
so readily that the solvent remains unaffected provided 
no excess of phthalic anhydride is used. 3 The structure 
of the quinone was proved by Scholl, 4 who showed that 
oxidation with potassium chlorate, nitric acid, chromic 
acid or potassium permanganate and sulphuric acid led 
to anthraquinone-i.2-dicarboxylic acid, yields of 75 per cent, 
being obtainable when the oxidation is carried out with 
permanganate. 

flwg.-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 5 or by boiling with zinc dust and 
ammonia 6 it yields the parent hydrocarbon (<mg.-benz- 
anthracene), which reverts to the quinone when oxidised. 

Very few homologues of <wg.-benzanthraquinone have 
been described. From a-methylnaphthalene Scholl 1 
obtained a monomethyl compound which was probably 
3-methyl-i .2-benzanthraquinone. jS-Methyl naphthalene also 
readily condensed with phthalic anhydride, but the resulting 
methylnaphthoyl benzoic acid would not pass into a quinone, 

See p. 134. 

Graebe, A. 340, 249. Elbs, B. 19, 2209. Gabriel and Colman, B 33, 
448 

Heller and Schulke, B. 41, 3627. Heller, D.R.P. 193,961. 
B. 44, 2992 ; D.R.P. 241,624. 6 Graebe, A. 340, 249. 

Elbs, B. 18, 2209. ' M. 32, 996. 



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 methyl group. 

From a-chlornaphthalene and phthalic anhydride Heller l 
obtained 3-chlor-i.2-benzanthraquinone, but ^3-chlornaphtha- 
lene led to a chlor-2.3-benzanthraquinone. Graebe and 
Peter 2 condensed 3.6-dichlorphthalic acid with naphthalene, 
but the closing of the anthraquinone ring was accompanied 
by 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 <mg.-benzanthraquinones have been very 
little investigated. Scholl 3 condensed phthalic anhydride 
with i-methyl-2-methoxy naphthalene and then, after 
reducing the ketonic acid, closed the ring and finally oxidised 
to the quinone. As the quinone when oxidised gave anthra- 
quinone-i.2-dicarboxylic acid, the methoxy and methyl 
groups must be in the benzene ring, and the quinone probably 
has the structure I. 





By demethylating the free hydroxy compound could be 
obtained, but it was found impossible to replace the hydroxyl 
group by an amino group. If, however, the methyl methoxy 
naphthoyl 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 methyl benzanthraquinone in which the 
amino group could be replaced by chlorine or iodine in the 

i B. 45, 669. Cf. G.C.I.B., D.R.P. 230,455. * A. 340, 265. 

3 M. 33, 507. 



THE BENZANTHRAQUINONES 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 dwg.-benzanthraquinone is nitrated l two mono- 
nitro compounds (IV and V) are formed : 








CO 

IV "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. &tt.-BENZANTHRAQUINONE (NAPHTHACENEQUINONE) 

When phthalic 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 

C 6 H 4 /\0 0/\C 6 H 4 ' C 6 H 4 /\CH-CH/\C 6 H 4 
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. 81, H59- Roser, B. 17, 2619. Cf. also B. 10, 391, 2199 ; 11, 
1007. 

10 



146 ANTHRACENE AND ANTHRAQUINONE 

Nathanson, 1 and Gabriel and l,eupold 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 carboxyl groups and the hydrogen 
atoms of the aliphatic chain, with the formation of bisdiketo 
hydrindene (II) and fc'so-ethine diphthalide, the ketonic 
form of this latter substance being identical with dihydro 
/m.-benzanthradiquinone : 

CO 





CO OH CO 

?$o-Ethinediphthalide or dihydro-Jiw.-Benzanthradiquinone. 
Enolic form. Ketonic form. 

Dihydro-^ft.-benzanthradiquinone is, of course, also the 
ketonic form of dihydroxy-^'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 



OH 

C=CHCOOH 
-> 



CO 



X C=CH 2 
C 6 H 4 < +C0 2 



*COOH 



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 4 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, 1160. 

3 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 



CO CO 

although Gabriel and I^eupold 1 have since shown that 
indenigo is almost certainly identical with their zso-ethine 
diphthalide. 

The reduction of sso-ethine diphthalide was also effected 
by Gabriel and I,eupold, 2 who thereby obtained two hydro- 
carbons, viz. C 18 H 12 , which they named naphthacene 
(/zw.-benzanthracene), and its dihydro compound C 18 H 14 
(dihydronaphthacene or dihydro-/^. -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 /w.-benzanthra- 
quinones, and in fact, up to the present the hydroxyl de- 
rivatives are the only ones which have been studied in any 
detail. By treating zso-ethine diphthalide with phosphorus 
pentachloride Gabriel and I^eupold obtained i.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 lyiebermann and 
Voswinckel, 3 by heating i-methyl-3-hydroxybenzene-4.5.6- 
tricarboxylic acid to 200 with succinic acid and potassium 
acetate, obtained a substituted ethine diphthalide which by 
treatment with sodium methylate gave a dimethyltetra- 
hydroxy-/m.-benzanthraquinone : 

:H, OH ^ ^ 

10H 




B. 31, 1272. t 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 l found that phthalic acid would 
condense with a-naphthol when heated in 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 3 ex- 
tended the method to i. 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 
hydroxy 1 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, 5 
and hemipinic acid 6 with naphthols, and nitro-hydroxy 
compounds have been obtained from nitrophthalic acid, 7 
and chlorhydroxy compounds from 3.6-dichlorphthalic 
acid and tetrachlorphthalic acid. 8 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 
slowly. 

1 B. 36, 547. 2 D.R.P. 134,985. 3 Soc. 89, 115 ; 91, 1588. 

4 Orchardson and Weizmann, Soc. 89, 115. 6 Ibid. 

6 Bentley, Friedl, and Weizmann, Soc. 91, 1588. 7 Ibid. 

8 Harrop, Norris, and Weizmann, Soc. 95, 279. 



THE BENZANTHRAQUINONES 149 

Hydroxyl groups can also be inserted into the molecule 
by 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-dihydroxy-2.3-benzanthra- 
quinone (0-ethinediphthalide) has been obtained from 
i-hydroxy-2.3-benzanthraquinone. l 

When sulphonic acid groups are present in the molecule 
they can be replaced by hydroxyl groups by fusion with 
caustic alkali, although this method has been very little 
applied. 2 Weizmann 3 records one case in which an amino 
group is replaced by hydroxyl by fusion with caustic alkali, 
but as a rule he appears to find it best to carry out the 
replacement by means of the diazo- reaction. 4 

Halogen atoms when present in a hydroxynaphthoyl 
benzoic acid are often replaced by hydroxyl groups when 
the ring is closed, and Weizmann has obtained several 
hydroxy i.2-benzanthraquinones by brominating the 
hydroxynaphthoyl benzoic acid and then closing the 
ring. 6 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-hydroxy-4-chlor- 
naphtho)d-(2)-o-benzoic acid, obtained by treating the 
hydroxynaphthoyl benzoic acid with sulphuryl 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 hydroxyl groups, 
Weizmann 7 considers that hydroxyl groups in the naphtha- 
lene ring tend to deepen the colour, whereas when in the 
benzene ring the tendency is rather to lessen it. Baly and 
Tuck 8 have examined the absorption spectra of some of 

1 Deichler and Weizmann, B. 36, 719. D.R.P. 138,324-5. 
8 Deichler and Weizmann, B. 36, 719. Bentley, Friedl, Thomas, and 
Weizmann, Soc. 91, 411. 

Soc. 91, 411. 

Deichler and Weizmann, B. 36, 2326. 

Orchardson and Weizmann, Soc. 89, 115. Bentley, Friedl, Thomas, 
and Weizmann, Soc. 91, 411. Harrop, Norris, and Weizmann, Soc. 95, 279. 

Geigy, D.R.P. 226,230. 

Soc. 91> 411. 

Soc. 91, 426, 



150 ANTHRACENE AND ANTHRAQUINONE 

the hydroxy compounds, but as very 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, 1 by treating hydroxynaphthoyl benzoic acid 
with phosphorus pentachloride, obtained the 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 11*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 hydrobromic 
acid. 

Heller, 2 by condensing phthalic acid with j3-chlornaphtha- 
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 i.4-dichlor 
compound by the action of phosphorus pentachloride on 
iso-ethinediphthalide has already been mentioned. 4 

A mononitro compound was obtained by Gabriel and 
I^eupold 5 by nitrating /m-benzanthraquinone, but they did 
not determine the position of the nitro group. Deichler 
and Weizmann, 6 by nitrating i-hydroxy-2.3-benzanthra- 
quinone, obtained i-hydroxy-4-nitro-2.3-benzanthraquinone, 
from which by reduction and diazotisatiott the dihydroxy 
compound (^so-ethinediphthalide) was obtained, thus 
determining the position of the nitro group. Further 

1 Soc. 89, 115. Cf. Pickles and Weizmann, Proc. 20, 220. 

a B. 45, 669. 3 B. 46, 1497. 4 Page 147. 

? B. 31, 1272. 6 B. 36, 2326. 



THE BENZANTHRAQUINONES 151 

nitration led to a dinitro compound. The analytical 
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 1 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 3 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. 4 Negative groups or atoms when present in 
the molecule are usually fairly readily replaced by arylamino 
groups by boiling with primary aromatic amines, 5 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 authraquinone ring, either by nitration 
and reduction, or byiorming an azo- dye and then reducing 
this. In the case of 4-amino-i-hydroxy-naphthoyl 
(2) -benzoic acid the formation of the quinone takes place 
with very great ease, it being sufficient to boil with nitro- 
benzene, 6 and the same amino-hydroxy quinone is formed 

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, Thomas, Friedl, and Weizmann, Soc. 91, 411. 
Harrop, Norris, and Weizmann, Soc. 95, 279. 

6 Bentley, Friedl, Thomas, and Weizmann, Soc. 91, 411. 



152 ANTHRACENE AND ANTHRAQUINONE 

directly when the corresponding hydroxy nitronaphthoyl 
benzoic acid is reduced with zinc and acetic acid. 1 

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 hydroxy com- 
pound with aqueous ammonia at 200. 



III. /W.-BBNZANTHRADIQUINONE (NAPHTHACENDIQUINONE) 

Of the numerous /m.-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 I^eupold 3 by oxidising 
1 4-dihydroxy-2.3-benzanthraquinone (^'so-ethinediphtha- 
lide) with nitric acid, and Deichler and Weizmann 4 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 5 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 undergoes rupture of one ring 
with the formation of a ketonic acid (III), although at the 
same time a small quantity of fcso-ethinediphthalide (IV) 
is formed. Probably the first action of the alkali is to bring 
about the formation of a ketone hydrate 6 (II), subsequent 
loss of two molecules of hypochlorous acid then taking 
place. 

1 Orchardson and Weizmann, Soc. 89, 115. 

2 Bentley, Friedl, Thomas, and Weizmann, Soc. 91, 411. 

3 B. 31, 1272. 
* B. 36, 719. 

5 B. 38, 4015. 

Cf. Zincke, B. 20, 3229. 



THE BENZANTHRAQUINONES 153 




With bromine a somewhat similar reaction takes place, 
but in this case the dibromide cannot be isolated although 
Voswinckel obtained a monobromketone monohydrate : 



OH 




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- compound 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 ^'so-ethinediphthalide. As obtained 
by this means, however, the substance is almost black, and 
its appearance is not appreciably altered by several le- 
crystallizations from nitrobenzene or ethyl benzoate, whereas 
a single recrystallisation 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 l inclines to regard it as quinhydrone 

* 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 1 : 



HO C 6 H 4 OH 



HO C 6 H 4 OH 
' OH 




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. 



(DlNAPHTH- 



ANTHRAQUINONE) 



trans - fo'sflwg.-Dibenzanthraquinone (1.2.5.6. - dibenz- 
anthraquinone) has been synthesised by Weitzenbock and 
Klinger 2 as shown by the following scheme : 

1 Voswinckel, B. 42, 458, 4648. 

2 Weitzenbock and Klinger, M. 39, 315. 



THE BENZANTHRAQUINONES 



155 





CH 




COOH 




3-4-5-6-Oibenzphenarrthrene 




E-5-6-Dibenzc?nfhrocene 



The closing of the rings in the diamino compound was 
effected by Pschorr's method, 1 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 



1 Pschorr, B. 29, 496. 



156 ANTHRACENE AND ' ANTHRAQUINONE 

obtained, 1 although this does not seem to have been 
attempted. 

2raws-fo's<zwg.03ibenzanthraquinone 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.-DIBENZANTHRAQUINONE (DINAPHTHANTHRAQUINONE) 

By condensing pyromellitic acid with benzene, Philippi 2 
and, at a later date, Mills and Mills 3 obtained two isomeric 
ketonic acids, both of which when treated with sulphuric 
acid gave to.-dibenz-i.4.5.8-anthradiquinone (dinaphth- 
anthradiquinone) : 



co co 




CO CO 



Philippi 4 also found that pyromellitic acid will condense 
with toluene, but he was unable to obtain a quinone from 
the ketonic acid. Scholl 5 obtained the same diquinone by 
a different means. He condensed the chloride of anthra- 
quinone-jS-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 
foimulael and II; but as the product on oxidation gave a 
diquinone monocarboxylic acid, which by loss of carbon 
dioxide passed into Philippics diquinone, the reaction in- 
dicated by I must be that which actually takes place. 




co 



1 See pp. 324, 328. Scholl, A. 394, in ; B. 44, 1656. 2 M. 32, 624 

3 Soc. 101, 2194. 4 M. 34, 705. 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 leuco-qwnizarm and then oxidising 
the product, 1 and compounds of similar structure are claimed 
as being obtained by using hydroxyanthracenes or other 
&wc0-hydroxyanthraquinones in place of fewco-quinizarin. 

By reducing their diquinone Mills and Mills 2 obtained a 
hydrocarbon and an anthrone, the latter on oxidation giving 
a monoquinone, viz. fe.-dibenzanthraquinone : 



CO 




Philippi, 3 however, has criticised Mills and Mills' work, 
and has concluded that some of their reduction products 
were impure. Russig 4 when studying the action of carbon 
dioxide under pressure on naphthoquinol obtained, in 
addition to i.4-dihydroxynaphthalene-2-carboxylic acid, a 
yellow substance which was probably a i.4.5.8-tetrahydroxy- 
/^.-dibenzanthraquinone (III) and a green substance which 
he regarded as 5.8-dihydroxy-/^.-dibenz-i.4.9.io-anthradi- 
quinone (IV) : 



wo co OH co co 





CO 

m TV 

By treating i.4-dihydroxynaphthalene-2-carboxylic acid 
with sulphuric acid he obtained the triquinone, /^w.-dibenz- 
i.4.5.8.9.io-anthratriquinone (V) . By distilling his dihydroxy 

1 By., D.R.P. 298,345. 2 Soc. 101, 2194. s 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, &w,-dibenzanthracene (VI). 

CO CO CO 





CO CO 

V VI 



The complicated 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 
anthr-aquinone 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, 1 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 carrying 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 sulphuric acid, and subsequently hydro- 
lysing the resulting acetate, and by this means have pre- 
pared anthraquinone-j3-aldehyde from j8-methylanthra- 
quinone. The method, however, is very troublesome owing 
to the very slight solubility of methylanthraquinone. 

The co-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 preparing the aldehydes. 3 It 
has also been applied to the preparation i.i'-dianthra- 
quinonyl-2.2'-dialdehyde from z.z'-dichlormethyl-i.i'-di- 
anthraquinony 1. 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. 

6 B.A.S.F., D.R.P. 241,472. 



160 ANTHRACENE AND ANTHRAQUINONE 

Amongst other methods of preparing aldehydes may be 
mentioned the preparation of i-nitroanthraquinone-6- 
aldehyde by Eckert l by the action of nitric acid on j3-anthra- 
quinonyl-j3- aery lie acid, and of i-aminoanthraquinone-2- 
aldehyde by Kalischer 2 by treating with acids the con- 
densation products obtained by heating i-amino-2-methyl- 
anthraquinone with aromatic nitro compounds 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. 4 
The chlorides of both anthraquinone-a-carboxylic acid and 
anthraquinone-j8-carboxylic acid react, but the latter reacts 
most readily. Ullmann 5 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 : 

M. 35, 290. 

A.P. 1,285,726-7 (1918). 

Ullmann and Klingenberg, B .46, 712. B.A.S.F., D.R.P. 240,520; 
786. 

Ullmann, B. 47, 566. Schaarschmidt, B. 48, 831. 
B. 47, 566. 
See p. 197- 



KETONES 



161 



CO 



CO 





CO CO CO CO 

The product was found to be a yellow vat dye, but the 
tinctorial properties were very feeble. 

Schaarschmidt * finds that the ketones derived from 
anthraquinone-a-carboxylic 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 compound as the 
pinacone and the green compound as its cyclic anhydride : 

OH OH O 





c c 

1 






1 
Ar Ar 




1 









C C 

i i 






1 1 
Ar Ar 








1 



Violet compound. Green compound. 

but this theory seems somewhat improbable, as it provides 
no explanation of the failure of the j8-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, 386. 



II 



162 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. CARBOXYUC ACIDS 

In a few cases anthraquinone carboxylic acids have been 
built up by the phthalic acid synthesis, e.g. from hemi- 
mellitic acid, 1 but as a rule it is much better to introduce 
the carboxyl groups into the molecule after the formation 
of the anthracene or anthraquinone ring. In the case of 
the a-carboxylic acids this can be done by treating anthracene 
with oxalyl chloride and aluminium chloride and then 
oxidising the resulting anthracene carboxylic 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 methyl anthraquinones. The hydrolysis of the 
nitriles takes a perfectly normal course, and the method 
has been made use of by several investigators. 3 

In preparing carboxylic acids by the oxidation of methyl 
compounds, either the methyl 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 carboxylic acids can be effected by boiling 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 4 (D=noo), although in some 
cases it is preferable to use other means. Thus i-nitro-2- 

1 See p. 140. 

z See p. 69. Also Butescu, B. 46, 212. 

3 Dienel, B. 39, 932. Ullmann, 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 anthraquinone is only oxidised with difficulty, 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. 1 

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 
satisfactory results. 3 In other cases it is claimed that oxida- 
tion can best be effected by the use of oxides of nitrogen, 4 
preferably in conjunction with some indifferent solvent. 

The ease with which oleum, nitrosyl sulphuric acid and 
manganese dioxide bring about hydroxylation would point 
to these reagents as being unsuited for the purpose of 
oxidising methyl groups to carboxyl groups. This, however, 
is not altogether the case, as Ullmann 5 has found that 
I -methyl-4-chlor anthraquinone is oxidised to the carboxylic 
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 -carboxylic acid, can be 
obtained by oxidation with nitrosyl sulphuric acid in the 
presence of boric acid. 6 

Instead of oxidising a methylanthraquinone directly to 
the carboxylic 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 7 has found 
it useful, particularly when dealing with large quantities. 
It seems probable that in many cases the benzanthrone 
derivative is a suitable source 1 of anthraquinone-a-carboxylic 

1 B.A.S.F., D.R.P., 229,394. Terres, B. 46, 1638. 

2 Birukoff, B. 20, 2068. 

3 B.A.S.F., D.R.P. 259,365. 

4 B.A.S.F., D.R.P. 250,742. 

6 A. 388, 217. Cf. O. Fischer and Sapper, J. pr. [2], 83, 207. Gresly, 
A. 234, 238. 

6 Ullmann, B. 52, 511, 2111 ; By., D.R.P. 273,341. 

7 B. 47, 561 ; 49, 735, 746. 



164 ANTHRACENE AND ANTHRAQUINONE 

acids, as Perkin l has found recently that anthraquinone-i- 
carboxylic acid itself can be obtained in 85 per cent, yield 
by oxidising benzanthrone with chromic acid in acetic acid 
solution. 

A few carboxylic acids have been described in which the 
carboxyl group is situated in the side chain, and is not 
directly attached to the nucleus. Thus j3-(2)-anthraquinonyl 
acrylic acid can be obtained from j3-dichlormethyl anthra- 
quinone 2 or anthraquinone-j3-aldehyde 3 by heating with 
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 literature. 4 It should be noted, 
however, that they all lose carbon dioxide rather easily, so 
that samples which have been purified by sublimation fre- 
quently show a low melting point. 5 One of the most readily 
accessible acids is anthraquinone-i.2-dicarboxylic acid, 
which is very easily obtained by oxidising i.2-benzanthra- 
quinone. 6 L,ike the isomeric anthraquinone 2.3-dicarboxylic 
acid, it readily gives a cyclic anhydride. From this latter 
acid Willgerodt and Maffelzzoli 7 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 fluores- 
ceine, which, however, was only feebly fluorescent. 

The halogen carboxylic acids can be obtained from a 
halogenated nitrile by hydrolysis, or from a halogenated 
methylanthraquinone by oxidation. Dichloranthraquinone 

1 Soc. 117, 706. 

2 By., D.R.P. 282,265. 

3 Eckert, M. 35, 290. 

4 In addition to those already given, the following are the more im- 
portant references: Limpricht and Wiegand, A. 311, 180. Weiler, 
B. 7, 1185. O. Fischer, B. 7, 1195. Liebermann and Rath, B. 8, 248. 
Schiiltz, B. 10, 118, 1049. Nietzki, B. 10, 2013. Wachendorff and 
Zincke, B. 10, 1481. Ciamician, B. 11, 269. Hammerschlag, B. 11, 82. 
Bornstein, 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. 

5 Limpricht and Wiegand, A. 311, 180. 

6 Scholl, B. 44, 2992. D.R.P. 241,624 ; 243,077. 

7 J- P r - t 2 ] 82, 205. 



CARBOXYLIC ACIDS 165 

carboxylic acids * can also be obtained by chlorinating the 
anthraquinone carboxylic acids themselves in concentrated 
sulphuric acid solution at 125. 

Nitrocarboxylic 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)-anthraquinonylacrylic acid with nitric acid, 
and then oxidising the resulting nitro aldehyde. 

lyiebermann and Clock 3 nitrated anthraquinone-/?- 
carboxylic acid and obtained a nitro acid, but did not 
determine the position of the nitro group. Ullmann 4 
nitrated anthraquinone-a-carboxylic acid and obtained 
5-nitroanthraquinone-i -carboxylic acid, the structure being 
proved by its preparation from i.5-dinitroanthraquinone 
through the nitro amino compound and nitro nitrile. 

Acid chlorides and acid amides are obtained by the usual 
means, 5 e.g. by phosphorus pentachloride and ammonia. 
They are much more stable than the corresponding com- 
pounds of the benzene series. Thus lyiebermann and Clock 
found that the chloride of anthraquinone-j8-carboxylic acid, 
after remaining in contact with water at the ordinary 
temperature for 120 hours, was only hydrolysed to the extent 
of 7^ 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 
anthraquinone sulphonates by heating with potassium 
cyanide or, in some cases, from the chloranthraquinones by 
heating with cuprous cyanide and an indifferent solvent. 6 
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, 7 

1 By., D.R.P. 255,121. z M. 35, 290. 

3 B. 17, 891. * A. 388, 207. 

6 Liebermann and Glock, B. 17, 888. Graebe and Blumenfeld, B. 30, 
1116. Wilgerodt and Maffelzzoli, J. pr. [2] 86, 205. Seer, M. 32, 163. 
Eckert, M. 35, 290. 

M.L.B., D.R.P. 271,790 ; 275,517. 

7 A. 388, 204. Cf. Dienel, B. 39, 932. 



166 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 1 obtained a yield of only 16 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. C/. also A. 388, 203. 
2 B. 46, 1646. 8 A. 405, 95- 



CHAPTER IX 

THE NITRO, NITROSO, AND HALOGEN 
ANTHRAQUINONES 

I. THE NITRO COMPOUNDS 

WHEN anthraquinone is nitrated the a-position is first 
attacked exclusively, no -nitroanthraquinone being formed. 
The preparation of a-nitroanthraquinone has been described 
by several investigators, 1 the most recent descriptions being 
those by Ullmann 2 and I,auth. 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 in vacuo* and gives the boiling point as 270-271 
at 7 mm. I/auth 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, 1118. 

2 A. 388, 203. 3 C. r. 137, 662. 4 D.R.P. 281,490. 

167 



168 ANTHRACENE AND ANTHRAQUINONE 

of dinitro compounds. 1 According to a patent specification 2 
this contains 60 per cent, of 1.5- and i.8-dinitroanthra- 
quinone, the remainder being chiefly i.6-dinitroanthra- 
quinone with small quantities of i.7-dinitroanthraquinone 
and very small quantities of 2.6- and 2.7-dinitroanthra- 
quinone. Eckert, 3 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 i.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 4 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 5 by 
heating anthraquinone-j8-diazonium nitrate with copper 
nitrite, 6 and by Scholl 1 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. 8 They obtained a mononitro 
compound but did not determine the position of the nitro 
group. 

The dinitration of 0-methyl anthraquinone has been 
effected by Schaarschmidt, 9 who found 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 i.3-dimethylanthraquinone Scholl 10 

1 Fritsche, J. pr. [i] 106, 287. Bottger and Petersen, A. 160, 185; 
B. 6, 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. 

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. 10 B. 43, 353. 



THE NITRO COMPOUNDS 169 

obtained i.3-dimethyl-4-nitroanthraquinone and 1.3- 
dimethyl-2.4-dinitroanthraquinone, and from 2.6-dimethyl- 
anthraquinone Seer 1 obtained 2.6-dimethyl-i.5-dinitro- 
anthraquinone. By nitrating i.3.5.7-tetramethylanthra- 
quinone Seer 2 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 dealing 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 nitroanthraquinones, 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, 3 and are 
very easily replaced by methoxy groups by treatment with 
alcoholic solutions of potassium methoxide. 4 



II. THE NITROSO COMPOUNDS 

Scarcely anything is known of the nitrosoanthraquinones. 
Walker 5 found that i-nitroanthraquinone-2-sulphonic acid, 
when reduced with glucose in alkaline solution, gave the 
corresponding hydroxylamine derivative, which on oxidation 
passed into i-nitrosoanthraquinone-2-sulphonic acid. From 
this the hydroxylamine derivative could be regenerated by 
reduction with glucose. As stated elsewhere, 6 1.5-dinitro- 
anthraquinone when heated to 50 with oleum containing 
30 per cent, of free anhydride passes into i-nitro-5-nitroso- 
8-hydroxyanthraquinone, reduction of this leading to the 
corresponding diamino compound. 

1 M. 32, 158. 8 M. 33, 33. s See p. 198. * Seep. 287. 
6 B. 35, 666. 6 Seep. 244. By., D.R.P. 104,282, 



i?o ANTHRACENE AND ANTHRAQUINONK 

III. THE HALOGEN COMPOUNDS 

DIRECT HALOGEN ATION. Anthraquinone itself is only 
attacked by halogens with the greatest difficulty, although 
Diehl, 1 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 sulphuric 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-tetrachlor anthraquinone, 
whereas 2.6- and 2.7-dichloranthraquinone yield hexachlor 
compounds. 

According to another patent specification 3 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 4 
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 i.4.5.8-tetrachloranthra- 
quinone. More recently Kckert and Steiner 6 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 were 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 By., D.R.P. 107,72?. 4 M. 36, 269. 

6 B". 11, 179. 6 M. 35, 175 ; 36, 269. B. 47, 2628. 



THE: HALOGEN COMPOUNDS 171 

benzoyl benzole acid and tetrachlorphthalic 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 i.2.34.5.6.8-heptachloranthra- 
quinone. Eckert and Steiner, however, prepared this 
compound from tetrachlorphthalic acid and i.2.4-trichlor- 
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 
i.2.3.4~tetrachloranthraquinone with antimony 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 i. 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 type of 
reaction. Ullmann l finds that when j8-methyl anthra- 
quinone is heated on the water bath with sulphuryl chloride 
in nitrobenzene solution, 2-methyl-i-chloranthraquinone is 
formed in 80 per cent, yield. On the other hand, sulphuryl 
chloride at 175 appears to convert j3-methylanthraquinone 
into j3-dichlor methy lanthraquinone . 2 

-Methylanthraquinone when chlorinated in nitrobenzene 
solution at 100 with molecular chlorine yields nuclear 
methy Ichloranthraquinones, 3 whereas with chlorine at 175 
halogenation seems to take place in the side chain. 4 The 
action of bromine at 160-175, with or without a solvent 

1 B. 49, 737. Agfa, D.R.P. 269,249. * B.A.S.F., D.R.P. 216,715. 
8 Agfa, D.R.P. 293,156. * B.A.S.F., D.R.P. 216,715. 



172 ANTHRACENE AND ANTHRAQUINONE 

such as nitrobenzene, seems to be very similar, Ullmann 
and Klingenberg, 1 and Hepp, Uhlenhuth, and Romer 2 
obtaining /^dibrommethylanthraquinone, and Eckert 3 ob- 
taining jS-tribrommethyl anthraquinone, although unable 
to obtain the jS-monobrommethyl anthraquinone described 
in the patent literature. 4 Among other similar results may 
be mentioned the preparation of co-dibrom compounds 
from 2-methyl-i-chloranthraquinone and from 2-methyl-3- 
chloranthraquinone by Ullmann, 6 by 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 6 was 
able to prepare i.3-dibromanthraquinone by brominating 
j8-aminoanthraquinone and then removing the amino group 
from the resulting 2-amino-i.3-dibromanthraquinone in the 
usual way by diazotising and reducing. 6 

RETROGRESSIVE SUBSTITUTION. Halogen atoms when 
in the a-position are fairly easily removed by reduction, 
whereas those in the j3-position are much more firmly 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 7 reduced 
i. 2. 3. 4-tetrachlor anthraquinone 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 i.2-dichlor anthraquinone, but which Ullmann 8 
has since shown to be 2.3-dichloranthraquinone. More 
recently Ullmann 9 has found that chlorine atoms when in 
the a-position, but not when in the j3-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. 2 B. 46, 709. 3 M. 35, 299. 

* B.A.S.F., D.R.P. 216,715. 6 B. 47, 55 ; W> 737- ' B. 49, 2157. 

9 A. 238, 344. 8 A. 381, 26. 9 B. 45, 687. 



THE HALOGEN COMPOUNDS 173 

although j8-chloranthraquinone is unaffected, a-chloranthra- 
quinone is reduced to anthraquinone itself, and i-methyl- 
4-chloranthraquinone to a-methylanthraquinone. In the 
case of i.2.34-tetrachloranthraquinone only two chlorine 
atoms are removed, the product being 2.3-dichloranthra- 
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. 1 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. 3 The cyclic carbonyl 
groups are unaffected. 

Nitro- groups either in the a-position or in the j8-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. 4 Methyl 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 very 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, 6 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 brqmine. 6 The nascent chlorine can 

1 Kauffler, B. 36, 60. Scholl, B. 40, 1696 ; 43, 354. Laube, B. 40, 
3566. By., D.R.P. 131,538. 
~ B.A.S.F., D.R.P. 215,006. 

UUmann and Conzetti, B. 53, 832. Afga, D.R.P. 290,879. 
B.A.S.F., D.R.P. 128,845, 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.B., D.R.P. 77,179, 78,642, 
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 sulphuric acid are 
halogenated without the sulphonic 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. 1 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 eo-dihalogenmethyl anthraquinones are 
unaffected by dilute alkali and can only be converted into 
the corresponding aldehyde by heating to 130 with con- 
centrated sulphuric acid. 4 Eckert, 5 however, states that 
j3-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 lime. In some ways the 
co-dibrommethyl compounds, however, are very reactive, 
and -dibrommethylanthraquinone when heated to 240- 
250 evolves torrents of hydrobromic acid and passes into 
dianthraquinonyldibromethylene, C 14 H 7 O 2 CBr : CBrC 14 H 7 O 2 , 
from which dianthraquinonyl acetylene can be obtained by 
the action of diethylaniline or sodium phenolate. 1 

Halogen atoms when directly attached to the nucleus 
are somewhat less firmly bound than is usually the case with 
aromatic halogen compounds. When in the a-position they 
are decidedly more reactive than when in the j8-position. 

Halogen atoms in the a-position direct the entering 
nitro group to the ^-position, so that a-chloranthraquinone 
gives i-chlor-4-nitroanthraquinone, and 1.5- and i.8-dichlor- 
anthraquinones give corresponding compounds. 2 From 1.4- 
dichloranthraquinone Walsch and Weizmann 3 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 4 
obtained a dinitro compound, but offer no information as 
to the position of the nitro group. Heller 5 by nitrating 
3-chloralizarin obtained a mononitro compound which must 
be 3-chlor-4-nitroalizarin, as it gives phthalic acid when 
oxidised. 

l Ullmann and Klingenberg, B. 46, 712. 

8 Eckert and Steiner, M. 35, 1138. By., D.R.P. 137,782, 249,721. 
3 Soc. 97, 687. 4 Soc. 95, 1318. 5 B. 46, 2703. 



CHAPTER X 

THE SULPHONIC ACIDS, MERCAPTANS, 
AND SULPHIDES 

I. THE STOPHONIC ACIDS 

ANTHRAQUINONE is not very easily sulphonated, but treat- 
ment with oleum leads first to the j3-monosulphonic acid and 
then to a mixture of disulphonic acids in which the 2.6- and 
the 2.7-disulphonic acids predominate. 1 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 found to contain considerable quantities of disulphonic 
acid. In any case the sulphonation of anthraquinone is 
always accompanied by a certain amount of simultaneous 
hydroxylation, and consequently a deep purple colour is 
developed when a portion of the melt is made alkaline. 
Under suitable conditions, however, the loss by hydroxyla- 
tion is only slight. 

Both the jS-sulphonic acid and the two disulphonic acids 
are manufactured on the technical scale and are used in the 
manufacture of alizarin dyes. The monosulphonic acid is 
isolated by diluting the sulphonation melt, filtering off the 
unchanged anthraquinone and then saturating the solution 
with sodium chloride. Under these conditions the sodium 

1 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, 1566. 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 silvery 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 j8-sulphonic 
acids although very 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 
totally 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 i.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 i.3.7-trisulphonic acids, can be obtained 

1 Diinschmann, B. 37, 331. Liebermann and Pleus, B. 37, 646. 
8 Iljinsky, B. 36, 4194. R. E. Schmidt, B. 37, 66. By., D.R.P. 
149,801. 

12 



178 ANTHRACENE AND ANTHRAQUINONE 

either by sulphonating an a-sulphonic acid without the 
addition of mercury, or by sulphonating a j3-sulphonic acid 
in the presence of mercury. 1 

By sulphonating anthraquinone itself in the presence of 
mercuric sulphate which is only coarsely powdered, it has 
been claimed that anthraquinone-i.6- and i.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 3 has found 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 which have been made by the author fail 
to support this claim. 4 

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 sulphuric acid, 5 although the reaction is by 
no means a general one, and many halogen compounds can 
be sulphonated in a normal manner. 6 In the case of 
i-amino-4-arylamino-2-halogen anthraquinones the halogen 
atom can be replaced by the sulphonic acid group by heating 
with aqueous sodium sulphite solution. 7 

Boiling with aqueous sodium sulphite solution in man) 
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 hydroxynitroanthra- 
quinones reacting in this way . 8 In the case of 1 4-dihy droxy - 

1 Wed., D.R.P. 170,329 ; 202,398. 

2 Wed., D.R.P. 202,398. 

3 D.R.P. 223,642. 

4 Thummler, D.R.P. 214,156. 

6 Perkin, A. 158, 319. Graebe and Liebermann, A. 160, 137. 

8 E.g. Walsh and Weizmann, Soc. 97, 688. By., D.R.P. 217,552, 
Ullmann, D.R.P. 223,642. 

7 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-aminohydroxyanthraquinones 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 oxygen of the cyclic carbonyl groups. 

The anthraquinone sulphonic acids are usually fairly 

easily desulphonated by hydrolysis, although the ease with 

which the sulphonic acid group is split off varies to a great 

extent in different individual substances. As a rule, the 

hydrolysis can be effected by heating to 170-190 with 

sulphuric acid of 80 per cent, strength, 2 but sulphonic acid 

groups in the a-position are somewhat less firmly held than 

similar groups in the j8-position and are usually readily 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 many 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. 4 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 desulphonated 

when boiled with sulphuric acid of 20 per cent, strength. 5 

It should be remembered that during hydrolysis bromine 

atoms if present are apt to wander. 6 

1 By., D.R.P. 287,867 ; 288,474; 289,112. 

3 By., D.R.P. 56,951 ; 172,688. Wed., D.R.P. 210,863. 

3 By., D.R.P. 160,104. 

* By., D.R.P. 190,476. 

5 M.L.B., D.R.P. 71,964 ; 77,720. 

6 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 

Desulphonation 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. 1 

The anthraquinone sulphonic acids are converted into 
the sulphochlorides by treatment with phosphorus 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. 3 

These sulphochlorides behave like other sulphochlorides. 
On reduction with sodium sulphide they give the corre- 
sponding sulphinic acids. 4 

The nitration of anthraquinone-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. 5 The 
nitration of anthraquinone-j3-sulphonic also leads to two 
isomeric mononitro compounds, one of which, according to 
Claus 6 and lyifschiitz, 7 can be converted into alizarin. 
R. B. Schmidt, 8 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 9 have severely criticised Claus' 
work and have shown that what Claus described as erythro- 
hydroxy anthraquinone 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 By., D.R.P. 103,898. z Ullmann, B. 52, 545. s M.L.B., D.R.P. 266,521. 

4 M.L.B\, D.R.P. 263,340. Cf. M.L.B., D.R.P. 224,019. 
5 R. E. Schmidt, B. 37, 71. 6 B. 15, 1521. 

7 B. 17, 899. 8 B. 37, 69. 9 B. 40, 1048. 

10 M.L.B., D.R.P. 263,340. Cf. M.L.B., D.R.P. 224,019. 



THE SULPHENIC (SULPHOXYLIC) ACIDS 181 

quinone-j8-sulphinic acid very readily condenses with 
tetramethyldiaminobenzhydrol (Mischler's hydrol) to form 
an ester, 1 C 14 H 7 O2.SOOCH(C 6 H 4 NMe 2 )2, and also readily 
adds on to quinonoid compounds, 2 e.g. with benzoquinone 
it gives C U H 7 O 2 .SO 2 .C 6 H 3 (OH) 2 . 

III. THE SuivPHENic (SuivPHGXYLic) ACIDS 

When an anthraquinone mercaptan or disulphide is 
treated with chlorine or bromine in chloroform solution an 
anthraquinone sulphur halide, Ci 4 H 7 O 2 .SHlg, is often obtained, 
although the reaction is by no means a general one and 
several exceptions are known. 3 The bromides are also often 
obtained by reducing the sulphinic acids in glacial acetic 
acid solution by means of hydrobromic acid. 4 

The sulphur halides of the anthraquinone series usually 
show reactions very similar to those of other aromatic 
sulphur halides, 5 although they are much more stable than 
is usually the case with compounds of this class. Thus 
anthraquinone-j8-sulphur chloride reacts with acetone to 
form an acetyl compound, and with water to give the 
anhydride of the sulphenic acid (C 14 H 7 O 2 S) 2 O. With 
alcohol it gives a mixture of disulphide, disulphoxide, and 
sulphinic acid. 6 

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 : 

H 2 N- S 





1 Hinsberg, B. 50, 472. 2 Hinsberg, B. 50, 953- 

3 Friess, B. 45, 2965. Friess and Schiirmann, B. 52, 2182. 

4 Friess and Schurmann, B. 47, 1192. M.L.B., D.R.P. 277,439. 

5 Cf. Zincke, A. 391, 55 ; 400, i ; 416, 86. 

6 Friess, B. 47, 2965. Friess and Schurmann, B. 52, 2170. 



182 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 r 1 

,0 

C 14 H 7 2 .Sf $ C 14 H 7 2 .S-OH 

NH 

Normal form. Pseudo form. 

Alkaline solutions of the acid are readily oxidised by 
the 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 : 

OEt 



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 by indirect methods. The diazonium salts react 

1 Friess, B. 45, 2965. Friess and Schiirmann, B. 52, 2170. 



THE MERC APT AN S 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. 1 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. 3 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-chloranthraquinone and j3-chloranthraquinone 
give the corresponding mercaptan when heated with alkali 
sulphide, sulphydrate, or poly sulphide, 4 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. 5 Mer- 
captans can also be obtained by reducing the corresponding 
sulphochlorides 6 or disulphides, 7 and in the case of ti- 
ny droxyanthraquinones and jS-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. 
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- 
maiin, B. 52, 2x76, 2186. 



184 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 hydroxyl groups are attached to the same 
nucleus, e.g. as in quinizarin, only one mercaptan group 
enters the molecule. 1 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 cyclic 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 
|8-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 mercaptati 
but is very loose to soap. Owing to their greater stability 
it is somewhat easier to apply the j8-mercaptans to the fibre, 
but the shades obtained are very poor. The benzoyl 
derivative of anthraquinone-a-mercaptan has been prepared 3 
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. 2 B.A.S.F., D.R.P. 247,412. 

3 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 



SH 



OH 



SH 



Red. 



Violet. 



