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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            

•     364 

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 

NH2  NHCH3       NHPh        NHCOCHa 


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 : — 

NH2  NH2  NHCOPh         NHCOPh 


Brick  red. 


NH 


OH 

Bluish  red. 


Yellow. 


NHCOPh 
Red. 


NHCH,        NHPh        NHPh 


NH2  NH2 

Violet.        Bluish  violet. 


\ 
/ 


NH2  NHCH3      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  patents7  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 

C6H4/\C6H4          _££^  C6H4/\C6H4 

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 

C6H4/j\C6H4  C6H4^\C6H4 

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 

C6H4^\C6H3C1          and          C6H3( 

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 

C6H4^>C6H4      $      C6H4<^[)C6H4      5>      C6H4<Q>;C6H4 

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  : 

C6H5 


C6H4 


| 
C6H5 

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


0  /COC6H5 


(MeO)  2C6H2<(  |  >C6H4        ->         (MeO)  2C6H2<; 

XC  XCOC6H5 

C6H5 

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 

C6H4/\C6H4      -»      C6H4/\C6H4      ->      C6H4/\C6H4 

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   ^CeH4  ->  CeH4x    ^CeH4 

CH2  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 


H4  ->  C6H4/J>C6H4 

CH2  CO 


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

OH 

1 

C6H4/|\C6H4         -> 

C  CeH4        C0H4 

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 

OCOCH3  H     OCOCH3 


C  CH  C 

C6H4<j\C6H4     <-    C6H4/j\C6H4    ->     C6H4/\C6H4 
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 
C6H4 


C6H4   H    H  C6H4 
^>C 
C6H4 


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 


C6H4/\C6H4 


C6H4/\C6H4 

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 

C6H4/\C6H 

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  : 

C6H4  C6H4  H    H  C6H4 


CeH4  C6H4        C6H4 

PARANTHRENE,  DIANTHRENE.  —  When  solutions  of  anthra- 
cene are  exposed  to  direct  sunlight  or  ultraviolet  light, 
polymerisation  takes  place,  and  an  almost  insoluble  bimole- 
cular  2  polymer  is  precipitated.  This  is  known  as  paranthrene 
or  dianthrene,  and  as  it  readily  reverts  to  the  monomolecular 
form  when  heated,  its  formation  has  been  employed  in  the 
laboratory  as  a  means  of  obtaining  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 

xc cr 

C6H4/\C6H4  C6H4/\C6H4 

/C : Cv 

W  XH 

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  : 

C6H5CH  :  CH2-|-C6H4(CH3)2       ->       C6H5C— CH2C6H4CH3 

l 

CH3 

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

1  B.  11,  269.  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  Megraw7  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 
C15H12  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,  C15H10O2,  which 
melts  at  187°,  and  which  is  slowly  reduced  by  sulphurous 
acid.  It  seems  improbable  that  Oudemas's  compound  was 
an  anthracene  derivative  at  all. 

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  : 


CH3  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  prepared2  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 


CH3  CH3    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 CHC6H5  C— CHC6H5— CHC6H5— C 

C6H4/\C6H4  and  C6H4<J\C6H4  C6H4/\C6H4 

C-     -CHC6H5  C— CHC6H5— CHC6H5— 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      C5HU  C5Hn 

\/ 

CO  C  C 

3H4      ->      C6H4/\C6H4      ->     C6H4/\C6H4 
C  C  C 


/\ 

HO      C5HU  HO      C5HU  C5Hn 

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 

C6H/      ,C6H5  ->  CeH/iNCeHd 


C\  C 

IXOH  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, 
C14H12,  is  known.  This  melts  at  108*5°,  and  is  dehydro- 
genated when  shaken  in  benzene  solution  with  finely  divided 
palladium.4  Two  tetrahydroanthracenes,  C14H14,  are 
known,  which  melt  at  101-103°  and  at  89°.  The  former 
is  obtained  by  means  of  hydriodic  acid,  and  the  latter  by 
catalytic  reduction.  As  the  latter  is  fluorescent  and  gives 
a  picrate  the  ws-carbon  atoms  are  probably  intact.  Two 
hexahydro  compounds,  C14H16,  have  been  described.  One 
is  obtained  by  reduction  with  hydriodic  acid  and  melts  at 
63°,  and  boils  at  290°.  The  other  is  obtained  by  loss  of 
water  from  octahydroanthranol  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,  C14H18,  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,  C14H20,  melts  at  73°;  dodekahydro- 
anthracene,  C14H22,  boils  at  140-150°  at  15  mm. ;  and 
perhydroanthracene,  C14H24,  melts  at  88°  and  boils  at 
270°.  None  of  them  form  picrates,  and  none  of  them  are 
fluorescent. 

