460 
:^imc  Acid^  ^uinone^  etc. 
(  km  Jour.  Pharm . 
I      Sept.,  1880. 
tylhydroquinone  is  formed  by  the  action  of  acetic  anhydride  on  quinone. 
He  is  of  opinion  that  quinone  is  to  be  regarded  as  the  aldehyd  of 
-quinone  acid  in  this  way  : 
Hydroquinone.  Quinone.  Quinonic  Acid. 
^6^6^2  ^6^i^2  ^6^^404 
Alcohol.  Aldehyd.  Acid. 
Hydroquinone. — In  consequence  of  a  statement  by  Hlasiwetz  and 
Habermann  Liebig's  Annalen,"  175,  62),  with  regard  to  the  melting 
point  of  this  body,  the  author  has  repeated  his  experiments  and  he  now 
gives  the  melting  point  as  168  or  169°  (uncorr.)  instead  of  172  or  173° 
((uncorr.).  Hydroquinone  is  insoluble  in  boiling  petroleum  benzin, 
almost  so  in  boiling  chloroform,  the  chief  part  of  it  separating  again 
from  the  latter  on  cooling.  It  forms  no  compound  with  phenol.  Its 
concentrated  aqueous  solution  gives  a  dark  green  or  almost  black  pre- 
cipitate of  quinhydrone  with  ferric  chloride  or  sulphate. 
^inhydrone  is  very  easily  soluble  in  slightly  warm  water,  and  this 
solution,  unless  disturbed,  has  a  great  tendency  to  remain  satu- 
rated without  crystallizing.  Although  in  all  cases  the  aqueous  filtrate 
from  the  quinhydrone  has  a  strong  odor  of  quinone,  yet  it  is  impossible 
to  obtain  a  complete  conversion  of  hydroquinone  to  quinone  by  this 
method,  nor  even  by  heating  the  hydroquinone  with  ferric  sulphate  in 
a  sealed  tube  at  80  to  100°,  Quinone  is,  however,  obtained  in  con- 
siderable quanti'ty  by  the  action  of  concentrated  nitric  acid  on  hydro- 
quinone;  by  continuing  the  action  of  the  nitric  acid  oxalic  acid  is 
produced. 
Diacetylhydroquimne.,  m.  p.  I2i°  (uncorr.),  is,  contrary  to  the  state- 
ments of  other  observers,  an  odorless  and  stable  substance,  even  after 
iong  keeping. 
Dinitrodiacetyihydroquinone.^  m.  p.  94°,  has  been  prepared  and  was  of 
interest  to  the  author,  as  he  hoped  that  by  the  substitution  of  NHg  for 
NO2  in  this  compound  a  substance  of  the  formula  CjoHj2N204  would 
be  obtained  ;  in  fact,  a  body  which  would  stand  in  near  relation  to 
chitenin,  CigH22N204,  the  dihydroxylquinia  of  Kerner.  It  was  easily 
reduced  by  zinc  and  hydrochloric  acid,  yielding  a  base  which,  however, 
had  no  resemblance  to  chitenin  or  to  any  other  alkaloid.  In  the  free 
state  this  base  was  very  unstable  ;  its  alcoholic  solution  gave  a  cherry- 
red  color  with  ferric  chloride. 
Dipropionylichydroquimne.^  m.  p.  113°  (uncorr.),  which  crystallizes  in 
colorless  laminae,  and  its  mononitro-derivative,.m.  p.  86°,  crystallizing 