OH 



Yellowish-Red. Bluish-Red, 

OH SH 



OH SH 

Violet. Blue. 

OH 



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, 1 and also from negatively substituted anthra- 
quinones, such as a-chloranthraquinone and j8-chloranthra- 
quinone, by heating with alkali selenides. 2 They are of no 
particular interest. 

1 By., D.R.P. 264,940. a By., D.R.P. 264,941. 



i86 ANTHRACENE AND ANTHRAQUINONE 

VI. THE SULPHIDES 

Sulphides of the anthraquinone series can be obtained 
by condensing anthraquinone mercaptans with alkyl, aryl, 
or anthraquinonyl halides, 1 but when an anthraquinone- 
a-mercaptan is condensed with an alykl halide 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 unnecessary to isolate the 
mercaptan, dianthraquinonyl sulphides, for example, being 
obtained in one operation when either a- or j3-chlor anthra- 
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. 4 

The sulphur chlorides of the anthraquinone series also 
condense quite readily with aromatic substances such as 
benzene under the influence of aluminium chloride, and in 
the case of dimethyl aniline and phenols, especially resorcinol 
and -naphthol, the sulphide is formed without the use of 
any condensing agent. 5 Very similar to this is the formation 
of sulphides 6 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. 7 All the 
above methods involve the preparation of anthraquinone 
mercaptans, but sulphides can also be obtained from 
anthraquinone compounds containing negative substituents, 

1 Gattermann, A. 393, 113. Friess and Schiirmarm, 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. 

Ullmann and Goldberg, D.R.P. 255,591. By., D.R.P. 272,298. 

By., D.R.P. 254,561. 

Friess and Schiirmann, B. 52, 2179, 2194. M.L.B., D.R.P. 277,439. 

M.L.B., D.R.P. 262,477. 

Cf. Davis and Smiles, Soc. 97, 1220, Preseott, Hutchison, and 
Smiles, Soc. 99, 640. 



THE BISULPHIDES 



187 



such as sulphonic acid groups, 1 nitro groups, 2 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- 
sulphides, 4 and as already stated are very readily produced 
by the oxidation of the mercaptans either by atmospheric 
oxygen or by potassium ferricyanide. 5 Ullmann 6 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 S-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 : 



SCOC 6 H 5 



SH 



s s 



j3-Chloranthraquinone does not condense with thiolbenzoic 
acid, but from j3-bromanthraquinone 2.2'-dianthraquinonyl 
disulphide can be obtained. 

The sulphonic acids of the disulphides have very great 

1 Decker and Wiirsch, A. 348, 238. By., D.R.P. 224,589. 
* By., D.R.P. 116,951 ; 224,589. 

3 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. 

4 Friess, B. 45, 2967 ; 52, 2176, 2186. Ullmann, B. 49, 739. By., 
D.R.P. 204,772 ; 206,536. 

5 Qattermann, A. 393, 113. 6 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 sulphide and /or 
sulphur. 1 The constitution of these compounds is quite 
unknown, 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 ; 4 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. 5 

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 j8-chloranthraquinone. 6 

IX. THE THIANTHRENES 

From thianthrene itself by the phthalic acid synthesis 
Scholl 7 obtained a compound which was probably lin.- 

1 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.B., D.R.P. 209,231-2-3 ; 211,967; 213,506; 265,194, 

3 Agfa, D.R P. 229,465. 4 Agfa, D.R.P. 229,110. 

8 Wed., D.R.P. 296,207 ; 297,079 ; 297,080 ; 297,567 ; 298,182-3 ; 

29Q,)lo. 

By., D.R.P. 264,941. 7 B. 44, 1233. 




THE THIANTHRENES 189 

diphthaloylthianthrene (I.), whereas from methylthianthrene 
he obtained what was most probably trans, bisang.-^.q'- 
dimethyldiphthaloylthianthrene (II.) : 

CO CH 3 

QO s co /\ 0. 

CO 

co " S " co 



trans. fo'sawg-Diphthaloylthianthrene itself can be obtained 
by condensing i.2-dichloranthraquinone with anthraquinone- 
1.2-dimercaptan. 1 

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 lin.~ compound has no tinctorial properties. 

1 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 no 
tinctorial properties, although some of the amino-hydroxy 
compounds are valuable dyes, e.g. Alizarin Saphirol. 1 The 
sulphonated aryl aminoanthraquinones are used as acid' 
wool dyes to a considerable extent, the best known being 
Alizarin Cyanine Green 2 : 

/CH 3 
NHC 6 H 3 < 

X S0 3 H 



CH 3 

C 6 H 3 NH 



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- 
quinonyl groups are present, these dianthraquinonylamino 
anthraquinones acting as a rule as vat dyes giving bordeaux 
shades, e.g. Indanthrene Bordeaux B : 



1 Solway Blue (Scottish Dyes, Ltd.). 

2 Kymric Green (Scottish Dyes, Ltd.). 



IQO 



THE A MI NO A NTHRA Q U I NONES 
h-NH 



191 



NH 



Although neither the primary arninoanthraquinones 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 30 (a-succinyl aminoanthraquinone) : 

NHCOC 6 H 5 NH.CO.CH 2 .CH 2 .CO.NH 



Algol Yellow W.G. 



Algol Yellow 30. 



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 compound to the hydroxylamine 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 piimary amino compounds ; but the second method, viz, 



192 ANTHRACENE AND ANTHRAQUINONE 

the replacement of negative groups, can be used for the 
production of primary, 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, 1 it is much better to carry out the reduction in 
alkaline solution by means of sodium stannite, 2 glucose and 
caustic soda, 3 zinc dust and caustic soda or ammonia, 4 or 
sodium sulphide or sulphydrate. 5 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 coloured 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 

1 Bottger and Petersen, A. 160, 149. Walsh and Weizmann, Soc. 97, 
687. Lifschiitz, B. 17, 899. 

2 Bottger and Petersen, A. 160, 149. R&mer, B. 15, 1790 ; 16, 366. 
8 Wacker, B. 34, 3922. 

4 Claus, B. 15, 1517. Przibram, D.R.P. 6,526. 

5 Bottger and Petersen, A. 160, 149 ; 166, 149. Ullmann, A. 388, 203. 
Schaarschmidt, A. 407, 184. Claus, B. 15, 1517. R. E. Schmidt, B. 37, 
171. Scholl 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 > I6 - Eckert, M. 35, 298. By., D.R.P. 100,138; 
119,228. Lauth, C. r. 137, 662. 



THE AMINOANTHRAQUINONES 193 

Terres l states that when i-nitro-2-aminoanthraquinone 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, 3 on the other 
hand, reduced both 2-nitro-3-aminoanthraquinone and 
i-nitro-2-aminoanthraquinone 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 yield of the diamino compound was 
almost theoretical, but that in the preparation of i.2-diamino- 
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 compound, the results as a rule 
are excellent, the preparation of a-aminoanthraquinone 
from a-nitroanthraquinone being particularly easy. 4 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 ammo 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 carrying out the reduction under carefully controlled 
conditions. Claus 5 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. Cf. Schaarschmidt, A. 407, 84. M.L.B., D.R.P. 
72,552 ; 73.68 4 ; 77,720 ; 81,741 ; 145,237- 

2 Cf. Romer, B. 15, 1790. 3 A. 407, 184. 

4 Lauth, C.r. 137, 662. Ullmann, A. 388, 203. 

5 B. 15, 1517. c M.L.B., D.R P. 78,772. 

13 



194 ANTHRACENE AND ANTHRAQUINONE 

that the reaction will take a different course, the nitro 
groups being replaced by sulphonic acid groups. 1 In the 
case of i.5-dinitroanthraquinone and i.8-dinitroanthra- 
quinone reduction of one nitro group is easily and quanti- 
tatively brought about by heating with secondary or tertiary 
aromatic amines, especially dimethyl aniline. 2 This is a 
rather remarkable reaction and merits greater 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, 4 although not confined to these 
substances. 5 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 w-nitraniline 
sulphonic acid from w-dinitrobenzene. 6 

The simultaneous reduction and bromination of nitro- 
anthraquinones can be effected by heating under pressure with 
hydrobromic acid with or without the addition of bromine. 7 

Instead of preparing aminoanthraquinones by nitrating 
and then reducing an anthraquinone compound, a benzoyl 
benzoic acid can be nitrated and reduced, 8 and the amino- 
benzoyl benzoic acid then converted into the aminoanthra- 
quinone by closing the anthraquinone ring in the usual 
way, viz. by heating with sulphuric acid. 9 In many cases 
the aminobenzoyl benzoic acid can be readily purified by 
converting it into its well-crystallised and sparingly soluble 
lactam. 10 

When crude dinitroanthraquinone, obtained by the 
nitration of anthraquinone, is reduced with sodium sulphide 
a mixture of diaminoanthraquinones is obtained. This has 
been examined by Noelting and Wortmann, 11 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. 4 By., D.R.P. 103,395 ; 152,013. 

6 See p. 283. 6 Nietzki, B. 29, 2448. D.R.P. 86,097. 

7 B.A.S.F., D.R.P. 128,845. 8 Agfa, D.R.P. 248,838. 

9 Agfa, D.R.P. 260,899. See also p. 140. 10 Agfa, D.R.P. 258,343. 

B. 39, 637. 



THE AMINOANTHRAQUINONES 195 

if the crude bases are recrystallised from aqueous sulphuric 
acid (i : i by volume) the difficultly soluble sulphate of 
i.5-diaminoanthraquinone 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 l obtained a dinitroanthraquinone by 
boiling anthracene with dilute nitric acid, and this on reduc- 
tion gives a diaminoanthraquinone, which Noelting and 
Wortmann 2 have identified as 2.7-diaminoanthraquinone, as 
they find that it gives isoanthraflavic acid when diazotised 
and boiled with water. 

Scholl 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-methylene 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. 3 



REPLACEMENT OF NEGATIVE GROUPS 

Negative atoms and groups, especially when in the 
a-position, are very readily replaced by primary amino 
groups by heating with ammonia, and if a primary or 
secondary amine is used in place of ammonia, secondary and 
tertiary amino compounds can be obtained. Piperidine 
behaves like a secondary' 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, 266. 

3 B. 39, 637. 

* Scholl, M. 34, ion. 



196 ANTHRACENE AND ANTHRAQUINONE 

only the more important of these will receive individual 
notice in the text. 1 

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. 

REPLACEMENT 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. 3 In preparing i-aminoanthraquinone- 
2-carboxylic acid from the corresponding chloro acid, 
Ullmann 4 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, 5 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 catalyst. 6 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; 
l8 3>395 ; 185,546 ; 191,731 ; 209,321 ; 265,725 ; 268,454 ; 269,749 ; 
272,614 ; 282,672 ; 286,092. 

2 Frey, B. 45, 1360. Ullmann, B. 47, 561. Schaarschmidt, A. 405, 
95. M.L.B., D.R.P. 231,091. By., D.R.P. 295,624. 

3 UlJmann, B. 49. 747. By., D.R.P. i95- T 39 ; 295,624. 

4 B. 49, 747. Cf. B. 47, 561. 5 D.R.P. 247,411 ; 256,344. 

6 Ullmann, 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 l 
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 i.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 4 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. 

4 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. 



198 ANTHRACENE AND ANTHRAQUINONE 

obtained, and this can then be condensed with a chloro- 
anthraquinone to a product which on hydrolysis gives an 
N-alkylaminoanthraquinone : 



Cl 



CH 3 C 6 H 4 S0 2 NHR 



/ 

N< 

\S0 2 C 6 H 4 CH 3 



NHR 



An exactly similar reaction takes place with N-aryl 
sulphonamides, the final product in this case being, of course, 
an N-aryl aminoanthraquinone. The sulphonamide process 
has proved to be of the utmost use in the study of the second- 
ary aminoanthraquinones, and Schaarschmidt 1 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 by the hydrolysis of the nitrile group. 

The replacement of halogen atoms by heating halogen 
anthraquinones with amines has been applied to the manu- 
facture of one or two dyestuffs. Thus Alizarin Pure Blue B 
is obtained from 2.4-dibrom-i-aminoanthraquinone by 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 2 

REPLACEMENT O F NITRO GROUPS. Nitro groups can be 
replaced by amino groups by heating the nitro compound 
with ammonia, 3 or with primary 4 or secondary aliphatic 
amines, 5 or primary aromatic amines. 6 An amino compound 
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 

A. 405, 95. 

B.A.S.F., D.R.P. 121,684. 
Przibram, D.R.P. 6,520. 
By., D.R.P. 139,581 ; i44. 6 34. 
By., D.R.P. 136,777-8. Cf. D.R.P. 151,512-3. 

Heller, B. 46, 2702. By., D.R.P. 125,578 ; 126,803 ; 148,767. 
M.L.B., D.R.P. 150,332. 



THE AMINOANTHRAQUINONES 



199 



easy and can be brought about simply by boiling this 
substance in aqueous solution with the amine. 1 

It is very doubtful if a nitro group in the /^-position is 
sufficiently reactive to be replaced by an amino or an alkyl 
or arylamino 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 ex- 
position, 2 and Kauffler 3 states that /J-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 jS-nitro- 
anthraquinone is very readily replaced by the methoxy 
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 i.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 scarcely 
altered. The difference in colour between Anthraquinone 
Violet and the isomeric i.4-compound (Alizarin Cyanine 
Green, p. 203) should be noted. 



SOH 



so 






Anthraquinone Violet. 



OH 



S0 3 H 



Erweco Acid Alizarin Blue R. 



HO 



Krweco Acid Alizarin Blue R is obtained by heating 
dinitroanthraflavic acid distilphonic acid with aniline. 5 It 



1 B.A.S.F., D.R.P. 247,411. 

z Cf. Wed., D.R.P. 235,776 ; 244,372 ; 245,014 ; 247,245. 
3 T* 2A KK 4 B.A.S.F., D.R.P. 108,274. 

5 Wed., D.R.P. 235,776. 



B. 36, 



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. 

REPLACEMENT 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 l was able to replace 
the nitro group in 3-chlor-4-nitroalizarin without affecting 
the hydroxyl groups or the halogen atoms, and Ullmann 2 
found that when i-chlor-2-rnethyl-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 4 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, 5 such as hydrochloric, sulphuric, phos- 
phoric, and, in particular, boric acids. The sulphite esters 
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. 6 

Replacement of hydroxyl by amino groups is also 

1 B. 46, 2702. z B. 52, 2109. 

3 By., D.R.P. 114,199. 4 M.L.B., D.R.P. 150,322. 

5 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- 
quinone to its leuco- 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 ordinary 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 /0wc0-quinizarin 
reacts with the toluidine to produce /^wco-ditolylamino 
anthraquinone, which then reduces an equivalent amount of 
quinizarin to fewco-quinizarin. being itself thereby oxidised 
to i.4-ditolylamino anthraquinone. The leuco-qumizaim 
thus produced then reacts with ^-toluidine and the process 
is repeated until the whole of the quinizarin has been 
converted into ditolylamino anthraquinone. It will be 
seen that the action of the /ewco-quinizarin is purely 
catalytic. 

When the /0wco-hydroxyanthraquinones are heated with 
ammonia or an amine the hydroxyl groups attached to the 
ws-carbon atoms remain unaffected, although under more 
drastic conditions it is probable that they 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, 4 by heating alizarin with 

1 Schrobsdorf, B. 35, 2930. By., D.R.P. 91,149- 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 ; 147,277 ; 148,079. 
1 J- pr. [2] 18, 133- 



202 ANTHRACENE AND ANTHRAQUINONE 

aqueous ammonia, obtained a substance which he considered 
to be i.2-diaminoanthraquinone, and L,iebermann and 
Troschke l by the same method obtain a substance which 
they considered to be an ammonium salt of an imide of 
alizarin. More recently Scholl and Parthey 2 have shown 
that the substances obtained by von Perger and by I^ieber- 
niann 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-hydroxy-2-aminoanthraquinone Scholl and Parthey con- 
sider that it must be : 





s or 

\/ 

CO 

Prudhomme, 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 hydroxyanthraquinones in which two or more 
hydroxyl groups are present, it is often possible to replace 
only one group by heating with an amine. 4 The remaining 
hydroxyl 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. 5 

Alkoxy groups and aryloxy groups can also be replaced 
by amino groups by heating with primary or secondary 
amines, and in many cases the reaction takes place more 
readily than when the free hydroxyl compound is used. 6 

The replacement of hydroxyl groups by amino 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. 

<> Bl [3] 35, 71. 

4 Schfobsdorf, B. 35, 2930. 

5 By., D.R.P. 86,539. 

6 By., D.R.P. 165,728 ; 205,881. M.L.B., D.R.P. 201,905. 



THE AMINOANTHRAQUINONES 203 

Alizarin Irisol D. l This is obtained by heating quinizarin 
with one molecule of ^-toluidine and then sulphonating the 
product. 2 It dyes silk and wool from an acid bath in 
bluish-violet shades 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-qmmza.rin with ^-toluidine-2-sulphonic acid. 



OH OH 

Alizarin Irisol D. Alizarin Direct Violet R. 

Alizarin Cyanol Violet R. 

By replacing both the hydroxyl groups in quinizarin 
several important dyestuffs have been obtained. By far 
the most important of these is Alizarin Cyanine Green or 
Quinizarin Green, 3 which is obtained by heating quini- 
zarin 4 or much better /^wco-quinizarin 5 with ^-toluidine 
and then sulphonating the product, 6 but i.4-dichloranthra- 
quinone or i-chlor-4-nitroanthraquinone can be used in 
place of quinizarin. 7 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 condensing leuco-qmrnzarin with ^-toluidine-2-sulphonic 
acid : 8 

1 Solway Purple (Scottish Dyes, Ltd.). 

2 By., D.R.P. 86,150 ; 91,149. 
Kymric Green (Scottish Dyes, Ltd.). 
By., D.R.P. 86,150; 86,539. 

By., D.R.P. 91,149 ; 91,150 ; 91,152 ; 92,591 ; 93,223 ; 94.396. 

By., D.R.P. 84, 509 ; 89,862 ; 93,310. 
By., D.R.P. 125,698 ; 126,803. 

8 B.A.S.F., D.R.P. 128,753; 137,566; 148,306; 151,018; 151,384; 
155,572. Cf. M.L.B., D.R.P. 172,464; 181,879; 201,905. 



20 4 ANTHRACENE AND ANTHRAQUINONE 



Alizarin Cyanine Green. 
Quinizarin Green. 



Alizarin Direct Green G. 
Alizarin Brilliant Green G. 



Isomeric green dyes in which the sulphonic acid groups 
are in the anthraquinone nucleus are obtained by condensing 
/tfwco-quinizarin sulphonic acid with ^-toluidine. 1 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 i. 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 hydroxyl 
group, or rather of its boric ester. 

As stated on p. 202, the two hydroxyl groups in quini- 
zarin and other polyhydroxy anthraquinones can be replaced 
by different aryl or alkylamino groups. This has been done 
in the case of Alizarin Astrol, in which one hydroxyl group 
has been replaced by a methylamino 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 : 

PTT OTT OTT 

NHC 6 H 3 <^ NHC 6 H 3 <C NHC 6 H 3 <" 

X S0 3 H 



Br 
NH 2 



NHCH, 



Alizarin Pure Blue. Alizarin Astrol. 

1 By., D.R.P. 95,625 ; 101,919. 



NHC 6 H< 

N S0 3 H 

Alizarin Cyanine Green. 
2 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 l 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 : 



NHC 6 H 4 SO 3 H OH 



NHC 6 H 4 S0 3 H 



or 



NHC 6 H 4 S0 3 H 



OH NHC 6 H 4 SO 3 H 

and cannot be a sulphonation product of 2-hydroxy-i.4- 
diphenylaminoanthraquinone as originally thought. 

REPLACEMENT OF SULPHONIC ACID GROUPS. The re- 
placement of sulphonic acid groups by amino groups is of 
very 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 sulphonic acid groups enter the anthraquinone nucleus 
in the j3-position when the sulphonation is carried out in the 
absence of mercury, the replacement of the sulphonic acid 
group renders j8-amino compounds easily accessible, although 
they are often troublesome to obtain by other methods. 
Thus j8-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 
1 Solway Blue-Black (Scottish Dyes, Ltd.). 2 By., D.R.P. 114,199. 



206 ANTHRACENE AND ANTHRAQUINONE 

methylamino compounds, obtained by the use of methyl- 
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, 1 
but it is much simpler and better to use aqueous ammonia ; 2 
and primary and secondary alkylamines and primary 
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, 5 such as manganese 
dioxide (preferably in the form of Weldon 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 6 that satisfactory -yields 
of j3-aminoanthraquinone are obtained by heating sodium 
anthraquinone /3-sulphonate with aqueous ammonia and 
nitrobenzene. In this case the nitrobenzene acts as an 
oxidising agent and is thereby reduced to aniline, so that the 
manufacture of aniline and of j8-aminoanthraquinone is 
combined in one process. As the aminoanthraquinones are 
not volatile with steam there is no difficulty in separating 
the j8-aminoanthraquinone from the aniline and unchanged 
nitrobenzene. 

HOFMANN'S REACTION. Aminoanthraquinones can be 
prepared from the amides of the anthraquinone carboxylic 
acids by Hofmann's method (treatment with hypochlorite or 
hypobromite), but the method has not been extensively 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. 

4 M.L.B., D.R.P. 267,212. Cf. Geigy, E.P. I2?,223 19 . 

5 B.A.S.F., D.R.P. 256,515. 6 G.C.I.B., A>. 1,255,719. 



THE AMINOANTHRAQUINONES 207 

as the amides are not particularly accessible and the amino- 
anthraquinones are usually more easily obtained by other 
methods. Hofmann's method, however, has been employed 
by Kckert l and by Willgerodt and MafMzzoli, 2 who prepared 
2-aminoanthraquinone-3-carbox34ic acid from the amide of 
anthraquinone-2.3-dicarboxylic acid. Other investigators 
have also made use of the method 3 although to no consider- 
able extent. 

AlvKYI,ATION AND ARYI.ATION. 

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 by 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 they merit special treatment. 

The alkylation of the aminoanthraquinones can be 
brought about in the usual way by means of alkyl halides, 
but in some cases abnormal results are obtained. Kckert, 4 
for example, endeavoured to prepare the glycine of 2-amino- 
anthraquinone-3-carboxylic acid by treating it with chlor- 
acetic ester, but instead of the glycine the chloracetyl 
compound C 16 H 6 O 2 (COOH)(NHCOCH 2 C1) was obtained. 
Seer and Weitzenbock 5 succeeded in preparing glycines 
from monamino and i.5-diamino anthraquinone and found 
that the diglycine of the latter compound had tinctorial 
properties and was capable of dyeing wool in red shades. 
They also prepared some benzyl derivatives and found 
that 1.5- and i.8-dibenzylaminoanthraquinone could not be 
reduced in alkaline solution. 

1 M. 35, 290. 2 J. pr. [2] 82, 205. 

3 Scholl, B. 40, 1691. Schaarschmidt, B. 50, 294 ; 51, 1074. Terres, 
B. 46, 1640. Graebe and Blumenfeld, B. 30, 1116. 

4 M. 35, 290. 5 M. 31 379- 



208 ANTHRACENE AND ANTHRAQUINONE 

Methylation with dimethyl sulphate sometimes leads to 
abnormal results as i-amino-4-arylamino anthraquinones 
are simultaneously sulphonated, 1 the product being a 
i-methylamino-4-arylaminoanthraquinone 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 sulphuric acid from the dimethylsulphate, as it 
takes place even in the presence of excess of sodium carbonate. 
Other amino anthraquinones are conveniently methylated 
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 ethylene oxide 3 giving 
Ci 4 H 7 O 2 NHCH 2 CH 2 OH, and epichlorhydrin 4 giving a com- 
pound which contains chlorine and probably has the formula 
C 14 H 7 O 2 NHCH 2 CHOHCH 2 C1. On sulphonation this yields 
a yellow acid dye. 5 

Glyoxylic acid combines with a- and jtf-aminoanthra- 
quinol to form the glycine of a- and j3-aminoanthraquinone. e 
Here probably the azomethine compound of anthraqumoJ 
is first formed, the azomethine group then being reduced 
at the expense of the quinol group : 

OH 

C CO 

C 6 H 4 <^C 6 H 3 N : CHCOOH -> C 6 H 4 <Q>C 6 H 3 NHCH 2 COOH 
C CO 

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. 4 By., D.R.P. 218,571. 

5 By., 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 by Wacker. 1 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 methylamino and diethylamino sulphonic acid when 
treated with methylamine carbonate or diethylamine : 

NHCH 3 /N 2 N(C 2 H 5 ) 2 



S0 3 H 



CH 3 NH, 



'3 (C 2 H ) 2 NH 



S0 3 H 



HN0 2 f |(NH 4 ) 2 C0 3 
HN 2 



When treated with aniline, however, the diazo anhydride 
gave first the diazoamino compound, 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 aminohydroxy compound, with methylamine the original 
diamino compound only, and with diethylamine only the 
dihydroxy compound, whereas the diazonium salt of i-amino- 
4-hydroxyanthraquinone when treated with methylamine 
gave quinizarin. 

Primary aminoanthraquinones combine with aldehydes 
and compounds of the type C 14 H 7 O 2 NHCH 2 [i]C 6 H 4 [4]NR 2 
are obtained by condensing a-aminoanthraquinone with 
formaldehyde and tertiary aromatic amines such as di- 
methyl aniline. 2 Kauffler 3 has studied the benzylidene 

1 B. 34, 2593, 3922. 2 M.L.B., D.R.P. 236,769. 8 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. 1 
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 usually necessary 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 110 
reaction takes place. Aminoanthraquinones also condense 
with benzoquinone and a-naphthoquinone to give compounds 
of the type (HO) 2 [i.4]C 6 H 3 [2]NHC 14 H 6 O 2 NH 2 , from which 
vat dyes giving fast shades of bordeaux can be obtained 
by condensation with halogen aiithraquinones so as to form 
a dianthraquinonylamine derivative. 4 

TINCTORIAL PROPERTIES. 

Although the primary aminoanthraquinones are highly 
coloured substances, they have little or no affinity and con- 
sequently are useless as dyestuffs. To a certain extent 
the same is true of the secondary and tertiary compounds, 
but in some cases these show very considerable affinity, 
and as has already been shown (p. 203), valuable acid dyes 
are formed by sulphonating the secondary i.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. 

a Laube, B. 40, 3564. * Cas., D.R.P. 267,414-5-6 ; 269,801. 



THE AMINOANTHRAQUINONES 211 

When the nitrogen atoms of two molecules of an amino- 
anthraquinone are joined by a carbon chain so as to produce 
a compound of the type C U H 7 O 2 NH X NHC 14 H 7 O 2 , 
tinctorial 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 syw-dianthraquinonyl- 
ethylenediamine, which Ullmann and Medenwald l prepared 
from j8-aminoanthraquinone 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 readily pass into a complex heterocyclic compound. 

In the above type of compound much greater affinity 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 molecule 
of an aromatic diamine such as ^-phenylene diamine, benzi- 
dine, 2 etc., or by condensing two molecules of an amino- 
anthraquinone with one molecule of an aromatic dihalogen 
compound such as ^-dichlorbenzene 3 (violet shades), p 2 - 
dichlorbenzil 4 (red shades), ^> 2 -dichlordiphenylmethane 5 
(bordeaux shades), dichlorphenanthraquinone 6 (red shades), 
dichlorbenzophenone " 7 (red shades), or ^> 2 -dichlordiphenyl 8 
(violet shades). The condensation product from amino- 
anthraquinone and ^> 2 -dichlordiphenyl can also be obtained 
from chloranthraquinone and benzidine, and Brass 9 has 
obtained it and similar compounds by oxidising diaryl- 
aminoanthraquinones with manganese dioxide and sulphuric 
acid. 

Vat dyes have also been obtained 10 by condensing 

1 B. 46, 1798. 2 Agfa, D.R.P. 243,489. 

3 By., D.R.P. 215,294. 4 B.A.S.F., D.R.P. 222,205; 230,400. 

' BA.S.F., D.R.P. 230,411. 6 B.A.S.F., D.R.P. 222,206; 230,400. 
7 B. A S.F., D.R.P. 220,579; 230,399. 8 By., D.R.P. 230,409. 

9 B. 46, 2907. W.T.M., D.R.P. 251,845. 10 By., D.R.P. 248,655 



212 ANTHRACENE AND ANTHRAQUINONE 

two molecules of a primary aminoanthraquinone with 
one molecule of a compound of the general formula 
ClAr 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 amino- 
anthraquinone with one molecule of a syw-dihalogen diaryl 
urea, 1 or with compounds of the type 2 HlgRNHCO(CH 2 ) n - 
CONHRHlg, where n is o, i, 2, 3, etc. Somewhat similar 
dyes are obtained by condensing dihalogen sulphones with 
aminoanthraquinones. 3 

The shades produced by the diarylaminoanthraquinones 
depend to a considerable extent on the position of the 
arylamino groups. As already shown (p. 203) the 1-4- 
diarylaminoanthraquinones give rise to green dyes, e.g. 
Alizarin Cyanine Green. When the arylamino 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. 

ACYI.AMINOANTHRAQUINONES 

Converting an aminoanthraquinone into an acylamino 
compound is always 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 affinity 
of the resulting acyl aminoanthraquinones being too slight 
for them to be of any value as technical dyes. Although 
the acyl aminoanthraquinones derived from monobasic 
aromatic carboxylic acids have great affinity, this is not 
the case with the derivatives of aromatic sulphonic acids, 

i M.L.B., D.R.P.2 4 i,83 7 . 2 M .L.B., D.R.P. 241,838. 

3 By., D.R.P. 234,518. 



THE AMINOANTHRAQUINONES 213 

the N-anthraquinonyl sulphonamides as a rule having no 
tinctorial properties. 1 

The acylaminoanthraquinones are very readily obtained 
from the amino compound by heating it with the acid 
chloride 2 or with the free acid 3 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 er 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 difficulty when less drastic methods 
are employed. 4 

In some cases an ester or an amide of the acid can be used 
for inserting the acyl group, 5 but in other cases the reaction 
takes a different course. 6 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 I 
OBtOEt 

Acylaminoanthraquinones can also be obtained by 
condensing a halogen anthraquinone with an acid amide, 7 
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 acylaminoanthraquinones 

1 Seer and Weitzenbock, M. 31, 371. 

2 By., D.R.P. 223,069 ; 225,232; 227,104; 227,398; 248,289. 

3 By., D.R.P. 210,019; 212,436; 216,980; 223,069; 223,510; 
224,808 ; 226,940. 

4 B.A.S.F., D.R.P. 211,958. 

5 By., D.R.P. 210,019 ; 212,436; 216,980. 

6 By., D.R.P. 270,579. 7 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. 1 The shades, however, are 
rather weak, and not particularly fast to light, so that the 
substances have but little technical interest. 

Of the acylaminoanthraquinones derived from dibasic 
fatty acids, compounds derived from oxalic, malonic, suc- 
cinic, adipic, maleic, malic, tartaric, and camphoric acids 
have been described. 2 These are all vat dyes, and are 
fairly 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 30 (succinyl- 
a-aminoanthraquinone), although it is probable that Algol 
Brilliant Violet R is succinyl diaminoanthrarufin. 

Of the aromatic acids which have been used for pre- 
paring acylaminoanthraquinones, benzoic, phthalic, tere- 
phthalic, salicylic and cinnamic have all been used, 4 and 
yellow and orange vat dyes have also been obtained by 
condensing the chloride of anthraquinone carboxylic acid 
with diamines such as benzidine, 5 and also with amino- 
anthraquinone. 6 They are, however, of no technical im- 
portance. ! Only the benzoyl derivatives have met with any 
wide technical application, and these are almost invariably 
prepared by means of the readily accessible benzoyl chloride. 
a-Salicylaminoanthraquinone has, however, been used to a 

1 B.A.S.F., D.R.P. 248,997. 

2 By., D.R.P. 210,019 ; 212,436 ; 216,980 ; 223,069 ; 226,940. For 
ureas, thioureas, urea chlorides and urethanes, see p. 219. 

3 By., D.R P. 223,510 ; 224,808. 

4 For references see p. 213. 

5 I3.A.S.F., D.R.P. 215,182 ; 236,442. 

6 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 : 

NHCOC 6 H 5 NHCOC 6 H 5 NHCOC e H 6 



OH 

Algol Yellow WG. Algol Pink R. 

NHCOC 6 H 5 



OCH 3 

Algol Scarlet G. 

NHCOC 6 H 5 



NHCOC 6 H 5 C 6 H 5 CONH 
Algol Red 50. * Algol Yellow R. 

HO NHCOC 6 H 5 HO NHCOC 6 H 5 



C 6 H 5 CONH 

Algol Red FF. 



C 6 H 5 CONH OH 

Algol Brilliant Violet 26. 



HO NHCOC 6 H 5 



HO OH 

Algol Violet B. 

The position and nature of substituent groups has a 
considerable effect on the colour of the benzoylaminoanthra- 
quinones. Thus when there is a benzoylamino group at i : 

1 Caledon Red 5G (Scottish Dyes Ltd.). 



216 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 hydroxy and methoxy group is seen by 
comparing Algol Pink R and Algol Scarlet G with Algol 
Yellow WO. 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 by com- 
paring the shades obtained from the following compounds : 

NHCOC 6 H 5 NHCOC 6 H 5 NHCOC 6 H 5 



NH 2 

Corinth. 



NHCH 3 

Blue. 



NHCOC 6 H 5 

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, very 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 liability 
to become reduced in the dyebath. 

Although the above remarks refer to the benzoyl amino- 
anthraquinones, they are equally applicable to other acyl- 
aminoanthraquinones, as will be seen by comparing the 
following succinyl derivatives : 

NHCOCH,CH,CONH NHCOCH 2 CH 2 CONH 



Yellow. 



OH HO 

Scarlet. 



THE AMINOANTHRAQUINONES 217 

NHCOCH 2 CH 2 CONH NHCOCH 2 CH 2 CONH 



OCH, 



CH.O 



NO, 



NO, 



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 influence 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 : 



NHCOC 6 H 5 



NHCOC 6 H 5 



CEUNH 



HO 



NHCOC 6 H 5 



N0 2 

Orange-red. 



Red. Yellow. 

NHCOCH 2 CH 2 CONH NHCOCH 2 CH 2 CONH 



NH. 



NH 2 NO 2 



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 



218 ANTHRACENE AND ANTHRAQUINONE 



reinforce one another. In connection with this it will be 
sufficient to give five examples : 

NHCOC 6 H 5 NHCOC 6 H 5 

NHCOC 6 H 5 



HCOC 6 H 5 

Orange. 
(Algol Brilliant Orange FR.) 

C 6 H 5 CONH NHCOC G H 5 



C 6 H 5 CONP 



NHCOC 6 H 5 



Bordeaux. 



HO NHCOC 6 H 5 



C 6 H 5 CONH NHCOC 6 H 5 

Red-violet. 



C 6 H 5 CONI 



OH 



Blue-violet. 
(Algol Brilliant Violet 2B.) 

HO NHCOC 6 H 5 



HO OH 

Red-violet. 
(Algol Violet B.) 

One or two acylamino dianthraquinonyls have been 
studied, e.g. 4.4'-dibenzoylamino-i.i'-dianthraquinonyl has 
been found to be a yellow vat dye, 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 

1 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 dilute acids, and 
can, therefore, be used as acid wool dyes. 1 



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 j3-aminoanthraquinone the reaction takes 
place without the use of any condensing agent, but a urea 
can only be obtained from a-aminoanthraquinone 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 calculated amount 
of phosgene is allowed to react with it at 40-120. Anthra- 
quinone ^'so-cyanates do not seem to be formed directly by 
the action of phosgene on the amino compounds, although 
they are obtained hi good yield by heating the urea chloride 
in nitrobenzene solution. 4 

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, 5 although under less drastic conditions the 
urethane is produced. 6 The urea is also formed when 

1 By., D.R.P. 223,069. 2 M.L.B., D.R.P. 232,739. 

3 M.L.B., D.R.P. 238,550 ; 241,822. 4 M.L.B., D.R.P. 224,490. 
6 M.L.B., D.R.P. 242,292. c By., D.R.P. 167,410; 171,588. 



220 ANTHRACENE AND ANTHRAQUINONE 

j8-aminoanthraquinone is heated to 70 with urea in nitro- 
benzene solution. 1 

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 alkylamine or arylamine. 
By using ammonia a monoanthraquinonyl urea is obtained. 3 
The procedure can, of course, be inverted and the urethane 
condensed with j8-aminoanthraquinone. In this case ure- 
thane itself gives dianthraquinonyl urea, 4 whereas mixed 
aryl anthraquinonyl ureas are obtained from aryl urethanes. 5 
Mixed ureas can also be obtained by condensing an amino- 
anthraquinone with an aryl ^'so-cyanate, 6 or by condensing 
an anthraquinone-fl'so-cyanate with a primary or secondary 
aliphatic amine or a primary aromatic amine. 7 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 very easily 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, 9 or by sulphonating the anthraquinonyl urea, 10 
but are of but little interest. The ureas can also be halo- 
genated. 11 

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 sGN, and a more complex 



- 1V1 JU..D. 

2 M.L.B. 
3 M.L.B. 
5 M.L.B. 


j-A.tY.r-. 130,551 , 

D.R.P. 236,375 ; 
D.R.P. 236,978. 
D.R.P. 236,981. 


^JODJ- W- *-> wllll > .u. TI, *-^Si- 

236,978-9 ; 236,980 ; 236,983-4 ; 238,550. 
4 M.L.B., D.R.P. 238,552. 
6 M.L.B., D.R.P. 229,111. 


M.L.B. 
9 MLB 


D.R.P. 231,853. 
D.R.P. 236,084. 


8 Agfa, D.R.P. 281,010. 
10 M.L.B., D.R.P. 229,408. 



11 M.L.B., D.R.P. 240,192. 



THE AMINOANTHRAQUINONES 



221 



dye, Helindon Brown 2GN, is obtained by condensing two 
molecules of anthraquinone-j8-urea chloride with various 
diaminoanthraquinones : 



-NHCONH- 



Helindon Yellow 3 GN. 



-NHCONHC 14 H 6 O 2 NHCONH- 



Hclindon Brown 3GN. 



The urea chlorides condense readily with phenols and 
naphthols when boiled with these in some indifferent solvent 
such as xylene. 1 The products are yellow vat dyes, but 
are of no particular interest. They have the structure 
C U H 7 O 2 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 undergo a 
little-understood condensation when boiled with sodium 
acetate or sodium carbonate and some indifferent solvent, 
such as nitrobenzene. 3 The products are vat dyes, Helindon 
Orange GRN being obtained from anthraquinone-j8-urea 
chloride by this reaction. The same products are obtained 
from the ^'so-cyanates and from the dianthraquinonyl 
ureas themselves. 4 

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 chloride, 6 



1 M.L.B., D.R.P. 242,291. 
3 M.L.B., D.R.P. 232,135. 



2 M.L.B., D.R.P. 236,982. 
Loc. cit. 5 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 thiocarbonyl chloride on j8-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 by 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 confirmation 
from the fact that Bayer & Co. claim the production of 
orange-yellow vat dyes by the prolonged heating of jS- amino- 
anthraquinone with excess of thiocarbonyl chloride. 2 

The anthraquinonyl thioureas can also be obtained by 
heating the aminoanthraquinones with carbon bisulphide, 
best by using pyridine as a solvent, 3 or with sodium xanthate, 4 
and in addition also seem to be formed when aminoanthra- 
quinones are heated with perchlormethyl mercaptan in an 
indifferent solvent, such as nitrobenzene, with or without 
the addition of copper or copper salts ana basic substances. 6 
They can also be built up from the thioureas of the amino- 
benzoyl benzoic acids by closing the anthraquinone ring by 
means of sulphuric acid. 6 

As in the case of the formation of anthraquinonyl ureas 
by this method the ring closes very 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 aryl anthraquinonyl thioureas can be 
obtained by condensing the anthraquinonyl ^'so-thiocyanates 
with primary or secondary aliphatic amines or primary 
aromatic amines. 7 The reaction is lacilitated and a much 
purer product obtained if a condensing agent such as 
aluminium chloride is used. 8 

1 B.A.S.F., D.R.P. 246,086. 2 By., D.R.P. 256,900. 

3 By., D.R.P. 271,475. 4 G.E., D.R.P. 291,984. 

5 B.A.S.F., D.R.P. 234,922. 6 Agfa, D.R.P. 282,920. 

7 M.L.B., D.R.P. 229,111. 8 M.L.B., D.R.P, 254,744. 



THE AMINOANTHRAQUINONES 223 

If an anthraquinone aldehyde or an w-dibrommethyl 
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. 1 These are red vat d}^es, the correspond- 
ing oxygen compounds, obtained in the same way from 
urea, being yellow : 

C 14 H 7 2 .C : N.C.N : C.C U H 7 O 2 C 14 H 7 O 2 .C : N.C.N : C.C U H 7 O.> 

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- 
densing one molecule of benzotrichloride with two molecules 
-aminoanthraquinone : 



C 6 H 5 CC1 3 +2C 14 H 7 2 NH 2 -> C 6 H 6 C\ 

X NHC 14 H 7 2 

or by condensing j3-aminoanthraquinone simultaneously with 
carbon tetrachloride or other derivative of carbonic acid, 
such as chlorcarbonic ester, and an aromatic hydrocarbon 
such as naphthalene, diphenyl, etc., the condensation taking 
place in the presence of copper. 2 The reaction is an interest- 
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 by 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.R.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 by nitro 
groups. They are briefly discussed on p. 226. 