HALOGEN  COMPOUNDS 

The  action  of  chlorine  and  bromine  on  anthracene  has 
been  studied  by  many  investigators,  but  often  with  contra- 
dictory results.  The  reactions  which  take  place  are  some- 
what 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,  Ci4H8Cl2.Cl4.  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.  r4]  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,  Ci4H10Br6) ;  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 

C6H4/\C6H4  C6H4/|\C6H4C12 

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 


14 


— 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, C14H9S2C1,  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 


C6H4<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 

C6H4/\C6H4   ->   C6H4/|\C6H4C12 


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 

/\ 
N02      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      N02 

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      OCOCH3 


C 

/\ 

H      N02 

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      OCH3 

\/  \/ 

C  C 

<"-w./\c6H4  -> 


H      N02  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 

C6H4/\C6H4  ->  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      C2H5 


H      NO2 


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 

C6H4/\C6H4  ->  C6H4/f>C6H4 

C  C 


H      NO2  NO2 

a  perfectly  stable  substance  which  melts  at  145-146°, 
and  which  distils  in  vacuo  at  over  300°  without  decomposi- 
tion. On  reduction  it  gives  the  corresponding  amino  com- 
pound.1 The  nitro-  compound  can  also  be  obtained  directly 
by  the  nitration  of  anthracene  in  acetic  acid  solution  in  the 
presence  of  acetic  anhydride,  but  it  is  more  easily  obtained 
by  the  hydrolysis  of  the  acetate. 

Perkin  2  nitrated  anthracene  in  the  presence  of  methyl 
alcohol,  and  obtained  a  compound  which  he  named  anthra- 
cene methyl  nitrate.  Other  alcohols,  such  as  ethyl  alcohol, 
propyl  alcohol,  and  iso-butyl  alcohol,  gave  similar  products, 
and  these  are  undoubtedly  formed  by  the  action  of  the 
alcohol  on  the  nitro.anthranol  nitrate  or  nitrite  first  formed  : 
H  ONO  H  OCH3 

\/  \/ 

C  C 

C6H4/\C6H4  C6H4/\C6H4 

C  C 

/\  /\ 

H      NO2  H      NO2 

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 


CGH4/\C6H4 
C 


H      NO2 

The  other  substance  is  insoluble  in  alkali,  but  is  left  behind 
as  a  decomposition  product.  Meisenheimer  obtained  it  in  the 
pure  state  by  fractional  precipitation  from  chloroform  by  the 
addition  of  petroleum  ether,  and  identified  it  as  trinitro- 
dihydroanthracene  : 

H      NO2 


C 

C6H4/\C6H4 
C 


N02      N02 

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     C2H5 

\/ 
C 

C6H4/\C6H4 

C 

/\ 
H     N02 

This  forms  stable  alkali  salts  from  which  it  is  reprecipitated 
as  such  by  acetic  acid,  although  mineral  acids  cause  an  im- 
mediate loss  of  water  and  formation  of  ethyl  nitroanthracene  : 

C2H5 

C 


N02 
a  stable  compound  melting  at  135°. 

The  further  action  of  nitric  acid  on  ethyl  anthracene 
takes  two  directions.  In  the  first,  oxidation  takes  place 
with  the  production  of  ethyl  nitroanthrone  : 

O 

II 
C 

C6H4<Q>C6H4 
C 


C2H5      N02 

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  : 

C2H5      N02 

\/ 
C 


C 

/\ 
N02      N02 

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 

C6H4/\C6H4  or  C6H4/\C6H4 

C  C 

/\  /\ 

ONO      ONO  ONO      NO2 

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      N02 

\/ 
C 

C6H4/\C6H4 

C 

/\ 
H     N02 

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

H        H 

C6H5CH=CHC6H5          ->          C6H6C-  - 


N02    N02 

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 

C6H4/\C6H4       ->       C6H4/\C6H4    or    C6H4/\C6H4 

C  C  C 

1  I  II 

NO2  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   N02  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      OCH3 


C 
/ 


O 


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

H      OCH3 


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 : 