Primary aminoanthraquinones are much more stable 
than the majority of primary aromatic amines, and can often 
be nitrated without previoiisly protecting the amino group. 
Thus, j8-aminoanthraquinone when treated with the calcu- 
lated amount of nitric acid in concentrated sulphuric acid 
at 5 is converted into 2-amino-3-nitroanthraquinone. 1 
Here the o-j8 position is the only one readily available for 
nitration, and the further action of nitric acid leads to the 
formation of a nitramine. 2 When the amino group is in 
the a- position, however, both the ortho- and para- positions 
are readily nitrated. Thus, i.5-diaminoanthraquinone gives 
a tetranitro compound, the further nitration of this leading 
to nitramine formation. 3 

If the amino groups are protected by conversion into 
acyl amino groups, then the products obtained on nitration 
seem to depend very largely on the experimental conditions. 
By nitrating i-acetylaminoanthraquinone, and 1.5 and 1.8- 
diacetylamino anthraquinone, Eckert and Steiner 4 obtained 
nitro compounds 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. 5 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 para- 
position. 6 The nitration of 2-acetylaminoanthraquinone 
leads to 2-amino-i-nitroanthraquinone. 7 

The products obtained by the nitration of i.4-diacyl- 
aminoanthraquinone depend very largely on experimental 

1 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. 

4 M. 35, 1137. 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. 7 Ullmann and Medenwald, B. 46, 1798. 



THE AMINOANTHRAQUINONES 225 

conditions, the action of mixtures of nitric and sulphuric 
acids leading to the heteronuclear nitration with the pro- 
duction of both i.4-diacylamino-5- and 8-nitroanthra- 
quinone, 1 whereas the action of nitric acid and an indifferent 
solvent such as nitrobenzene leads to homonuclear nitration, 
the product being i.4-diacylamino-2-nitroanthraquinone. 2 
If i.4-diaminoanthraquinone is heated to 50-60 with 
oleum containing 45 per cent, of free sulphur trioxide a 
sulphonamide, Ci 4 H 6 O 2 (N:SO 2 )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 chlorcarbonic ester or by the action 
of carbonyl chloride followed by treatment of the result- 
ing urea chloride 3 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 taking the ortho- and para- positions to the 
amino groups. The urethane of j8-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 
acylamino compounds. The diurethanes of the hetero- 
nuclear j8j8-diaminoanthraquinones behave in the same way. 
Ullmann and Medenwald 5 have also studied the nitration 
of the urethane of 2-aminoanthraquinone and find that the 

1 By., D.R.P. 268,984. 

2 By., D.R.P. 267,445. Cf. M.L.B., D.R.P. 254,185. 

3 See p. 219. 

4 By., D.R.P. 167,410; 171,588. * B. 48, 1798. 

15 



226 ANTHRACENE AND ANTHRAQUINONE 

chief product is 2-amino-i-nitroanthraquinone, but that 
about 20 per cent, of 2-amino-3-nitroanthraquinone 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 may 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. 1 The oxaminic acids are 
said to be particularly 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. 2 

THE NITRAMINES. When a primary or secondary 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. 3 Thus, 
if jS- aminoanthraquinone is nitrated first 2-amino-3-nitro- 
anthraquinone is formed. 4 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-amino-24-dinitro- 
anthraquinone is formed, and then i-nitramino-2.4-dinitro- 
anthraquinone. The behaviour of i.5-diaminoanthra- 
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. 

4 Scholl and Eberle, B. 37, 4434. M. 32, 1037. Ullmann and Meden- 
wald, B. 46, 1798. 



THE AMINOANTHRAQUINONES 227 

no readily nitrated ring position is available so that nitration 
leads at once to the dinitramine. 

The sodium salts of the nitramines can be obtained by the 
action of sodium hypochlorite on the anthraquinone diazonium 
sulphates, and the free nitramines can be liberated from 
these salts by the action of weak acids such as carbonic or 
acetic acid. 1 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 anthraquinone j8-nitra- 
mines can be obtained, however, by oxidising the iso- 
diazotates with hypochlorites. 3 

The nitramines are rather unstable compounds which are 
more or less explosive but can, as a rule, be nitrated, 4 e.g. by 
the action of fuming nitric acid at o. Owing to their 
instability they act as nitrating agents towards easily 
nitratable substances, 5 such as phenol, benzene, etc., and 
frequently undergo self-nitration when treated with con- 
centrated sulphuric acid. 6 During this self-nitration the 
nitro group takes the ortho- position to the amino group, 
i-nitraminoanthraquinone passing into i-amino-2-nitro- 
anthraquinone, whereas when the nitramine is treated with 
nitric acid the entering nitro group takes the para- position, 
i-nitraminoanthraquinone forming i-nitramino-4-nitro- 
anthr aquinone . 1 

The nitramines 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 dye mordanted or unmordanted wool brown. 8 



HAI^OGENATION 

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. 2 Q. EM D.R.P. 262,076. 

3 G.E., D.R.P. 259,432. * M.L.B., D.R.P. 156,803. 

5 B.A.S.F., D.R.P. 148,109. G.E., D.R.P. 259,432. 

7 G.E., P,R,P, 156,803. 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 
certain 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 readily. 1 Thus 
a-aminoanthraquinone when brominated under suitable con- 
ditions yields N-brom-a-aminoanthraquinone, Ci 4 H 7 O 2 NHBr, 
and i.5-diaminoanthraquinone' gives an octachlor com- 
pound in which some of the chlorine atoms are attached 
to the nitrogen atoms. 2 Scholl and Berblinger 3 have also 
found that the bromination of i.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 may 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. 4 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- compounds can also sometimes be obtained by 
the action of hypochlorous acid, i-acetylaminoanthraquinone 
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 6 that aminoanthra- 
quinones are very smoothly chlorinated by sulphuryl 

1 By., D.R.P. 104,901 ; 115,048; 126,392-3. 
2 B.A.S.F., D.R.P. 125,094. 8 B. 37, 4180. 

By., D.R.P. 146,691. 6 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-aminoanthraquinone is brominated in glacial 
acetic acid solution the first bromine atoms enter the ortho- 
position, 1 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, 3 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. 4 The exhaustive 
chlorination of a-aminoanthraquinone has recently been 
studied by Friess and Auffenberg, 5 who find that the amino 
group is split out and then the anthraquinone ring opened, 
the products being 2.34.5.6-pentachlorbenzophenone and 
finally phthalic acid and pentachlorphenol. 

The behaviour of i.5-diaminoanthraquinone when bromi- 
nated is analogous to that of a-aminoanthraquinone, the 
2.4.6.8-tetrabrom derivative being formed. 6 On chlorination 
an octachlor compound is formed as mentioned on p. 228, 
and also a hexachlordihydroxyanthraquinone and octachlor- 
anthraquinone. 7 It is curious to notice that both dibrom* 
and tetrabrom-i-5-diaminoanthraquinone give tetra-acetyl 
derivatives, although the unbrominated product will give 
only a diacetyl compound. 8 

Probably owing to the instability of the N-halogen 
compounds the presence of a primary amino group in the 
- position greatly facilitates the entrance of halogen atoms 
into the anthraquinone ring. The halogenation of jS-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 monohalogen 

1 By., D.R.P. 160,169. 

Ullmann, B. 49, 2165. B.A.S.F., D.R.P. 199,758. 
By., D.R.P. 164,791. 

Compare the behaviour of the nitramines (p. 227). 
B. 53, 23. 

Scholl and Berblinger, B. 37, 4180. B.A.S.F., D.R.P. 137,783. 
B.A.S.F., D.R.P. 125,094 ; 137,074. 
Scholl and Berblinger, B. 37, 4180. Romer, B. 16, 366. 



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- 
i.3-dihalogenanthraquinone and unchanged 2-aminoanthra- 
quinone. 1 If, however, 2-aminoanthraquinone is treated 
with bromine dissolved in an organic solvent, such as glacial 
acetic acid or nitrobenzene, it is possible, under 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 by 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. 3 

The acetyl derivative of 2-aminoanthraquinone is much 
less readily halogenated than the primary compound itself, 
and by chlorinating 2-acetaminoanthraquinone a monochlor 
compound can be obtained. 4 In this, however, the halogen 
atom is in the a-position, as Junghaus has found that it 
gives i.2-diaminoanthraquinone when the chlorine atom is 
replaced by an amino group by the sulphonamide process. 5 
It is interesting to observe that whereas a primary amino 
group in the jS- 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 Scholl, B. 40, 1701. Junghaus, A. 399, 316. D.R.P. 273,809. M.L.B., 
D.R.P. 253,683. 

2 Junghaus, loc. cit. 3 B.A.S.F., D.R.P. 261,270-1. 
4 B.A.S.F., D.R.P. 199.758- 6 A. 399, 316. 



THE ANIMOANTHRAQUINONES 231 

the 8-halogen compound must be regarded as the more 
stable, as the halogen atom in all homonuclear halogen 
derivatives of both a- and j8- aminoanthraquinone wanders 
to the /?- position which is contiguous to the amino group if 
this position is unoccupied. 1 This wandering of the halogen 
atom is brought about by heating the substance alone or 
with sulphuric or phosphoric acids. If the j8- position con- 
tiguous to the amino group is occupied by a sulphonic 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-amino-i-bromanthraquinone-3-sulphonic acid, for 
example, passing into 2-amino-3-bromanthraquinone when 
boiled with sulphuric acid of 80 per cent, strength. 2 This 
wandering of the halogen atom can often be avoided by 
carrying out the hydrolysis 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 mercury. 3 

When an aminoanthraquinone sulphonic acid is haloge- 
nated the halogen can enter the molecule either by the 
replacement of hydrogen or by the replacement of the 
sulphonic acid groups. Which reaction takes place depends 
very 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. 4 

THE DIANTHRAQUINONYI.AMINES 

Although dianthraquinonylarnines can be obtained by 
heating a-aminoanthraquinone or j8-aminoanthraquinone 
with a-nitroanthraquinone 5 or with an anthraquinone-a- or 
-j8-sulphonic acid, 6 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. 

3 B.A.S.F., D.R.P. 265,727 ; 266,563. 

4 Ullmann and Medenwald, B. 46, 1798. B.A.S.F., D.R.P. 113,292 ; 
114,840; 128,196; 138,134; 138,166. 

5 M.L.B., D.R.P. 201, 327. 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. 1 By 
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. $8-Dianthra- 
quinonylamines can also be obtained by condensing anthra- 
quinone-j8-diazonium salts with ammonia and then heating 
the resulting product with a solvent of high boiling point, 
with or without a condensing agent. 2 

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 i . i '-dianthraquinonylamine. 

If one group is in the ft- position the reaction takes place 
with rather greater difficulty, and in this case it is best to 
condense the /?-halogen compound with the a-amine. 3 Thus, 
j8-chloranthraquinone and a-aminoanthraquinone yield 1.2' 
dianthraquinonylamine rather more readily than do a-chlor- 
anthraquinone and j8- aminoanthraquinone. When both 

1 Seer, M. 32, 162. Eckert, M. 35, 762. Eckert and Steiner, M. 35, 
1129. Ullmann, 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 trianthraqumonyl- 
amines, a nomenclature which would suggest that three anthraquinonyl 
groups are attached to the same nitrogen atom (cf. triphenylamine). 

* M.L.B., D.R.P. 308,666. 3 By., D.R.P. 174,699. 



THE DIANTHRAQUINONYLAMINES 233 

the halogen atom and the amino group are in the jS- position, 
e.g. /J-chloranthraquinone and j8-aminoanthraquinone, the re- 
action only takes place with great difficulty, 1 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 hydroxyl 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, 2 or by the 
replacement of halogen atoms or nitro groups by heating 
with alcoholic caustic potash. 3 

On nitration i.i '-dianthraquinonylamine gives a dinitro 
compound in which the nitro groups must be in the para- 
positions to the imino group, as the same compound is obtained 
by condensing i-chlor-4-nitroanthraquinone with i-amino- 
4-nitroanthraquinone. Further nitration leads to a tetra- 
nitro, and possibly also to a pentanitro, compound. 4 

The nitration of 1.2 '-dianthraquinonylamine gives first 
4. 1 '-dinitro-i. 2 '-dianthraquinonylamine 5 and then 2.4.1'- 
trinitro-i .2'-dianthraquinonylamine. 6 

Reduction of 4.4'-dinitro-i.i '-dianthraquinonylamine 
with sodium sulphide gives the corresponding diamino 
compound, 7 but reduction with boiling sodium stannite 
leads to replacement of the nitro groups by hydroxyl groups, 
the product being 4.4'-dihydroxy-i.i '-dianthraquinonyl- 
amine. 8 The tetranitro compound on reduction with alkaline 
stannite also loses two nitro groups and forms 2.2'-diamino- 
4.4'- dihy droxy - 1 . i ' - dianthraquinonylamine . 9 Reduction 
with sodium sulphide, however, appears to lead first to the 

1 Eckert and Steiner, M. 35, 1129. 

3 M.L.B., D.R.P. 249,938. See also p. 251 et seq. 

3 By., D.R.P. 232,262. Cf. Eckert and Steiner, M. 35, 1129. 

4 Eckert and Steiner, loc. cit. By., D.R.P. 213,501. M.L.B., D.R.P. 
254,186. 

5 Eckert and Steiner, loc. cit. B.A.S.F., D.R.P. 186,465. 

6 Eckert and Steiner, loc. cit. By., D.R.P. 178,129. 

7 M.L.B., D.R.P. 255,822. 

8 Eckert and Steiner, M. 35, 1129. Cf. By., D.R.P. 178,129. 

9 Eckert and Steiner, loc. cit. 



234 ANTHRACENE AND ANTHRAQUINONE 

tetramino compound, which at once loses a molecule of 
ammonia and passes into diaminoindantbrone : l 



NH HN 



v 
SNH/ 



NH 2 H 2 N NH 2 H 2 N 

The reduction of 4.i / -dinitro-i.2 / -dianthraquinonylamine 
by sodium stannite also leads to the replacement of the nitro 
groups by hydroxyl groups (4.i'-dihydroxy-i.2'-dianthra- 
quinonylamine), although the diamino 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. 3 

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. 4 

The dianthraquinonylamines when treated with con- 
densing agents such as caustic alkali, 5 aluminium chloride, 6 or 
zinc chloride, 7 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. 8 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 

1 Eckert and Steiner, loc. cit. 

2 Ibid. 3 Ibid. * By., D.R.P. 220,581. 
5 M.L.B., D.R.P. 208,969 ; 251,021. By., D.R.P. 230,407. 

G M.L.B., D.R.P. 240,080 ; 262,788. 

7 M.L.B., D.R.P. 251,350. 8 M.L.B., D.R.P. 267,522 ; 267,833. 



THE DIANTHRAQUINONYLAMINES 235 



the name Algol Orange R, and Algol Red B is also a dianthra- 
quinonylamine although containing also a pyridone ring. 1 
The introduction of a benzoylamino group, however, confers 
tinctorial properties, 2 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 
anthraquinonylaminodianthraquinonylamines are usually 
powerful dyes 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 : 



-NH- 



__NH 



Indanthrene Bordeaux B. 



NH- 



_NH_ 



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 interesting 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, 3 
but the subject is a very 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. 2 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 AMINOHYDROX Y- 
ANTHRAQUINONES AND ETHERS 

I. THE HYDROXY COMPOUNDS 

THE hydroxyanthraquinones 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 Cyanine Green. 
The actual constitution of many of the hydroxyl com- 
pounds is open to some doubt, as although hydroxyl groups 
in any position can be readily acylated, hydroxyl groups when 
in the ortho- position to a carbonyl group cannot be alkylated, 
or can only be alkylated with the utmost difficulty, by 
the usual means, e.g. by treatment with dimethyl sulphate 
or methyl iodide and caustic potash. Hydroxyl groups in 
the /J- position, however, behave in a perfectly normal 
manner towards alkylating agents. The abnormal behaviour 
of hydroxyl 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 hydroxyanthracenes, the a-anthrols, can 
be alkylated without any trouble. It has been suggested 
that the a-hydroxyanthraquinones really have the tautomeric 
o-quinonoid structure : 

CO OH 




and this would explain the difficulty in alkylation. 

Although, as stated above, hydroxyl groups both in the 

236 



THE HYDROXY COMPOUNDS 237 

a- and j8- position can be acylated with ease, groups in the 
j3- position are more easily attacked than those in the ex- 
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 l 
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 necessary to 
acetylate the /J-hydroxyl groups. Only the calculated amount 
of acetic anhydride must be used, as otherwise all thehydroxyl 
groups will be attacked, although those in the a-position react 
only slowly with acetic anhydride 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 hydroxyl 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 very large 
number of different hydroxy compounds according to the 
conditions employed. As has been already stated, hydroxy- 
anthraquinones can often be built up from phenolic ethers 
by the phthalic acid synthesis, and in many cases the reduc- 
tion of the higher hydroxylated anthraquinones leads to 
the loss of hydroxyl groups. The oxidation of the hydroxy 
anthracenes, or rather of their acetyl derivatives or methyl 
ethers, also leads to hydroxyanthraquinones, although the 
method is of little importance except as a means of identify- 
ing the anthrols. 2 

A great many of the hydroxyanthraquinones have 
received special names, and for ease of reference these have 
been tabulated together with the melting point 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. 

1 B. 53, 481. 

8 Liebermann and Boeck, B. 11, 1616 ; 12, 185. Liebermann and 
Hermann, B. 12, 259. Dienel, B, 38, 2862. 



23$ 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 


289-290 


184 


1-3- 


( Purpuroxanthin. Xantho- "1 
\ purpurin / 


262-263 


184 


4- 


Quinizarin 


194 


200 


5- 


Anthrarufin 


280 


244-245 


.6- 


i 


276 


205-206 


7- 





291-293 


199 


.8- 


Chrysazin 


191 


227232 


2-3- 


Hystazarin 


f Decomp. "1 
[ above 260 j 


206-207 


2.6- 


Anthraflavic acid 


Above 330 


228 


2.7- 


iso-Anthraflavic acid 


Above 330 


About 195 


1.2.3- 


( Anthragallol, \ 
\ Anthragallic acid / 


310 


181-182 


.2.4- 


Purpurin 


256 


192-193 


.2.5- 


Hydroxyanthrarufin * 


278 


228 


.2.6- 


Flavopurpurin 


Above 330 


195-196 


.2.7- 


Anthrapurpurin. iso-Purpurin 


369 


224 


.2.8- 


Hydroxychrysazin ~ 


239-240 


219 


4-5- 


3 








.4.6- 


. 4 


256 





.4.8- 


5 







.2.3.4- 








205 


.2.4.6- 


Hydroxyflavopurpurin 


202 




.2.4.7- 


Hydroxyanthrapurpurin 





214 


.2.4.8- 











.2.5.6- 


Rufiopin 6 








.2.5.8- 


Quinalizarin. Alizarin Bordeaux 


Above 275 


201 


.2.7.8- 


7 








3-5-7- 


Anthrachrysazin 


Above 360 


253 






.fO 


J Decomp. 


.4.5.8- 




240 


(about 250 


.?.?.8- 


8 


217 


195 


? ? 8- 


9 


292 


238-240 


.2.4.?- 


Hydroxypurpurin 10 


Above 290 


Above 240 



1 Frobenius and Hepp, B. 40, 1048, 

2 Wed., D.R.P. 205,965 ; 210,863. 

3 By., D.R.P. 161,026; 163,041. 

4 Dimroth and Fick, A. 411, 315. 



Wed., D.R.P. 202,398. 



states 



Crossley, Am. Soc. 40, 404, 
that the substance does not melt below 300. 

5 R. E. Schmidt, Bull. Soc. Ind. Mull. 84, 409. 

6 Liebermann and Chojnacki, A. 162, 323 (from hemipinic or opianic 
acid and cone. H>SO 4 ). By., D.R.P. 103,988 (from anthraruftn). 

7 By., D.R.P. 103,988. See also note 9. 

8 Schrobsdorf, B. 36, 2936. 

9 Wolbling, B. 36, 2941. Probably identical with i.2.7.8-tetrahydroxy- 
anthraquinone. 

1 Diehl, B. 11, 185. Gattermann, J. pr. [2] 43, 251. 



THE HYDROXY COMPOUNDS 

HYDROXYANTHRAQUINONES continued. 



239 



Position 
of Hydroxyl. 


Usual name. 


M.p. 


Acetyl deriva- 
tive m.p. 


1.2.3.5017- 
1.2.3.5017- 
1.2.3.5.7- 


a-Hydroxyanthragallol 1 
/?-Hydroxyanthragallol l 
Dihydroxyanthragallol 


Above 350 
Above 380 
Above 360 


207-209 
189 
229 


1.2.3.6.7- 


2 








1.2.4.5.8- 


Alizarin Cyanine R 








1.2.3.5.6.7- 


Rufigallic acid 





282-283* 


1.2.4.5.6.8- 


Anthracene Blue WR 








1.2.4.5.7.8- 


, 4 














( Decomp. 


1.2.3.4.5.6.7.8- 






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 alkali 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 
hydroxylation 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 j3- position without simultaneous oxidation 
taking place, although the yields are usually poor. Thus, 
Graebe and lyiebermann 6 found j3-hydroxyanthraquinone 
in crude alizarin, and I/iebermann and Simon 7 were able to 
obtain the same substance from anthraquinone-j8-sulphonic 

1 From gallic acid and m-hydroxybenzoic acid. Noah, A. 241, 270. 

* Bentley and Weizmann, Soc. 93, 438. (Tetramethyl ether.) 
3 R. E. Schmidt, J. pr. [2] 43, 242. Gattermann, ibid. 250. 

* By., D.R.P. 103,988. 5 Georgievics, 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 
/so-anthraflavic acid which Romer and Schunck l 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 fc'so-anthraflavic 
acid from anthraquinone-2.7-disulphonic acid. Since then 
many other cases have been discovered in which replacement 
of sulphonic acid groups takes place in the alkali melt 
without simultaneous oxidation, 3 but as a rule it is difficult 
to avoid oxidation taking place unless one of the modified 
methods described below is employed. It should be noted 
that the above remarks apply chiefly to anthraquinone sul- 
phonic acids in which the sulphonic acid group is in the /3- 
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 hydroxy anthraquinone. 

Sulphonic acid groups in the a- position are somewhat 
more reactive than similar groups in the ft- 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 erythro- 
hydroxy anthraquinone when treated in this way. 4 They 
can also often be replaced by the use of caustic alkali, foi 
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 comparatively low 
temperature, 5 and anthraquinone-a-sulphonic acids are 
often fairly readily 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. z B. 15, 1040. 

3 Wolbling, B. 36, 3941- By., 103,686 ; 103,988; 178,631. Cf. also 
Lifschutz, B. 17, 901. Frobenius and Hepp, B. 40, 1048. 

4 By., D.R.P. 197,649. M.L.B., D.R.P. 149,781, 
6 By., D.R.P. 172,642. 



THE HYDROXY COMPOUNDS 241 

quinone molecule can be replaced by hydroxyl groups by the 
use of aqueous solutions of calcium or barium hydroxide 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 hydroxyl 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 affecting the amino group, e.g. i-amino- 
anthraquinone 5- and -8- sulphonic acids give respectively 
i-amino-5- and -8- hydroxy anthraquinone. 2 As the sodium 
or potassium salt of the sulphonic acid is almost invariably 
used, hydroxylation by means of alkali earth hydroxide 
leads to the liberation of sodium or potassium sulphite : 

2C 1 4H 7 2 S0 3 Na+Ca(OH) 2 =2C u H 7 2 .OH+CaS03+Na 2 SO3 

and it is advisable to destroy this or to render it harmless 
as rapidly 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. 3 

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, 4 e.g. in the cases of anthraquinone-2.6- 
and -2.7-disulphonic acids. From alizarin-5-sulphonic acid, 
hydroxyanthrarufin has been obtained, alizarin-8-sulphonic 
acid giving hydroxy chrysazin. 5 Sulphonic acid groups can 
also be replaced by heating the sulphonic acid with methyl 
alcoholic caustic potash, but in this case a methoxy and not 
a hydroxy 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. By., D.R.P. 172,642 ; 197,607. M.L.B., 
D.R.P. 106,505 ; 145,188. 

2 M.L.B., D.R.P. 148,875. 

3 Wed., D.R.P. 195,874. 

4 M.L.B., D.R.P. 106,505. 

5 Wed., 170,329 ; 202,398 ; 210,863. Cf. Frobenius 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 ammo 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 groups, e.g. 1.5- 
and i.8-dinitroanthraquinone give respectively anthrarutln 
and chrysazin, but the yields are usually very poor. 1 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 erythrohydroxyanthraquinone 
and 1.5- and i.8-dinitroanthraquinone giving respectively 
anthrarufin and chrysazin. 4 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 /?- position, but in ah 1 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 hydroxyl 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. 

2 Kaufler, B. 37, 63. Eckert, M. 35, 290. M.L.B., D.R.P. 73,860; 
75>54; 77 8 i8; 167,699. 

3 See p. 287. 4 By., D.R.P. 145, 238. 5 Nienhaus, B. 8, 778. 



THE HYDROXY COMPOUNDS 243 

place, and 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. 1 

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 difficult to co-ordinate the various claims. 

It appears that the nitro group is paiticularly 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 of 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 I,iebermann, 3 

1 B.A.S.F., D.R.P. 76,941. 2 By., D.R.P. 125,579. 

3 B. 3, 905 ; 4, 231. 



244 ANTHRACENE AND ANTHRAQUINONE 

Bottger and Petersen, 1 and lyiebermann and Hagen. 2 These 
last treated the product with nitrous acid and obtained 
erythrohydroxyanthraquinone and a dihydroxyanthra- 
quinone which they regarded as xanthopurpurin. Their 
analyses agreed with the figures required by the formula 
C28Hi 8 O 7 N 2 , 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 formulae : 

(OS0 3 H r (S0 8 Hi 

C 14 H 5 O 2 OH and C 14 H 4 O 2 OH 2 O 

(N0 2 L IN0 2 J 

but he was unable to obtain them in a state of purity ; and 
L,ifschiitz, 4 on repeating Claus' experiments, was unable to 
obtain either. 

L,ifschiitz 5 studied the action on concentrated sulphuric 
acidoni.5-dinitroanthraquinone and isolated four substances. 
All these when diazotised and reduced gave dihydroxy- 
anthraquinones, such as anthrarufin, and lyifschiitz regarded 
them as anhydrides (ethers) of aminohydroxyanthraquinones, 
e.g. [C 14 H 4 O 2 (OH)(NH 2 ) 2 ] 2 O. 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 anhydride at 50 a molecular rearrangement takes 
place and i -hy droxy-4-nitroso-8-nitroanthraquinone is formed, 
i.8-dinitroanthraquinone and also, apparently, i.8-dinitro- 
naphthalene reacting in the same way. These ^-nitroso- 
phenols are, of course, tautomeric with the quinone mon- 



1 A. 180, 155 ; 166, 152. B. 4, 229, 301. * 
3 B. 15, 1521. * B. 17, 902. 6 
s By., D.R.P. 104,282 ; 105,567. 



2 B. 15, 1801. 
B. 17, 891. 



THE HYDROXY COMPOUNDS 



245 



oximes so that hydroxylation can take place by the addition 
of the elements of water, subsequent loss of water leading 
to the formation of a quinoneimide : 



NO 



HONO 2 9 N 2 HO NO 2 



NO 



NO, 



NO 



HON 



HO 
HONH 



HO 



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 

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 i.5-dinitroanthraquinone is 1.2.4. 5.6. 8-hexa- 
hydroxy 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 hexahydroxy anthraquinone, 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, 1 
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 hexahydroxyanthra- 
quinone by concentrated sulphuric acid or oleum is preceded 
by 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 hydroxylamine 
groups, and then immediate rearrangement of these hydroxyl- 
amine compounds to ^>-hydroxyamines : 3 

N0 2 HONH NH 2 OH 



H 



NO 



HNOH HO NH 2 



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. 4 

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, oni.5-dinitroanthraquinone is 1.2.4.5.6.8- 
hexahydroxyanthraquinone disulphonic acid, a water- 
soluble product used to some extent as a mordant dye under 
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. 

2 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. 

3 R. E. Schmidt and Gattermann, B. 29, 2934. B y- D.R.P. 81,694. 
* R, E, Schmidt and Gattermann, B. 29, 2934. B y- D.R.P. 119,229, 



THE HYDROXY COMPOUNDS 247 

Hydrolysis, e.g. by heating with concentrated sulphuric 
acid, has the effect of removing the sulphonic groups aiid 
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 polyhydroxyanthraquinones 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- 
rufin, tetranitrochrysazin, nitroalizarin, nitroflavopurpurin, 
nitroanthrapurpurin, etc., but without results of any 
particular interest. 1 

REPLACEMENT OF HALOGEN ATOMS. Halogen atoms 
when attached to the anthraquinone nucleus are not easily 
replaced by hydroxyl groups by the action of alkali, although 
the first synthesis of alizarin was effected by Graebe and 
Iviebermann 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 hydroxyl compound is obtained, 3 although, of 
course, the alkyl group can be removed by subsequent 
hydrolysis, and according to O. Fischer and Sapper 4 this 
is generally the most satisfactory method of replacing halogen 
atoms by hydroxyl groups. In some cases, however, 
alcoholic alkali can be employed for replacing halogen atoms 
directly by hydroxyl groups, and Decker and I/aube 5 have 
found that when i-chIor-2-methoxyanthraquinone is heated 
with methyl alcoholic caustic potash a mixture of alizarin 
dimethyl ether and alizarin j3-monomethyl ether is obtained. 
The use of solutions of caustic potash in ethyl alcohol gave 
very similar results, viz. a, mixture of alizarin methyl ethyl 
ether and alizarin /?-monomethyl ether. Schrobsdorf 6 
has obtained a tetrahydroxy compound from dibromchrys- 
azin by fusing it with caustic potash, and this tetrahydroxy 

1 By., D.R.P. 101,486; 119,229. 

2 B. 2, 14, 332, 505. Mon. Sci. 1869, 384. 

3 See p. 287. 4 J. pr . [2] 83, 206. 
6 B. 39, ii2. B. 86,2936. 



248 ANTHRACENE AND ANTHRAQUINONE 

compound is not identical with that obtained by Wolbling 1 
from chrysazin disulphonic acid, as it melts at 217 and its 
acetyl 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 
hydroxyl 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-hydroxy-2.4-dichloranthraquinone 
gives 2-chlorquinizarin. 

Although halogen atoms are only replaced by hydroxyl 
groups with difficulty under 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 compound 
(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 4 had previously obtained 1.4-5.8-tetra- 
hydroxyanthraquinone by heating 4.8-dichlorquinizarin with 
water and a trace of copper at 250. 

Halogen atoms when in the a- position can sometimes be 
replaced by hydroxyl 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 i.4-dichloranthraquinone or i-hydroxy-4-chlor anthra- 
quinone, 5 and Ullmann 6 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 hydroxyl groups, O. Fischer and Rebsa- 
men 1 having found that i-methyl-4-chloranthraquinone is 

J B. 36, 2941. * B. 53, 833. Cf. By., D.R.P. 203,083. 

3 B. 47, 1210. B. 45, 1361. " 5 By., D.R.P. 203,083. 

B. 52, 2 1 10. 7 B. 47, 461. 



THE HYDROXY COMPOUNDS 249 

converted into i-methyl-4-hydroxynitroanthraquinone under 
the influence of nitric acid and boric acid, whereas without 
boric acid a methyl dihydroxynitroanthraquinone 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 unlikely that the nitro group is 
situated in the side chain. 

In the case of the phthalic acid synthesis, when halogen 
atoms are present in the benzoyl benzoic acid there is a 
possibility of their being replaced by hydroxyl groups during 
the closing of the anthraquinone ring, e.g. dichlordihydroxy- 
benzoyl-benzoic acid when heated with oleum and boric acid 
gives chlorpurpurin. 1 

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. 3 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, 4 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 
compound and the replacement of the amino group in one 

1 Mettler, B. 45, 801. 

2 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. 

4 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. 1 
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 /2-nitro (or amino) compounds, as 
Simon 2 has found that 2-hydroxy-i.3-dinitroanthraquinone 
gives anthragallol when reduced in boiling alkaline solution. 
Amino groups can also often be replaced by hydroxyl 
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-aminohydroxyanthraquinone, 1.4- 
hydroxynitroanthraquinone or i.4-diamino anthraquinone 
by stannous chloride and hydrochloric acid. 3 

It must be borne in mind, however, that the reduction 
of the cyclic carbonyl group also loosens other groups 
attached to the anthraquinone ring and these may be 
simultaneously split off. Thus, in the above reactions 
i.4-aminoalkoxyanthraquinone and i.4-alkoxynitroanthra- 
quinone are dealkylated on reduction and yield quinizarin 
and not quinizarin monoalkyl ether. Alkoxy 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. 4 The production of 
hydroxyanthraquinones by the reduction of nitroanthra- 
quinones in concentrated sulphuric acid or oleum is usually 
accompanied by simultaneous hydroxylation, the reaction 
being due to the production of hydroxylamine 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 by halogen 
also takes place, e.g. 1.5- and i.8-diamino anthraquinone 

1 M.L.B., D.R.P. 75,490. 2 D.R.P. 119,755. 

8 M.L.B., D.R.P. 148,792 ; 207,668. * M.L.B., D.R.P. 183,332. 
5 See p. 244. 



THE HYDROXY COMPOUNDS 251 

give a mixture of hexachloranthrarurin, hexachlorchrysazin, 
and octachlor anthraquinone. 1 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 
hydroxyl, the product being anthragallol ; and other j3-amino- 
hydroxyanthraquinones behave in the same way. 2 

DIRECT OXIDATION 

Anthraquinone differs from other aromatic compounds 
in the great ease with which hydroxyl 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 hydroxyanthra- 
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 very great majority of the 
work having only been published in the form of patent 
specifications. Consequently there is little or no data on 
which any theory of the actual mechanism of the change can 
be based, and, indeed, it is probable that the actual mechanism 
depends in some degree on the oxidising agent used. 3 

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 hydroxyanthraquinol. 
The anthraquinols are well-known compounds and are 
extremely readily oxidised to the corresponding anthra- 
quinone, in this case the hydroxyanthraquinone. On this 

1 B.A.S.F., D.R.P. 125,094 ; 137,074. 

2 By., D.R.P. 126,015. B.A.S.F., D.R.P. 126,603. 

3 Cf. Bucherer, " Lehrbuch der Farbenchemie " (1914), pp. 327-328. 



252 ANTHRACENE AND ANTHRAQUINONE 

basis the formation of a hydroxy anthraquinone would take 
place in successive stages thus : 

H OH 




Further hydroxylation might then take place in exactly 
the same way, or through the production of a compound of 
quinonoid structure by the wandering of the hydroxyl 
hydrogen atom : 

OH ? . W CO OH 






CO CO CO 



It should be noted that when hydroxylation is brought 
about without the use of an oxidising agent, e.g. when 
anthraquinone-j8-sulphonic acid is fused with caustic soda 
without the addition of a nitrate or chlorate, the hydroxyl 
compound is obtained as its reduction product. 

Hydroxyl groups can be introduced into the anthra- 
quinone molecule by 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 by this means that 
alizarin is manufactured. 

AI^KAUNE SOLUTION. As stated on p. 239, when an 
anthraquinone-^S-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 hydroxy compound 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 satisfactory yield of the hydroxyanthra- 
quinone it is usual to carry out the alkali melt in the presence 
of an oxidising agent such as air or an alkali nitrate or chlorate, 
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 
hydroxylation, as further hydroxyl groups can be introduced 
into the hydroxyanthraquinones themselves by fusion with 
caustic alkali and an oxidising agent. Thus, Schunck and 
Romer 1 obtained flavopurpurin and anthrapurpurin by 
fusing anthraflavic acid and fcso-anthraflavic acid with 
caustic potash, and more recently several patents have been 
granted for improved methods of carrying out these re- 
actions. 2 Anthrarufm and chrysazin are also readily con- 
verted into trihydroxy compounds (hydroxyanthrarufin and 
hydroxychrysazin) by heating with caustic alkali 3 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 dyestuff being obtained almost 
universally by fusing the sodium salt of anthraquinone-/?-sul- 
phonic acid with caustic soda and sodium chlorate. 4 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 flavopurpurin and anthrapurpurin, derived from the 
disulphonic acid present as an impurity in the technical 

1 B. 9, 678. 

2 Wed., D.R.P. 194,955. By., D.R.P. 205,097 ; 223,103. 

3 M.L.B., D.R.P. 195,028 ; 196,980. 

4 For references to the literature dealing with the earlier history of 
alizarin, see Schultz, " Chemie des Steinkohlenteers," vol. ii. pp. 250-262, 
and Auerbach, "Das Anthracen." 

8 For technical details see Ullmann, " Enzyklopadie der technischen 
Chemie." 



254 ANTHRACENE AND ANTHRAQUINONE 

monosulphonic acid, and purpurin, derived from alizarin 
by 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 different 
brands. 1 

Another method 2 of carrying 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 j8-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 yield 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 hydroxyl 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." 2 B.A.S.F., D.R.P. 287,270. 

3 By., D.R.P. 50,164 ; 50,708. 



THE HYDROXY COMPOUNDS 255 

seems well adapted to its manufacture. 1 The alkaline oxida- 
tion of anthraquinone under other conditions can lead to 
various hydroxyanthraquinones, 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 j8-hydroxyanthraquinone, 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 hydroxyanthraquinone 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 SOLUTION. The preparation of hydroxyanthra- 
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, nearly 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 an}^ 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 hydroxyanthra- 
quinones by direct oxidation in acid solution and has found 
that the yields obtained are usually quite satisfactory. 

Oxidation in acid solution is always brought about in 
concentrated sulphuric acid, and may be effected with 
concentrated sulphuric acid or monohydrate alone, with 
oleum, with nitrosyl sulphuric 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. 

3 M.L.B., D.R.P. 17,627. 



256 ANTHRACENE AND ANTHRAQUINONE 

dioxide, arsenic acid, ammonium persulphate, etc. The 
introduction of hydroxyl 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 hydroxyl 
group becomes protected. This is best done by carrying 
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 hydroxylates 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 necessary 
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 hydroxyl- 
ated anthraquinone from destruction by further oxidation. 
Much more satisfactory results are obtained, however, by 
carrying 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 
H 2 SO 4 , i.e. the monohydrate of sulphur trioxide. 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 H 2 SO 4 .H 2 O. 



THE HYDROXY COMPOUNDS 257 

the 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 
filtered 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 
i .4. 8-trihydroxy anthraquinone. 

It is impossible to detect with certainty any regularities 
in the positions taken by entering hydroxyl groups, but it 
seems to be a fairly general rule that the a-position is pre- 
ferred, and that the j8-position is never taken unless there is 
a hydroxyl group in the contiguous a- position. Even when 
there is such a group present the entering hydroxyl group 
often prefers the a- position. The ease with which hydroxyl- 
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 rapidly and 
quantitatively formed from chrysazin, and from anthra- 
chrysazin its formation is almost instantaneous. 

Oxidation by means of sulphuric acid is a catalytic 

17 



258 ANTHRACENE AND ANTHRAQUINONE 

reaction and does not take place if chemically pure acids 
are used. When ordinary commercial acids are employed 
the small quantities of selenium present act as the catalyst : 

SeO 2 =Se+O 2 
Se +2SO 3 =SeO 2 +2SO 2 

Oxidation by means of sulphuric acid is also facilitated by 
the presence of mercury compounds, 1 and bromine is stated 
to facilitate attack by oleum, although this can hardly 
be regarded as a catalytic effect as bromination and 
hydroxylation take place simultaneously. 2 Hydroxylation 
by oxidation with sulphuric acid or oleum often leads to 
the production of polyhydroxyanthraquinone sulphonic acids, 
but in many cases the sulphonic acid groups are readily 
removed by hydrolysis by heating the product with sulphuric 
acid of about 70 per cent, strength. 3 

Hydroxylation by means of sulphuric acid or oleum 
often leads to the simultaneous replacement of other groups 
such as halogen atoms 4 and amino and nitro groups 5 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. 6 The behaviour of the nitroanthraquinones 
towards oleum is particularly interesting but has already 
been discussed. 7 Amino groups in aminoanthraquinones, 
although often replaced by hydroxyl groups under the 
influence of oleum, by no means always behave in this way, 
both a-amino and a-alkylaminoanthraqtrinones being often 
converted into ^0ra-hydroxyaminoanthraquinones by treat- 
ment with 80 per cent, oleum at 30-40, or with 20 per cent, 
oleum, monohydrate or concentrated sulphuric acid 8 in 
the presence of boric acid at 200. 