CH30      OCH3 

\/ 
C 


and 


\)K 


CH30      OCH3 

v 

c 

C6H4/\C6H4 
C 

Br     NO2 


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      N02 

v 

c 

C6H4/\C6H4    -> 
C 

NO2      NO2 

H      NO2 

\/ 
C 

CeH4/\C6H4 
C 

HO      NO2 

N02 

->    C6H4/^C6H4 

C 

1 
NO2 

and  dinitrodihydroanthracene  by  a  very  similar  reaction 
gives  mononitroanthracene  : 


H      NO2 

H      OH    "" 

H 

C 

\/ 
C 

< 

i 

C6H4/\C6H4    -> 

C6H4/\C6H4 

->     C6H4<^ 

> 

C 

C 

C 

/\ 

/\ 

i 

H      N02 

H      NO2  - 

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 

C6H4/\C6H4  C6H4/\C6H4 

C  C 


H      NO2  ] 

XOH 

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 


C6H4<J\C6H4 


NO2 

This  compound  was  described  by  Perkin,2  but  Meisen- 
heimer 3  has  shown  that  Perkin's  substance  was  really  pure 
nitroanthrone  (colourless  variety). 

Kurt  Meyer4  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 

C6H4<f>C6H4  C6H4</|N>C6H4 


C  C 

/\  I 

H      N02  N02 

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-I460 

1.2 

— 

131°  decomp.                  145° 

— 

Z.4 

.  —  . 

169° 

— 

— 

1-5 

Rufol 

265°  decomp.              196-198° 

224° 

I79° 

1.8 

Chrysol 

225°  decomp.                  184° 

198° 

139° 

2.3 

— 

Decomp.  180°              155-160°               204° 

?  ? 

Flavol 

260-270° 

254-2550 

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,  Ci4H9N(CH3)3I,  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  (Ci4H9NH)2NO.  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  NH2. 

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  UINONES—DIA  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 
Dienel4  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. 


ANTHRAQUINONES—DIANTHRAQUINONYLS     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,i7802. 

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.  I34.52218. 

7  Heinemann,  E.P.  55I415. 

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  UINONES—DIA  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  UINONES—DIA  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 

C6H/\C6H4 

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  C35H33O2N3S. 

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 


ANTHRAQUINONES—DIANTHRAQUINONYLS    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 

C6H  /|\C6H4      -»      C6H/\C6H4      ->      C64 

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  : 

C6H4  OH    OH  C6H4 


C6H4 

which  by  loss  of  water  passes  into  dianthryl  : 

C6H4        C6H4 


C6H4 

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  : 

C6H4        C6H4  HCi         C6H4  H    H  c6H4 


HO-C^C— C^-AC— OH  NaOH 

C6H4        C6H4  C6H4        CgH4 

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      [  C6H4  ^  C6H4        C6H, 

SCr^ 

HO     p  TT 
L6M, 

From  a  commercial  point  of  view  alkaline  sodium  hydro- 
sulphite  (Na2S2O4)  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 
C6H4/|\C6H4 


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 


NHCH2C6H5 


C6H5CO, 


I 

1 

/COC6H5 

K 

\fATT     f^    TJ 

V^-TL  2Vx  gXl  g 

CH. 


>N 


C6H4[/>]CH 


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

COOH 


C6H4[/>]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. 


ANTHRAQUINONES—DIANTHRAOUINONYLS    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 

C6H4/\C6H4  C6H4/\C6H4 

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 

C6H4/\C6H4 
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 


C6H4/\C6H4 

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. 


ANTHRAQUINONES—DIANTHRAQUINONYLS    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  Stahling1  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 : 

CH3      OH  CH3      OCH3 

\/  V 

C  C 

C6H4<^>C6H4  -> 

C  C 

/\  /\ 

CH3      OH  CH3      OCH3 

*  I 

CH2  CH2 

C  C 

C6H4/\C6H4  C6H4<Q>C6H4 

C  C 

/\  /\ 

CH3      OH  CH3      OCH3 

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      OCH3  CfiEIs      OCH3 

Y      •  Y 

C6H /^>C6H4  ->  C6H/\C6H4 

C  C 

CH3      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 

C6H4/\C6H4      ->      C6H4/\C6H4      ->      C6H4/\C6H4 
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.OCH3  C— OCH3  C 

CeH^/CeH,      ->      C^^/C^      ->      C6H4/\C6H4 
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 


6H4<( 


c  c 

/\  I 

Ph       OH  Ph 


)>C6H< 


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


A  NTHRA  Q  UINONES—DIA  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 

(CH30)2C6H2<^/C6H5       ->        (CH30)2C6H2<(J>C6H4 
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 

C6H4/\C6H4 
C 

A 

Ph      ArN(CH3)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 

C6H4/\C6H4 

C 

/\ 
Ph       C6H4NMe2 

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 


C6H4<J>C6H4 

C 

/\ 

Ph       Cl 


C6H4 


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. 


ANTHRAQUINONES—DIANTHRAQUINONYLS     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. 


ANTHRAQUINONES—DIANTHRAQUINONYLS    93 

Schultze1  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. 


ANTHRAQUINONES—DIANTHRAQUINONYLS    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  Ullmann8  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  Q6H*NMe 


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 


C6H4/ 


A 

Ph       Ph 


and  also  by  condensing  dichloranthrone  or  phenylchlor- 
anthrone  with  benzene 

CO  CO 

C6H4/\CGH4  ~>         C6H4/\C6H4 

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          -»         C6H4/\C6H4 
CH3  CC12 

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  CPh2 

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    cci2ph  cicph 

c  c 

CG^X     xC6H4  C6H4<T/C6H4 

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 : 

C6H4  C6H4 

O  = 

C6H4 

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

C6H4        NH  C6H4        S 


C6H4        CO  C6H4        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 

C6H5CHCH(COOBt)  2  C6H5CHCH<( 

|  |  xCOOEt 

CH  CH 

H4  C6H4<f>C6H4 


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 

C6H5CHCH2COOH 
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  Guyot2  have  shown  that  dichlor- 
anthrone  condenses  with  dimethylaniline  in  the  presence  of 
anhydrous  aluminium  chloride  to  form  a  compound 
Me2NC6H4  C6H4NMe2 

V 

c 

C6H4/\C6H4 

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       C6H3(OH)2  C6H3(OH)2 

Y  i          I 

C6H4/\C6H4      ,  or        C6H4/|\C6H4 

C  C 

II  I 

O  OH 

As  the  compound  apparently  is  not  fluorescent  the  first 
formula  is  the  more  probable.     The  triacetyl  derivative, 
1  A.  396,  152.  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 
C2oH13O  and  66|  per  cent,  of  C4oH26O2.  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 


C6H4  C6H5  C6H5 

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  Me2NC6H4      C6H4NMe2 

\/  \/ 

C  C 

C6H4<^>C6H4+2C6H5NMe2      -»      C6H4<(^>C6H4 
CO  CO 

In  the  case  of  aryl  chlor  anthranones  the  reactivity  of  the 
chlorine  atom  is  very  much  greater,  and  by  condensing  phenyl 
chloranthrone  with  benzene  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 


CC12  C 

C6H4<Q>0-|-C6HG  ->  C6H4<^>C6H4   «- 

CC12  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 

C6H  4<f>C6H4          -»         C6H4<f>C6H4 
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  C52H3e  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 

C6H4<J>C6H4  ->  C6H4<Q>C6H4 


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 

C6H4<Q>C6H4  -»  C6H4/\C6H4 

CO  CH2 

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 : 

C2H5 


C 


OC2H5 

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 

C6H/\C6H4  ->  C6H/\C6H4 

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 

OCH3  CH30      OH 

I  \/ 

c  c                        c 

C6H4/\C6H4  -»     C6H4/\C6H4     ->     C6H4/\C6H.4 

C  C                                   C 

I  /\                             /\ 

CH3  CH3      NiNAr            CH3      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 

C6H4/\C6H4     ^     C6H4/\C6H4      l5£    C6H4/|\C6H4 

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.  462 


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 

C6H4/[>C6H4      ->     C6H4/\C6H4      ->      C6H4/\C6H4 

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|CH3  OCH3 


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  : 

Me2NC6H4     OH  Me2NC6H4     OH 

V  V 

c  c 

C6H40C6H4  -»  C6H4/\C6H4 

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  : 

C6H4 


C6H4 

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  (C14H9) 
group,  and  the  numbers  indicate  the  carbon  atoms  at  which 
junction  is  effected.  These  compounds  do  not  seem  to 
have  been  described  as  yet,  although  some  of  the  corre- 
sponding quinones  of  the  three  last  are  well  known.  Di- 
anthryl was  first  obtained  by  Schulze  1  by  the  action  of 
dehydrating  agents  on  anthrapinacone  : 