Georgievics, M. 32, 347. By., D.R.P. 162,035 ; 172,688. 
By., D.R.P. 97.674 ; 99,3i4- 

By., D.R.P. 172,688. Cf. M.L.B., D.R.P. 71,964. 
By., D.R.P. 81,962 ; 83,055. 

M.L.B., D.R.P. 75,490. By., D.R.P. 79,768 ; 81,244 ; 83,055 ; 
83,085. 

By., D.R.P. 68,775 ; 69,835. 
Page 242. 
8 By., D.R.P. 154,353 ; 155,44- 



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 hydroxyl groups enter the other ring. Thus 
anthraquinone-a-sulphonic acid when treated with oleum 
gives alizarin-5-sulphonic acid l and purpurin-8-sulphonic 
acid, 2 the use of boric acid and mercury apparently not 
influencing the positions taken by the hydroxyl groups. 
The influence of sulphonic acid groups in the j3- position is 
uncertain. 

The data available as regards the product obtained 
when fresh hydroxyl groups are introduced into a molecule 
in which such groups are already present are confusing and 
insufficient to allow any reliable deductions to be made. 
Many 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 hydroxyl groups are present in the 
para- position to one another, the tendency of the entering 
hydroxyl group is to attach itself to the same ring, e.g. 
quinizarin gives purpurin, 3 and quinizarin-8-sulphonic 
acid gives purpurin-3.8-disulphonic acid. 4 This is the 
behaviour that would be expected on the assumption that 
direct hydroxylation is primarily the addition of the elements 
of water to a compound with a quinonoid structure, as 
quinizarin is faiily easily oxidised to anthradiquinone, a 
compound which is a true quinone in its chemical re- 
actions. Gattermahn, 5 however, finds that quinizarin 
when oxidised with oleum under certain conditions gives 
quinalizarin. 

Anthraquinone itself when oxidised with oleum containing 
about 80 per cent, of free anhydride and boric acid gives 
anthrarufin, 6 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. 172,688. M.L.B., D.R.P. 158,413. 

2 R. E. Schmidt, B. 37, 71. By., D.R.P. 155,045. 

3 By., D.R.P. 81,481. 4 By., D.R.P. 172,688. 
5 J. pr. [2] 43, 246. 6 By., D.R.P. 101,220. 



260 ANTHRACENE AND ANTHRAQUINONE 

purpurin. 1 Oleum of high concentration also seems capable 
of oxidising anthraquinone to a hexahydroxy compound, 2 
probably Anthracene Blue WR. 

Erythrohydroxy anthraquinone on oxidation with oleum 
of high concentration gives anthrarufin, 3 but the effect of 
more dilute acids does not seem to have been studied, and 
there appears to be no record of the hydroxylation of jS- 
hydroxyanthraquinone by acids. 

Alizarin when oxidised by oleum of high concentration 
gives quinalizarin 4 (Alizarin Bordeaux B, Alizarin Cyanine 
3R) and hydroxy anthrarufin, 5 chrysazin gives 1.4.5-111- 
hydroxy anthraquinone, 6 and anthragallol when oxidised 
with dilute oleum or concentrated sulphuric acid in the 
presence of boric acid gives i.2.3.4-tetrabydroxyanthra- 
quinone. 7 

Oxidation with monohydrate in the presence of mercuric 
sulphate and boric acid has resulted in the preparation of 
octahydroxyanthraquinone, Georgievics 8 having prepared 
this substance from rufigallic acid by this method. 

Polyhydroxyanthraquinones have also been obtained by 
the action of oleum or sulphuric acid upon purpurin, 9 
anthrapurpurin, l flavopurpui in, 1 1 hydroxy anthrarufin, 1 2 
hydroxy chrysazin, 13 rufigallic acid, 14 and many other similar 
compounds. 15 

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. 2 By., D.R.P. 65,182. v 

3 By., D.R.P. 97,674. 4 By., D.R.P. 60,8^5. 

5 By., D.R.P. 156,960. 6 By., D.R.P. 161,026. 

7 By., D.R.P. 86,968. Cf. By., D.R.P. 60,855. 

s M. 32, 347. 9 By., D.R.P. 60,855. 

10 By., D.R.P. 60,855 ; 67,061. ll By., D.R.P. 60,855 ; 67,061. 

12 By., D.R.P. 67,063. 13 By., D.R.P. 67,063. 

14 By., D.R.P. 62, 531. 

15 By., D.R.P. 63,693 ; 64,418 ; 65,375 ; 65,453 ; 69,013 ; 81,481 ; 
8i,959; 172,688. 



THE HYDRO XY COMPOUNDS* 261 

boric, arsenic, or phosphoric acid l is added to protect the 
hydroxyl 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 ol substance to be oxidised, but it is probable 
that in many cases better results would be obtained by 
using different proportions. Thus Dimroth and Fick 2 
found that the oxidation of flavopurpurin and anthrapurpurin 
to the tetrahydroxy compounds by means of nitrosyl 
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 necessary to carry out the oxidation 
at a higher temperature and the yields obtained were much 
poorer. 

Hydroxylation with nitrosyl sulphuric acid is a catalytic 
reaction and depends on the presence of mercury. If the 
nitrosyl sulphuric acid is made from pure sulphuric acid no 
hydroxylation takes place, but as a rule commercial sulphuric 
acid which has been made from pyrites contains sufficient 
mercury. 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 sulphuric 
acid at 120 in the presence of boric acid and mercuric sul- 
phate converts anthraquinone into i-hydroxyanthraquinone- 
4-diazonium sulphate, 4 this being converted into quinizarin 
when heated with concentrated sulphuric acid at i7O-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 hydroxylation, j8-methyl- 
anthraquinone, for example, being converted into quinizarin 
carboxylic acid, 5 and i.5-dinitroanthraquinone yielding 
5-nitroquinizarin. 6 

1 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. 4 By., D.R.P. 161,954. 

5 By., D.R.P. 84,505. 6 By., D.R.P. 90,041. 



262 ANTHRACENE AND ANTHRAQUINONE 

Oxidation with nitrosyl sulphuric acid seems specially 
adapted to the preparation of hydroxyanthraquinones in 
which two hydroxyl groups are in the para- position to one 
another, and it appears that a hydroxyl group does not 
enter a j3- position unless both a- positions in that ring are 
already occupied by hydroxyl. Too great reliance, however, 
must not be placed on this rule, as the data available are 
insufficient to establish it beyond doubt. 

Anthraquinone on oxidation with nitrosyl sulphuric 
acid gives quinizarin, 1 reference having already been made 
to the production of i-hydroxyanthraquinone-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 j8-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, 4 although in 
poor yield, and this is one of the very few cases in which a 
hydroxyl group enters the j3-position. 

Chrysazin gives i. 4. 5-trihydroxy anthraquinone very 
readily and in a state of purity, as, curiously enough, no 
1. 4. 5. 8-tetrahydroxy anthraquinone is formed. 5 

Flavopurpurin on oxidation yields hydroxyfiavopurpurin 
(1.2.4.6.), and anthrapurpurin yields hydroxyanthrapurpurin 
(1.2.4.7), the position of the hydroxyl groups being proved 
by the fact that both hydroxyfiavopurpurin and hydroxy- 
anthrapurpurin on reduction and subsequent oxidation of 
the leuco- compound give i.4.6-trihydroxyanthraquinone, 
the orientation of the hydroxyl groups in this compound 

1 By., D.R.P. 81,245 ; 161,954. B.A.S.F., D.R.P. 154.337- 

2 By., D.R.P. 162,792. 

3 By., D.R.P. 86,630. 

4 By., D.R.P. 86,630. B.A.S.F., D.R.P. 153,129. 

5 By., D.R.P. 163,041. 



THE HYDROXY COMPOUNDS 263 

being known by its formation from 4-hydroxyphthalic acid 
and hydroquinone. 1 

Anthraquinone-j8-sulphonic acid when heated with 
nitrosyl 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. Hydroxyl 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 very beneficial influence by 
protecting the hydroxy 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 
sulphonic acid when dissolved in concentrated sulphuric 
acid at 10 and then treated with nitric acid gives purpurin 
sulphonic acid, 4 alizarin itself when nitrated giving a mixture 
of nitroalizarin, purpurin, and nitropurpurin. 5 Flavo- 
purpurin and anthrapurpurin are also oxidised by nitric 
acid when dissolved in concentrated sulphuric acid and give 
tetranitro compounds. 6 The action of nitric acid on the 
poly hydroxyanthraquinones is often complicated by the 
formation of diquinones, 7 although to some extent this can 
be avoided by the protecting influence of boiic acid. Highly 
hydroxylated derivatives often undergo complete decom- 
position, rufigallic acid giving only oxalic acid, 8 and amino 
groups when present are often replaced by nitro groups. 9 

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 Dimroth and Pick, A. 411, 326. 2 B.A.S.F., D.R.P. 154,337. 
3 By., D.R.P. 102,638. 4 M.L.B., D.R.P. 84,774. 

s M.L.B., D.R.P. 150,322. 6 M.L.B., D.R.P. 84,774. 

7 By., D.R.P. 70,782. 3 Klobukowski, B. 8, 931; 9, 1256. 

9 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 hydroxyanthraquinones to higher 
hydroxylated compounds, the product usually being obtained 
in the form of an anthradiquinone, which can be reduced 
to the corresponding hydroxyanthraquinone by sulphur 
dioxide. 2 The most important application of this reaction 
is the oxidation of quinalizarin to i.2.4.5.8-pentahydroxy- 
anthraquinoiie (Alizarin Cyanine R, 2R, RA Extra, etc.), the 
diquinone at first obtained being subsequently reduced. 3 
The pentahydroxy 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-tetrahydroxy- 
anthraquinone by manganese dioxide and sulphuric acid in 
the presence of boric acid at or about the ordinary tempera- 
ture. The presence of boric acid is absolutely essential, as 
otherwise the anthragallol is completely destroyed. 4 

Alizarin-3-carboxylic acid is also oxidised by manganese 
dioxide and sulphuric acid at or about the ordinary tempera- 
ture and passes into purpurin-3-carboxylic acid, a substance 
which has proved to be identical with the " ^s^w^o-purpurin " 
present in madder. 5 

In addition to the oxidising agents mentioned above 
hydroxyl groups can be introduced into the anthraquinone 
ring by means of lead dioxide, bleaching powder, arsenic 
acid, ferric salts, chromates, persulphates, and perchlorates, 6 
but for further details the reader is referred to the original 
literature. Electrolytic oxidation has also been described. 7 

REDUCTION OF POI^YHYDROXY COMPOUNDS 

Hydroxyanthraquinones can sometimes be obtained 
from the higher hydroxylated compounds by removing one 

1 See pp. 242-247. 2 By., D.R.P. 66,153 ; 68,113 ; 68,114. 
3 By., D.R.P. 62,018. * By., D.R.P. 102,638. 

5 By., D.R.P. 260,765 ; 272,301. 

6 By., D.R.P. 62,018 ; 62,504-5-6; 66,153; 68,123; 68,113; 68,114; 
69,842; 69,933-4; 73942; 102,638; 104,244; 107,238; 111,919. 

' By., D.R.P. 74,353. 



THE HYDROXY COMPOUNDS 265 

or more hydroxyl groups by reduction, although the method 
is not one of great importance. The cyclic 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 readily converted into the 
anthraquinone derivative by air oxidation. 

Exhaustive reduction of hydroxyanthraquinones by 
means of hydriodic acid and red phosphorus leads to 
hydrogenated anthracenes, 1 but under less drastic conditions 
it is often possible to split off one hydroxyl group without 
reducing the carbonyl groups beyond the anthraquinol 
stage. Thus lyiebermann 2 and Pleus 3 by reducing quini- 
zarin obtained i-hydroxy-anthraquinol from which erythro- 
hydroxy anthraquinone was obtained by mild oxidation. 
Hydriodic acid, however, is not a particularly suitable 
reducing agent for removing hydroxyl groups while avoiding 
complete reduction of the cyclic carbonyl groups. 

The reduction of purpurin with alkaline stannite solution 
leads to xanthopurpurin, 4 and the same substance is said to 
be obtained in quantitative yield when the reduction is 
carried out by sodium hydrosulphite and ammonia. 5 In 
acid solution it seems, however, that a different hydroxyl 
group is split off, the product being quinizarin. According 
to one patent 6 the reduction of purpurin with zinc and 
glacial acetic acid leads to two products which are designated 
as /tf^co-quinizarin I and /^wco-quinizarin II. Of these the 
analytical figures and the melting point (150) quoted in the 
specification for leuco-qumiz&rm II agree closely with those 
of i.4-dihydroxyanthraquinol. 7 The analytical figures 
quoted for leuco-qmmzsnin I, however, agree with those 
required for a trihydroxyanthraquinol,* so that the so-called 
" leuco-qmrnzann I " would appear to be nothing but 

1 Liebermann, A. 212, 26. 2 A. 212, 14. B. 10, 607 ; 11, 1610. 

3 B. 35, 2923. 4 Plath, B. 9, 1204. 

5 M.L.B., D.R.P. 212,697. 6 B Y" D.R-P. 89,027. 

7 Liebermann, A. 212, 14. B. 10, 608. Grandmougin, J. pr. [2] 76, 
138. tt 

* Found =65-11, 65-08; H=3'95, 3-90. Calculated for C 14 Hi O 5 , 
0=65-12; H=3'88. 



266 ANTHRACENE AND ANTHRAQUINONE 

leuco-pwpufw, the reduction not having been taken far 
enough to remove the hydroxyl group. In spite of this, 
however, the specification states emphatically in two places 
that " leuco-qwniza.nn I " is more readily oxidised to 
quinizarin than is leuco-qmrnzarin II. This is rather difficult 
to understand if the analytical figures given were really 
obtained experimentally.* In a later patent l the same 
firm claims that the best yields of fewco-quinizarin are 
obtained by reducing purpurin with aluminium bronze and 
concentrated sulphuric acid in the presence of boric acid. 
Elimination of hydroxyl groups can also be brought about 
by reducing other polyhydroxyanthraquinones with zinc 
and glacial acetic acid, Dimroth and Fick, 2 for example, 
obtaining i.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 any 
extensive use owing to the tendency of nitrosyl sulphuric 
acid to introduce fresh hydroxyl groups. 4 

Hydroxyl groups can in some cases be removed by an 
indirect method. Thus Schrobsdorf, 5 by heating chrysazin 
with ammonia, replaced one hydroxyl group by an amino 
group, and by then diazotising and reducing the i.8-amino- 
hydroxyanthraquinone .obtained erythrohydroxyanthraqui- 
none. 

MISCELLANEOUS 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, 6 /Miydroxyanthra- 
quinone, 7 chrysazin, 8 and other hydroxyanthraquinones 

* For explanation of this reaction see "Addenda." 

1 By., D.R.P. 246,079. 2 A. 411, 330. 

3 B. 8, 778. 4 See p. 260. 

5 B. 35, 2930. 6 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 hydroxyl groups in the 
hydroxyanthracenes. The ws-nitro derivatives of anthra- 
cene, such as dihydrotrinitroanthracene and Meisenheimer's 
nitroanthrone, l 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. 2 



PROPERTIES AND REACTIONS 

The hydroxyanthraquinones show the ordinary reactions 
of the phenols and dissolve in caustic alkali to form highly 
coloured solutions. Hydroxyl groups when in the a- 
position are influenced by the cyclic carbonyl groups and 
are then only alkylated with the utmost difficulty, and are 
rather more difficult to acetylate than when in the jS- 
position. Whether the influence of the carbonyl group upon 
a hydroxyl 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 3 of erythrohydroxyanthraquinone 
and anthrarufin in alkaline solution are almost identical, 
each showing one and only one broad band with its head at 
5oojufi. In concentrated sulphuric acid solution erythro- 
hydroxyanthraquinone shows a broad band with its head 
at 475/^ft and also two narrow bands with their heads at 
305^ and 260^, and closely resembles that of anthraqui- 
none in sulphuric acid solution. Anthrarufin, on the other 
hand, when in concentrated sulphuric acid solution has an 
absorption 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. a G.E., D.R.P. 292,247. 

3 R. 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 quini- 
zarin to a considerable extent. 

The absorption spectrum of jS-hydroxyanthraquinone in 
alkaline solution differs from that of erythrohydroxyanthra- 
quinone by showing two narrow bands with heads at 305^ 
and 235^, whereas in concentrated sulphuric acid solution 
it shows very shallow bands at 410^ and 325^, and a 
slightly deeper band at 290^, these in addition to the broad 
band with its head at 500^. 

The spectrum of the sodium salt of alizarin in the 
absence of excess of alkali resembles that of j3-hydroxy- 
anthraquinone, whereas when excess of alkali is present 
the absorption spectrum is very 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 
fc'so-anthraflavic 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 ultraviolet, 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 hydroxyl 
group in the j8- position. In concentrated sulphuric acid 
solution, however, ultraviolet absorption seems to be 
exhibited by all hydroxyanthraquinones including anthra- 
quinone itself. 1 

A comparison of the absorption spectra of the hydroxy- 
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 hydroxyl 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 especially 
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, 
5"- 



THE HYDROXY COMPOUNDS 269 

both purpurin and quinizarin are readily oxidised to phthalic 
acid by the action of atmospheric oxygen on their alkaline 
solutions, whereas alizarin is not destroyed under similar 
conditions. 1 

The further hydroxylation of hydroxyanthraquinones 
by direct oxidation has already been discussed, 2 and so also 
has the formation of anthradiquinones, 3 and but little 
information is available as to what products are obtained 
under different conditions. 

Scholl 4 has found that when alizarin is oxidised in 
alkaline solution with a hypochlorite 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 with ferricyanide 
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-acry- 
lic acid. 5 

Naphthoquinonyl derivatives have also been obtained 
by Dimroth and Schulze 6 by the degradation of carminic 
acid and other naturally occurring hydroxyanthraquinone 
derivatives, and Bamberger and Praetorius 7 have obtained 
3-hydroxy-(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 : 

P 
COOH 




The same investigators have also found that the oxidation 

1 Dralle, B. 17, 376. z Pp. 251-264. 3 Pp. 92-94. 

4 B. 52, 1829 ; 2254. Cf. By., D.R.P. 146,223 ; 167,461. 

5 Scholl, B. 51, 1419. 6 A. 411, 339. ' M. 23, 688. 



270 ANTHRACENE AND ANTHRAQUINONE 



of purptirin in alkaline solution by hydrogen peroxide in 
the presence of a cobalt catalyst leads to 2-hydroxy-3-acetyl- 
i.4-naphthoquinone, a change which they explain by a 
similar series of reactions to those just given. 

Wolffenstein and Paar l have studied the action of 
boiling nitric acid on anthraflavic acid, i.7-dihydroxy- 
anthraquinone and anthrarufin. The first action of the 
nitric acid is to nitrate the hydroxyanthraquinone, but 
further action leads to the rupture of the central ring and 
formation of 3.5-dihydroxy-2.4.6-trinitrobenzoic acid. 

The hydroxyanthraquinones in many cases combine 
with formaldehyde to yield hydroxyanthraquinonyl carbinols, 
and in this way resemble the ordinary phenols. Thus 
anthrachrysazin 2 combines very readily with formaldehyde 
to form a dicarbinol (I), which in turn will combine with 
tertiary aromatic amines, 3 such as dimethyl aniline, to 
produce compounds such as II, or with ammonia or with a 
primary or secondary aliphatic amine 4 or a primary 
aromatic amine 5 to produce such compounds as III : 

OH OH 

HO CHoOH HO CH 2 C H 4 NR 2 



HOCH 2 
HO 



OH R 2 NC 6 H 4 CH. 



OH 



HO 



II. 



OH 
HO CH 9 NHAv 



ArNHCH 2 
HO 
III. 



OH 



Attention has already been drawn to the acetylation of 
hydroxyanthraquinones by means of acetic anhydride and 

1 B. 46, 586. 2 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. 4 M.L.B., D.R.P. 188,189. 

5 M.L.B., D.R.P. 184,808 ; 188,596. 



THE HYDRO XY COMPOUNDS 271 

pyridine, 1 but it may 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 
benzoyl chloride. 2 It is claimed that j8-hydroxyanthra- 
quinone, anthraflavic acid, flavopurpurin and anthra- 
purpurin are especially easily benzoylated by this method. 

The reduction of the hydroxyanthraquinones 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 dehydroxylation taking place simulta- 
neously. Reduction can also be effected by means of zinc 
dust and acid, 3 and some of the hydroxy anthranols have 
been recommended as valuable remedies for psoriasis and 
other skin diseases. 



TINCTORIAL PROPERTIES 

The absorption spectra of the hydroxyanthraquinones 
in alkaline and in concentrated sulphuric 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 hydroxyanthra- 
quinones on various mordants. Georgievics 5 has discussed 
the position of hydroxy 1 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 j8- positions favour the pro- 
duction of yellows 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, 6 who consider that they have 
sufficient evidence to support the following conclusions : 

(a) Two homonuclear hydroxyl groups in the ortho- or 

1 Page 237. a \yed ., D.R.P. 297,261. 

3 By., D.R.P. 296,091 ; 301,452 ; 305,886. * Soc. 109, 545. 

s M. 32, 329. 6 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. 

(b) 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. 

(d) Three hydroxyl groups at i, 2, and 3 produce a 
brown. 

The connection between the position of the hydroxyl 
groups and the capacity of a hydroxyanthraquinone to form 
a lake is quite obscure, and is likely to remain so until some 
satisfactory definition as to the meaning of " mordant dye " 
is evolved. The old rule (Rule of Kostanecki and I^ieber- 
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 all the hydroxyanthraquinones which have proved 
to be of commercial value have such hydroxyl 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 monohydroxy compounds, have slight capacity for 
forming lakes. 1 

Increase in the number of hydroxyl groups does not 
necessarily increase tinctorial properties, as although quini- 
zarin is a comparatively powerful mordant dye, 1.4.5.8- 
tetrahydroxyanthraquinone has no capacity for forming 
lakes 2 except, curiously enough, on a beryllium mordant, 3 
and octahydroxyanthraquinone has very feeble tinctorial 
properties. The presence of other groups or atoms in the 
molecule also affects the capacity for forming lakes, as 
although rufigallol itself is a very feeble mordant dye its 
affinity is very greatly enhanced by halogenating. 4 

1 Georgievics, F.T. 1, 623. 2 Georgievics, F.T. 4, 185. 

3 Georgievics; Grandmougin, " Lehrbuch der Farbenchemie," fourth 
edition, p. 257. 

4 By., D.R.P. 114,263. Cf. also L. B. Holliday & Co., Ltd., and 
H. D. Law, E.P. I26,528 18 , 



THE HYDRO XV COMPOUNDS 273 

The constitution of the lakes formed by the hydroxy- 
anthraquinones and, for example, the exact function 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. 3 

HAI.OGENATION 

A considerable amount of work on the halogenation of 
the hydroxyanthraquinones has been recorded, but as in a 
great many cases the positions of the halogen atoms in the 
product have not been determined, it is difficult to detect 
with certainty any rules relating to the directing influence 
exerted by the hydroxyl groups, although from the data 
available one or two conclusions can be drawn. 

When hydroxyl 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 erythrohydroxyanthraquinone when treated with mole- 
cular or nascent halogen (e.g. NaBrO 4 +HBr) gives first 
4-brom-i-hydroxyanthraquinone and then 2.4-dibrom-i- 
hydroxyanthraquinone, 4 and anthrarufin and chrysazin 
behave in the same way. 5 The bromination can be carried 
out in boiling glacial acetic acid solution, but unless sodium 
acetate is added the reaction is very slow. In the presence 
of sodium acetate, however, the reaction is rapid and the 
bromo- compound crystallizes out on cooling. 6 The reaction 
can also be conveniently carried out by suspending the 

1 Mohlau, B. 46, 443. Wieland and Binder, B. 47, 977. 

2 Soc. 75, 433 ; 83, 129. J.S.C.I. 22, 600. A. 398, 151. B. 41, 1062, 
3469 ; 44, 2653 ; 45, 148, ni6 ; 47, 738, 977- F.T. 1, 624 ; 3, 366 ; 4, 186. 

3 B. 51, 1419-1428. 

4 By., D.R.P, 127,532. ; 131,403. Wed., D.R.P. 202,770. Cf. Eckert 
and Steiner, M. 35, 1144. 

5 SchroDsdorf, B. 35, 2930. By., D.R.P. 127,699 ; 197,082. 

6 Friess and Schurmann, 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, 1 and in many cases molecular halogen 
can be used in aqueous solution 2 at the ordinary temperature 
or at 100. Krythrohydroxyanthraquinone, anthrarufin, and 
chrysazin have all been chlorinated and brominated by 
these methods, but the claim that chrysazin is chlorinated in 
aqueous suspension has been contradicted, 3 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 conveniently by heating 
with sulphury 1 chloride in nitrobenzene solution, erythro- 
hydroxyanthraquinone being readily converted by this means 
into i-hydroxy-4-chloranthraquinone and i-hydroxy-2.4- 
dichloranthr aquinone . 4 

In the case of quinizarin, in which there is no vacant 
para- position, chlorination in glacial acetic acid 5 leads to 
3-chlorquinizarin, the same product being obtained by the 
action of hydrochloric acid on i.4.9.io-anthradiquinone. 6 

Comparatively little work has been done on the chlorina- 
tion and bromination of hydroxyanthraquinones in which 
hydroxyl groups are only present in the j3- 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 bromine atoms 
first attack those j8- positions which are contiguous to the 
hydroxyl groups, no a- position being entered until all 
such ft- positions have been occupied. 7 Anthraflavic acid 
is not chlorinated in aqueous suspension at 100, but if 
sulphuric acid is added so as to raise the boiling point a 
dichlor compound is formed. 8 The melting point of this 
compound and also the melting points of its acetyl 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. 
4 Ullmann and Conzetti, B. 53, 829. 5 By., D.R.P. 114,199. 

6 Dimroth and Schulze, A. 411, 348. 7 Wed., D.R.P. 175,663. 
8 Wed., D.R.P. 187,685. 



THE HYDRO XY COMPOUNDS 275 

obtained by the action of sodium hypochlorite on anthra- 
flavic acid, but their solubilities 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. 1 
This is resinified 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, 3 
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 compounds 
are often easily and smoothly chlorinated by the action of 
sodium hypochlorite on their alkaline solutions. By this 
means Decker and L,aube 4 obtained 2-hydroxy-i-chlor- 
anthraquinone from /2-hydroxyanthraquinone, 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 hydroxyanthraquinones, in which hydroxyl 
groups are present both in a- positions and in /?- positions, 
the behaviour on .halogenation becomes complicated and 
seems to depend on which hydroxyl groups have the pre- 
dominating 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, 6 the bromine entering the vacant 
j8- positions, and aqueous suspensions of flavopurpurin 
when treated with sodium chlorate and hydrochloric acid 
give a monochlor derivative, the position of the chlorine 

1 Wed., D.R.P. 179,916. 2 Wed., D.R.P, 181,659. 

3 B. 36, 2938. 4 B. 39, 112. 

5 Wed., D.R.P. 152,175 ; 153,194. 6 Wed., D.R.P. 175,663. 



276 ANTHRACENE AND ANTHRAQUINONE 

being unknown. 1 Xanthopurpurin when brominated also 
gives a dibromo compound which is probably i.3-dihydroxy- 
2.4-dibromanthraquinone. 2 The chlorination of 1.7- di- 
hydroxyanthraquinone can be effected by sodium hypo- 
chlorite, but the reaction proceeds with difficulty and only 
one chlorine atom is taken up. 3 The chlorination of alizarin 
in aqueous suspension by sodium chlorate and hydrochloric 
acid leads to 3 -chlor alizarin. 4 

The bromination of hydroxyanthraquinones 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 ms-carbon atoms ; but subsequent 
oxidation leads to the brominated hydroxyanthraquinone, 
e.g. monobromalizarin. 5 

One of the most convenient methods of chlorinating the 
hydroxyanthraquinones is to treat them with sulphuryl 
chloride. The reaction takes place quite readily by heating 
the hydroxyanthraquinone on the water bath with sulphuryl 
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- 
hydroxyanthraquinone and 5.8-dichloranthrarufin, and has 
been extended by Iy. B. Holliday and Co., 1/td., to various 
poly hydroxyanthraquinones such as alizarin, anthraflavic 
acid, iso-anthraflavic acid, Alizarin Bordeaux, etc. Ap- 
parently under some conditions one or more of the hydroxyl 
groups is simultaneously replaced by chlorine. 7 

SUI.PHONATION 

Comparatively little reliable information is available 
concerning the sulphonation products of the hydroxy- 
anthraquinones, but it has been claimed that a-hydroxy 

1 Wed., D.R.P. 189,937. 2 pi a th, B. 9, 1204. 

3 Wed., D.R.P. 152,175 ; 153,194. 4 Wed., D.R.P. 189,937. 

5 By., D.R.P. 117,923. 6 D.R.P. 282,494. 

7 L. B. Holliday and Co., Ltd., and H. D. Law, E.P. i26,727-8 18 . 



THE HYDROXY COMPOUNDS 277 

compounds sulphonate in the j3- position, and that further 
sulphonation then leads to ajS-polyhydroxyanthraquinones. 1 
Anthrarufin, for example, gives anthrarufin-2.6-disulphonic 
acid 2 and chrysazin gives chrysazin-2.7-disulphonic acid. 3 
Wolbling, 4 on the other hand, by sulphonating chrysazin 
obtained a disulphonic acid from which a tetrahydroxy- 
anthraquinone was obtained, which may or may not be 
identical with the i.2.7.8-tetrahydroxyanthraquinone de- 
scribed in the patent literature. 5 They are both stated to 
give blue solutions in caustic soda, but whereas Wolbling 
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 Wolbling 
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 6 
described a dibromchrysazin which yielded a tetrahydroxy- 
anthraquinone which one would expect to be i.4.5.8-tetra- 
hydroxyanthraquinone, but which differs widely from this 
substance in its properties, 7 and also cannot be 1.2.7.8- 
tetrahydroxyanthraquinone 8 or i.2.5.8-tetrahydroxyanthra- 
quinone (quinalizarin), 9 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 chrysazin, so that any error 
arising from their starting-out substance would vitiate both 
their results. 

The sulphonation of anthraflavic acid 10 and iso-anthra- 
flavic acid n and their methyl ethers 12 also appears to lead 
to the entrance of sulphonic acid groups into the j8- positions. 

1 By., D.R.P. 141,296. 2 By., D.R.P. 96,364- 

3 By., D.R.P. 100,136. 4 B. 36, 2941. 

5 By., D.R.P. 103,988. 6 B. 36, 2936. 

7 B., D.R.P. 125,579 ; 143,804. 8 By., D.R.P. 103,988. 

9 By., D.R.P. 60,855. 10 M.L.B., D.R.P. 99,6n ; 99,874- 

11 By., 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 anthrachrysazin dimethylether). 



278 ANTHRACENE AND ANTHRAQUINONE 



In the case of 1.4.5- an ^ i.4.6-trihydroxyanthraquinone 
siilphonation 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 sulphonic acid group 
enters at 7. 1 

On account of its technical importance the sulphonation 
of alizarin has attracted considerable attention, sulphonation 
with oleum leading to alizarin-3-sulphonic acid 2 (Alizarin 
Red S), alizarin-6- and -7-sulphonic acids being only obtain- 
able from anthraquinone disulphonic acids by fusion with 
caustic potash under suitable conditions. 3 Further sulpho- 
nation of alizarin-3-sulphonic acid leads to disulphonic 
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. 5 

When alizarin is sulphonated in the presence of mercury 
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 sulphonated 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 /?- position more powerfully than the mercury directs 
to the a- position ; but in the ring free from hydroxyl groups 
the mercury exerts its usual influence. 6 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, 7 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. 

3 See p. 241. 

4 By., D.R.P. 56,952. 

5 By., D.R.P. 56,951. 

6 Wed., D.R.P. 205,965 ; 210,863. 

7 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 sulphonated 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 i.4~hydroxy- 
aminoanthraquinones and the i.4-diaminoanthraquinones 
are sulphonated in the same way, the intermediate product 
in these cases being the quinone imide or di-imide. 

Only a few hydroxyanthraquinone 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 S (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- an d 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- 
hexahydroxyanthraquinone (Anthracene Blue WR) is ob- 
tained by the action of oleum on i.5-dinitroanthraquinone, 
the subsequent hydrolysis being omitted. It has received 
several trade names, such as Acid Alizarin Blue BB, Alizarin 
Cyanine WRS, BBS, and sRS, and Anthracene Blue SWX. 

NITRATION 

The hydroxyanthraquinones 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 hydroxyl 

1 By., D.R.P. 287,867 ; 288,474 ; 289,112. 



2 8o ANTHRACENE AND ANTHRAQUINONE 

group greatly lessens the danger of simultaneous hydroxyla- 
tion ; but, on the other hand, the directing influence of a 
protected group is often quite different from that of a free 
hydroxyl group, and to some extent depends on how the 
protection is effected. 

When hydroxyl groups are present only in a- positions 
they direct entering nitro groups to the para- position, but 
the ortho- position is also readily taken, so that there is 
usually no difficulty in inserting two nitro groups for each 
hydroxyl group present. Erythrohydroxyanthraquinone, 
anthrarufin, and chrysazin l are fairly easily nitrated in the 
free state, although much purer products are obtained by 
nitrating the boric esters, 2 and the nitration and subsequent 
demethylation of chrysazin dimethyl ether has been recom- 
mended as the best method of obtaining mononitrochrysazin. 3 

In the case of quinizarin the nitration is somewhat more 
troublesome owing to the tendency to form nitropurpurin, 
and in this case the boric ester method fails. By nitrating 
in an organic solvent, however, such as glacial acetic acid or 
nitrobenzene, quinizarin can be converted into 2-nitroquini- 
zarin. 4 

When hydroxyl groups are present only in the ft- position 
the entering nitro groups take the ortho- positions to them, ex- 
positions usually being preferred to ft- positions. j3-Hydroxy- 
anthraquinone itself readily gives a dinitro compound, 6 the 
position of the nitro groups being proved by its conversion 
into anthragallol. Anthraflavic acid 6 and ^'so-anthraflavic 
acid 7 give both dinitro and tetranitro compounds, and 
hystazarin gives a mono and a dinitro compound, 8 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. 

2 Eckert and Steiner, M. 35, 1144. By., D.R.P. 163,042. 

3 M.L.B., D.R.P. 193,104. 

4 By., D.R.P. 272,299. 

5 Liebermann and Simon, A. 212, 25, 53. B. 14, 464 ; 15, 692. Simon, 
D.R.P. 119,755- 

6 Schardinger, B. 8, 1487. M.L.B., D.R.P. 112,179. 

7 Romer and Schwazer, B. 15, 1040. 

8 Schrobsdorf, B. 36, 2938. 



THE HYDRO XY COMPOUNDS 281 

itself is nitrated in ordinary concentrated sulphuric acid 
solution a mixture of 3-nitroalizarin, purpurin, and 3-nitro- 
purpurin is obtained owing to simultaneous hydroxylation 
taking place. 1 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 by the action of nitrous acid on alizarin, 3 although 
the action of nitrous acid in concentrated sulphuric acid 
solution leads to y-nitroalizarin. 4 

If the diacetyl derivative of alizarin is nitrated the nitro 
group enters a different position, and 4-nitroalizarin is 
obtained, 5 but the nitration is rather troublesome to carry 
out, as the acetyl groups are readily lost by hydrolysis 
during the nitration, and for this reason it is better to use 
the dibenzoyl derivative, 6 the subsequent hydrolysis being 
very readily effected by cold caustic soda. This method 
has also been extended to the nitration of other hydroxy- 
anthraquinones such as anthrapurpurin, flavopurpurin, 7 
etc. Instead of protecting the hydroxyJ groups by forming 
an ester with an organic acid, the sulphate 8 or arsenate 9 
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 o. It is very remarkable that whereas 
the nitration of the sulphate or arsenate gives 4-nitroalizarin, 

1 Schunck and Rdmer, B. 12, 583. M.L.B., D.R.P. 150,322. Cf. also 
By., D.R.P. 50,164 ; 50,708. , 

2 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- 

4 Grawitz, B. 10, 1165. Caro, Mon. Sci. 1879, 424. Girard and Pabst, 

C. r. 91, 570. 

5 Perkin, Soc. 2, 578 ; B. 8, 780. Caro, A. 201, 353. 

6 M.L.B., D.R.P. 66,811. 7 M.L.B., D.R.P. 70,515 ; 74,212. 
8 M.L.B., D.R.P. 74,431. 9 By., D.R.P. 74,598. 



282 ANTHRACENE AND ANTHRAQUINONE 

the nitration of the borate gives the isomeric j3-nitroalizarin, 
but other hydroxyanthraquinones such as flavopurpurin, 
anthrapurpurin, and Alizarin Bordeaux exhibit the same 
peculiarity. The a-nitro compound is also formed when 
alizarin monomethyl ether is nitrated, 1 although as already 
stated alizarin itself yields the j8-isomer. 

Xanthopurpurin is fairly easily nitrated to a dinitro 
compound, 2 and anthrachrysazin is easily and quantitatively 
converted into a tetranitro compound. 3 

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 Ziegler 4 
found that i-methyl-4-methoxyanthraquinone 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 hydroxyanthraquinone quinolines 
(hydroxy pyridino anthraquinones), but 3-nitroalizarin is 
used to a considerable extent as a dye under the name 
Alizarin Orange A, W, SW, Cy, etc. It gives orange shades 
in both chrome and alumina mordants. 



II. AMINOHYDROXY COMPOUNDS 

When i.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-diaminoanthrarufin, 5 the same product being obtained 
by oxidising i.5-diaminoanthraquinone with manganese 
dioxide, etc., in concentrated sulphuric acid solution. 6 
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. 

3 M.L.B., D.R.P. 73,605. 4 J. pr. [2] 86, 292. 

5 J3y., D.R.P. 81,694. " G B y- D.R.P. 106,034. 



THE AMINOHYDROXY COMPOUNDS 283 

or bromine atoms. 1 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 solubility, 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 anthrarufin 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 dye is formed 
by 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, 6 
and from dibromanthrarufindisulphonic acid by heating 
with ammonia and a copper catalyst. 7 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 chrysazin 
either by sulphonation, . nitration, and reduction, 10 or by 
heating dinitrochrysazin with sulphites or bisulphites, 11 or 



By., D.R.P. 102,532. 2 Solway Blue (Scottish Dyes, Ltd.; 

108,362; 119,228. 
,395- 

8 By^ D.R.P. 106^034. 

9 By., D.R.P. 113,724 ; 116,746. See also p. 245. 

10 By., D.R.P. 100,136. " By., D.R.P. 103,395. 



By., D.R.P. 102,532. 2 Solway Blue (Scottish Dyes, Li 

3 By., D.R.P. 96,364 ; 100,137; 105,501; 108,362; 119,2: 

4 By., D.R.P. 108,578. 5 By., D.R.P. 103, 
6 By., D.R.P. 163,647. 7 By., D.R.P. 195, 

fl T2* T\ T> T"> T ^/: 



284 ANTHRACENE AND ANTHRAQUINONE 

by heating dinitrodibromchrysazin with a sulphite. 1 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 iso-anthraflavic 
acid, 3 that from anthraflavic acid giving fiery red shades and 
that from iso-anthraflavic acid giving yellowish-red shades. 
The formulae of the various dyes are * : 



NH 9 OH 



S 
OH 



HO OH 

S S 



NH 2 NH 2 



NH 2 


NH 2 NH 2 


S 




OH 


HO 




OH 




1 






1 




HO 




S 


S 




S 


NH 2 " 




From anthraflavic 


From sso-anthra 


acid. 


flavic acid. 


Fiery red shades, 


Yellowish-red 


bordeaux on 


shades. 


chrome. 


Bordeaux on 




chrome. 



NH 2 

Alizarin Saphirol. From chrysazin. 
From anthrarufin. Greener than 

Reddish-blue Alizarin Saphirol. 
shades. 



In addition to Alizarin Saphirol one or two hydroxy- 
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 by heating Alizarin Cyanine 
R with ammonia, 5 the latter by heating Anthracene Blue 
with ammonia and caustic soda. 6 Both give blue shades 
on alumina. 

The other hydroxyaminoanthraquinones which are of 

1 By., D.R.P. 163,647. 2 M.L.B., D.R.P. 99,611 ; 99,874. 

3 M.L.B., D.R.P. 99,612. * S = SO,H. 

4 By., D.R.P. 66,811. 5 By., D.R.P. 62,019. 

6 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 hydroxyl groups when in the - position 
are readily alkylated by heating with the alkyl iodide or 
dimethyl sulphate and caustic potash in alcoholic or aqueous 
alcoholic solution. 1 In the case of a-hydroxyl compounds, 
however, this method fails, and although Plath 2 claimed to 
have obtained dimethyl and diethyl ethers of xanthopurpurin 
it is fairly certain that he really obtained only the mono- 
methyl and monoethyl ethers. Methylation of a-hydroxy 
compounds, however, can be effected by heating the dry 
potassium salts with dimethyl sulphate, 3 and in many cases 
the alkylation can be brought about without difficulty by 
first reducing the hydroxyanthraquinone to the anthrone. 4 
These are usually easily alkylated and the resulting ether 
can then be oxidised to the anthraquinone. The method 
fails, however, when there are hydroxyl groups in the 
ortho- position to both cyclic carbonyl groups. In spite of 
the well-known difficulty in alkylating hydroxyl 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. 5 This 
compound has been assigned the structure : 




but this can only be accepted with reserve pending further 
confirmation. 