C6H4  OH  OH  C6H4  C6H4        C6H4 


C6H4         C6H4  C6H4        C6H4 

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  : 

C6H4        C6H4 


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  : 


C6H4        C6H4  C6H4        C6H4 

* 

C6H4        C6H4 


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 
C6H4 


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 
C6H4  C6H4         C6H4 

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

Orndorff  and  Bliss5  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 
C6H4        C6H4  C6H4        C6H4 

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  : 

C6H4Br  H  C6H4  C6H4        C6H4 

0:C<Q>C--  C<^>C:0    ~>    O  :  C<Q>C  :  C<^>C  :  O 
C6H4  C6H4 


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 

C6H4/\C6H4          ^ 


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 


C6H/\C6H 

6  4Nx^  6 


H4v  I  x 


CH2  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 

C6H4/|\C6H4         $         C6H4/\C6H4 
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 

C6H4/\C6H4          ->          C6H4/\C6H4 
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 
C6H/\C6H4 


C  C 

H      OMe  OMe 


C6H4  OMe  OMe  CaH4 

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 

C6H4/\C6H5  C6H4<^>C6H4 

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 

C6H/)>C6H4  C6H/\C6H4 

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  : 


C6H4        C6H4         HCI         C6H4  H    H  C6H4 

C—  C^COH    KOH    O  :  C<^^>C—C<^>C  :  O 
C6H4        C6H4  C6H4  C6H4 

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  : 

C6H4  H   H   C6H4  C6H4         C6H4 

HN  :  C<>C—  C<C  :  NH     -> 


C6H4  C6H4  C6H4        C6H4 

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  Romer1  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- 
mann2  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 

C6H4/\0+C6H6    ->    C6H4/\C6H5    ->    C6H4<^>C6H4 
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  S3rnthesis  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 
C6H4— C— C(X 

|  ||  yC6H4,  although  this  has  never  been  proved. 

C6H4— C— COX 

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 

C6H4/\0         0/\C6H4 '  C6H4/\CH-CH/\C6H4 
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 


XC=CH2 
C6H4<  +C02 


*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.  C18H12,  which  they  named  naphthacene 
(/zw.-benzanthracene),  and  its  dihydro  compound  C18H14 
(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    C6H4OH 


HO    C6H4OH 
'    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  acid4  (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  source1  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-  Pr-  t2]  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,  C14H7O2CBr :  CBrC14H7O2, 
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  Weizmann4 
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  C14H7O2.SOOCH(C6H4NMe2)2,  and  also  readily 
adds  on  to  quinonoid  compounds,2  e.g.  with  benzoquinone 
it  gives  CUH7O2.SO2.C6H3(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,  Ci4H7O2.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  (C14H7O2S)2O.  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  : 

H2N-  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  r1 

,0 

C14H702.Sf  $  C14H702.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  : 


SCOC6H5 


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    CH3 

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  : 

/CH3 
NHC6H3< 

XS03H 


CH3 

C6H3NH 


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)  : 

NHCOC6H5        NH.CO.CH2.CH2.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  ;   73.684  ;   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; 
l83>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-T39  ;   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 


CH3C6H4S02NHR 


/ 

N< 

\S02C6H4CH3 


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 
sulphonating2 

REPLACEMENT  OF  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  ;   i44.634. 
By.,  D.R.P.  136,777-8.     Cf.  D.R.P.  151,512-3. 

Heller,  B.  46,  2702.     By.,     D.R.P.     125,578  ;      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 


S03H 


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. 


204     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 

NHC6H3<^  NHC6H3<C  NHC6H3<" 

XS03H 


Br 
NH2 


NHCH, 


Alizarin  Pure  Blue.  Alizarin  Astrol. 

1  By.,  D.R.P.  95,625  ;   101,919. 


NHC6H< 

NS03H 

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  : 


NHC6H4SO3H  OH 


— NHC6H4S03H 


or 


NHC6H4S03H 


OH  NHC6H4SO3H 

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?,22319. 

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  C16H6O2(COOH)(NHCOCH2C1)  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 
Ci4H7O2NHCH2CH2OH,  and  epichlorhydrin  4  giving  a  com- 
pound which  contains  chlorine  and  probably  has  the  formula 
C14H7O2NHCH2CHOHCH2C1.  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 

C6H4<^C6H3N  :  CHCOOH  ->  C6H4<Q>C6H3NHCH2COOH 
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  : 

NHCH3  /N2  N(C2H5)2 


S03H 


CH3NH, 


'3  (C2H0)2NH 


S03H 


HN02f  |(NH4)2C03 
HN2 


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  C14H7O2NHCH2[i]C6H4[4]NR2 
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]C6H3[2]NHC14H6O2NH2,  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  CUH7O2NH— X— NHC14H7O2, 
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),  p2- 
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(CH2)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.24i,837.  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  Per  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 : — 

NHCOC6H5  NHCOC6H5  NHCOCeH6 


OH 

Algol  Yellow  WG.  Algol  Pink  R. 

NHCOC6H5 


OCH3 

Algol  Scarlet  G. 

NHCOC6H5 


NHCOC6H5        C6H5CONH 
Algol  Red  50.  *  Algol  Yellow  R. 

HO   NHCOC6H5  HO    NHCOC6H5 


C6H5CONH 

Algol  Red  FF. 


C6H5CONH  OH 

Algol  Brilliant  Violet  26. 


HO    NHCOC6H5 


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  : 

NHCOC6H5  NHCOC6H5  NHCOC6H5 


NH2 

Corinth. 


NHCH3 

Blue. 


NHCOC6H5 

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  NHCOCH2CH2CONH 


Yellow. 


OH  HO 

Scarlet. 


THE   AMINOANTHRAQUINONES  217 

NHCOCH2CH2CONH  NHCOCH2CH2CONH 


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 : 


NHCOC6H5 


NHCOC6H5 


CEUNH 


HO 


NHCOC6H5 


N02 

Orange-red. 


Red.  Yellow. 

NHCOCH2CH2CONH  NHCOCH2CH2CONH 


NH. 


NH2  NO2 


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  : 

NHCOC6H5  NHCOC6H5 

NHCOC6H5 


HCOC6H5 

Orange. 
(Algol  Brilliant  Orange  FR.) 

C6H5CONH    NHCOCGH5 


C6H5CONP 


NHCOC6H5 


Bordeaux. 


HO    NHCOC6H5 


C6H5CONH    NHCOC6H5 

Red-violet. 


C6H5CONI 


OH 


Blue-violet. 
(Algol  Brilliant  Violet  2B.) 

HO    NHCOC6H5 


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. 

^J°ODJ-       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  3GN. 


-NHCONHC14H6O2NHCONH- 


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 
CUH7O2NHC— 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  : 

C14H702.C  :  N.C.N  :  C.CUH7O2  C14H7O2.C  :  N.C.N  :  C.CUH7O.> 

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  : 


C6H5CC13+2C14H702NH2  ->  C6H6C\ 

XNHC14H702 

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,  Ci4H6O2(N:SO2)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,  Ci4H7O2NHBr, 
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/ 


NH2  H2N  NH2       H2N 

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° 

227—232° 

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>SO4).     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  : 

2C14H702S03Na+Ca(OH)2=2CuH702.OH+CaS03+Na2SO3 

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  ah1  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»8i8;  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 
C28Hi8O7N2,  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  : 

(OS03H  r  (S08Hi 

C14H5O2    OH  and          C14H4O2    OH      2O 

(N02  L  IN02  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.  [C14H4O2(OH)(NH2)2]2O.  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 


HONO2        9    N°2    HO    NO2 


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 

N02  HONH  NH2  OH 


H 


NO 


HNOH        HO    NH2 


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.     By-»  D.R.P.  81,694. 
*  R,  E,  Schmidt  and  Gattermann,  B.  29,  2934.     By-»  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 
H2SO4,  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  H2SO4.H2O. 


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 : 

SeO2=Se+O2 
Se  +2SO3  =SeO2  +2SO2 

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;  73»942;  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  BY"  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  C14Hi  O5, 
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        CH2C0H4NR2 


HOCH2 
HO 


OH         R2NC6H4CH. 


OH 


HO 


II. 


OH 
HO        CH9NHAv 


ArNHCH2 
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.  I26,52818, 


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.  NaBrO4+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  piath,  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.  i26,727-818. 