1 Graebe, A. 349, 201. Graebe and Aders, A. 318, 369. M.L.B., 
D.R.P. 158,277. 

2 B. 9, 1205. 

3 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. 6 M.L.B., D.R.P. 280,975. 



286 ANTHRACENE AND ANTHRAQUINONE 

But little work has been done on the direct arylation of 
hydroxyanthraquinones, although it has been claimed l 
that hydroxyl 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 hydroxyanthraquinone 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 /Mrydroxy 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 



V 



and are yellow vat dyes although apparently of no technical 
value. In their formation an a-halogen atom reacts with 
a j3-hydroxyl group so that aj8-dlanthraquinonyl ethers 
would seem obtainable by this method. It is very improb- 
able, however, that an a-halogen atom would react with 
an a-hydroxyl group to produce an aa-dianthraquinonyl 
ether. 

Cyclic dianthraquinonyl ethers are also formed from 
2 -dihydroxy dianthraquinonyl compounds by heating with 
condensing agents such as zinc chloride. 4 Here loss of water 
takes place between two hydroxyl groups with the formation 
of a furfurane ring : 

1 M.L.B., D.R.P. 243,649. 

2 M.L.B. 216,268. 

3 Wed., D.R.P. 257,832 ; 263,621 ; 265,647 ; 269,215. 
J Scholl, D.R.P. 274,783. 



THE ETHERS 



287 



OH HO 



>\ 



According to one patent specification 1 when quinizarin 
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 may or may not be ethers. The analytical figures 
given agree with the formulae C 2 8H 14 O 8 and C 28 H 13 O 8 . 
Both substances give blue alkali salts. 

Both alkyl and aryl ethers can be obtained directly by 
the replacement of halogen atoms, 2 or sulphonic acid 
groups, 3 or nitro- groups. 4 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 aryl 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. 5 The reaction with 
nitro compounds, however, although quite common, is by 
no means a general one. 6 - 

1 By., D.R.P. 146,223. 

2 Frey, B. 45, 1359. Ullmann, B. 49, 2162 ; 2168. 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. 

4 By., 75,054; 77,818; 145,188; 158,531- M.L.B., D.R.P. 158,278 ; 
167,699. 

8 M.L.B., D.R.P. 167,699- 6 M.L.B., D.R.P. 158,278. 



288 ANTHRACENE AND ANTHRAQUINONE 

In some cases heating a nitroanthraquinone with potas- 
sium carbonate in nitrobenzene solution leads to a dianthra- 
quinonyl ether. 1 

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 hydroxyl 
groups during nitration. On sulphonation the alkyl ethers 
are dealkylated, but the aryl ethers are more stable and can 
be sulphonated in the aryl group. 2 

The methyl ethers of the a-hydroxyanthraquinones show 
considerable tendency to form oxonium salts such as hydro- 
bromides, zincibromides, and perchlorates. 3 The hydro- 
bromides, however, are unstable and readily undergo 
spontaneous demethylation. 

1 Agfa, D.R.P. 283,482. 2 By., D.R.P. 164,129. 

3 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 ws-carbon 
atom of the anthracene residue forms part of the pyridine 
ring, and compounds in which the p3^ridine ring is fused 
into one of the benzene rings of the anthracene nucleus, 
both ws-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 

Anthraquinoline Anthraquinonequinoline 

I (N).2-Pryidinoanthracene. i .2(N)-Pyridinoanthraquinone. 
289 j 



2go 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 





CO 

Py r anthridone . 



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 : l 






or 



A similar reaction is also brought about when the a-acetyl 
amino compound is heated with a formate or acetate, 2 or 
with an acid chloride such as sulphuryl chloride or phos- 

* In the literature the term usually 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. 

2 B.A.S.F., D.R.P. 191,111 ; 192,970. By., D.R.P. 209,033, 



PYRIDINE AND QUINOLINE DERIVATIVES 291 

phorus oxy chloride. 1 In a great many cases it is not 
necessary 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 anhydride and concentrated 
sulphuric acid or oleum. 3 

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. 4 Under these conditions the pyridoneanthrone 
carboxylic acid is first formed, but this readily passes into 
the pyridanthrone itself by loss of carbon dioxide : 

CO 

CH(|NH 

OX) 

CO 

Another variation consists in condensing an aryl sulphone 
acetyl chloride of the type ArSO 2 .CH 2 COCl with a primary 
or secondary a-aminoanthraquinone and then boiling the 
product with aqueous alcoholic alkali. 5 Under these con- 
ditions the arylsulphone group is split off, and at the same 
time the pyridine ring is closed, the product being a hydroxy- 
pyridone anthrone : 

ArS0 2 CH 2 ( 

H HOC 






Pyridoneanthronepyridinium chlorides are obtained when 
a-chloracetylaminoanthraquinones are treated with pyridine, 
formation of the pyridinium chloride and of the pyridone 
ring taking place simultaneously 6 : 

* B.A.S.F., D.R.P. 198,048. 2 By., D.R.P. 209,033. 

3 B.A.S.F., D.R.P. 198,025 ; 200,015. 4 M.L.B., D.R.P. 250,885, 

5 M.L.B., D.R.P. 284,209. By., D.R.P. 290,984. 



292 ANTHRACENE AND ANTHRAQUINONE 

Phf!lCH 2 





CO 

Other tertiary bases behave in the same way. 

The C-alkyl and aryl pyridanthrones can be obtained by 
condensing a primary a-aminoanthraquinone with a ketone 
which has at least one methyl group directly attached to 
the carbonyl group, 1 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 
i.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 compounds prepared from 
primary aminoanthraquinones by all the above methods 
except the last can be regarded either as pyridoneanthrones 
or as hydroxypyridanthrones (see formulae on p. 290), 
although those prepared from secondary aminoanthra- 
quinones must have the pyridone structure. Those prepared 
from the primary aminoanthraquinones are probably 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 
pyridanthrones. 5 In them the chlorine atom is very 

1 By., D.R.P. 185,548. a B.A.S.F., D.R.P., 198,025; 200,015. 

3 By., D.R.P. 185,548. 4 M.L.B., D.R.P. 256,297. 

5 By., D.R.P. 264, cio. 



PYRIDINE AND QUINOLINE DERIVATIVES 293 

reactive and is readily replaced by a hydroxyl group by 
boiling with 10 per cent, alcoholic alkali, 1 and by an aryl- 
amino 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 primary secondary amine, 3 or by 
condensing a Bz. -halogen or Bz.-aminopyridanthrone with 
halogen compounds or amino compounds. 4 Some of the 
products thus obtained have been described as vat dyes 
and their sulphonic acids as acid wool dyes, 5 but they do 
not seem to have found any technical application. 

II. THE ANTHRAQUINONK QUINOUNES 

There are three possible anthraquinone quinolines 
(pyridinoanthraquinones) viz. : 



u 

CO 



i (N).2-Pyridinoanthra- 2.3-Pyridinoanthra- 2(N).i-Pyridinoanthra- 
quinone, 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 under 
special conditions. Mejert 6 claimed to have obtained a 
quinoline from aminoanthraquinone by 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. 

3 By., D.R.P. 201,904. B.A.S.F. 205,095. 

4 B.A.S.F., D.R.P. 217,395-6 ; 218,161. By., D.R.P. 194,252. 

5 By., D.R.P. 194.253 i 233,126. 6 D.R.P. 26,197. 






294 ANTHRACENE AND ANTHRAQUINONE 

be accepted with considerable reserve. Bally l was unable 
to obtain a quinoline from a-aminoanthraquinone by 
carrying 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 sulphuric 
acid, and if nitrobenzene sulphonic acid is used as an 
oxidising agent. 2 By this means i(N).2-pyridinoanthra- 
quinone has been obtained from a-aminoanthraquinone and 
i(N).2.5(N).6-dipyridinoanthraquinone has been obtained 
from i.5-diaminoanthraquinone. In the case of j3-amino- 
anthraquinone the tendency to form a benzanthrone com- 
pound 3 is so great that it is almost impossible to obtain 
the pyridinoanthraquinone. A small amount of a substance 
which melts at 322, and which has the formula Ci 7 H 9 O 2 N, 
is obtained, however, and this is probably 2.3-pyridino- 
anthraquinone 4 although it has never been properly investi- 
gated. The third isomer, 2 (N) . I -pyridinoanthraquinone is best 
obtained from the corresponding 2(N).i-pyridinoanthracene 
(anthraquinoline) by oxidation by chromic acid. 5 The pyridi- 
noathracene can be obtained by distilling Alizarin Blue with 
zinc dust, 6 or from j3-anthramine by Skraup's method. 7 

The pyridinoanthraquinones have been but little in- 
vestigated, although a certain amount of work has been 
recorded in connection with the technically important 
hydroxy derivatives. All three isomers are smoothly 
nitrated, the nitro group entering the benzene ring to which 
the quinoline group is not attached. 8 Dinitro compounds 
do not appear to have been described. 

The hydroxyanthraquinone quinolines can be obtained 
from the corresponding aminohydroxyanthraquinones by 
Skraup's method, and by this means quinolines have been 
prepared from 3-aminoalizarin, 9 4-aminoalizarin, 10 amino- 

1 B. 38, 194- 2 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. 6 Graebe, A. 201, 344. 

' Graebe, B. 17, 170. Kniippel, B. 29, 708. 

8 B.A.S.F., D.R.P. 218,476. 

9 Prud'homme, Bl. 28, 62. Graebe, B. 11, 522, 1646 ; 12, 1416 ; 15, 
1783 ; A. 201, 333. Kniippel, B. 29, 708. Auerbach, Chem. Ztg. 3, 525, 
682. Cf. Ort, M.L.B., D.R.P. 62,703. 10 M.L.B., D.R.P. 67,470. 



PYRIDINE AND QUINOLINE DERIVATIVES 295 

flavopurpurin, aminoanthrapurpurin, l aminoquinalizarin, 2 
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 



1 

Ali2 


OH 
.XT pfl 


1 

Al 


OH 
xCH OH 


< 1 

X CH=CH 

arin Blue. 


( 1 
X N=CH 

izarin Green. 



HO 



/ 



Alizarin Black P. 



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 j8-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, 4 who 
states that 3.7-dihydroxy-i.2(N)4.5(N)-dipyridinoanthra- 
quinone is obtained when 8-hydroxyquinoline-6-carboxylic 
acid is heated with concentrated sulphuric acid and phos- 
phorus pentoxide. He describes it as an orange vat dye. 
Other dipyridinoanthraquinones have also been described. 5 




Hydroxyl 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. 2 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. e 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 hydroxylation by oxidation. 
If Alizarin Blue is oxidised under carefully controlled 
conditions, e.g. by 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 compound (Alizarin Indigo Blue) are obtained 2 : 

HO OH HO OH 

OH HO IOH 



,N=CH 



HO 
Alizarin Green X. 



HO 



^CH-CH 



Alizarin Indigo Blue. 



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 united to the quinoline ring and not to 
the cyclic carbonyl groups. 4 

1 By., D.R.P. 171,836. 

2 Graebe and Philips, A. 276, 21. B.A.S.F., D.R.P. 46,654 ; 47,252. 

3 B.A.S.F., D.R.P. 17,695 ; 23,008. 

4 Brunck and Graebe, B. 15, 1783. 



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 intermediate in structure between 
the pyranthrones (p. 335) and the flavanthrones (p. 300), 
and were studied by Scholl during his 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. 

2 B. 51, 441 . D.R.P. 307,399. Cf. 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 acid, 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'-methyl-i.2.a.j3-pyridanthrone anthraquinone. These 
two compounds had obviously been formed from two of the 
dianthraquinonyls thus : 





' 2- Mef hy I -l-Z<|3-py rip/cm throne 

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 
yellow vat dye although the tinctorial properties were very 
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 : 

CO 





OH 

Red product. 



OH 
Blue product. 



PYR1DINE AND QU INOLINE DERIVATIVES 299 

The chief interest attached to methylpyridanthrone- 
anthraquinone lies 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 powerful vat dye which dyes in orange-red shades 
which are somewhat yellower than those obtained from 
pyranthrone itself, but much redder than those obtained from 
flavanthrone. Its bromo derivatives are also orange-red dyes. 
Pyranthridone when reduced by sodium hydrosulphite 
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 
pyranthridene itself : 



H H 




H H 

Dihydropyranthridene. 




Pyranthridene. 



300 ANTHRACENE AND ANTHRAQUINONE 

V. THE FI.AVANTHRONES * 

When /2-aminoanthraquinone is fused with caustic alkali 
a mixture of the reduction products of indanthrone and 
flavanthrone is obtained, 1 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 jS-aminoanthraquinone is heated with aluminium 
chloride without a solvent at 250-280 considerable 
quantities of flavanthrone are obtained. 4 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. 5 The 
best method, both for laboratory and for manufacturing 
purposes, of obtaining flavanthrone is to boil j8-aminoanthra- 
quinone with antimony pentachloride in nitrobenzene 
solution. 6 

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. 7 He 
started with 2.2'-dimethyl-i.i'-dianthraquinonyl and first 
oxidised this to the corresponding dicarboxylic acid. This 
he then converted into its amide and then endeavoured to 
obtain diaminodianthraquinonyl from this by Hofmann's 
method. In this he was not successful as the diamino- 
dianthraquinonyl 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. 

1 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. 

5 B.A.S.F., D.R.P. 138,119; 206,464. 

6 Scholl, B. 40, 1691. B.A.S.F., D.R.P. 138,119. 
' B. 41, 1691. 



PYRIDINE AND QUINOLINE DERIVATIVES 301 
CO CP 





At a later date Scholl 1 showed that i.i'-dianthraquinonyl 
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. Benesh 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 catalyst and 
splits out two molecules of hydrobromic acid, the product 
being indanthrone (see p. 345). If this catalytic effect 
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, 4 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 / -diamino-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 

1 B. 43, 1740. 2 M> 32> 447 . 

B. 40, 1699, 4 B. 51, 452. 



302 ANTHRACENE AND ANTHRAQUINONE 

to the blue vat of flavanthrone. This method of preparing 
flavanthrones has been used by Ullmann l 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 subsequently 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 tetraminodihydroxy compound, 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 4 
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 110 and rapidly 
at 150. It gives a disodium salt but only a monobenzoyl 
derivative, and this monobenzoyl derivative is insoluble in 
alkali. Scholl therefore concludes that in the blue vat 
there is only one true hydroxyl group present, and represents 
the hydrate by formula I and its disodium salt by formula II : 





CO 
I. Flavanthranol hydrate. 6 

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. 
* Caledon Yellow G (Scottish Dyes, Ltd.). 3 B. 43, 340. 

4 B. 41, 2304, 2534. c f- Potschiwauscheg, B. 43, 1748. By., D.R.P. 
139,634. 5 Dihydroflavanthrene hydrate (Scholl). 



PYRIDINE AND QUINOLINE 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. Scholl represents them by 
formulae III, IV, V, and VI : 




IH. F/avan-fhrcxcfuinol Hydrate 
OH 





OH 

hrercfuino/ Hydrate. 2 



V Flavcmfhrenol Hydrate. 3 ' VI. Flctvomthrene Hydrate. 4 

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 
(formulae VII and VIII). 

OH CO 





Dihydroflavanthranol. 6 



1 a-Tetrahydroflavanthrene hydrate (Scholl). 2 a-Hexahydroflavan- 
threne hydrate (Scholl). 3 Flavanthrinol hydrate (Scholl). 4 Flavan- 
thrine hydrate (Scholl). 5 ^-Tetrahydroflavanthrene (Scholl). 



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 : 




IX. jS-Dihydroflavanthraquinol. 1 

When the reduction of flavanthrone with hydriodic acid 
and phosphorus is carried out at 200 flavanthrene hydrate 
(formula 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 by 
heating with ammonia, and then boiling this with antimony 
pentachloride in nitrobenzene solution. 3 Nothing is known 
of its structure, but it is improbable that it is a flavanthrone. 

1 ^-Hexahydroflavanthrene (Scholl). z Flavanthrine (Scholl). 

3 G.C.I.B., D.R.P. 230,455. 



CHAPTER XIV 

THE ACRIDONES, XANTHONES, 
AND THIOXANTHONES 

I. THE ACRIDONES * 

THE anthraquinone acridones are almost invariably obtained 
by loss of water from arylaminoanthraquinones or dianthra- 
quinonylamines in which there is a carboxyl group in the 
ortho- position to the imino group, although this carboxyl 
group may be either in the anthraquinonyl group or in the 
aryl group. Such carboxylic acids can be obtained (a) by 
condensing an o-aminoanthraquinone carboxylic acid with 
an aromatic halogen compound or halogen anthraquinone ; 

(b) by condensing an o-halogen anthraquinone carboxylic 
acid with a primary aromatic amine or aminoanthraquinone ; 

(c) by condensing an aminoanthraquinone with an aromatic 
o-halogen carboxylic 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 
0-chlorbenzoic acid and anthranilic acid. When the con- 
densation is being carried out with o-chlorbenzoic acid 
Ullmann l finds that improved yields are obtained by using 
the methyl ester in place of the free acid. In cases in which 
the carboxyl group is attached to the anthraquinone nucleus 
(methods (a) and (b)) the use of sodium acetate as a 

* These can be named either as anthraquinone acridones or aa phthaloyl 
acridones, and both methods of nomenclature are in use. 
1 B. 51, 9. Cf. M.L.B., D.R.P. 254, 475. 

305 20 



306 ANTHRACENE AND ANTHRAQUINONE 

condensing agent often leads to very poor yields 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, 2 but in many 
cases it is sufficient to boil the carboxylic acid with some 
indifferent solvent of high boiling point, such as nitro- 
benzene, 3 with or without the addition of acetic anhydride 
or acetyl chloride. 4 The fact that the acridone ring can 
sometimes be closed merely by boiling with a solvent has 
enabled Eckert and Halla 5 to obtain an acridone by boiling 
i-aminoanthraquinone-2-carboxylic acid with j8-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 6 in many cases 
prefers to convert the carboxylic 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- 
quinonylamines when oxidised in alkaline solution pass 
into the corresponding carboxylic acid, from which simulta- 
neous loss of water takes place with the immediate pro- 
duction of the acridone. 8 In a very similar way o-methyl- 
arylamino anthraquinones, in which the methyl group may 
be either in the anthraquinone residue or in the aryl group, 

1 B.A.S.F., D.R.P. 268,219. 

8 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. 

a B.A.S.F., D.R.P. 248,170. Ullmann, B. 47, 748. M. 35, 755. 

A. 381, i. B. 43, 538 ; 47, 553, 562. D.R.P. 221,853. 

J 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 
sulphury 1 chloride. 1 Schaarschmidt, 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 aryl 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 carboxylic 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-carboxylic acid by 
warming on the water-bath in aqueous solution, and then 
closing the ring by heating with sulphuric acid 4 : 



CO OH 



CO 




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 arylamino- 
anthraquinone. The isatin is then converted into the 
acridone by treatment with aluminium chloride, sulphuric 
acid or alkali 5 : 

1 B.A.S.F., D.R.P. 272,296 ; 275,671 ; 283,724. 

2 A. 405, 95. D.R.P. 269,800. 

3 B. 49, 735 ; 50, 164, 403, 1356, 1360, 1526. 

4 Cas., D.R.P. 280,712. 6 By., D.R.P. 286,096, 



308 ANTHRACENE AND ANTHRAQUINONE 




In all the above methods the acridone ring is closed 
through the carbonyl 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 orfho- 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- 
pounds like 2-0-chlorbenzoyl-i-chloranthraquinone pass 
directly into the acridone when treated with toluene-^- 
sulphonamide. 1 

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 78 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 i.5-dichloranthraquinone and condensing this 
with anthranilic acid, Ullmann and Billig 3 were able to obtain 
a compound containing two acridone groups (formula I.), 
but from i.4-dichlor anthraquinone could only obtain a 
compound containing one anthraquinone ring, and only a 
monoacridone was obtained from i.4-diaminoanthraquinone 
and ochlorbenzoic acid. 4 From this it would appear that 
two carbonyl groups in the ortho- position hinder one another 
( c f- P- 337) > but Schaarschmidt 5 claims to have obtained 
a compound corresponding to formula II by his nitrile 
method : 

1 B.A.S.F., D.R.P. 272,297. * B.A.S.F., D.R.P. 253,090. 

8 A. 381, i. 4 M.L.B., D.R.P. 243,586. 

5 A. 405, 95- 



THE ACRIDONES 



309 



/ co \ 

'\NH/ 



\CO/ 



C 6 H 4 



\CO/ 

/ C0 \ 
\NH/ 



I. 



II. 



An acridone containing two anthraquinonyl residues 
(i.2.5.6-diphthaloyl acridone) is obtained by oxidising 
2 - methyl -1.2'- dianthraquinonylamine, 1 and Schaar- 
schmidt 2 has obtained the same substance by his nitrile 
method : 



CH 3 
NH 



/ C0 \ 



CN 



NH 



Both in the patent and in Schaarschmidt's paper this is 
described as an orange-red vat dye. On the other hand, 
Bckert and Halla 3 prepared the substance by two methods, 
viz. (i) by condensing i-aminoanthraquinone-2-carboxylic 
acid with -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. 



. 35, 755. 



a A. 405, 95, 



3io ANTHRACENE AND ANTHRAQUINONE 





1 


1 


?H 2 
COOH Cl 








NH 
-COOH 








/ NH \ 

\co/ 




1 


+ 


1 


" 


1 




1 


-> 


1 





NH 2 

OOH Br 



PhCH : N 



- 

PhCH : N 



\COOH 



PhCH : N 





1 




/NH\ 




' 


\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 
Kckert and Halla's first synthesis the ring might close in 
two ways, giving either 





1 


/NH\ 






\CO/ 




1 





or 



/ 



NH- 



CO- 



The second synthesis, however, leaves no doubt that the 



THE ACRIDONES 



former structure is the correct one. In the patented method 
two alternatives are also possible : 



\CO/ 





1 




/NH 




1 


\CH 3 





/NH 
\CO 



but as the product is different from that obtained by Kckert 
and Halla the latter must be the correct one. This con- 
clusion is supported by the preparation of an acridone by 
Ullmann l by condensing i-chloranthraquinone-2-carboxylic 
acid with j3-aminoanthraquinone. Here again two alterna- 
tives are possible : 



/NH 
\CO 



NH 
-COOH 





1 


/ NH \ 




1 


\co/ 





but as the product formed is an orange vat dye it must be 
concluded that the former structure is correct. It is 
difficult 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 by arylamino or anthraquinonyl amino 
groups by heating with primary aromatic amines or amino- 
anthraquinones in the usual way, 2 and the same compounds 

1 B. 47, 553. a Ullmann and Billig, A. 381, i. B. 43, 538- 



312 ANTHRACENE AND ANTHRAQUINONE 

can also be obtained by condensing an aminoacridone with 
a halogen compound. 1 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 j8- 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 ex- 
position the product dyes in very bluish shades of red and 
the dyeings ar^ 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, 3 who prepared all three isomeric monophthaloyl 
acridones : 



\CO/ 



/ co \ ( 

\NH/ 



-co 



NH 



Bluish-red. Orange. Brownish-yellow. 

Only the first of these (Indanthrene Red BN Extra 4 ) 
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 5 : 

1 M.L.B., D.R.P. 239,543. z B.A.S.F., D.R.P. 287,614-5. 

3 A. 381, i ; B. 43, 538 ; 47, 553, 748. Cf. Schaarschmidt, A. 405, 95. 
By., D.R.P. 286,095. 

4 Caledon Red (Scottish Dyes, Ltd.). 6 B.A.S.F., D.R.P. 234,977. 



THE ACRIDONES 



313 



CH 



/ C0 \ 



\CO/ 



C 6 H 4 



Indanthrene Violet RN Extra. 1 

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 anthraquinone acridones thus behaving like the 
indigoid and thioindigoid dyes. 3 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 frequently obtained by 
the introduction of an aryl mercapto group. 5 

In the case of acridones in which the heterocyclic ring 
lies between two anthraquinone ring systems (diphthaloyl 
acridones), the colour seems to depend very largely on con- 
stitution, as will be seen from the following formulae : 





1 


/ co \ 




1 


\NH/ 





Bluish- violet. 1 



\CO/ 



Violet.' 



CO 



NH- 



Orange. 8 



1 Caledon Violet RN Extra (Scottish Dyes, Ltd.). 

2 Schaarschmidt, A. 405, 95- B.A.S.F., D.R.P. 242,063. 

8 Ullmann, B. 51, 9. Cf. Ullmann, B. 49, 2168. M.L.B., D.R.P. 
239,543; 243,586; 256,626. 

4 B.A.S.F., D.R.P. 263,078. B.A.S.F., D.R.P. 248,996. 6 See p. 309. 
T Eckert and Halla, M. 35, 755. 8 Ullmann, B. 47, 553, 562. 



314 ANTHRACENE AND ANTHRAQUINONE 



/NH 
\CO/ 



/ C0 \ 
\NH/~ 



Reddish- brown. 1 



CO 



\ 



\NH/ 



Reddish-brown. : 



/ NH \ 
\CO/ 



CO 



\ 



\NH' 



Blue. 1 



Very little is known of the anthraquinone acridines, 
but Ullmann 2 by heating 2.2'-dihydroxy-i.i'-dianthryl- 
methane with ammonia obtained a diantbrylacridine which 
on oxidation passed into the anthraquinone acridine : 



/OH HO\ 



Vr- 

\CH/ 

This was found 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 

Closely related to the acridones and acridines are the 

1 Schaarschmidt, A. 405, 109. a B. 45, 2259. 

3 B.A.S.F., D.R.P. 269,194. 



THE XANTHONES 



315 



bluish-green vat dyes which are obtained, by condensing 
two molecules of an aminoanthraquinone with one molecule 
of 0-chlorbenzaldehyde. 1 



II. THE XANTHONES 

The anthraquinone xanthones (phthaloylxanthones) are 
rather troublesome to prepare, as attempts to condense a 
halogen anthraquinone with salicylic acid generally leads to 
loss of the carboxyl 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 : 



/OC 6 H 4 CHO 



-- -\ 

HOCO/ 



\co/ 



The method, however, is not a very satisfactory one, as 
the aldehyde is extremely stable and very difficult to oxidise. 
In the above case, for example, the aldehyde could only be 
oxidised by boiling it for five hours with chromic acid in 
a mixture of glacial acetic acid and sulphuric 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 pentachloiide. The 
xanthone is then obtained by subsequent oxidation : 2 



OH HO/ 



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. 
8 Ullmann and Urmenyi, B. 45, 2259. 



3i6 ANTHRACENE AND ANTHRAQUINONE 

/ CO X 



O 



The condensation of the anthrol with formaldehyde 
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. Acet aldehyde 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\vCH. 



/ C0 \ 
\0/1 



Benzaldehyde also condenses with j8-anthrol, but in 
this case subsequent oxidation of the phenyl xanthene leads 
only to the anthraquinone phenyl xanthene (diphthaloyl 
phenyl xanthene) : 



H\ /C 6 H 
X 




/ \ 

\0/ 




1 




1 



The xanthones can also be obtained by condensing an 
o-chloranthraquinone carboxylic acid with a phenol, and then 
closing the xanthone ring by treatment with phosphorus 
pentachloride l : 

* UUmann, B. 47, 566. B.A.S.F., D.R.P. 251,696. 



THE THIOXANTHONES 317 



COOH 



-O 



C 



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 carboxyl group is present in the ortho- position to 
the sulphur atom. This carboxyl 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 o- 
halogen anthraquinone carboxylic acid with a mercaptan, 1 
or the carboxyl group may be present in the aryl group. 
In this case the sulphide can be prepared by condensing an 
anthraquinone mercaptan with an ohalogen 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 4 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. 

2 Ullmann, B. 43, 539; 44, 3125. Frey, B. 45, 1361. By., D.R.P, 
216,480. B.A.S.F., 234,977. 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 

243.75. 

* 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. 1 They can be converted into arylamino- 
and anthraquinonylamino-anthraquinone thioxanthones by 
treatment with a primary aromatic amine or aminoanthra- 
quinone. 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 dyes the replacement of the cyclic imino 
group by a sulphur atom is accompanied by a shifting of 
the colour towards the red end of the spectrum, and a 
precisely 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 sulphur atom is in the a- position are more highly 
coloured than the isomeric substances in which the sulphur 
atom is in the )3- position : 



/ co \ 
\s/ 



:C 6 H 4 



Yellow. 



s 
\co 



Orange. 



C 6 H 4 



\co/ 



s \ 

\co/ 



Red. 



1 Ullmann, D.R.P. 242,386. B.A.S.F., 258,561. 
a Ullmann, D.R.P. 242,386. Cf. M.L.B., D.R.P. 231,854 ; 248,996. 
8 Schaarschmidt, D.R.P. 250,271-2. Cf. M.L.B., D.R.P. 243,587 
248,469. 



THE THIOXANTHONES 



319 



/ 



C 6 H 



/ C0 \ 



/ S \ 
\CO/ 



/ C0 \ 

\s/ 



/ s \ 

\co/ 



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 

g.io-Benzanthrone. 

The chemistry of the benzanthrones has become ex- 
tremely important during recent years, owing to the very 
valuable tinctorial properties exhibited by some of the more 
complex members. 

I. SIMPLE BENZANTHRONES 

The discovery of the benzanthrones originated in the 
observation 1 that only very little anthraquinonequinoline 
(pyridinoanthraquinone) is obtained when j3-aminoanthra- 
quinone is treated with glycerine, sulphuric acid and an 
oxidising agent (Skraup's quinoline synthesis), the main 
product of the reaction being a compound which melts at 
251, and which has the formula C 20 H n ON. The same 
compound is obtained by treating anthraquinone quinoline 
with sulphuric acid and glycerine, 2 and Bally and Scholl 3 

1 B.A.S.F., D.R.P. 171,939. 2 Bally, B. 38, 194. 

8 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 C 17 H 10 O. 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- 
carboxylic 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, 2 1.2- 
benzanthraquinone, 3 hydroxyanthraquinones, 4 halogen 
anthraquinones, 5 and other anthraquinone derivatives, 
provided always 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. 7 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. 8 
The mechanism of benzanthrone formation has been discussed 
by Bally and Scholl, 9 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 Scholl, 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.R, D.R.P. 181,176. 

4 B.A.S.R, D.R.P. 187,495. A. G. Perkin, Soc. 117, 697. 

5 B.A.S.R, D.R.P. 205,294. 6 B.A.S.R, D.R.P. 176,018, etc. 
B.A.S.R, D.R.P. 176,019. 8 B.A.S.R, D.R.P. 283,066. 

9 B. 44, 1656. 

21 



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. 

/L/JuL '. LJii.2 
\/ 



HOCH CH : CH 2 HC 



C 6 H 4 <(| 



CH C C 

]\C 6 H 4 -> C 6 H 4 /|)>C 6 H 4 -> C 6 H 4 /\< 
COH COH CO 




In place of glycerine it is, of course, possible to use 
mono- or di-chlorhydrin, epichlorhydrin, triacetin, 1 etc., 
and Jacob Meyer 2 has prepared benzanthrones by 
condensing anthraquinone with ketones of the type 
R.COCH 3 . 

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 
highly condensed benzanthrone, anthranthrone, by loss of 
two molecules of water from i.i'-dinaphthyl-8.8'-dicarboxylic 
acid, or from ia'-dinaphthyl-2.8-dicarboxylic acid, 3 the 
product being an orange-yellow vat dye. 

1 B.A.S.F., D.R.P. 204,354. 2 D.R.P. 247,187. 

Kalb, B. 47, 1724. Cf. Weitzenbock, M. 39, 307. 



THE BENZANTHRONES 



323 






CO 1 



Schaarschmidt l extended the method by showing that 
allochrysoketone (34-benzfluorenone) on fusion with caustic 
potash gives two monocarboxylic acids, one of these by loss 
of water passing back into allochrysoketone, whereas the 
other yields benzanthrone : 



COOH 





He also found that i-phenylnaphthalene-2.3-dicarboxylic 
acid by loss of water gave both allochrysoketone carboxylic 
acid 2 and benzanthrone carboxylic acid, 3 the latter acid 
being obtained by heating for three hours with sulphuric 
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 by 
loss of water in another direction : 





COOH 



COOH 



COOH 



In confirmation of this Schaarschmidt showed that the 
cyclic imide of i-phenylnaphthalene-2.3-dicarboxylic acid 
can be converted into the amide of allochrysoketone car- 
boxylic acid, and that this in turn gives the amide of the 
benzanthrone carboxylic acid. This method of preparing 



B. 51, 1082. 



B. 48, 1827. 



3 B. 50, 294 ; 51, 1074. 



324 ANTHRACENE AND ANTHRAQUINONE 

benzanthrones is not invariably successful. Thus, starting 
with the fluorenone derivative (I) Schaarschmidt J en- 
deavoured to prepare the benzanthrone derivatives (II), but 
was not successful as the product obtained was the 
isomeric fluorenone (III) : 




m 



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, 2 
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 anhydrous 
aluminium chloride to about 140, the two carbon atoms 
in the peri- position to one another becoming united. 
Thus, phenyl-i-naphthyl ketone (a-benzoyl naphthalene) 
gives benzanthrone itself, o- and ^>-tolyl-i-naphthyl ketone 
give the corresponding methyl benzanthrones, the new 
bond being shown in the formulae as a dotted line : 






CH 3 | 
CO CH S CO CO 

In the case of w-tolyl-i-naphthyl ketone, two possible 
isomers (A^and B) might be formed : 

i B. 51, 1230. 2 Scholl, A. 394, in ; B. 44, 1656 ; M. 33, i. 



THE BENZANTHRONES 



3*5 



CH 3 




CH 3 




CO 
A 



CO 
B 



As the compound obtained is identical with that obtained 
from 2-methylanthrone by the glycerine method, 1 formula A 
must be the correct one. 

Benzanthrone on reduction 2 with sodium hydrosulphite 
yields dihydrobenzanthrone (I), which is very sensitive to 
oxidation by atmospheric oxygen. Further reduction leads 
to benzanthrene (II or III), and then to dihydrobenzan- 
threne (IV or V) : 




CH 



IV 



This last compound is identical with the *'so-chrysofluorene 
which Graebe 3 obtained by passing benzyl naphthalene over 
red-hot pumice. 

When benzanthrone is halogenated 4 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 Ite.-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.). 

2 Bally and Scholl, B. 44, 1656. B< 27 953< 

4 B.A.S.F., D.R.P. 193,959. 



326 ANTHRACENE AND ANTHRAQUINONE 

The majority of the benzanthrone dyes are of complicated 
structure and are treated elsewhere in this chapter, but 
orange and brown vat dyes have been claimed as being 
obtained by condensing halogen benzanthrones with primary 
aromatic amines, or by condensing aminobenzanthrones with 
halogen compounds. l A black vat dye of unknown 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 011 the addition of water. From 
benzanthrone itself, however, a crystalline ferrichloride, 
stannichloride and platinichloride can be obtained, and 
other benzanthrones form similar compounds. 3 In these 
the metal chloride is probably loosely joined to the carbonyl 
oxygen atom, and their formation is not surprising as similar 
double compounds are formed by other ketones. Thus, 
benzophenone and fluorenone both form nitrates by 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, 4 and the union of ketones with aluminium 
chloride is well known. 5 Phenanthraquinone, benzil and 
other ketones exhibit the same tendency to form addition 
compounds with metal chlorides 6 and perchloric acid, 7 
but in anthraquinone and its derivatives this tendency 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 usually well crystallised 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. 

3 A. G. Perkin, Soc. 117, 696. 4 Kurt Meyer, B. 43, 157. 

6 See p. 130. e Kurt Meyer, B. 41, 2568. 

7 K. A. Hofmann and Metzler, B. 43, 178. 



THE BENZANTHRONES 327 

up to the present. The dihydroxybenzanthrone (benzalizarin) 
obtained from alizarin has been prepared by Perkin, 1 who 
finds that both hydroxyl groups can easily be methylated 
by treatment with methyl iodide and caustic potash. Con- 
sequently benzalizarin is probably 7.8-dihydroxy-i.9-benz- 
anthrone : 




Curiously enough its tinctorial properties are very similar 
to those of alizarin, and a more detailed study of the hydroxy 
benzanthrones would probably lead to valuable information 
as regards the constitution of the hydroxy ketone dyestuffs. 

II. THE COMPLEX BENZANTHRONES 

The complex benzanthrones can be broadly divided into 
two classes, viz. derivatives of perylene and derivatives of 
pyrene. The former class comprises violanthrones, zso-violan- 
thrones, cyanthrones, and helianthrones, whereas the latter 
class comprises the pyranthrones. * In the following formulae 
the characteristic ring system is shown by heavy lines. 2 





CO 
Violcrnthrone. V/* iso-Viblcmffirone. 

1 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 dealing with 
the indanthrones (indanthrenes), the change in this case being particularly 
advisable owing to Indanthrene being a registered trade name. 



328 ANTHRACENE AND ANTHKAQUINONE 

CO CO 





CO 

Helianffirone 



CO 

Ipyrcmtlirone. 



The hydrocarbons, perylene and pyrene, themselves have 
been studied by Scholl. The former he obtained by heating 
naphthalene, or better i.i'-dinaphthyl, with anhydrous 
aluminium chloride. 1 The latter has, of course, been known 
for many years, but has also been investigated by 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, 2 he concludes that pyrene 
quinone must have formula I or II, and not formula III, as 
proposed by Bamberger, 3 and as usually given in the 
literature : 





t-o 




By oxidising dibenzoyl pyrene Scholl obtained what 
he thought was probably impure pyrene quinone, and there- 
fore he gives preference to formula I. Goldschmidt, 4 on the 
other hand, gives preference to formula II. 



1 B. 43, 2202. 

3 A. 240, 158. 



2 See p. 337- 
4 A. 351, 230. 



THE BENZANTHRONES 329 

VIOI,ANTHRONES. When benzanthrone is fused with 
caustic potash 1 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 
(Caledon Dark Blue B). 2 The constitution of the dye was 
definitely proved by Scholl, 3 who synthesised it by his 
peri- method by heating 4.4'-dibenzoyl-i.i'-dinaphthyl with 
aluminium chloride, 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 yet 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 union 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). 

3 Scottish Dyes, Ltd. 3 B. 43, 2208. 



330 ANTHRACENE AND ANTHRAQUINONE 





I H 

Benzwnfhrone. Nnphthmdenon. 




m 

Naphihinolandion. 





= c -co 




co-c 



c -co 



VI' 



A violanthrone is also obtained when the benzanthrone 
prepared from i.2-benzanthraquinone is fused with caustic 
alkali. It dyes in rather greener shades than violanthrone 
itself. Its structure, however, is doubtful, as i.2-benzanthra- 
quinone might form three isomeric benzanthrones. 6 

Nitration of violanthrone 7 yields a green vat dye, which 
was formerly known as Viridanthrene B, although the 
name was subsequently altered to Indanthrene Green B 
(Caledon Green B). 8 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 Kardos, D.R.P. 276,357-8; 276,956; 286,098. B.A.S.F., D.R.P. 
280,880. 

4 Kardos, D.R.P. 275,220 ; 278,660; 280,839; 282,711; 284,210. 

5 Kardos, D.R.P. 286,468. Cf. Graebe, A. 276, 17. 

6 B.A.S.F., D.R.P. 185,223. ' 

7 B.A.S.F., D.R.P. 185,222 ; 226,215. 

8 Scottish Dyes, Ltd. 



THE BENZANTHRONES 331 

without the nitro group being reduced. From nitroviolan- 
throne the corresponding amino- compound can be prepared, 
and this can be alkylated, arylated, 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. By heating this with a condensing 
agent such as boric acid at 160, however, it is converted 
into a powerful green dye, the tinctorial properties of which 
are improved by bromination, although the shade becomes 
somewhat yellower. 2 Violanthrone itself can be halogenated, 3 
the halogenated product being placed on the market as 
Indanthrene Violet RT. 

*so-Vioi,ANTHRONES. zso-Violanthrone is isomeric with 
violanthrone, and is obtained when brombenzanthrone is 
fused with caustic akali. 4 The patentees assigned to it 
formula I, but Scholl regards it as a perylene derivative and 
prefers formula II. 