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-  and  alizarin-8-sulphonic  acids  and 
gives  bordeaux  shade  on  both  chrome  and  alumina.  Flavo- 
purpurin-3-sulphonic  acid  is  used  to  a  small  extent  under  the 
names  Alizarin  Red  3WS  or  SSS,  and  gives  brownish-red 
shades  on  alumina.  The  disulphonic  acid  of  1.2.4.5.6.8- 
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. 


28o     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. 

5J3y.,  D.R.P.  81,694.    "  G  By-»  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  *  : — 


NH9  OH 


S 
OH 


HO    OH 

S       S 


NH2  NH2 


NH2 

NH2  NH2 

S 

OH 

HO 

OH 

1 

1 

HO 

S 

S 

S 

NH2  " 

From  anthraflavic 

From  sso-anthra 

acid. 

flavic  acid. 

Fiery  red  shades, 

Yellowish-red 

bordeaux  on 

shades. 

chrome. 

Bordeaux  on 

chrome. 

NH2 

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 
02-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  specification1  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  C28H14O8  and  C28H13O8. 
Both  substances  give  blue  alkali  salts. 

Both  alkyl  and  aryl  ethers  can  be  obtained  directly  by 
the  replacement  of  halogen  atoms,2  or  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  ArSO2.CH2COCl  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  : 

ArS02CH2( 

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!lCH2 


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  Ci7H9O2N, 
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 

XCH=CH 

arin  Blue. 

(             1 
XN=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.     cf-  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 
(cf-  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/ 


C6H4 


\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  : 


CH3 
— 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 

?H2 
COOH  Cl 

—  NH  
-COOH 

/NH\ 

\co/ 

1 

+ 

1 

" 

1 

1 

-> 

1 

NH2 

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 

\CH3 

/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 


C«H 


/C0\ 


\CO/ 


C6H4 


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  : 


/OC6H4CHO 


--0-\ 

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 

/COX 


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\    /C6H 
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/ 


:C6H4 


Yellow. 


s 
\co 


Orange. 


C6H4 


\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 


/ 


C6H 


/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  C20HnON.  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  C17H10O.  In 
all  these  cases  it  is  obvious  that  one  of  the  cyclic  carbonyl 
groups  has  become  involved  in  the  condensation,  and  as 
benzanthrone  itself  on  oxidation  yields  anthraquinone  a- 
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  :  CH2       HC 


C6H4<(| 


CH  C  C 

]\C6H4    ->   C6H4/|)>C6H4    ->   C6H4/\< 
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.COCH3. 

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 


CO1 


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  : 


CH3| 
CO  CHS  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 


CH3 


CH3 


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  halogenated4  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!  Oa  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.  4iBy.,  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.  &isa«gr.-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  rThe  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  02-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  02-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-tl4\/(-6-tl2\/(- 

CO  NH 

CO 


OH 
C 


H 

NH 


CO 


C6H4+H20 


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.  C28H16O2N2,  C28H18O2N2  and 


CO 


NH 


CO 


N 


CO 


CH          NH          CO 


CH2         N  CO 

Anthronazine,  C28H18O2N 


CO 


NH 


CH2 


CH 


CH2    NH    CO 

N-Dihydroanthronazine,  C28H18O2N2 


N 


N 


CH 


CO 


CH 


CH 


NH    CH2  ;  CH    N      CH 

NH    CO  CH    N      CH 


CH  N  CH 

Anthrazine,  C28HliN2 


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 

C28H16N2.  The  last  of  these  is  anthrazine,  and  of  the  two 
former,  the  second  is  readily  oxidised  to  the  first  either  by 
loss  of  hydrogen  when  heated  alone  to  340°,  or  by  boiling 
with  nitrobenzene,  and  hence  is  probably  a  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 
INH2 


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°  : 

NHC6H3(NH2)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 

/\C6H4CH3  ()C6H3CH3 

NCH3 


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 


NAr 


CO  CO 

In  this  case  the  formation  of  the  pyrrol  ring  is  accom- 
panied by  simultaneous  loss  of  carbon  dioxide.  If  the 
glycine  is  esterified  and  the  ester  then  heated  with  an  alkali 
and  an  indifferent  solvent  such  as  xylene,  this  loss  of  carbon 
dioxide  is  avoided  and  a  pyrrolanthrone  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)CuH702 


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 
NHCOC6H5 


— 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 


CC6H5 


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 

cns 


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  : 

HOC6H4Crj 


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-S04H 


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-S04H 


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 


CH3 


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  By->  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 

^N2 
formula  C14H6O2^      ,  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. 
245»973;  250,274. 