I II 

Scholl 5 endeavoured to confirm his formula by effecting 
a synthesis of the dyestuff from dibenzoyl perylene by his 
peri- method, thus : 

1 B.A.S.F., D.R.P. 267,418 ; 268.224 ; 284,700. 

2 B.A.S.F., D.R.P. 259,370 ; 260,020 ; 280,710. 

3 B.A.S.F., D.R.P. 177,574- 

4 B.A.S.F., D.R.P. 194,252. 

5 B. 43, 2208. 



332 ANTHRACENE AND ANTHRAQUINONE 

CO 




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. 
z'so-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). 1 Its dichlor derivative is Indanthrene 
Violet RR Extra (Caldeon Brilliant Purple RR) l and its 
dibrom derivative Indanthrene Violet R Extra. 2 Its nitro 
derivative is of no value. 3 

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 /^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 : 6 




Its halogen derivatives have also been described. 6 

1 Scottish Dyes, Ltd. 2 B.A.S.F., D.R.P. 217,570. 

3 B.A.S.F., D.R.P. 234,749. 4 B.A.S.F., D.R.P. 171,939. 

5 Baely, B. 38, 196. B.A.S.F., 172,609. 6 B.A.S.F., D.R.P. 177,574. 



THE BENZANTHRONES 333 

A much more simple benzanthrone quinoline is obtained 
by condensing &.-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. 1 
The product is a green vat dye, although it is not used 
commercially : 




HEUANTHRONES. 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 
by 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 dihydroxy and 
tetrahydroxy derivatives. 3 

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 by the dotted line, should be formed 
by heating with aluminium chloride : 

1 B.A.S.F., D.R.P. 212,471. 

3 Scholl, B. 43, 1734. D.R.P. 190,799; 197,933. Cf. Eckert and 
Tomaschek, M. 39, 839. 

3 B. 44, 1091. -fcy. Seer, M. 34, 631. 



334 ANTHRACENE AND ANTHRAQUINONE 

CO 




wiS-Naphthadianthrone . 

This Scholl has found to be the case, and he has also prepared 
the same compound by distilling dianthraquinonyl with zinc 
dust. 1 Meyer, Bondy, and Eckert 2 claim that it is more 
readily obtained by exposing glacial acetic acid solutions of 
dianthrone to sunlight or ultra-violet light, but their observa- 
tions require independent confirmation as they deduce the 
formula from four analyses in which values obtained for 
carbon vary 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, 
Kckert and Tomaschek 4 describe several halogen derivatives 
which they 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 by Potschiwauscheg, 5 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 unknown constitution which are obtained by 

B. 52, 1829. 2 M. 33, 1451. 3 CO^H! O a requires C = 88' 4 , H=3'i6. 
4 M. 39, 839. * B> 43 



THE BENZANTHRONES 335 

the action of concentrated sulphuric acid and copper powder 
on anthraquinone derivatives. 1 They are probably helian- 
throne derivatives, although their structure has never been 
investigated. The brown and bronze vat dyes which are 
obtained from i.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, 3 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, synthetically, from the corresponding 
halogen dimethy Idianthr aquinony 1 . 4 

Pyranthrone formation also takes place when i.i'- 
dianthraquinonyl-2.2'-dialdehyde is reduced, e.g. with sodium 
hydrosulphite and the leuco-prodvLct thus formed then 
oxidised, 5 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 hydro- 
sulphite bath followed by oxidation. The corresponding 
dianthraquinonyl diketones also yield pyranthrones on 
reduction, e.g. 2. 2 '-dibenzoyl-i.i '-dianthraquinonyl gives 
dipheny Ipy ranthrone . 6 These diary Ipy ranthrones are yellow 
vat dyes, and Scholl has found that alkyl groups also 
decrease the colour. 7 The structure of pyranthrone was 
definitely established by Scholl by synthesis 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. 

3 Scholl, B. 43, 346, 512 ; 44, 1448, 1662 ; M. 32, 687. B.A.S.F., 
D.R.P. 174,494 ; 175,067; 212,019; 287,270. 

4 Scholl, B. 43, 352 ; M. 39, 231. B.A.S.F., D.R.P. 186,596 ; 211,927 ; 
218,162. 5 B.A.S.F., D.R.P. 238,980. 

6 B.A.S.F., D.R.P. 278,424. 7 M. 32, 687. 



336 ANTHRACENE AND ANTHRAQUINONE 

the mechanism of pyranthrone formation from 2.2'-dimethyl- 
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-n- 
propyl dianthraquinonyls should behave in exactly the 
same way, giving rise to dimethyl and diethyl pyranthrone. 
In the case of di-*'s0-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 by loss of water owing to the necessary hydrogen 
being absent. Scholl l 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 very similar to pyranthrone itself 
in their tinctorial properties although they give paler shades. 

The synthesis of pyranthrone and of many very 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 

i M. 32, 687. 2 A. 394, in ; M. 33, i. D.R.P. 239,671. 



THE BENZANTHRONES 



337 



aluminium chloride, and in this way 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) : 



CO 





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 found impossible, however, to cause these 
to unite, and it seems to be a general rule that in the case of 
six-membered rings pen- condensation cannot take place 
twice at the same side of the pyrene 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 jS-naphthoyl 
chloride with pyrene Scholl obtained dinaphthoyl pyrenes, 
which when heated with aluminium chloride passed into 
complex pyranthrones (III and IV) : 





nr 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-j3-naphthoyl 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, x and also that in the case of j8-anthraquinony 1- 
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-naphtrryl 
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 o 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) : 



co 





1 See p. 324. 2 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 formula VII is 
the most powerful. 

Pyranthrone itself on reduction in alkaline solution gives 
only 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 very unstable towards 
atmospheric oxygen, and Scholl l 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 hydrocarbon, pyranthrene, which is represented by 
formula X : 





X 



Brown and green dyes can be obtained by the nitration 
and reduction of pyranthrone. 2 



1 B. 43, 346. 

2 Scholl, B. 43, 346. By., B.R.P. 220,580. B.A.S.F., D.R.P. 268,504. 



CHAPTER XVI 

THE CYCLIC AZINES AND HYDRO- 
AZINES 

THE cyclic aziues and hydroazines of the anthraquinone series 
can be conveniently divided into two groups, viz. mixed 
compounds in which only one anthraquinone ring system 
is present, and simple compounds in which the azine ring lies 
between two anthraquinone residues. Of these two groups 
the latter has been studied most fully, as some extremely 
important vat dyes have been found to be simple anthra- 
quinone hydroazines. 

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 by condensing i.2-diaminoanthraquinone 
with ethyl oxalate. 1 Somewhat more complicated are the 
blue-black vat dyes which are obtained by condensing two 
molecules of an o-diamino anthraquinone with one molecule 
of glyoxylic acid by boiling in glacial acetic acid solution, 
or in alcoholic solution in the presence of a little sulphuric 
acid. 2 Their structure probably corresponds to formula II : 

N NH 
xv . 

1COH 





1 Ertl, M. 35, 1427. Scholl, B. 44, 1729. Terres, B. 46, 1644. 

2 G.E., D.R.P. 264,043. 

340 



THE CYCLIC AZINES AND HYDROAZINES 341 

The first of these compounds is of some interest, as it 
is also obtained by the oxidation of indanthrone. 

Mixed azines have been obtained by condensing both 
i.2-diaminoanthraquinone and 2.3-diaminoanthraquinone 
with a large number of a-diketonic compounds such as benzil, 
phenanthraquinone, /3-naphthaquinone and isatin. 1 With 
the latter substance under certain conditions yellow 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 obtained from i.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 
i.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. 3 

N-Substituted cyclic hydroazines are said to be obtained 
by condensing o-aminoarylamino anthraquinones with 
aldehydes and ketones, and it has been claimed that their 
sulphonic acids are blue wool dyes. 4 o-Aminoazo- com- 
pounds are also said to yield cyclic azines under certain 
conditions. 5 

Of greater importance is the cyclic azine synthesis devised 
by Ullmann. 6 He found that when an o-nitrophenyl-i- 
amino-anthraquinone is reduced with sodium hydrosulphite 
the corresponding primary amino- compound is formed, 
but that if the reduction is brought about by means of sodium 
sulphide an almost quantitative yield of the cyclic hydro- 
azine is obtained. The mechanism of this reaction consists, 
no doubt, primarily in the production of a hydroxylamine 
derivative, the azine ring being then closedlby loss of a mole- 
cule of water : 

1 Scholl, M. 32, 1043. Scholl and Kacer, B. 37, 4531. Terres, B. 46, 
1634. By., D.R.P. 170,562. 

2 By., D.R.P. 251,956. 

3 Scholl, M. 32, 1043. 4 iBy., D.R.P. 184,391 ; 252,529. 
5 M.L.B., D.R.P. 230,005 ; 232,526. ft ^A. 380, 324. 



342 ANTHRACENE AND ANTHRAQUINONE 




A somewhat similar synthesis has been devised by Ull- 
mann and Medenwald l who obtain azines by oxidising 0- 
aminoaryl 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 acetyl groups, 2 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 hydroazines pass into 
the corresponding azine. These are yellow compounds 
and are much more stable than the hydroazines. 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 very 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. &tsflwg.-anthraquinonedihydro azine. This was 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 " indan throne " is used to denote the ketonic hydroazine, indanthrene 
(without a capital) being used for the parent, oxygen free hydroazine 
(trans. &isag r .-dihydroanthrazine). 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 alizarin, best by heating with boric acid 
and a solvent of high boiling point, 1 or with i.2-anthra- 
quinone. 2 In the latter case, of course, the product is an 
anthracene anthraquinone azine (trans, fo'sflwg.-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 nit ro- compound, oleum or sulphuric 
acid and manganese dioxide. 3 r The o-nitrodianthraquinonyl- 
amines also give cyclic hydroazines on reduction with 
sodium sulphide, although in this case it is necessary to 
carry out the reduction by fusion with crystallised sodium 
sulphide, as treatment with aqueous solution leads only to 
brown substances of unknown constitution. 4 Better results 
are usually obtained by reducing 2 -dinitrodianthraquinonyl- 
amines with stannous chloride and hydrochloric acid in 
acetic acid solution, one nitro group being split out. 5 This 
method is of very general application for the preparation of 
azines and by it phenazine itself can be obtained in excellent 
yield from 2 -dinitrodiphenylamine. 6 

From a practical point of view by far the most important 
method of obtaining the indanthrones is by fusing the 
j3-aminoanthraquinones with caustic alkali, and this method 
has been very widely applied not only to j8-aminoanthra- 
.quinone itself, 7 but also to diaminoanthraquinones 8 and 
/3-aminoanthraquinone sulphonic acids, 9 although in the 
latter case the sulphonic acid group is often lost. Even 
j8-anthramine is said to yield a cyclic hydroazine (anthrazine) 
when fused with caustic alkali. 10 The anthraquinonyl-/?- 
hydroxylamines, however, do not give cyclic azines. 11 

1 By., D.R.P. 178,130. 

2 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. 

Eckert and Steiner, M. 35, 1129. 

Eckert, 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. 

8 B.A.S.F., D.R.P. 157,685. 

9 B.A.S.F., D.R.P. 129,846. 

10 By., D.R.P. 172,684. Cf. B. 34, 3410. " M. 32, 1035. 



344 ANTHRACENE AND ANTHRAQUINONE 

The mechanism of the conversion of j3-aminoanthra- 
quinone into indanthrone is not understood. At one time 
it was thought probable that the first product formed was 
a hydrazo compound, and that this then underwent an 
o^Ao-semidine rearrangement. This, however, can hardly 
be the case, as it has been found that no indanthrone is 
formed when j3-azoxyanthraquinone 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 ordinary form, the azine ring 
being completed by a second condensation of a similar 
nature : 



OH 




OH 



OH 



Theories of this nature, however, are merely speculative and 
lack experimental verification. 

In the alkali melt of j8-aminoanthraquinone the ind- 
anthrone is not present as such but as its reduction product 
(vat), from which, however, the indanthrone is readily 
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 almost exclusively produced. 1 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 3 claiming the production 
of indanthrone by oxidising j3-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- 
quinones by treating them with halogens, 4 or by 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. 6 The 
yields, however, are usually very poor although the last 
method has been extended to the preparation of complex 
indanthrones from aminobenzanthrones and arnino- 
benzanthrone quinolines. 7 

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 
0-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 8 : 

1 B.A.S.F., D.R.P. 135,408. 

2 Morton, Dandridge, 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 
yield and purity of the indanthrone is improved by carrying out the alkali 
fusion in the presence of sucrose, glucose, lactose, or the like. 

3 B.A.S.F., D.R.P. 139,633 ; 141,355 ', 238,979. 

4 By., D.R.P. 161,923. 

5 By., D.R.P. 175,626. 

6 B.A.S.F., D.R.P. 186,636-7 ; 238,979. 

7 B.A.S.F., D.R.P. 198,507 ; 204,905; 210,565. 

8 By., D.R.P. 158,287; 193,121. 



346 ANTHRACENE AND ANTHRAQUINONE 

CO CO 




CO 



For the extension of this method to the preparation of 
indanthrone derivatives the reader is referred to the original 
literature. 1 

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 very 
stable substances and strongly resist further oxidation 
although they 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 investigated 
in detail it will 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 only one 
which is of any practical importance consists in fusing 
/3-aminoanthraquinone with caustic alkali. 2 The dye itself 
forms an insoluble blue powder which usually 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 )^ellow on washing, although the original 
blue shade can be restored by treatment with a mild reducing 
agent. The oxidation to the azine is best carried out in the 
laboratory by means of nitric acid, a bimolecular product 
in which the two molecules are joined through the nitrogen 
atoms being formed as an intermediate product. 3 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. 

2 For laboratory details see Scholl, 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 l 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 always lead to the entrance of halogen atoms 
into the molecule with simultaneous reduction and acylation 
of the cyclic carbonyl groups. 2 In this way indanthrone 
resembles indigo, 3 benzoquinone, 4 chloranil, 6 and the 
oxazines and thiazines, 6 but Scholl 7 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 hydrolysis 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 8 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 by means of sodium hydro- 
sulphite in alkaline solution, first a blue vat and then a brown 
vat is obtained, both being very readily 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 under the name 
Indanthrone Blue RS 9 has been used in printing. 10 Scholl, 

1 B. 44, 1727. 

2 Scholl and Berblinger, B. 40, 395. B.A.S.F., D.R.P. 229,166. 

3 Heller, B. 36, 2762. 

4 Buchka, B. 14, 1327. Sarauw, A. 209, 129. 

5 Graebe, A. 146, 12. 

6 Scholl, B. 40, 399. Private communication from Bernthsen. 

7 B. 44, 1732. 8 Liebermann and Dickhuth, B. 24, 4133. 

9 Caledon Blue R (Scottish Dyes, Ltd.). 10 B.A.S.F., D.R.P. 129 848. 



348 ANTHRACENE AND ANTHRAQUINONE 



Steinkopf and Kabacznik * have prepared the dibenzoyl 
derivative, and Scholl and Stegmuller 2 have shown that if 
the sodium salt is heated to 22O-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- 
dihydroazine (formula II) and indanthrone : 



CO 



NH 



OH 

I 
C 



CO NH C 

I 
I OH 

CO NH 

P TT / \r* TT f Np 

( -6- tl 4\/ ( -6- tl 2\/ ( - 

CO NH 

CO 



OH 
C 



H 

NH 



CO 



C 6 H 4 +H 2 



CO 



NH 



CO 



II 



The former compound, however, is much more readily 
obtained by 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 3 and Scholl, Steinkopf, and Kabacznik 4 have 
prepared a tetrabenzoyl derivative. 



1 B. 40, 390. 

3 Scholl, B. 36, 3410. 



2 B. 40, 924. 
4 B. 40, 390. 



THE CYCLIC AZINES AND HYDROAZINES 349 



Exhaustive reduction of indanthrone by means of zinc 
and caustic soda gives N-dihydroanthrazine. 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 (0=1400) gives a compound which is probably penta- 
nitrotetrahydroxy anthrazine, although it has not been 
obtained in a state of purity. 1 

The reduction of indanthrone by hydriodic acid has 
been studied by Scholl 2 and by Kaufler, 3 who find that three 
products are formed, viz. C 2 8H 16 O 2 N2, C28H 18 O 2 N 2 and 



CO 



NH 



CO 



N 



CO 




CH NH CO 



CH 2 N CO 

Anthronazine, C 28 H 18 O 2 N 



CO 



NH 



CH 2 



CH 



CH 2 NH CO 

N-Dihydroanthronazine, C 28 H 18 O 2 N 2 




N 



N 



CH 



CO 



CH 



CH 



NH CH 2 ; CH N CH 

NH CO CH N CH 



CH N CH 

Anthrazine, C 28 H li N 2 



1 Scholl, B. 40, 933- Cf. Scholl, B. 86, 3442. By., D.R.P. 172,684. 
2 B. 36, 3410. 3 B. 36, 930. 



350 ANTHRACENE AND ANTHRAQUINONE 

C 28 H 16 N 2 . 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 dihydroazine. 
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 hydrogen 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 dihydroazine to the azine. Such 
oxidation is obviously impossible if the iminohydrogen 
atoms are replaced by methyl groups, and N-dimethyl 
indanthrone, made from i-methylamino-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, 3 or by halogenating indanthrone 
itself by treatment with molecular or nascent chlorine, 4 or 
with sulphury 1 chloride, 5 thionyl chloride, 6 sulphur chloride 
or stannous chloride, 7 antimony pentachloride, 8 or the 
cjiloride of an organic acid. 9 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. 

2 By., D.R.P. 240,265. 

8 Ullmann, A. 399, 341. By., D.R.P. 158,474; 167,255. 

4 Scholland Berblinger, 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. 

6 B.A.S.F., D.R.P. 157,449. M.L.B., D.R.P. 293,971. 

6 M.L.B., D.R.P. 287,590. 

7 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 
compound. 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, 3 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 4 and Indanthrene 
Blue GC 5 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 indanthrones can be synthesised from the corre- 
sponding aminohydroxy halogen anthraquinone. Thus i- 
amino-4-hydroxy-2-bromanthraquinone when heated with 
sodium acetate and a contact substance such as cuprous 
chloride or copper powder gives dihydroxy indanthrone 6 
(Algol Blue 3G). Hydroxyl groups can also be introduced 
into the indanthrone molecule by direct oxidation with a 
mixtuie of nitric and sulphuric acids, but nitroso and nitro 
groups enter at the same time. Thus from indanthrone 
Scholl and Mansfield 7 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 

1 G.C.I.B., E.P. 113,783 (1918). 

2 Scholl, B. 36, 3436. Scholl and Berblinger, B. 40, 320. By., D.R.P. 
147.872. 

3 Scholl and Berblinger, B. 40, 320. 

4 Caledon Blue GCD (Scottish Dyes, Ltd.). 

5 Caledon Blue GC (Scottish Dyes, Ltd.). 

ti By., D.R.P. 193,121. 7 B. 40, 326. 



352 ANTHRACENE AND ANTHRAQUINONE 

capable of being replaced by hydroxyl groups. Thus 
indanthrone sulphonic acid when heated with concentrated 
sulphuric acid gives a vat dye which dyes in rather greener 
shades than indanthrone itself and is probably a hydroxy 
indanthrone. The same dye is obtained by heating indan- 
throne with sulphuric acid, with or without the addition of 
boric acid, at a temperature insufficient to cause sulphona- 
tion. 1 

Amino indanthrones 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 2 found that the azine obtained from indanthrone by 
oxidation reacts with aqueous ammonia at 200 or with 
boiling aniline and is converted into amino or phenylamino 
indanthrone. These are vat dyes and dye 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. 4 They 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 with formaldehyde in the presence of sulphuric 
acid. 5 The other is a green dye obtained by treating 
indanthrone with nitric acid in the presence of nitrobenzene. 6 
Neither are of any technical value. 

1 B.A.S.F., D.R.P. 227,790. 2 B. 36, 3438. 

3 B.A.S.F., D.R.P. 129,846. 

4 B.A.S.F., D.R.P. 129,847 ; 216,891 ; 220,361. 

5 By., D.R.P. 159,942. * By., D.R.P. 198,024. 



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 l : 

HOCO 
:0 




CO 




and N-phenylpyridazoneanthrone can be obtained by using 
phenylhydrazine in place of hydrazine itself. 2 By treating 
anthraquinone-a-ketones with hydrazine Schaarschmidt 3 
has prepared C-arylpyridazineanthrones : 





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)-thioxarj- 
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. 

4 Ullmann and Sone, A. 380, 336 ; B. 43, 537. B.A.SvF., D.R.P. 
248,582. 

5 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 dyes. It 
is interesting to notice, however, that whereas the anthra- 
quinonylaminopyridazoneanthrone obtained by condensing 
the above chloro compound with j3-aminoanthraquinone is 
easily reduced to its vat, the isomeric compound obtained 
by combination with a-aminoanthraquinone is only reduced 
with the utmost difficulty. 

Ullmann 2 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 extremely feeble. 
The same remarks apply to the compounds obtained by 
condensing N-^-bromphenylpyridazoneanthrone with amino- 
anthraquinone. 

II. THE PYRIMIDONEANTHRONES 

These are isomeric with the pyridazoneanthrones and 
can be obtained from the a-aminoanthraquinone or a- 
alkylamino-anthraquinone by treatment with a urethane 3 : 

CO 




CO CO 

The reaction is a very general one and can be brought about 

1 Ullmann, A. 388, 217 ; D.R.P. 248,998. Agfa, D.R.P. 271,902. 

2 A. 388, an. 3 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 
modified by first converting the a-aminoanthraquinone into 
its urea chloride or urethane and then treating this with 
ammonia. 1 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 
i.4-diamino anthraquinone. The pyrimidone derivatives 
have been very 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. 4 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-hydroxy- 
arylamino anthraquinones are oxidised by means of 
manganese dioxide, lead dioxide, chromic acid, oleum, or 
an organic nitro compound, 5 and consequently are often 

1 By., D.R.P. 225,982. 2 By., D.R.P. 220,314. 

8 M.L.B., D.R.P. 205,914- 4 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. 1 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. 3 In this case the di- 
anthraquinonylamine is first formed and is then oxidised 
to the oxazine : 



CO 





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. 4 

If the o-hydroxyarylaminoanthraquinone is obtained by 
heating an o-hydroxynitroanthraquinone with a primary 
aromatic amine, oxazine formation often takes place without 
the use of an oxidising agent, the necessary oxygen being 
supplied at the expense of the nitrous acid liberated during 
the formation of the arylaminoanthraquinone. Thus an 
oxazine is obtained when 2-hydroxy-i-nitroanthraquinone 

1 By., 153,77. 2 M.L.B., D.R.P. 273,444. 

s M.L.B., D.R.P. 266,945- 4 M.L.B., D.R.P. 266,946. 



HETEROCYCLIC COMPOUNDS 357 

is boiled with a primary aromatic amine, and 2.4-dihydroxy- 
i-nitroanthraquinone undergoes oxazine formation particu- 
larly easily under similar conditions. 1 

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 2 in which this reaction is described, 
purpurin gives a hydroxyoxazine 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 dihydroxyoxazine would be produced. 

A very curious case of oxazine formation has been 
described as taking place when i-arylamino-2-hydroxy-3- 
halogen anthraquinones 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 o 





1 By., D.R.P. 141,575. 2 M.L.B., D.R.P. 156,477. 

3 By., D.R.P. 153,517- 



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. 

Ivittle or nothing is known of the substituted anthra- 
quinone oxazines, but sulphonic acids can be obtained by 
sulphonation. 1 

IV. THE THIAZINES 

Very little is known of the thiazines of the anthraquinone 
series although a few such compounds have been described, 
Scholl 2 obtained what was probably /m-thiodianthra- 
quinonylamine 

/ NH \ 



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 extremely poor. The 
same was also found to be the case with the N-methyl 
derivative. Ullmann 3 found that a thiazine was formed 
when 2-amino-i.3-dibromanthraquinone was boiled with 
anthraquinone-a-mercaptan in nitrobenzene solution : 



Br 
INH 2 



Br 



/ s \ 

NIL 



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. 3 B. 45, 832. 



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 boiling point) or by heating with concentrated 
sulphuric acid and boric acid. 1 Thiazines are also formed 
when an o-aminoanthraquinone mercaptan is condensed 
with a halogen anthraquinone in which the ortho- position 
with reference to the halogen atom is occupied by an amino, 
methoxy, or carboxyl group, the group being split off during 
the condensation. 2 

Thiazine formation takes place very readily, it merely 
being necessary to heat the components together in some 
suitable solvent such as nitrobenzene, pyridine or naphthalene, 
no catalyst or condensing agent being required. 

As would be expected a thiazine is also obtained when 
i.2-dichloranthraquinone is condensed with i-aminoanthra- 
quinone-2-mercaptan. 3 

A few thiazines containing only one anthraquinone 
residue have been prepared. Thus I^aube and lyibkind 4 
obtained a green vat dye by condensing i-chlor-2.4-dinitro- 
benzene with a-aminoanthraquinone, reducing the nitro 
groups and finally fusing the diaminophenylammoanthra- 
quinone with sulphur and sodium sulphide at 150 : 

NHC 6 H 3 (NH 2 ) 2 



It will be observed that thiazine formation takes place by 
loss of an amino group. From j3-aminoanthraquinone a 
thiazine could not be obtained by this method. 

Ullmann 5 has also obtained a thiazine containing only 
one anthraquinone residue by condensing 2-amino-i.3-di- 
bromanthraquinone with thio-^>-cresol and then treating 

1 B.A.S.F., D.R.P. 248,169. 2 B.A.S.F., D.R.P. 266,952. 

3 B.A.S.F., D.R.P. 248,171. * B. 43, 1730. s B. 49, 2163, 2165. 



360 ANTHRACENE AND ANTHRAQUINONE 



the product with formaldehyde and concentrated sulphuric 
acid : 

S S 

/\C 6 H 4 CH 3 ()C 6 H 3 CH 3 

NCH 3 



V. THE CARBAZOLS 

Compounds in which a pyrrol ring lies between two 
anthraquinone 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 * : 



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 by 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 Scholl, B. 44, 1249. 

2 Ehrenreich, M. 32, 1113. Cos., 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. 1 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 aryl group is 
unoccupied 2 : 



CO 





As a rule, the oxidation is effected by means of chromic 
acid, ferric chloride, or hydrogen peroxide ; but if an 
acylamino 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 3 by a somewhat different method. He found 
that the diazotisation of 2-amino-i-arylamino 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 off nitrogen and pass into 
monophthaloyl carbazols : 

1 M.L.B., D.R.P. 240,080; 251,021; 251,350. Cf. also 267,522. These 
compounds were formerly wrongly regarded as complex indanthrones. 

2 By., D.R.P. 288,824. 

3 B. 47, 380. 



362 ANTHRACENE AND ANTHRAQUINONE 




Both the monophthaloyl 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 satisfactory. 1 

VI. THE PYRROI.ANTHRONES 

If an a-arylaminoanthraquinone is condensed with 
chloracetic acid, a glycine is obtained which passes into a 
pyrrolanthrone when boiled with acetic anhydride 2 : 

COOH( 
CO 




CH 



NA r 




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 carboxylic acid 
obtained which can be used as an acid wool dye. 3 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 : 

1 Cas., D.R.P. 261,495. 2 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. 1 

The C-aryl pyrrolanthrones can be obtained by condens- 
ing an arylchloracetic acid with an a-aminoanthraquinone 
and then boiling the product with acetic anhydride 2 : 

COOK 

**> 

CO 



ceo 




CO 

An indolanthrone has been obtained by Scholl 3 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 : 




The reduction product is soluble in alkali and is readily 
oxidised to the indolanthrone by atmospheric oxygen. The 
indolanthrone can, therefore, be used as a vat dye. It gives 
violet-brown shades, but the affinity is very poor. 

VII. THE PYRRAZOI^ 

The a-anthraquinonylhydrazines when boiled with 
water or glacial acetic acid readily lose water and pass 
into pyrazol compounds, 4 a monopyrazol being obtained 

1 M.L.B., D.R.P. 284,208. 2 M.L.B., D.R.P. 279,198. 

3 B. 44, 2370; M. 32, 1001. 4 By., D.R.P. 171,293. 



364 ANTHRACENE AND ANTHRAQUINONE 

from anthraquinone-i-hydrazine and a dipyrazol from 
anthraquinone-i.5-dihydrazine : 





CO 

In the case of i.8-dichloranthraquinone a pyrazol is 
formed by boiling 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 : 

CO 




II 

N 




CO 



VIII. THE INDAZOLS 
Anthraquinone indazols having the structure : 





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 

1 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. 1 

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 

The imidazols are always obtained from o-diaminoanthra- 
quinones and are formed when the acyl derivatives of these 
substances are heated with dehydrating agents such as 
sulphuric acid, zinc chloride, or the anhydride or chloride 
of an organic acid. 4 Imidazol formation therefore takes 
place when o-diamino anthraquinones are boiled for some 
time with acid chlorides or anhydrides, 5 or when the base is 
heated with a carboxylic 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 under conditions which are insufficient to 
bring about the hydrolysis of the nitrile. 

A variation of the above method has been introduced 
by Ullmann and Medenwald, 7 who find that 2-acetamino- 
i-nitroanthraquinone passes directly into the imidazol on 
reduction with sodium sulphide : 

1 By., D.R.P. 269,842. 

2 By., D.R.P. 268,505. 

3 By., D.R.P. 280,840. 

4 Schaarschmidt, A. 407, 176. 

5 By., D.R.P. 238,981. Cf. Ullmann, A. 380, 322. 

6 Schaarschmidt, A. 407, 176. D.R.P. 251,480; 254,033. 

7 B. 46, 1807. 



366 ANTHRACENE AND ANTHRAQUINONE 




NHCOCHj 




C-Methylanthraquinone- 1 .2 -imidazol . 

Another variation consists in heating an 0-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 acylamino group reacting 
in the enolic form l : 



-NHCOR 
-Cl 



NH OH 

I 

Ar 



-N 

I 
Ar 



A somewhat different method of preparing imidazols 
consists in condensing o-diaminoanthraquinone with an 
aliphatic or aromatic aldehyde or with an cu-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 dyes of unknown constitu- 
tion are obtained. 3 

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 dyes, and it is 
doubtful if they contain the imidazol ring system. 1 

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- 
quinonyl anthraquinone imidazols, have good affinity. 

The majority of the imidazols are yellow, but Schaar- 
schmidt states that C-j8-anthraquinonyl-anthraquinone-i.2- 
imidazol : 

V(j3)C u H 7 2 



which he prepared in three ways, viz. from i.2-diamino- 
anthraquinone and anthraquinone-/3-carboxylic acid, anthra- 
quinone-jS-nitrile and eo-dichlor-j8-methyl anthraquinone, is 
red, whereas in a patent specification 3 the same substance is 
described as being prepared from i.2-diaminoanthraquinone 
and is stated to be a violet dye. 

The only imidazolon of the anthraquinone series which 
has been described up to the present was obtained by Ull- 
mann 4 by treating i.2-diamino-3-bromanthraquinone with 
chloroformic ester. It has the formula : 



Br 



1 By., D.R.P. 264,290. 

3 B.A.S.F., D.R.P. 261,737. 



2 A. 407, 176. 
* A. 399, 332. 



368 ANTHRACENE AND ANTHRAQUINONE 



and is a yellow vat dye with good affinity although the 
shades are very loose to alkali. 

X. THE OXAZOLS 

Oxazol formation takes place when o-hydroxyacylamino 
anthraquinones are heated with dehydrating agents, jS-amino- 
alizarin, for example, giving an oxazol when boiled with 
excess of benzoyl chloride l : 

OH OH 



OH 
NHCOC 6 H 5 



O 



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. 3 

A somewhat similar reaction has been described by Ull- 
mann, 4 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-hydroxy-3-bromanthraquinone when heated 
with sulphuric acid of 80 per cent, strength : 

OH 



CC 6 H 5 



Br 



NIL 



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. 8 M.L.B., D.R.P. 286,093. 4 A. 339, 330. 



HETEROCYCLIC COMPOUNDS 369 

2.6-Diammo-i.3.5.7-tetrabromanthraquinone reacts in 
exactly the same way and gives a dibromanthraqtiinone 
dioxazol. 

Oxazols and dihy dro-oxazols are also formed by condensing 
o-aminohydroxyanthraquinones with aldehydes, ketones or 
the corresponding eo-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 meso- carbon atoms form part of an isoxazol ring 
have been prepared by Freund and Achenbach 2 and by 
Schaarschmidt. 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 : 

lO 



and 



The isoxazols prepared by Schaarschmidt were isomeric 
with these, and were obtained by boiling anthraquinone- 
a-azides with water. By this means one mono-isoxazol and 
two di-isoxazols were obtained : 








Gattermann 4 also obtained these compounds from the 
azides but named them "semi-azo" compounds, and sug- 
gested, with some reserve, that they contained monovalent 

1 By., D.R.P. 252,839. 2 B. 43, 3251. 

3 B. 49, 1632. ' 4 B. 49, 2117. 

24 



370 ANTHRACENE AND ANTHRAQUINONE 

nitrogen, although he has offered no evidence whatsoever in 
support of this view : N . 




CO 



XII. THE THIOPHENES 

The i(S)-9-thiopheneanthrones have been prepared by 
Gattermann, 1 who found that the anthraquinonyl-a-thio- 
glycollic acids, obtained by condensing anthraquinone- 
a-mercaptans with chloracetic acid, lose water and carbon 
dioxide when boiled with acetic anhydride. 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- 
quinonyl thioglycollic 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. : 

COON 

c n s 




co> 



Friess and Schiirmann 2 also prepared thiopheneanthrones. 
Their starting-out substance was anthraquinone-a-sulphur 
chloride, which they condensed with sodio-acetoacetic ester, 
the thiophene ring being formed on subsequent hydrolysis : 

COOEl 





CO 

They also found that a thiophene anthrone is produced 
1 A. 393, 122, 190. 2 B 52 2I72 



HETEROCYCLIC COMPOUNDS 371 

when sodium anthraquinone-a-mercaptide is condensed with 
^-hydroxy-w-chloracetophenone : 

HOC 6 H 4 Crj 




CO 

This reaction is by no means a general one, as no thio- 
phene derivative is formed from either onitrobenzyl chloride 
or />-nitrobenzylchloride. 



XIII. THE 

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 anhydride 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 0-amino or o-acylamino halogen anthra- 
.quinones are treated with a sulphide, thiocyanate or other 
substance capable of replacing the halogen atom by a mer- 
captan group, the reaction being usually best carried out in 
pyridine solution. 3 ' 

In the above reactions carbon disulphide would seem to 
act to some extent as an acid anhydride, as it has been 
claimed 4 that i-aminoanthraquinone-2-mercaptan when 
heated with carbon disulphide in 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 : 

1 By., D.R.P. 250,090. 

2 B.A.S.F., D.R.P. 260,905. 

a B.A.S.F., D.R.P. 260,905. M.L.B., D.R.P. 311,906, 
4 By., D.R.P. 250,090. 



372 ANTHRACENE AND ANTHRAQUINONE 



/ 



NH< 



S : C : S 
-> 



or 



C.SH 



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 aldehyde. 2 

Somewhat similar to the above methods is the formation 
of thiazols from o-aminohalogenanthraquinones by means 
of thiolbenzoic acid 3 : 



NIL 



Br 



IX 



HS' 



:cph 



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 : 



PhC 



/ S \ 



1 By., D.R.P. 252,839; 259,037. B.A.S.F., D.R.P. 260,905. 

" M.L.B., D.R.P. 253,089. 

3 Ullmann, A. 399, 345. D.R.P, 254,743. 



HETEROCYCLIC COMPOUNDS 



373 



Benzyl and benzylidene aininoanthraquinones in which 
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. 1 Here again there is no need to 
isolate the benzyl or benzylidene derivative as the reaction 
can be carried out by heating the amine with benzalchloride 
or benzo-trichloride, preferably in the presence of an in- 
different solvent such as naphthalene. 2 

fo's-Thiazolines in which the two molecules are joined by 
the carbon atoms of the thiazoline rings can be obtained 
by fusing the o-acetamino chloranthraquinones with sulphur, 3 
or by treating the o-aminoanthraquinone mercaptans with 
oxalyl chloride. 4 They are vat dyes and have the structure 



\ 
C=C 

NNH/ " 



but have not been studied in detail. 

A series of vat dyes giving red, bordeaux or violet shades 
has been described 5 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 ISO-THIAZOI,ANTHRONES 

The sso-thiazolanthrones are formed when an anthra- 
quinone mercaptan is heated with ammonia and a poly- 
sulphide, 6 and consequently can be obtained by heating 
any suitable a-substituted anthraquinone, such as an a- 
chloranthraquinone, an anthraquinone-a-sulphonic acid, or 

1 Ullmann, A. 399, 345. Agfa, D.R.P. 229,165 ; 232,711-2 ; 233,072. 
a B.A.S.F., D.R.P. 264,943 ; 267,523. 

3 B.A.S.F., D.R.P. 280,882. 4 B.A.S.F., D.R.P. 280,883. 

5 Cas., D.R.P. 283,725 ; 287,005 ; 287,523. 6 By., D.R.P. 216,306. 



374 ANTHRACENE AND ANTHRAQUINONE 

an 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 iso-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 : 






/so-Thiazolanthrones can also be prepared from the 
anthraquinone-a-sulphur chlorides by converting these into 
the sulphamide by means of ammonia and then closing the 
zso-thiazol ring by treatment with mineral acids. 2 The a- 
sulphochlorides behave in a very similar way, as the corre- 
sponding sulphonamides y ield sulphone zso-thiazolanthrones 
by loss of water 3 : 





CO 



The 2'sothiazols are pale yellow substances which are 
of no particular interest. The iso-selenazolanthrones have 
also been described. 4 They are obtained by treating the 
anthraquinone-a-selenocyanides 5 with ammonia. 

XV. CCEROXENE DERIVATIVES 

When pyrogallol is condensed with phthalic anhydride 
a pyronine dye, gallein, is produced which forms a mono- 
methyl ester, isomeric colourless and coloured tetramethyl 

1 Gattermann, A. 393, 123, 192. By., D.R.P. 217,688. 
3 Friess and Schiirmann, B. 52, 2172. 

3 Ullmann, B. 52, 545. 

4 By., D.R.P. 264,139. 

5 By., D.R.P. 256,667. 



HETEROCYCLIC COMPOUNDS 



375 



derivatives, a tetra-acetyl derivative, and a compound with 
three molecules of phenyl zso-cyanate. 1 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 o 




OH o OH 




OOH 



When gallein is heated with concentrated sulphuric 
acid at 190-200 a molecule of water is lost and a new dye, 
coerulein (Alizarin Green, Anthracene Green), is obtained. 2 
This forms a triacetate, two monomethyl ethers which are 
soluble in caustic alkali, and a trimethyl ether which is 
insoluble in caustic alkali. The carboxyl group present in 
gallein seems to have disappeared so that the new dye is no 
doubt represented by formula III : 



OH o 




This, it will be seen, contains the anthrone ring system, 
and the formation of similar compounds, coeroxenes, from 
other pyronine dyes has been recorded. 3 

1 Orndorff and Brewer, Am. 23, 425 ; 26, 96. 

2 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. 

3 M.L.B., D.R.P. 86,225. Cf. By., D.R.P._I96,752. 



376 ANTHRACENE AND ANTHRAQUINONE 

Very similar to the above synthesis is the preparation 
of the highly coloured cceroxonium sulphate (IV) by Decker l 
by heating fluorane with concentrated sulphuric acid : 





0-S0 4 H 



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 cceroxonium salts consists 
in heating the aryl ethers of erythrohydroxyanthraquinone 
with sulphuric acid of 70 per cent, strength, or with zinc 
chloride at 160-180 : 



0-S0 4 H 





Both the a-naphthyl and the j8-naphthyl ethers react in 
the same way, as do also the aryl ethers of di-a-hydroxyan- 
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 cceroxonium salts are highly coloured, but on 
neutralisation or when their solutions are sufficiently diluted 

1 A. 348, 214, 223. 

2 Laube, B. 39, 2245. Decker, A. 348, 232, 245. By., D.R.P, 
X86.882. 



HETEROCYCLIC COMPOUNDS 



377 



with water the colourless carbinol base, coeroxonol, formula 
V, is obtained : 





These carbinols are decomposed by light and atmo- 
spheric oxygen, but when boiled with alcohol, or when the 
coeroxonium sulphate is recrystallised from alcohol, 1 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 hydriodic 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 oxygen, and hence are best 
isolated in the form of their stable acetyl derivatives. They 
can also be obtained direct from the phenyl xanthene 
carboxylic acids by loss of water, the reaction being effected 
by concentrated sulphuric acid at the ordinary temperature 
or, more rapidly, 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. 

2 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 160 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 extremely easily and may take 
place with evolution of heat under the influence of sulphuric 
acid monohydrate at the ordinary temperature. 2 

The coerthionium salts are more highly coloured than 
the corresponding cceroxonium salts. They behave like 
the corresponding cceroxonium salts on reduction, but the 
parent substances, the ccerthi'enes, have not yet been isolated : 




CO 
Coerthionium salt. 



CO 
Ccerthionol. 



OH 
Ccerthienol. 



1 Decker and Wursch, A. 348, 238. By., D.R.P. 186,882. 

2 By., D.R.P. 252,530. 



HETEROCYCLIC COMPOUNDS 



379 



XVII. THE CCBRAMIDINB DERIVATIVES 
Cceramidines can be obtained by treating a-arylamino 
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 i.5-diarylamino anthraquinone is used 
compounds can be obtained in which two acridine ring 
systems are present 1 : 




CH 




CH 3 




From i-tolylamino 

anthraquinone. 
Yellowish-brown. 



From i.4-ditolylamino 
anthraquinone. 
Dark red. 



From i.5-ditolylamino 
anthraquinone. 
Dark blue. 



i . i '-Dianthraquinonylamine and i . 2'-dianthraquinony 1- 
amine also give cosramidine derivatives when treated with 
dehydrating agents, the products being yellow or orange vat 
dyes. 2 The reaction is a very general one and has been 
applied to the preparation of complex compounds from a- 
anthraquinonylamino acidrone and from a-anthraquinonyl- 
amino thioxanthone. 3 It has also led to the preparation 
of cceramidine carboxylic acids from a-arylamino anthra- 
quinone carboxylic acid, but when the carboxyl group is 
in the ortho-position to the arylamino group acridone 
formation takes place simultaneously and, as would be 
expected, the acridone is usually the predominant product. 4 

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 finally treating this with 
aluminium chloride 6 : 

1 By., D.R.P. 126,444. 2 B y-> D.R.P. 239,544. 3 Agfa, D.R.P. 258,808. 
4 By., D.R.P. 262,469. 5 Bernthsen, A. 224, 45. 6 Dammann and 
Gattermann, F.T. 1, 325. Cf. Decker and Schenk, A. 348, 242. 



380 ANTHRACENE AND ANTHRAQUINONE 





When treated with dimethyl sulphate this gives the 
quaternary ammonium sulphate from which caustic alkali 
liberates the carbinol base, N-methylcceramidonol l : 




XVIII. MISCELLANEOUS COMPOUNDS 

Anthraquinone-a-sulphochloride when treated with 
hydrazine )delds a sulphohydrazine 2 : 




Anthrone condenses with true ^-quinones such as benzo- 
quinone or chloranil to give blue or green vat dyes. 3 The 
reaction is brought about by 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 

o 




1 Decker and Shenk, A. 348, 242. 2 Ullmann, B. 52, 545, 

3 M.L.B., D.R.P. 251,020 ; 267,417. 



HETEROCYCLIC COMPOUNDS 



Oxazoneanthrones are obtained when anthraquinone- 
a-carboxylic acids are warmed with hydroxylamine in 

aqueous solution 

/\ 

ICO 




An anthraquinonyl thioglycollic acid can be obtained 
either by condensing i-alkyl (or aryl) amino-2-chloranthra- 
quinone with thioglycollic acid or its ester, chloiide or amide, 
or by condensing i-alkyl (or aryl) aminoanthraquinone-2-mer- 
captan with chloracetic acid. Such anthraquinonyl thio- 
glycollic 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 




When an anthraquinone mercaptan is condensed with a 
hydroxyanthraquinone by treatment with concentrated 
sulphuric acid at 160, compounds are obtained which 
probably have the structure : 



Instead of the mercaptan the disulphide, thiocyanate or 
xanthate can be used. The products are usually red vat 
dyes. 3 

1 Ullmann, A. 388, 211; B. 44, 129. 2 By., D.R.P. 232,076. 

a 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. 1 The aminoanthraquinones are not arsinated 
when heated with arsenic acid, 2 but the anthraquinone 
arsinic acids can be readily obtained from the amino com- 
pounds by Bart's method, i.e. by treating the diaozonium 
salts with alkali arsenite. In many cases the yields are 
almost quantitative although in others the method fails 
completely, e.g. aminoalizarin gives no arsinic acid at all. 
The arsinic acids are usually fairly stable, well-crystallised 
bodies which are only decomposed when heated to a high 
temperature, and then split off arsenious oxide and form the 
hydroxy 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 necessary 
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 compounds that the anthra- 
quinone arsinic acids owe their great toxidity. 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 

1 J. pr. [2] 95, 74. 2 Bechamp, C. r. 56, 1172. 

382 



MISCELLANEOUS COMPOUNDS 



383 



series which under similar conditions only form arsenoxides, 
the use of hydrogen 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 l 
obtained aceanthrenequinone (I), the structure being proved 
by the fact that oxidising agents convert it into anthraqui- 
none-a-carboxylic acid : 



CO COOH 




CO 

At a later date the same investigators described several 
substituted aceanthrenequinones, 2 and I^iebermann, Kardos 
and Miihle 3 by the action of oxalyl-chloride on dianthryl 
.obtained similar compounds, the diquinone (II) and the 
monoquinone dicarboxylic acids (III) being the most 
interesting compounds obtained, although dianthryl tetra- 
carboxylic acid was also formed : 

COOH COOH 





1 B. 44, 202. a B. 44, 852, 1213 ; 45, 1187, 1213. 3 B. 48, 1648. 



384 ANTHRACENE AND ANTHRAQUINONE 

The action of malonyl chlorine on anthracene 1 is very 
similar to that of oxalyl chloride and leads to anthracene 
i.g-indandion, but according to Freund and Fleisher 2 the 
reaction in the case of dimethyl malonyl chloride takes a 
different course and leads to either IV or V, from which the 
corresponding anthraquinone can be obtained by oxidation : 





CO 

IV V 

Aceanthrenequinone gives a monoxime 3 which is capable 
of dyeing wool yellow 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.g-dicarboxylic acid and its monamide 
and cyclic imide. 4 The amide and cyclic imide can also be 
obtained fromanthracene-i.Q-dicarboxylicacid by the action 
of ammonia, and the imide is also formed when the monoxime 
of aceanthrene quinone undergoes the Beckmann rearrange- 
ment. 5 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 6 and 
probably has the structure represented by formula VI : 

CO 




Hydrolysis of aceanthrene quinone by caustic soda leads 
to a mixture of anthracene-i-aldehyde-g-carboxylic acid, 

1 Kardos, B. 46, 2090. D.R.P. 275,248. 

2 A. 373, 291 ; 399, 193. 

3 Kardos, B. 46, 2086. D.R.P. 280,839. 

4 Kardos, D.R.P. 282,711. 

5 Kardos, B. 46, 2086. 

6 Kardos, B. 46, 2086. D.R.P. 275,220 ; 278,660 ; 284,210. 



MISCELLANEOUS COMPOUNDS 



385 



the anhydride of anthracene-i.g-dicarboxylic acid and 
anthracene hydroxydion (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 
imide on fusion with caustic potash gives a green vat dye 
(XI or XII) which has been named zso-aceanthrene green. 1 





JX 



XI 




CO 




III. DIAZONIUM SAI/TS 

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. 



2 Lauth, C. r. 137, 662. 
25 



386 ANTHRACENE AND ANTHRAQUINONE 

the solution to stand in the ice chest overnight. Benda l 
finds that a large number of primary aminoanthraquinones 
are most easily diazotised by dissolving in concentrated 
sulphuric acid and then rapidly adding a large excess of 
nitrosyl sulphuric acid, no artificial cooling being used. By 
this means he claims that j8-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 i-hydroxy-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. 3 

The anthraquinone diazonium salts are sometimes soluble 
in water, but more usually they are only sparingly soluble, so 
that they are often easily isolated. Kacer and Scholl 4 find 
that the fo's-diazonium sulphate derived from i.8-diamino- 
anthraquinone is readily soluble, whereas that derived from 
i.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-hydroxyanthraquinone-4-diazonium sul- 
phate is only converted into quinizarin when heated to 
170-180 with concentrated sulphuric acid. 5 Anthraquinone- 
i -diazonium sulphate chars if slowly heated, and only explodes 
feebly if rapidly heated. 6 Even anthraquinone- 1. 5-fo's- 
diazonium sulphate only explodes when heated to 172. 
The a-diazonium salts are somewhat more stable than the 
corresponding j3- compounds. 7 

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. 

4 B. 37, 4183. 5 By., D.R.P. 161,954. 

s Kacer and Scholl, B, 37, 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 tendency to produce 
dianthraquinonyls. 1 According to Schaarschmidt 2 i-chlor- 
anthraquinone-4-diazonium chloride when warmed gives a 
nitrogenous, chlorine free product. To this he gives the 

^N 2 
formula C 14 H 6 O 2 ^ , but further confirmation is necessary 

^O 

before this can be accepted. When anthraquinone-2-di- 
azonium sulphate is heated with ammonia a product is 
obtained which contains 6*11 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 hydroxy azoanthraquinone. The 
diazonium sulphates also give nitrogenous condensation 
products with primary aromatic diamines 4 and with 
primary aminoanthraquinones. 5 In the former case at 
least nitrogen is evolved during the condensation, and in 
the latter case the products are yellow 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. 6 
Azo compounds are also formed when either a-amino anthra- 
quinone or /3-aminoanthraquinone is oxidised with bleaching 
powder. 7 

The o-amino azo compounds when oxidised, especially 
when oxidised with chromic acid, give triazols, 8 e.g. : 

1 B.A.S.F., D.R.P. 215,006.' 

2 B. 46, 2678. 8 M.L.B., D.R.P. 253,238. 
4 M.L.B., D.R.P. 246,085. 5 M.L.B., D.R.P. 255,340. 

3 Lauth, C. r. 137, 662. Kauffler, F.T. 2, 469. Cf. also G.E., D.R.P. 
245973; 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, 



3 88 ANTHRACENE AND ANTHRAQUINONE 

N 

n TT [a]N : NC 14 H 7 O 2 _> r TT / \-vrp TT n 
C 10 H 6r01 N H LKjHeN^JNLHH,!^ 

N 

Some of these have been claimed as vat dyes, but they are 
of no practical importance. They are also formed 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, 1 and when o-diamino anthraquinones are treated 
with nitrous acid. 2 

Azimino compounds (azides) are obtained when diazonium 
salts are treated with sodium azide, 3 and Gattermann 4 has 
prepared a-aziminoanthraquinone by treating anthraquinone- 
a-diazonium sulphate with hydroxylamine and then causing 
loss of water from the resulting diazo-hydroxyamino com- 
pound by treatment with acetic anhydride : 

/^ 
C 14 H 7 2 N 2 HS0 4 -> C 14 H 7 2 N : N.NHOH -> C 14 H 7 O 2 N( || 

X N 

The j3-aziminoanthraquinones are more stable than the 
a-azimino compounds, these latter when heated losing a 
molecule of nitrogen and passing into oxazols, 5 although 
Gattermann 6 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. 2 Byf> D R<R 254 , 745 . 

3 Schaarschmidt, B. 49, 1632. 4 B. 49,2117. 

5 Schaarschmidt, B. 49, 1632. See also p. 360. 

8 B. 49,2117. 



MISCELLANEOUS COMPOUNDS 389 

Scholl l obtained /8-azoxyanthraquinone by reducing /3- 
nitroanthraquinone 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 sulphur in oleum, but 
in this case they are extremely difficult to isolate owing to 
the acid causing a very rapid rearrangement to the amino 
hydroxy compound. 4 Phenyl hydrazine can also be used 
as a reducing agent, and by this means R. B. Schmidt and 
Gattermann 5 were able to confine the reduction to one nitro 
group in the case of i.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 ferricyanide 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. 6 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 Scholl, M, 32, 1033. Wacker, B. 35, 666. 

4 By., D.R.P. 119,229. See also p. 244. 

5 B. 29, 2934. 

6 Mohlau, B. 45, 2233, 2244. By., D.R.P. 163,447 



390 ANTHRACENE AND ANTHRAQUINONE 

the entrance of a second sulphonic acid group, a hydrazine- 
aj8-disulphonic acid being produced. The hydrazines them- 
selves are readily prepared from the sulphonic acids by 
hydrolysis with dilute hydrochloric acid. 

Hydrazines can also be prepared by condensing halogen 
anthraquinones with hydrazine, the reaction being best 
carried out in the presence of pyridine. 1 As would be 
expected halogen atoms when in a- positions react most easily. 
Thus, i.5-dichloranthraquinone when boiled with hydrazine 
in pyridine solution gives i-chloranthraquinone-5-hydrazine, 
and when heated with hydrazine 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 hydrazines 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 aldehydes 
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 dyeing cotton either from a hydrosulphite vat or 
from their solution in sodium sulphite. The hydrazone formed 
from anthraquinone-i.5-dihydrazine with ^>-hydroxybenz- 
aldehyde gives greenish-blue shades, blueish-red shades being 
obtained with the hydrazone derived from w-hydroxy 
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 /J- anthraquinone hydrazines form hydrazones 
when treated with acetoacetic ester. When heated with 
acetic anhydride the j3-hydrazone loses water and undergoes 
1 Mohlau, B. 45, 2245. > M .L.B., D.R.P. 256,76) 



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. 1 

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--sulphonic acid, C u H 6 O 2 [i.8](NH.NHSO 3 H) 2 , 
gives scarlet shades. 2 The introduction of hydroxyl 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 

C 14 H 7 2 .NHNH.C 14 H 7 2 , 

do not seem to have been prepared, although one or two 
mixed hydrazo compounds have been described. Thus, 
dichloranthrachrysazin disulphonic acid condenses very 
readily with phenylhydrazine to produce a hydrazo com- 
pound 3 (di-phenylhydrazo-anthrachrysazin disulphonic 
acid ?), and a mixed hydrazo- compound is also formed by 
condensing phenylhydrazine, or phenylhydrazine sulphonic 
acid, with leuco- quinizarin. 4 

1 Mohlau, B. 45, 2233. See also p. 363. a By., 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, benzal 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-Q.io-dihydroanthracene, but gives its melting 
point as 159 as compared with 164*2 found by I^inebarger, 2 
who prepared it from benzal chloride and benzene by means 
of aluminium chloride. Haller and Guyot 3 have also 
prepared the compound by reducing g.io-diphenyl anthra- 
cene, but give the melting point as 218. Their product 
evolved hydrogen when heated, whereas that obtained by 
Ivinebarger does not appear to have done so. Ray's product 
prepared from chloroform appears to have been impure 
(found : =93*2, [=67. C 2 6H 20 requires 0=94*0, 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 4 found that g.io-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 diacetyl derivative. It is difficult 
to see how a diacetyl derivative could be obtained from a 
hydrocarbon by the method employed, and in any case such 
a diacetyl compound would contain thirty carbon atoms and 
not twenty-eight as Ray states. (Found: 0=85-3, H =7 -4. 

1 Soc. 117, 1335- 2 Am - 13, 554. 

3 C. r. 138, 1252. 4 Page 20. 

393 



394 ANTHRACENE AND ANTHRAQUINONE 

C 2 8H 24 O2 requires =857, H=6'8; C 3 oH 24 O2 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.io.io-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*o, 
94-0 ; H=6-8, 5-1. C 38 H 28 requires C=94'2, H=5'8 ; 
^26^20 requires C=94'0, H=6'o.) 

Page 68. ws-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. 1 

Page 99. When anthranol is treated with a cold con- 
centrated solution of formaldehyde, it passes readily into 
methylene anthrone (methylene anthraquinone) 2 : 

CO 



C 

CH 2 

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. 3 

1 A. G. Perkin, E.P. 151, yoy 19 . Cf. M.L.B., D.B.P. 249,124. 

2 K. Meyer, A. 420, 134. 3 K. Meyer and Schlosser, A. 420, 131. 



ADDENDA 395 

Page 112. The alkylation of anthranol has been further 
studied by Kurt Meyer and Schlosser. 1 They find that 
alkylation with dimethyl sulphate or diethyl sulphate leads 
to the formation of O-alkyl 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) : 

OCH 3 

C CO 

C 6 H 4 /\C 6 H 4 C 6 H 4 </\C 6 H 4 

C C 

I /\ 

CH 3 CH 3 CH 3 

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 3 leads to a product which must 
be regarded as the anthrone, as the equilibrium mixture in 
alcohol ("L-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-hydroxyanthraquinol. The corresponding enole, i(?4).9- 
dihydroxy anthrone can be obtained by brominating 
i -hydroxy anthrone and then replacing the bromine atom 
by the hydroxyl 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. 2 K. Meyer and Sander, A. 420, 113. 

3 M.L.B., D.R.P. 242,053. 



396 ANTHRACENE AND ANTHRAQUINONE 



leads to i.4.9-trihydroxy 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 /3-hydroxyanthra- 
quinone was also examined, but quantitative results as to 
the state of the equilibrium mixture could 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 hydroxyl 
groups would seem to be confined to those occupying a- 
positions. In connection with this it is interesting to notice 
that Willstatter and Wheeler l have found that hydro- 
juglone exists in two forms. One of these is probably the 
true phenol (i.4.5-trihydroxynaphthalene), whereas the other 
is probably i.4-dihydroxy-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 



CH 2 

CH 2 
CH 2 



n 



M.p. 108-110. M.p. 181. 

1 B. 47, 2796. 2 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. l 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 1 60. 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. 4 

Page 168. By nitrating anthraquinone to the dinitro 
compound Dhar 5 obtained i.5-dinitroanthraquinone (m.p. 
360), i.3-dinitroanthraquinone (m.p. 240) and two other 
isomers which he was unable to identify. For the analysis 
of the i.3-dinitro compound 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. 6 

1 Lawrence, Am. Soc. 42, 1871. 

2 Schaarschmidt and Herzenberg, B. 53, 1809. 

3 Cas. E.P. 148,339 (1915)- 

4 Schaarschmidt and Herzenberg, B. 53, 1809. 

5 Soc. 117, 1001. 

* Schaarschmidt and Herzenberg, B. 53, 1809. 



398 ANTHRACENE AND ANTHRAQVINONE 

Page 173. i-Ammo-2-methylanthraquinone can be con- 
verted into 2-methyl-i-chloranthraquinone by Sandmeyer's 
method, but the reaction must be carried out in the cold in 
order to avoid the formation of anthraquinone-i^-indazol. 1 

Page 208. Both a-aminoanthraquinone and j8-amino- 
anthraquinone can be methylated by boiling 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 
tewco-quinizarin I and /^wco-quinizarin II. The former 
can also be obtained from leuco-purpmn 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 oxygen. In view of 
these facts Meyer and Sander consider that leuco-qumi- 
zarin I must be 2-hydroxy-i.4-diketo-i.2.34-tetrahydro- 
anthraquinol (I). I^oss of a molecule of water from this 
substance would give rise to 9.io-dihydroxy-i.4-anthra- 
quinone (II), which would pass into the i.4-dihydroxy-9.io- 
anthraquinone (quinizarin, formula III) by ketonisation of the 
hydroxyl groups and simultaneous enolisation of the quino- 
noid carbonyl groups : 

OH o OH co OH 






OH 6 OH 

i ii m 

Page 324. By condensing the chloride of i-chloranthra- 
quinone-2-carboxylic acid with ^-xylene, Schaarschmidt 
and Herzenberg 3 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 

1 Loc. cit. * Atack and Haworth, E.P. 147,964. 

3 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 xylyl anthraquinonyl 
ketone itself, also obtained by condensing the chloride of 
anthraquinone-2-carboxylic acid with ^-xylene ; (c) a fluore- 
none derivative (formula II) in about 25 per cent, yield ; 
and (d) a benzanthrone derivative (formula III) in about 
50 per cent, yield : 




11 



The phthaloyl fluorenone (II) passed into the benzanthrone 
derivative (III) when heated with zinc chloride. Both 
II and III yielded the carboxylic acid (IV) when fused with 
caustic alkali, the carboxyl being formed by the opening of 
the fluorenone ring. 

Page 328. An investigation of perylene and its deriva- 
tives has been commenced. 1 

1 Hansgirg and A, Zinke, M. 40, 403. A. Zinke and Unterkreuter, M. 
40, 405. 



400 ANTHRACENE AND ANTHRAQUINONE 

Page 370. Compounds which are probably isoxazols of 
the type : 

N 



CR 



are obtained by treating i-nitro-2-alkylanthraquinones with 
oleum. 1 Compounds which may or may not be isoxazols 
of the above structure are obtained by treating 2-methyl- 
i-aminoanthraquinone with alkali alcoholates. 2 

PMhaloyl acenaphthene * Phthalic anhydride will con- 
dense fairly readily with acenaphthene to give a ketonic 
acid in which the carbonyl group occupies one of the 
o-positions 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 w r ith 
phosphorus pentachloride. The yields, however, are poor. 

1 M.L.B., E.P. 147,001 (1918). - M.L.B., D.R.P. 293,576. 

3 Groebe, A. 327, 99- 



INDEX TO GERMAN PATENTS 



D.R.P. Patentee. Date. Page 

3565 Pryzibram ...... ^78 278 

6,526 ...... !8 7 8 192, 198 

17,627 M.L.B ......... I8 8i 255 

695 B.A.S.F ......... 1881 296 

21,178 Agfa ........ 1882 64, 65 66 

23,008 B.A.S.F ......... 1882 296 

26,197 [Majert ........ !88 3 293 

38,417 Reney and Erhart .. .. 1886 17 

42,053 Chem. Fab. A.G. . . . . 1887 17 

46,654 B.A.S.F. ... ...... 1888 296 

47,252 ........ 1888 296 

50,164 By ......... X 888 254,281,295 

50,708 ........ I8 88 254,281,20^ 

54,624 M.L.B. ........ zSgo 295 

56.951 By ......... ^90 179,278 

56.952 ........ 1890 278 

58,48o .... 1890 295 

6o 8 55 ,, ...... 18.90 260, 277 

6i,9i9 ........ 1890 200 

62.018 ........ I890 26 

62.019 ........ 1890 284 

62.504 ........ 1890 264 

62.505 ........ 1890 264 

62.506 ........ I890 264 

62,531 ........ 1890 260 

62,703 Ort and M.L.B ....... 1891 294 

63,693 By. ........ I 8 90 260 

6 4>4j8 ...... I 8 QO 260 

65,182 ...... I8 g 260 

65,375 .... 1891 260 

65.453 ,, ...... 1891 260 

65,650 .... 1890 200 

66,153 ...... iSgi 92, 264 

65,811 M.L.B ......... X 8 9 2 281,284 

66,917 By ......... ^91 200 

67o6i ........ I8go 26o 

67,063 ......... I89 i 2 6o 

67,470 M.L.B ......... 1892 294 

68,113 By. .. I8gl 92 % 64 

6*>4 .. .. 1891 92,264 

^ I2 3 ........ 1891 92 

68,474 ...... 1892 17 

68,775 ........ 1890 258 

69,013 ........ !8 9 i 260 

69,835 ........ 1891 258 

401 26 



402 



INDEX TO GERMAN PATENTS 



D.R.P. 


Patentee. Date. 


Page. 


69,842 


By. 1892 


92, 264 


69,933 


1892 


264 


69,934 


1892 


264 


7O SIS 


ML.B. .. .. .. .. 1892 


281 


l^iD^J 
70,665 


1892 


295 


70,782 


By. 1891 


263 


71,964 


1893 


179, 258 


72,226 


Soc. Anon. 1893 


62 


72,552 


M.L.B 1893 


193 


73.605 


1892 


282 


73.684 


1893 


193 


73,860 


1893 


2 4 2 


73,942 


By. 1892 


264 


73,96i 


Soc. Anon. . . . . . . 1893 


62 


74,212 


M.L.B 1893 


281 


74.353 


By. . . . . . . . . 1892 


264 


74.431 


M.L.B 1892 


281 


74.562 


By 1893 


281 


74.598 


1893 


281 


75.054 


M.L.B 1893 


242, 287 


75.288 


1893 


136 


74.490 


1893 


249, 250, 258 


76,262 


B.A.S.F 1892 


246 


76,280 


Soc. Anon. . . . . . . 1893 


62 


76,941 


B.A.S.F 1892 


243 


77,179 


M.L.B .. .. 1893 


173 


77.3" 


Soc. Anon. . . . . . . 1893 


62 


77.720 


M.L.B 1894 


179, 193 


77,721 


B.A.S.F 1892 


206 


77,818 


M.L.B 1893 


242, 287 


78,642 


1894 


173 


78,772 


M.L.B. 1894 


193 


78,861 


By. 


1894 


17 


79,768 




1893 


258 


80,407 


M!L.B. 


1894 


140 


81,244 


By. 


1893 


258 


81,245 




1893 


262 


81,481 


tf 


1893 


259, 260 


81,694 


tt 


.. 1893 


246, 282 


81,741 


M.L.B. 


1895 


193 


81,742 




1895 


249 


8i,959 


By. 


1893 


260 


81,960 


. 


1893 


260 


81,962 




1894 


258 


83,055 


tt 


1893 


258 


83,068 


M.L.B. 


1894 


4 


83,085 


By. 


1894 


258 


84,505 


,, 


1895 


261 


84,509 


tl 


1894 


203 


84,774 


M.L.B. 


1895 


263 


86,097 


Nietzki 


1895 


194 


86,150 


By. 


1894 


200, 203 


86,225 


M.L.B. 


1895 


375 


86,539 


By. 


.. 1895 


202, 203 


86,630 


lt 


1895 


262 


86,968 


By. 


. . 1895 


260 


87,620 


K. 


1894 


126 


87,729 


B.A.S.F. 


1892 


246 



INDEX TO GERMAN PATENTS 



403 



D.R.P. Patentee 


88,083 B.A.S.F. 


. . 


89,027 By. 




89,144 B.A.S.F. 


. . 


89,862 By. 




90,041 ,, 




90,720 B.A.S.F. 


. . 


91,149 By. 




91,150 




91,152 


. . 


91,508 B.A.S.F. 




92,591 By. 




92,800 B.A.S.F. 




92,998 




93,223 By. 




93,3io 




94,396 




95,625 


. 


96,197 


. . 


96,364 


. . 


97,287 M.L.B. 


. . 


97,674 By. 
97,688 M.L.B. 




98,639 By. 


. . 


99,078 M.L.B. 


. . 


99,314 By. 


. . 


99,611 M.L.B. 


. . 


99,612 


. . 


99,874 


. . 


100,136 By. 




ioo,i37 


. . 


100,138 ,, 


. . 


101,220 By. 




101,486 ,, 


m 


101,805 ,, 


f 


101,806 ,, 


t 


101,919 ,, 




102,532 




102,638 




103,395 


. . 


103,396 


. . 


103,686 


. . 


103,898 


. . 


103,988 


. . 


104,244 M.L.B. 


. . 


104,282 By. 




104,317 




104,367 M.L.B. 




104,901 By. 




105,501 




105,567 ,, 


. 


106,034 ,, 


. . 


106,227 B.A.S.F. 


. . 


106,505 M.L.B. 


. . 


107,238 


. . 


107,721 By. 




107,730 




108,274 B.A.S.F. 


. . 


108,362 By. 


.. 



Date. 

1893 
1895 
1892 

1895 
1895 
1892 

1895 
1896 
1896 

1895 
1896 
1896 
1896 
1896 
1896 
1896 

1897 
1892 
1897 

1897 
1897 
1897 
1897 
1897 
1897 

1897 
1897 
1897 
1897 

1897 
1899 
1897 
1892 
1897 
1898 
1898 
1898 
1898 
1897 
1898 
1898 

1897 
1898 
1897 
1898 
1898 
1898 
1898 
1898 
1897 
1898 
1898 
1898 

1899 
1898 
1898 
1898 
1899 



Page* 
246 
265 
246 
203 
26l 
206 

2OI, 203 
2OI, 203 
203 

188 
203 
246 
246 
203 
203 
203 
204 
246 
277, 283 

173 

258, 260 

249 

280 

196, 391 

258 

277, 284 

277, 284 

277, 284 

277, 283 

283, 389 

192 

259 

247 

196 

196 

204 

283 

263, 264 

194, 283 

196 

240 

180 

238, 239, 240, 277 

263, 264 

169, 244 

277 

249 
228 
283 

244, 246 
282, 283 
196 
241 

263, 264 
170 
196 

196, 199 
246, 283 



404 



INDEX TO GERMAN PATENTS 



D.R.P. 


Patentee. 


108,420 


M.L.B. 




108,459 


B.A.S.F. 


. . 


108,578 


By. 




108,837 


Soc. Anon 




109,613 


B.A.S.F. 




in,359 


A. G. fur Teer 


111,866 


B.A.S.F. 




111,919 


M.L.B. 




112,179 


,, 




112,297 


Soc. Anon 




112,913 


,, 




113,011 


B.A.S.F. 




113,291 


Wilton 




113,292 


B.A.S.F. 




II 3,724 


By. 




H3,934 


B.A.S.F. 


. . 


114,197 


Soc. Anon 




114,198 


,, 




114,199 


By. 




114,263 






114,840 


B.A.S.F. 




115,002 


By. 




115,048 






116,746 


,, 




116,867 


,, 




116,951 







119,228 


;; 


. . 


119,229 


fl 


. . 


119,755 


Simon 


.'. 




B.A.S.F. 


. . 


121,155 


,, 




121,315 


tl 


. . 


121,684 


,, 




125,094 


,, 




125,578 


By. 




125,579 


,, 




125,666 


, , 




125,698 


,, 




126,015 


tt 




126,392 


>r 




126,393 


,, 




126,444 


,, 




126,542 


tt 


. 


126,603 


B.A.S.F. 




126,803 


By. 




126,804 


M.L.B. 




127,295 


,, 




127,399 


By. 


. . 


127,458 






127,459 


,, 




127,532 


,, 


. . 


127,699 


,, 




128,196 


B.A.S.F. 


. . 


128,753 


,, 


. . 


128,845 


,, 




129,845 


it 




129,846 


,, 





Date. 




Page. 




1898 


I 9 6 






I8 97 


249 






1899 


283 






1898 


140 






1897 


246 






1899 


17 






1899 


196, 


226 




1898 


263, 


264 




1899 


280 






1898 


140 






1898 


140 






1899 


196 






1899 


17 






1899 


2 3 I 






1899 


2 4 6, 


283 




1899 


196 






1898 


140 






1898 


I 4 






1899 


200, 


205, 


274 


1899 


272 






1899 


2 3 I 






1897 


2 4 6 






1899 


228 






1899 


2 4 6, 


283 




1900 


I 9 6 






1899 


I8 7 






1899 


276 






1899 


283 






1900 


246, 


247. 


389 


1899 


250, 


280 




1899 


284 






1900 


196, 


226 




1898 


246 






1898 


198 






1899 


228, 


229, 


251 


1900 


196, 


198 




1900 


243, 


277 




1900 


I 9 6 






1900 


203 






1899 


251 






1899 


228 






1899 


228 






1900 


379 






1900 


196 






1900 


251 






igoo 


198, 


203 




igoi 


194 






1900 


58 






igoi 


50, 53, 67 


1900 


196 






1900 


196 






1900 


196 






I9OI 


273, 


274 




1899 


231 






1900 


203 






1900 


173 






1901 


194. 


343 




igoi 


343, 


352 





INDEX TO GERMAN PATENTS 



405 



D.R.P. 


Patentee. 


Date. 


Page. 


129,847 


B.A.S.F 


1901 


352 


129,848 


. . 


1901 


347 


I3I,4 3 


By. 


1901 


273 


131,538 




1900 


173, 286 


133,686 


B.A.S.F. '.*. 


1901 


300 


134,985 


Deichler and Weizmann . . 


1900 


148 


I 35,47 


B.A.S.F 


. . 1901 


343 


I35,4 8 


,, 


. . 1901 


3o, 343, 345 


135,409 


M.L.B 


. . 1901 


389 


J 35,634 


By 


. . 1901 


206 


136,015 


B.A.S.F 


. . 1901 


300 


136,777 


By 


1900 


197, 198 


136,778 


,, . . 


1900 


197, 198 


136,872 


,, . . . . . . 


1901 


79, 201 


137,074 


B.A.S.F 


1901 


229, 251 


137,078 


By 


. . 1901 


196 


1 37,495 


Sadler & Co 


. . 1901 


74 


137,566 


B.A.S.F 


. . 1900 


203 


137,782 


By 


. . 1900 


175 


137,783 


B.A.S.F 


. . 1898 


229 


J 1 > / O 

138,119 




. . 1902 


300 


138,134 


,, . . . . . . 


. . 1900 


231 


138,166 


. . 


. . 1901 


231 


138,167 


,, 


. . 1902 


35 


138,324 


Deichler and Weizmann . . 


1900 


149 


138,325 




1900 


149 


139,425 


M.L.B. 


1902 


277 


139,581 


By 


1900 


198 


139,633 


B.A.S.F. .. 


. . 1900 


300, 345 


139,634 




. 1901 


302 


141,296 





1902 


277 


i4i,355 


. . 


. . 1901 


300, 345 


i4i,575 


By. 


. . 1902 


355, 356 


141,982 




. . 1902 


358 


142,052 


,, 


. . 1899 


196 


142,154 


,, 


. . 1902 


206 


143,804 


,, 


. . 1900 


277 


143,858 


M.L.B 


1902 


277 


144,111 




1901 


196 


*44, 6 34 


By. - .. 


1900 


198 


145,188 


M.L.B 


1902 


241, 287 


145,237 


,, 


. . 1902 


193 


145,238 


By. ..... 


. . 1902 


242 


145,239 




. . 1902 


196 


146,223 




. . 1902 


91, 269, 287 


146,691 


,, . . 


. . 1900 


228 


146,848 


BA.S.F 


1900 


224, 226 


147,277 


By. 


1902 


79, 201 


147,851 




1902 


194 


147,872 


,, . . . . . . 


1902 


35i 


148,079 


,, 


1902 


79, 201 


148,109 


B.A.S.F 


. . 1901 


227 


148,306 




. . 1902 


203 


148,767 


By 


. . 1903 


196, 198 


148,792 


M.L.B 


1903 


250 


148,875 


,, 


. . 1903 


241 


149,780 


,, 


. . 1903 


196 


149,781 


,, 


, , 1903 


240, 295 



406 



INDEX TO GERMAN PATENTS 



D.R.P. 


Paten 


i.ee 


149,801 


By. 




150,322 


M.L.B. 




151,018 


B.A.S.F. 




151,384 


,, 




ISI^^ 


By. 




152,013 


" 




152,175 


Wed. 


. . 


153,129 


B.A.S.F. 




153,194 


Wed. 




153,517 


By. 




153,77 


,, 




154,337 


,, 




154,353 


,, 




155,045 


,, 




155,415 


B.A.S.F. 




155,44 


By. 






B.A.S.F. 




*56,477 


M.L.B. 




156,759 


By. 




156,762 






156,803 


M.'L.B. 


, . 


156,960 


By. 





157,449 


B.A.S.F. 


\\ 


157,685 


lt 




158,076 


M.L.B. 


, . 


158,257 


,, 


. . 


158,277 


f) 


. . 


158,278 


tl 


. . 


158,287 


By. 


. . 


158,413 


M.L.B. 


. . 


158,474 


By. 


. . 


158,531 




. . 


158,891 


tt 


. . 


158,951 


B.A.S.F. 


. . 


159,129 


By. 




159,942 


, 




160,104 




, 




160,169 




t 


. . 


161,026 




t 




161,923 








161,954 




, 




162,035 




t 




162,792 




t 




162,824 




, 




163,041 




, 


. . 


163,042 










163,646 




9 




163,647 




t 




164,129 




t 


. . 


1:64,292 




, 


. , 


164,791 




t 


. , 


165,140 




, 


. . 


165,728 




, 


. , 


165,860 




, 





Date. 


Page. 


1902 


177 


1903 


198, 200, 263, 28l, 282 


1902 


203 


1900 


20 3 


1902 


I 9 6 


1903 


198 


1903 


198 


1900 


194 


1902 


275, 276 


1903 


261, 262 


1903 


275, 276 


1903 


357 


1902 


356 


1903 


261, 262, 263 


1903 


258 


1903 


259 


1903 


35 


1903 


258 


1903 


203 


1903 


357 


1901 


224 


1903 


287 


1904 


227 


1903 


260 


1903 


17 


1903 


35 


1904 


343 


1900 


224, 226 


1904 


196 


1904 


285 


1905 


287 


1903 


345. 346, 35 


1903 


259 


1903 


346, 35 


1903 


287 


1903 


242 


1903 


228 


1901 


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 


igoi 


196 


1904 


283, 284 


1904 


288 


1903 


178, 194 


igoi 


229 


1904 


196 


1903 


202 


1904 


278 



INDEX TO GERMAN PATENTS 



407 



D.R.P. Patentee. 


Date. Page. 


166,433 By. 


. . 1904 196 


166,748 


1904 287 


167,169 


. . 1903 178, 194 


167,255 


. . 1904 346, 350 


167,410 


. . 1904 219, 225 


167,461 


. . 1904 91, 269 


167,699 M.L.B 


. . 1904 168, 242, 287 


167,743 Wed 


. . 1904 274 


168,042 B.A.S.F 


1903 35 


170,113 By. 


. . 1904 204 


170,329 Wed. 


. . 1903 178, 241 


170,562 By. 


. . 1904 341 


171.293 ,. 


1904 363 


171,588 


. . 1904 219, 225 


171,836 


1905 296 


171,939 B.A.S.F 


. . 1904 294, 320, 332 


172,105 M.L.B. 


1904 128 


172,300 Wed. 


I9O5 274 


172,464 M.L.B. 


**y 3 ** /T^ 
. . 1903 203 


172,575 By. 


. . 1905 188 


172,609 B.A.S.F. 


.. 1904 332 


172,642 By. 


1903 240, 241 


172,684 


1905 343, 349 


172,688 


. . 1904 179, 258, 259, 260, 278 


172,733 ,, 


. . 1904 302 


174,131 M.L.B. 


. . 1905 208 


174,494 B.A.S.F 


1905 335 


174,699 By. 


. . 1905 232 


174,984 B.A.S.F 


. . 1905 159 


175,024 By. 


. . 1902 206 


175,067 B.A.S.F 


1905 335 


175,069 By. 


. . 1905 210 


175,626 


. . 1905 345 


175,629 


. . 1905 188 


175,663 Wed 


. . 1901 274 


176,018 B.A.S.F 


. . 1904 275, 321 


176,019 


. . 1904 321 


176,641 By. 


. . 1905 188 


176,955 ,, 


. . 1905 188 


176,956 


. . 1905 232 


177,574 B.A.S.F 


1905 33L332 


178,129 By. 


- 1905 233,343 


178,130 . . * . . 


1905 343 


178,631 


. . 1904 240 


178,764 Agfa 


. . 1906 17 


178,840 By. 


. . 1905 188 


179,608 


. . 1905 i 88 


179,671 


. . 1905 188 


179,893 B.A.S.F 


.. 1905 94 




1905 27<5 


180,016 By. 


* " J ** / J 

. . 1905 188 


180,157 B.A.S.F 


. . 1905 92 


181,176 


. . 1904 321 


181,659 Wed 


. . 1905 275 


181,722 By. 


. . 1903 206 


181,879 M.L.B 


. . 1903 203 


183,332 ,. 


1906 250 


183,395 


. . 1903 196 



408 



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 


I8 4 ,905 


B.A.S.F. . . 


. . 1906 


232 


185,221 


,, . . 


. . 1904 


329 


185,222 


>. 


. . 1904 


330 


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 




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. . . 


JQQC 


q2Q 


188,596 


M.L.B. 


. . . . I9O6 


27O 


188,597 


,, 


. . I9O6 


27O 


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 


tf 


. . 1906 


290 


193.104 


M.L.B. . . 


1906 


280 


193,121 


By. 


1907 


345. 346, 347, 35i 


193,272 


T 


IQO7 


IOO 


193.959 


B.A.S.F. . . 


. . 1906 


325 


I93.96I 


Heller. . . 


1906 


134. !43 


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 


J 97.554 


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 



INDEX TO GERMAN PATENTS 



409 



D.R.P. Patentee. 


Date. Page. 


199,713 By. 


. . 1907 2QO 


199,756 B.A.S.F. . . 


1905 95 


199,758 


. . 1907 229, 230 


200,014 By. 


. . 1907 326 


200,015 B.A.S.F 


. . 1907 291, 292 


200,335 


1905 34. 321 


201,327 M.L.B. 


. . 1907 231 


201,542 By. 


. . 1907 96 


201,904 


. . 1907 293 


201,905 M.L.B. 


1907 2OI, 203 


202,398 Wed. 


. . 1903 178, 239, 241 


202,770 ,, 


. . 1907 273 


203,083 By. 


. . 1906 248 


203,436 


1906 335 


203,752 


. . 1907 290 


204,354 B.A.S.F. .. 


. . 1905 322 


204,411 M.L.B. 


1907 391 


204,772 By. 


. . 1907 183, 187 


204,905 B.A.S.F. 


1907 345 


204,958 G.C.I. B 


. . 1907 188 


205,035 M.L.B. 


1907 354 


205,095 B.A.S.F 


- 1907 293 


205,096 M.L.B. 


. . 1907 201 


205,097 By. 


1907 253 


205,149 M.L.B. 


. . 1907 201 


205,195 By. .. .. 


. . 1907 173 


205,212 G.C.I.B. . . 


. . 1907 188 


205,217 


. . 1907 188 


205,218 


1907 188 


205,294 B.A.S.F. 


1905 321 


205,442 By. 


1906 335 


205,551 M.L.B 


1907 2OI 


205,881 By. 


1903 2O2 


205,913 


. . 1907 173 


205,914 M.L.B. 


1907 355 


205,965 Wed. . . . . 