'  M.L.B.,  D.R.P.  247,352. 

8  G.E.,  D.R.P.  238,253  ;  245,191 ;  250,274  ;  253,088.  M.L.B.,  D.R.P, 
245,191, 


388     ANTHRACENE  AND  ANTHRAQUINONE 

N 

n    TT  [a]N :  NC14H7O2       _>       r     TT  /  \-vrp    TT  n 
C10H6r01NH  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  : 

/^ 
C14H702N2HS04  ->  C14H702N :  N.NHOH  ->  C14H7O2N(  || 

XN 

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,  CuH6O2[i.8](NH.NHSO3H)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 

C14H702.NHNH.C14H702, 

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.  C26H20  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 

C28H24O2    requires    €=857,    H=6'8;     C3oH24O2   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.  C38H28  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 

CH2 

This  forms  pale  yellow  prisms  which  melt  at  148°.  It 
unites  instantaneously  with  one  molecule  of  bromine  to 
form  brom-methylbromanthrone,  also  obtained  by  the 
action  of  bromine  on  methylanthranol  methyl  ether.3 

1  A.  G.  Perkin,  E.P.  151,  yoy19.     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)  : 

OCH3 

C  CO 

C6H4/\C6H4  C6H4</\C6H4 

C  C 

I  /\ 

CH3  CH3      CH3 

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 


CH2 

CH2 
CH2 


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  0  co  OH 


OH    6  OH    0 

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°  writh 
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 

3»565  Pryzibram             ......  ^78  278 

6,526  „                     ......  !878  192,  198 

17,627  M.L.B  .........  I88i  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       ........  !883  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  .........  X888  254,281,295 

50,708  „      ........  I888  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»855  ,,           ......  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.     ........  I890  260 

64>4j8  „           ......  I8QO  260 

65,182  „           ......  I8g0  260 

65,375  „                ....  1891  260 

65.453  ,,           ......  1891  260 

65,650  „                       ....  1890  200 

66,153  „                ......  iSgi  92,  264 

65,811  M.L.B  .........  X892  281,284 

66,917  By  .........  ^91  200 

67»o6i  „      ........  I8go  26o 

67,063  „      .........  I89i  26o 

67,470  M.L.B  .........  1892  294 

68,113  By.                    ..  I8gl  92%64 

6*>«4  „      ..             ..  1891  92,264 

^•I23  »       ........  1891  92 

68,474  „           ......  1892  17 

68,775  „      ........  1890  258 

69,013  „               ........  !89i  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 

242 

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. 

II3,724 

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 

I96 

I897 

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 

23I 

1899 

246, 

283 

1899 

196 

1898 

140 

1898 

I40 

1899 

200, 

205, 

274 

1899 

272 

1899 

23I 

1897 

246 

1899 

228 

1899 

246, 

283 

1900 

I96 

1899 

I87 

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 

I96 

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,403 

By.  „   

1901 

273 

131,538 

1900 

173,  286 

133,686 

B.A.S.F.  '.*. 

1901 

300 

134,985 

Deichler  and  Weizmann  .  . 

1900 

148 

I35,4°7 

B.A.S.F  

.  .   1901 

343 

I35,408 

,, 

.  .   1901 

3°o,  343,  345 

135,409 

M.L.B  

.  .   1901 

389 

J35,634 

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 

*44,634 

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 

203 

1902 

I96 

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 

I84,905 

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 

J97.554 

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, 

2I4 

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 

23I 

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 

I44. 

304 

1909 

196 

1909 

220 

1909 

318 

1909 

381 

1909 

208 

1909 

221 

1909 

233 

1910 

341 

1910 

373 

1910 

373 

1909 

219 

1909 

221 

1909 

221 

1910 

373 

1909 

293 

1908 

76 

1909 

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 
2I4 
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 

3I2>  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 
I83 

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 

3°6,  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 

l89,  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 

OXO»  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-yxv7   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. 

274.783 

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 

3°8 

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 

3°7 

373 

75 

75 

75 

368 

366 

363 
291 

330,  384 

33i 

44 

173 

196 

368 

368 

312 

3°7 

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  l84 

290,814 

1914  224 

290,879  Agfa. 

•  •  1914  I73 

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   48 

292,395 

I9H   224 

292,457 

1914  l83 

292,59° 

1914  49 

292,681 

1914  76 

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 

297»567 
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 


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