. . 1903 238, 278 


206,054 By. 


. . 1907 183 


206,464 B.A.S.F 


. . 1907 300 


206,536 By. 


. . 1908 183, 187 


206,645 B.A.S.F. . . 


. . 1907 196 


206,717 


. . 1908 232, 235 


207,668 M.L.B 


. . 1908 250 


208,162 By. . . * 


. . 1908 232, 235 


208,559 G.C.I.B 


. . 1908 188 


208,640 By. 


. . 1907 183 


208,969 M.L.B. 


. . 1908 234 


209,033 By. 


1907 290, 291 


209,231 G.C.I.B. . . 


. . 1907 188 


2OQ 232 


. 1908 188 


209,233 


. . 1908 188 


209,321 M.L.B. 


. . 1908 196 


209,331 G.C.I.B. . . 


. . 1907 188 


209,351 


. . 1908 188 


210,019 By. 


. . 1908 213, 214 


210,565 B.A.S.F 


. . 1908 345 


210,863 Wed 


. . 1908 179, 238, 241, 278 


211,383 B.A.S.F 


1908 300 


211,927 


, . 1908 335 



410 



INDEX TO GERMAN 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 





. . 1907 


290 






212,436 


By 


1908 


213, 


2I 4 




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 


1 86 






214,150 


,, 


. . 1908 


173 






214,156 


Thiimmler 


. . 1909 


178 






214,714 


B.A.S.F 


. . 1908 


174 






215,006 


it 


. . 1908 


91, i 


73, 


387 


215,182 


tt 


. . 1908 


214 






215,294 


By 


. . 1907 


211 






216,071 


B.A.S.F 


. . 1907 


174 






216,083 


M.L.B 


. . 1907 


2 3 I 






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. .'.' 


. . 1908 


352 






216,980 


By 


. . 1908 


213, 


214 




217,395 


B.A.S.F 


. . 1907 


232, 


293 




217,396 


,, 


. . 1907 


232, 


293 




217,552 


By 


. . 1908 


178 






217,570 


B.A.S.F 


. . 1909 


332 






217,688 


By 


. . 1908 


374 






2l8,l6l 


B.A.S.F 


. . 1907 


232, 


293 




218,162 





. . 1909 


335 






218,476 


tl 


. . 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 




IQOQ 


211 






220,580 


By. 


. . 1909 


339 






220,581 




. . 1909 


232, 


234 


,235 


220,627 


,, 


. . 1909 


208 






221,853 


Ullmann 


. . 1909 


306 






222,205 


B.A.S.F 


. . 1909 


210 






222,206 




. . 1909 


211 






223,069 


By 


. . 1909 


213, 


214 


, 219 


223,103 


, 


. . 1908 


253 






223,176 


G.C.I.B 


. . 1901 


188 






223,210 


Kinzlberger & Co. 


.. 1908 


"5 






223,510 


By 


. . 1908 


213, 


214 




223,642 


Ullmann 


. . 1909 


178 






224,019 


M.L.B 


. . 1908 


180 






224,490 





. . 1909 


219 







INDEX TO GERMAN PATENTS 



411 



D.R.P. Patentee. 




224,500 M.L.B 




224,589 By. 




224,808 




224,982 Ullmann 




225,232 By. 




225,982 




226,215 B.A.S.F 


. . 


226 230 Geigy. 




226,879 By. 




226,940 


. . 


226,957 




227,104 




227,324 Ullmann 




227,398 By. 




227,790 B.A.S.F 




228,876 




228,901 By. 




229*110 Agfa. 




229,111 M.L.B. 


. . 


229,165 Agfa 


. . 


229,166 B.A.S.F 


. . 


229,316 By. 


. . . 


229,394 B.A.S.F 


. . 


229,408 M.L.B 


. . 






230,005 M.L.B. 




230,052 By. 




230,399 B.A.S.F. 




230,407 By. 


. . 


230,409 




230,411 B.A.S.F 


. . 


230,454 Ullmann 


. . 


230,455 G.C.I.B 




231,091 M.L.B. 


. 


231,853 


. . 


231,854 




232 O?6 Bv 




.232,127 M.L.B 


. . 


232 13=5 




232 262 By 




232,526 M.L.B. 




232,711 Agfa. 




232,712 




232,739 M.L.B. 




232, f 91 ,, 


. . 


232,792 


. . 


233,072 Agfa 


. . 


233,126 By. 


. . . . 


234,289 Griinau, Landshoff, 


atid Meyer 


234,294 By 


. . 


234,518 




234,749 B.A.S.F 




234.922 


. . 


234.977 


. . 


235,094 By. 




235,312 ! 


. . 


235,776 Wed 





Date. 



Page 



1909 


35 




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 


I 44. 


304 


1909 


196 




1909 


220 




1909 


318 




1909 


381 




1909 


208 




1909 


221 




1909 


233 




1910 


34 1 




1910 


373 




1910 


373 




1909 


219 




1909 


221 




1909 


221 




1910 


373 




1909 


293 




1908 


76 




1909 


35 




1910 


212 




1910 


332 




1910 


222 




1909 


312, 


317 


1910 


381 




1910 


208 




1909 


199 





412 

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 



INDEX TO GERMAN PATENTS 



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. 

Scholl 

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. 

1909 

1910 

1910 

1910 

1909 

1909 

1909 

1909 

1909 

1909 

1909 

1910 

1909 

1910 

1910 

1910 

1909 

1909 

1909 

1909 

1910 

1910 

1910 

1910 

1910 

1910 

1909 

1910 

1910 

1909 

1910 

1909 

1910 

1909 

1909 

1910 

1909 

1910 

1910 

1910 

1910 

1910 

I9II 

I9II 

I9II 

1909 

I9IO 

1910 

1908 

1910 

1911 

1909 

1909 

1910 

1910 

igil 



1909 



Page. 
22O 
2I 4 
209 
297 
22O 
22O 
220 
220 
221 
220 
220 
335 

188 
297 
387 
235 

219, 220 
220 
22O 
22O 

345, 350 
335 

220, 365 
366 
317 
343 

3 I2 > 313 
379 
336 
183 
306 
218 

234, 36i 
220 

350 

232 

306 

1 60 

188, 350 

92, 159 

33, 143, 164 

335 
1 60 
223 
255 
219 

212 
212 
I8 3 

188 
313 

221 
219, 221 

285 
318 

188 
164 

2IO, 2IJ 



INDEX TO GERMAN PATENTS 



413 



D.R.P. 


Patentee. 


Date. 


Page. 


243,586 


M.L.B 


. . 1909 


36, 308, 313 


243,587 


,, 


. . 1910 


317. 318 


243.649 


,, . . . . . . 


. . 1910 


286 


243,750 


B.A.S.F 


I9II 


317 


243,751 


G.C.I.B 


I9II 


188 


243,788 


Ullmann 


. . 1909 


162 


244,372 


Wed 


I9IO 


199 


245,014 


,, 


. . 1910 


199 


245,191 


M.L.B 


. . 1910 


387 


245,768 


,, 


. . 1910 


350 


245,875 


,, 


. . 1910 


306 


245,973 


G.E 


. . 1910 


387 


245,987 


By. 


. . I9II 


255 


246,079 




. . igil 


266 


246,085 


M'.L.B. ! ! 


I9IO 


387 


246,086 


B.A.S.F 


IQII 


222 


*tf.V^j 

246,477 




A v^ J. A 
I9II 


223 


246,867 


Agfa! 


. . 1909 


188, 350 


246,966 


B.A.S.F 


I9II 


306 


247,187 


J. Meyer 


. . I9II 


o v ^ 

322 


247,245 


Wed 


.. I9II 


199 


247,246 


By 


.. I9II 


366 


247,352 


M.L.B 


. . 1909 


387 


247,411 


B.A.S.F. .. 


.. I9II 


196, 199 


247,412 




I9II 


184. 


247,416 


Casella 


.. I9II 


T^ 

1 88 


248,169 


By 


.. I9II 


359 


248,170 


B.A.S.F 


.. I9II 


306 


248,171 


,, 


.. 1913 


l8 9, 35 


248,289 


By 


. . 1908 


213 


248,469 


M.L.B 


. . 1910 


3i8 


248,582 


B.A.S.F 


.. I9II 


353 


248,655 


By 


. . 1910 


211 


248,656 


B.A.S.F 


.. I9II 


223 


248,838 


Agfa 


.. I9II 


194 


248,996 


B.A.S.F 


IQII 


313. 318 


248,997 




*y+ * 
I9II 


O X O 3*" 
214 


248,998 


Ullmann . . 


. . I9II 


354 


248,999 


,, 


. . I9II 


92, 297, 302 


249,225 


M.L.B 


. . 1908 


1 86 


249,368 


By. .. ... 


. . I9II 


255 


249,721 


,, 


.. I9II 


175 


249,938 


M.L.B 


. . 1910 


233 


250,075 


K. Meyer .*. 


. . 1910 


23,46 


25O,O9O 


By 


.. I9II 


37i 


250,271 


Schaarschmidt 


. . 1910 


3i8 


250,272 


,, 


I9IO 


319 


250,273 


B.A.S.F 


I9II 


187 


250,274 


G.E 


I9II 


387 


2^0,742 


B.A.S.F 


I9II 


163 


* J^ t / ^\~ 
250,885 


M.L.B 


-7 * 

. . 1911 


***^J 

291 


25I,O2O 




I9II 


380 


251,021 





.. igil 


234, 361 


25LII5 


B.A.S.F 


.. I9II 


187 


251,234 


M.L.B 


.. I9II 


188 


251,235 


, 


.. igil 


188 


251,236 
251,350 


By 
M.L.B 


.. I9II 
.. I9II 


255 
234, 36i 



414 



INDEX TO GERMAN PATENTS 



D.R.P. Patentee. 


Date. Page. 


251,480 Schaarschmidt . . 


I9IO 365 


251,695 By 


I9II 62 


251,696 B.A.S.F 


I9II 316 


25L709 


I9II 187 


251,845 W.t.M 


I9II 211 


251,956 By 


I9H 341 


252,529 


I9II 341 


252,530 


I9II 378 


252,578 B.A.S.F 


I9II 173 


252,759 By 


1911 74 


252,839 


1911 368, 369, 372 


253,088 G.E. 


1911 387 


253,089 By. 


1911 372 


253,090 B.A.S.F 


1911 308 


253,238 M.L.B 


1910 387 


253,507 


1908 186 


253,683 


1909 179, 230, 231 


253,983 Sanders 


1911 317 


254,033 Schaarschmidt 


1911 365 


254,091 Agfa 


1911 136 


254,097 B.A.S.F 


1912 353 


254,098 G.C.I.B. 


1911 188 


254,185 M.L.B. 


1911 225 


254,186 


1911 233 


254,450 B.A.S.F 


1911 173 


254,475 M.L.B 


1911 305 


254,561 By 


1912 186 


254,710 Grunau, Landshoff, and Meyer 


1910 76 


254,743 Ullmann 


1911 372 


254,744 M.L.B 


I9H 220 


254,745 By 


1912 388 


255,031 


1912 129, 138 


255,121 


1912 165 


255,340 M.L.B 


1910 387 


255,591 Ullmann and Goldberg 


1910 186 


255,641 G.E. 


1912 364 


255,821 M.L.B 


1911 210 


255,822 


1911 233 


256,297 


1911 292, 293 


256,344 B.A.S.F 


1912 196 


256,515 


1911 206 


256,623 M.L.B 


1911 76 


256,626 


1911 306, 313 


256,667 By. 
256,761 M.L.B 


1912 374 
1912 390 


256,900 By. 


I9II 222 


257,811 M.L.B 


1909 232 


257,832 Wed 


1912 286 


258,343 Agfa 


1912 194 


258,556 M.L.B 


1911 93 


258,561 B.A.S.F 


1910 318 


258,808 Agfa 


IQIO 37Q 


259,037 By 


J -y xv7 j/y 
I9II 368, 372 


259,365 B.A.S.F 


1912 163 


259,37 


1912 331 


259,432 G.E 


1912 227 


259,881 M.L.B 


1912 95 


260,020 B.A.S.F. 


1912 331 



INDEX TO GERMAN PATENTS 



D.R.P. 


Patentee. 


Date. 


Page. 


260,562 


B.A.S.F 


. . 1912 


49 


260,662 


M.L.B 


.. 1911 


95 


260,765 


By 


.. 1911 


264 


260,899 


Agfa 


. . 1912 


194 


260,905 


B.A.S.F 


1911 


371. 372 


261,270 




1911 


230 


261,271 





1911 


230 


261,495 


Caseila 


.. 1911 


360, 362 


261,557 


G.C.I.B 


. . 1912 


188 


261,737 


B.A.S.F 


.. 1911 


366, 367 


261,885 


Agfa 


. . 1912 


196 


262,076 


G.E 


. . 1912 


227 


262,469 


By 


. . 1912 


379 


262,477 


M.L.B 


.. 1911 


186 


262,478 


G.C.I.B 


1912 


326 


262,788 


M.L.B 


1911 


234 


263,078 


B.A.S.F 


. . 1912 


313 


263,340 


M.L.B 


. . 1912 


1 80 


263,395 


B.A.S.F 


.. 1911 


179, 231 


263,423 


By 


.. 1911 


287 


263,424 


,, 


.. 1911 


196 


263,621 


Wed 


1911 


286 


264,010 


By 


. . 1912 


292 


264,043 


G.E 


. . . . 1912 


340 


264,139 


By 


. . 1912 


374 


264,290 




. . 1912 


367 


264,940 





. . 1912 


185 


264,941 


, 


. . 1912 


185, 188 


264,943 


B.A.S.F 


. . 1912 


373 


265,194 


G.C.I.B 


. . 1912 


1 88 


265,647 


Wed 


. . 1912 


286 


265,725 


M.L.B 


. . 1912 


196 


26>,727 


B.A.S.F 


1911 


179, 231 


A* V^J| / ** / 

266,521 


M.L.B 


. . 1912 


1 80 


266,563 


B.A.S.F 


1911 


179, 231 


266,945 


,, 


1912 


356 


266,946 


,, 


. . 1912 


356 


266,952 


B.A.S.F 


.. 1911 


359 


267,O8l 


Afga. 


1912 




-267,212 


M.L.B 


. . 1912 


206 


267,414 


Casella . . 


. . 1912 


210 


267,415 


,, 


. . 1912 


210 


267,416 


,, 


. . 1912 


210 


267,417 


M.L.B. . . - 


1912 


380 


267,418 


B.A.S.F 


1912 


331 


267,445 


By 


1912 


225 


267,522 


M.L.B 


. . 1912 


234, 361 


267,523 


B.A.S.F 


.. 1912 


373 


267,544 


M.L.B 


.. 1911 


173 


267,546 


,, . . . . 


. . 1909 


95 


267,833 





. . 1912 


234, 360 


268,049 


B.A.S.F. .. 


. . 1909 


76 


268,219 




1912 


306 


268,224 


.. 


. . 1913 


*J 

331 


268,454 


M.L.'B 


. . 1912 


196 


268,504 


B.A.S.F 


. . 1912 


339 


268,505 


By 


.. 1913 


365 


268,646 


Brass 


. . 1912 


306 



416 



INDEX TO GERMAN PATENTS 



D.R.P. 


Patentee. 


268,793 


By. 




268,984 






269,194 


B.'A.S.F. 




269,215 


Wed. 




269,249 


Agfa. 




269,749 


M.L.B. 


. . 


269,800 


Schaarschmidt 


269,801 


Cassella 


. . 


269,842 


By. 




269,850 


B.A.S.F. 




270,579 


By. 




270,789 


M.L.B. 




270,790 


,, 




27L475 


By. 


. . 


271,681 


M.L.B. 




271,790 


,, 


. . 


271,902 


Agfa 




271,947 


G.E. 


, 


272,296 


B.A.S.F. 




272,297 


lt 


. . 


272,298 


By. 




272,299 


f 




272,300 


,, 




272,301 


f> 




272,613 


M.L.B. 




272,614 


fl 




273,318 


M.L.B. 




273.3I9 


tl 




273.341 


By. 




273.443 


G.E. 


. . 


273.444 


M.L.B. 


. . 


273,809 


Junghaus 




274.357 


By. 




274.7 8 3 


Scholl 




274,784 


>, 




275,220 


Kardos 




275,248 


, 




275.299 


By. 




275.517 


M.L.B. 


. . 


275,670 


B.A.S.F. 


. . 


275,671 


fj 




276,357 


Kardos 


. . 


276,358 


lt 




276,956 


lt 


. . 


277.393 


G.E. 


. . 


277.439 


M.L.B. 


. . 


277.733 


Hofmann 


_ 


278,424 


B.A.S.F. 




278,660 


Kardos 


. . 


279,198 


M.L.B. 


. . 


279,866 


B.A.S.F. 




279,867 


tl 


. . 


280,092 






280,190 


M.L.B. 




280,646 


Agfa. 


. . 


280,710 


B.A.S.F. 




280,711 


Cassella 


. . 


280,712 


,, 





Dale. 



Page. 



1912 


293 


1912 


225 


1911 


314 


1912 


286 


1913 


171 


1913 


196 


1912 


307. 317 


1912 


2IO 


1913 


365 


1912 


306 


1912 


213 


1912 


362 


1912 


196 


1911 


222 


1911 


173 


1913 


165 


1912 


354 


1913 


350 


1913 


307 


1913 


38 


1911 


1 86 


1912 


280 


1912 


1 86 


1913 


264 


1912 


362 


1912 


196 


1912 


76 


1912 


76 


1913 


163 


1913 


388 


1913 


356 


1911 


230 


1911 


1 86 


1913 


286 


1913 


9i 


1913 


330, 384 


1913 


384 


1912 


231 


1913 


165 


1912 


360 


1913 


307 


1913 


33 


1913 


33 


1913 


330 


1913 


179 


1912 


181, 186 


1913 


75 


1913 


335 


1913 


330, 384 


1914 


363 


1913 


226 


1913 


232 


1913 


69 


1913 


290, 362 


1913 


196 


1913 


331 


1913 


315 


1913 


307 



INDEX TO GERMAN PATENTS 



417 



D.R.P. 


Patentee. 


280,839 


Kardos 




280,840 


By. 


. 


280,880 


B.A.S.F. 


. . 


280,881 






280,882 






280,883 






280,975 


M.L!B. 




281,010 


Agfa. 


. . 


281,102 


By. 




281,490 


Ullmann 


. . 


282,265 


By. 




282,493 


Ullmann 


. . 


282,494 






282,672 


M.L.B. 


. . 


282,711 


Kardos 


. . 


282,818 


M.L.B. 




282,920 


Agfa. 




283,066 


B.A.S.F. 




283,106 


M.L.B. 




283,213 


G.E. 




283,365 


B.A.S.F. 




283,482 


Agfa. 




283,724 


B.A.S.F. 




283,725 


Cassella 




284,083 


G.E. 


. . 


284,084 


tt 


. 


284,179 


t 


. 


284,181 


M.L.B. 


. 


284,207 




. 


284,208 


M 


. . 


284,209 




. . 


284,210 


Kardos 




284,700 


B.A.S.F. 


. . 


284,790 


M.L.B. 


. . 


284,976 


M 




286,092 


( 




286,093 


, 




286,094 


, 




286,095 


By 




286,096 


Kardos 




286,098 




. 


286,468 


t 


. . 


287,005 


Cassella 


. . 


287,270 


B.A.S.F. 


. . 


287,523 


Cassella 


. . 


287,590 


M.L.B. 


. . 


287,614 


B.A.S.F. 


. . 


287,615 






287,867 


By. 




288,464 


B.A.S.F. 




288,474 


By. 




288,665 


Agfa. 




288,824 


By. 




288,825 




, 


288,842 


M.L.B. 




288,878 


By. 


. . 


289,112 




. . 


289,279 


M.L.B. 





Date; 
1913 
1913 
1913 
1913 
1913 
1913 
1913 
1913 
1913 
1914 

1913 
1914 
1914 
1913 
1913 
1913 
1913 
1913 
1912 

1913 
1913 
1914 

1913 
1913 
1914 
1914 
1914 
1913 
1913 
1913 
1913 
1913 
1913 
1913 
1913 
1913 
1913 
1913 
1914 

1914 
1914 
1914 
1914 

1913 
1914 

1913 
1914 
1914 
1914 
1914 

1914 
1914 
1914 
1914 

1913 
1914 
1914 
1914 



Page. 

330. 384 
365 
330 
2IO 

373 

373 
285 
220 

183 
167 
164 

127, 138 
276 
196 

33. 384 
47 

222 
321, 330 

43 
75 
330 

288 

37 

373 

75 

75 

75 

368 

366 

363 
291 

330, 384 

33i 

44 

173 

196 

368 

368 

312 

37 

330 

330 

373 

254. 335, 343 

373 

350 

306, 312 

312 

179, 279 

206 

179, 279 

196 

361 

208 

368 

178 

179, 279 

35 

27 



4i8 



INDEX TO GERMAN PATENTS 



D.R.P. Patentee. 


ijatc. .rage 


290,079 B.A.S.F. . . 
290,084 G.E. 


1914 329 

1914 l8 4 


290,814 


1914 224 


290,879 Agfa. 


1914 I 73 


290,983 M.L.B. 


1913 355 


290,984 By. 


1914 291 


291,984 G.E. 


1914 222 


292,066 Ullmann . . 


1914 138 


292,127 G.E. 


1915 35 


292,247 


1913 267 


292,356 M.L.B. 


1914 4 8 


292,395 


I9H 22 4 


292,457 


1914 l8 3 


292,59 


1914 49 


292,681 


1914 7 6 


293,100 B.A.S.F. . . 


1914 197 




. 1913 171 


293,567 M.L.B. 


1913 393 


293,970 Wed. 


1913 88 


293,971 M.L.B. 


1914 35 


295,624 By. 


. . 1912 196 


296,019 M.L.B, 


1915 5 


296,091 By. 


1915 84, 271 


296,192 G.E. 


1915 35 


296,207 Wed. 


1912 188 


296,841 M.L.B. 


1914 35 
... .. 1912 188 


297,080 , 


1912 188 


297,261 , 


1915 271 


297567 
298,182 


1913 188 
1913 188 


298,183 


1913 188 


298,345 By. 


1916 13, 157 


298,706 M.L.B. 


1913 366 




. . 1913 188 


301,452 By. 


1916 84,271 


301,554 G.E. 


1914 364 


302,259 


1914 364 


302,260 


1916 364 


305,886 By. 


1917 84, 271 


307,399 Scholl. 


. . 1916 297 


308,666 M.L.B. 


. . 1916 232 


311,906 


1913 188,371 



INDEX TO AUTHORS 



ACHENBACH, 77, 78, 369 

Aders, 285 

Akt. Ges. f. Anilin Fabrikation 
(Agfa), 17, 64-66, 136, 159, 173, 
188, 194, 196, 210, 211, 220, 222, 
288, 354, 373, 379 

Akt. Ges. f. Teer u. Erdol 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, 317, 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 
Bischofif, 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 
Claus, 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, 162,165,237,266 

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 
Drew son, 127 
Dumas, 1, 14 
Dunschmann, 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 

PICK, 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 
Frey, 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, 369, 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.), 144, 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 
Herfter, 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 
Holliday (L.B.) & Co., Ltd., 7, 272, 

276 

Hermann, 64, 65, 237, 266 
Hovermann, 139, 248 
Hutchison, 186 

ILJINSKY, 3, 5, 177 
Imhoff, 43 
Ipatjew, 40 
Isler, 4, 5 

JACKSON, 15 
Jacowlew, 40 
Jones, 33, 36, 37 
Jowett, 27 
Jungermann, 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, 118, 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 
Landshoff, 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 

Lifschutz, 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 

Meyer, J., 322 

Meyer, 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 

Meyer, V., 78 

Michael, 145 

Mills, 156, 157 

Mohlau, 273, 364, 389-391 

Molinari, 17 

Morton, 345 

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 
Perkin, A. G., 50, 53, 54, 57, 60, 

103, 164, 321, 326, 327, 329, 345, 
Perkin, W. H., 3, 15, 43, 176, 178, 

281 

Perrier, 70 
Peter, 144 
Petersen, 167, 168, 192, 244, 249, 

386 

Philippi, 76, 156, 157 
Phillips, 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 

Ritte'r, 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 
I Russig, 157 
( Rubidge, 133 

! SACHS, 206 

I Sadler & Co., 74 

i 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 

Schepper, 133, 139 

Schiff, 126 

Schilling, 47, 49, 174 

Schlenk, 17, 18, 102 

Schlosser, 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 

Scholl, 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 
Schiiler, 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 
Schiirmann, 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 
Stahling, 87 
Stahlschmidt, 192, 295 
Staudinger, 14, 78 
Strecker, 2 
Stein, 315 
Steiner, 170, 171, 175, 224, 232, 234, 

273, 280, 343 
Stegmuller, 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 
Tschilikin, 86, 87 
Tuck, 149 

UPPERS, 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 

Urmenyi, 315 

VOSWINCKEL, 147, 152-154 

WACKER, 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 Her (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 

Wieland, 39, 273 

Willgerodt, 164, 165, 207 

Willstatter, 396 

Wirth, 17 

Wislicenus, 146 

Wittich, 29 

Wolbling, 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 hydroxyl, and all alkyl groups as methyl. Both bromine and 
iodine are treated as equivalent to chlorine. 



ACEANTHRENE GREEN, 384 

wo-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 
Brilliant 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, 266-269, 272, 276, 
278-280, 285, 287, 343, 357 



Alizarin Astrol, 204 
Black, 295 
Blue Black, 205 

Blue, A, AB1, 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 
Allochrysoketone, 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, 207, 

305, 306, 309 
mercaptan, 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 

dianthraquirionylamine, 292, 343 
dibromanthraquinone, 172, 198, 
229, 230, 258, 259, 368, 372 
dichloranthraquinone, 229 
dihydroxyd ianthraquinonyl- 

amine, 234 

dinitroanthraquinone, 225, 226 
e r y t h rohydroxyanthraquinone, 

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 
phthalic acid, 129 
pyridanthrone, 293 
quinizarin, 129, 295 
violanthrone, 331 
Amyl anthracene, 18 
dihydroanthracene, 18 
hydroxyanthrone, 38, 110 
Angular structure, 10 
Anilido anthrone, 120 
Anisol, 139 
Anthracene, Action of nitric acid 

on, 50 

Estimation 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 

Anthraflavic acid, 126, 238, 240, 
253, 255, 268, 270, 271, 274- 
277, 280, 284 

iso-Anthraflavic acid, 126, 195, 238, 
240, 253, 268, 276, 277, 280, 
284 

Anthraflavone G, 94 
Anthraflavones, 80, 94 



426 



INDEX TO SUBJECTS 



Anthragallic acid. See Anthra- 

gallol. 
Anthragallol, 126, 238, 250, 251, 

260, 264, 269, 280 
Anthramine. See Ammoanthra- 

cene. 

Anthranilic acid, 195 
Anthranol, 22, 67, 77, 96, 98, 105, 
1 15, 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 Hydroxyanthrone. 
Tautomerism of, 121, 124 
anthraquinone dihydroazine, 347 
diethyl ether, 111 
dihydroazine, 348 
dimethyl ether, 111 
ethyl ether, 111 
methyl ether, 111, 122 
Anthraquinoline. See Pyridino- 

anthracene. 

Anthraquinone (1.2) 65, 72, 73, 343 
(1.4) 65, 72, 73 
(1.6) 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 sea., 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, 176-178, 

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 
quinoline. 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, 353 
trisulphonic acid, 177 
violet, 199 
xanthones, 315-317 
Anthraquinonyl acrylic acid, 160, 

164, 165 
aminoacridone, 379 

anthraquinone. See Dianthra- 

quinonylamine. 
dianthraquinonylamine, 233 et 

seq. 



INDEX TO SUBJECTS 



427 



Anthraquinonyl aminoacridone, 379 
thioxanthone, 379 
pyridanthrone, 293 
anthraquinone imidazol, 367 
arsenoxide, 383 
azide, 369, 388 
so-cyanate, 219 
glycy laminoanthraqu inone , 214 
hydrazine, 340-352, 363, 364, 389 

sulphonic acid, 389, 390 
hydroxylamine, 343, 389 
mercaptan, 181-187, 358, 359, 

370, 371, 373, 381 
oxaminic acid, 226 
piperidine, 195 
pyridazoneanthrone, 354 
selenocyanide, 185, 374 
sulphide, 186, 187 
thiocyanate, 183, 374, 381 
45o-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 
disulphonic 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 Anthrone. 
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, 3'89 

BARNETT'S notation, 12 

Basic dyes, 5 

Benzal acetoacetic ester, 100 

acetophenone, 101 

malonic ester, 100 
Benzalizarin, 327 
ang. Benzanthracene, 143 



lin. Benzanthracene, 147 
anthradiqu inone, 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 
quinoline, 332 
anthronylaminoanthraquinone , 

333 

dianthrone, 333 
fluorenone, 323 
Benzoic acid, 125 
Benzoyl aminoanthraquinone, 191, 

215 

chlor anthraquinone, 297 
dianthraquinonylamine, 235 
hydroxy anthraquinone, 2 15, 217 
nitroanthraquinone, 216, 217, 

368 
trihydroxyanthraquinone, 215, 

218 

anthracene, 70, 71 
anthraquinonyl 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 
Bisthiazolines, 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 
erythrohydroxy anthracene, 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 
alizarin, 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 

erythrohydroxy anthraquinone , 
127, 248, 274, 276 

flavopurpurin, 275 

naphthalene, 144, 150, 304 

nitro alizarin, 175, 200 

anthraquinone, 175, 203 
Chloroform, 15, 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 
iso-Chrysofluorenone, 325 
Chrysol, 66 
Cibanon, 7 

Coccinic acid, 129, 140 
Cceramidine, 379 

carboxylic acid, 379 
Cceroxene, 374-378 
Cceroxenol, 377 
Cceroxonol, 377 
Cceroxonium salts, 376 
Ccerthiene, 378 
Ccerthienol, 378 
Coerthionol, 378 
Ccerthionium salts, 378 
Ccerulem, 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 
anthraflavic acid disulphonic acid, 

284 
iso-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 anthrarunn, 93, 282 

disulphonic acid, 283, 284 
bromanthraquinone, 367 
chrysazin disulphonic acid, 284 
dianthraquinonylamine, 233, 234 
dianthraquinonyl, 300, 301, 360 
dianthryl, 115, 124 
dihydroxy dianthraquinonvl- 

amine, 233 

dinitroanthraquinone, 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 
fcis-Dibenzalanthracene, 37 
Dibenz anthracene, 158 
anthradiquinone, 156 
anthraquinone, 135, 142, 143, 

154-158 

anthratriquinone, 157 
Dibenzoyl amino anthraquinone, 

215, 216 

anthrarufin, 215, 218 
dianthraquinonyl, 218 
hydroxyanthraquinone, 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 
so-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 
anthrachrysazin 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 



43<> 



INDEX TO SUBJECTS 



Dichlor dihydroanthracene, 15, 31 
erythrohydroxyanthraquinone, 

248, 274 

indanthrone, 351 
methyl anthraquinone, 164, 171, 

366, 367 

nitroanthraquinone, 175 
phthalic acid, 45, 49, 128, 137- 

139, 144, 148 
pyranthrone, 335 
quinizarin, 248 
iso-violanthrone, 332 
Diethoxy anthracene, 66 
Diethyl amino anthroquinone sul- 

phonic acid, 209 
aniline, 141 
anthrone, 106 
dianthraquinonyl, 336 
dihydroanthracene, 106 
pyranthrone, 336 
Dihydro anthracene, 15, 16, 25, 31, 

39, 40, 56, 80, 84 
anthrazine, 342, 349 
benzanthradiquinone. See Di- 

hydroxy - lin - benzanthraqui- 

none 

benzanttirene, 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 
Dihydroxy 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 
dianthrylmethane, 314 
dibenzanthradiquinone, 157 
dichlor anthraquinone, 136 
benzoyl benzoic acid, 249 
dinitrosodinitroflavanthrone, 302 
dipyridinoanthraquinone, 295 
helianthrone, 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 

anthraquinone, 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 

anthragallol, 126 

anthramine, 68 

anthraquinone, 29-34, 79, 134, 

141, 168 
carboxylic 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, 1 75 

dihydroxy dihydroanthracene, 87 

dimethoxydihydroanthracene, 87 

dinitroanthraquinone, 1 69 

diphthaloyl thianthrene, 189 

indanthrone, 350 

malonyl chloride, 384 

nitroanthraquinone, 169 

pyranthrone, 336 

tetrahydroxybenzanthraqu inon e, 
147 

trihydroxyanthraquinone, 34 
Dinaphthanthradiquinone, 156 
Dinaphthanthraquinone. See Di- 

benzanthraquinone . 
Dinaphthoyl pyrene, 337 
Dinaphthyl dicarboxylic acid, 322 
Dinitramino tetrabromanthraqui- 
none, 227 

tetranitroanthraquinone, 226 
Dinitro anthracene, 50, 54, 59 

anthrachrysazin, 194 

anthraflavic acid, 280 

t'so-anthraflavic, 280 



INDEX TO SUBJECTS 



431 



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, 115, 124 

dihydroanthracene, 57, 59 

diphenylamine, 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 

py ran throne, 335 
Diphthaloyl acridone, 309, 313, 314 

carbazol, 360-362 

oxazine, 356-358 

phenylxanthene, 316 

thianthrene, 189 

thiazine, 358-360 
Dipropyl dianthraquinonyl, 336 
Dipyridinoanthraquinone, 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 
Durylic acid, 35, 126 
Dyeing, 5 

EMODIN, 27 

Erweco 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 diphthalide, 145 
iso-Ethine diphthalide. See Dihy- 

droxybenzanthraquinone. 
Ethyl anthracene, 52 

anthranol ethyl ether, 106 

anthraquinone, 80, 94, 134 

benzene, 80, 134 

benzyl aniline, 141 

dihydroanthracene, 52, 55 

ethoxy anthracene, 106 

hydroxy 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 
Furyl naphthyl ketone, 338 

GALLE'IN, 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 
Helianthrone, 92, 327, 328, 333- 

335 
Helindon, 7 

Brown 3 GN, 221 
Orange GRN, 221 
Yellow 3 GN, 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 brom anthracene, 42, 43 
chlor anthracene, 42, 47 
anthraquinone, 170 
anthrarunn, 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 
methyl anthracene, 36 
phenyl ethane, 102 
Hydranthrene, 7 
Hydrindene, 396 
Hydro-anthracene nitrite, 56 
Hydro-anthracenes, 39-41, 265 
Hydrojuglone, 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 
anthrarunn, 238, 241, 253, 



260 



257, 



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 

Salicylic acid, 
brom anthraquinone, 273 
chlor anthraquinone, 127, 128, 

138, 248, 274-276, 286 
benzanthraquinone, 149 
chrysazin, 238, 241, 253, 260 
dianthraquinonylamine, 233 
dibromanthraquinone, 273 
dichloranthraquinone, 248, 274 
dihydroanthracene, 81, 82, 110, 

140 
diketo hexahydroanthraquinol, 

398 



j8-Hydroxy dinitroanthraquinone, 

250, 280 
diphenylamino anthraquinone, 

205 

ethyl aminoanthraquinone, 208 
flavopurpurin, 238, 262, 266 
hydroquinone triacetate, 129, 

140 
naphthoquinonyl acetic acid, 269 

acrylic acid, 269 
naphthoyl benzoic acid, 139, 

148 

nitroanthraquinone, 250, 356 
benzanthraquinone, 150 
dihydroanthracene, 51 
nitroso nitroanthraquinone, 169, 

244 
phthalic acid, 129, 139, 140, 148, 

263 

purpurin, 238 
pyridanthrone. See Pyridone- 

anthrone. 

pyridinoanthraquinone, 294-296 
pyridone anthrone, 291 
toluic acid, 126 
Hydroxy lamino anthraquinone, 169, 

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 j 
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 j 
chloranthraquinone, 247 
dianthraquinonylamine, 356 
nitroanthracene, 59 
phthalic 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 
benzanthrone, 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 
ery throhydroxy anthr 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, 144 
naphthalene, 143 
nitroanthraquinone, 195, 247 
pentabrom anthracene, 48 



Methyl phenyl hydroxy methoxy 

dihydroanthracene, 87 
phthalic acid, 128 
pyridanthrone, 292 

anthraquinone, 298, 299 
quinizarin, 128, 163, 248 
tetrahydroxy anthraquinone, 126 
thianthrene, 189 
thiodianthraquinonylamine, 358 
tolylanthraquinone, 84, 136 
trihydroxy anthraquinone, 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 
Naphthy lanthraquinony 1 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, 199, 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 
chrysazin, 280 

dimethyl ether, 280 
dianthraquinonyl, 92 

amine, 343 
erythrohydroxyanthraquinone, 

243, 250 

disulphonic acid, 343 
flavopurpurin, 247, 282 
hystazarin, 280 
naphthalene disulphonic acid, 

58 

phenylaminoanthraquinone, 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 such as Alizarin 

Cyanine R. 

Pentanitro dianthraq uinonylamine, 

233 

Perchlorethylene, 15 
Perhydroanthracene, 41 
Perylene, 327, 328, 399 
Petroleum, 14 
PfafFs 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 

xanthone, 316 
anthrone, 96, 120, 123, 135 
azo anthranol, 103 
benzoylbenzoic acid, 135 
chloranthraquinonyl ketone, 160 
chlor anthrone, 97, 102, 103 

methylene anthrone, 99 
cceroxene, 378 
dichlormethyl anthrone, 99 
diphenylmethane carboxylic 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 
Phthalic 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 
'so-Propyl anthraquinone, 134 
Propyl benzene, 80 
iso-Propyl benzene, 134 
Propyl hydroxy anthrone, 110 



INDEX TO SUBJECTS 



435 



Pseudocumene, 34, 36, 132, 134 
Pseudopurpurin, 264 
Purpurin, 93, 238, 239, 254,' 259, 
260, 262, 263, 265, 266, 
268-270, 278, 281, 356, 357 
carboxylic acid, 264 
disulphonic acid, 278 
sulphonic acid, 259, 263, 278 
iso-Purpurin. See Anthrapurpurin. 
Purpuroxanthin, 238, 244, 265, 272, 

276, 282, 285 
Pyranthrene, 4, 335, 339. See also 

Pyranthrone. 
Pyranthridene, 299 
Pyranthridone, 290, 297, 299 
Pyranthrone, 254, 299, 327, 328, 

335-337 

Pyrazinoanthraquinone, 347 
Pyrazolanthrone, 363, 364 
Pyrene, 327, 328, 336 
Pyrenequinone, 328 
Pyridanthrene, 289 
Pyridanthrone, 289, 290-293 
Pyridazineanthrone, 353-355 
Pyridazoneanthrone, 353 
Pyridino anthracene, 289, 294 
anthradiquinone, 296 
anthraquinone, 289, 293, 294, 

320 

benzanthrone, 332 
Pyridone anthrone carboxylic acid, 

291 

pyridinium chloride, 291, 292 
Pyrimidone anthrone, 354 
Pyrocatechol, 128, 130 
Pyrrol anthrone, 362, 363 

carboxylic 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 
/ewco-Quinizarin I, 265, 266, 396 

II, 265, 266, 296 
Quinizarin carboxylic acid, 163, 

261 

disulphonic acid, 259 
Green. See Alizarin Cyanine 

Green, 
sulphonic acid, 204, 259 

RUFIGALLIC acid. See Rufigallol. 
Rufigallol, 126, 239, 260, 263, 272 
Rufiopin, 238 
Rufol, 66 



SALICYLAMINO anthraquinone, 214 
Salpetersaureanthracen, 51, 52, 56 
Scholl's Peri synthesis, 324 
iso-Selenazolanthrone, 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 
phthalic acid, 42, 128, 138, 139, 

148, 171 
quinizarin, 248 
Tetraethyl diamino diphenyl- 

anthrone, 103 

Tetrahydro anthracene, 39, 40 
dianthrol, 83 
flavanthrene, 303 

hydrate, 303 

Tetrahydroxy 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 dinitroanthraq uinone , 
169 

tetranitroanthraquinone, 169 

azine, 351 

Tetramino dianthraquinonylamine, 
234 

dihydroxy flavanthrone, 302 

tetrahydroxy indanthrone, 351 
Tetranitro anthraflavic acid, 280 

iso-anthraflavic acid, 280 

anthraquinone dinitramine, 224 

anthrapurpurin, 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 
Thiazolines, 372 
Thienyl naphthyl ketone, 338 
Thiodianthraquinonylamine, 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 

trihydroxy 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 

trihydroxyanthraquinone, 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 
Untersalpetersaureanthracen, 57 

VAT dyes, 4, 6 
Veratrol, 139 
Vinyl bromide, 15 
Violanthrene, 4. See also Viol- 
anthrone. 

BS, 329 

R Extra, 332 

Violanthrone, 327, 329, 330 
aso-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 



Printed by William Clowes & Sons, Ltd., Beccles, for 
Batiliere, Tindall & Cox, 8, Henrietta Street, Covent Garden, W.C. a. 



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