4S8 
^nic  Acid,  ^inone,  etc. 
(  Am.  Jour.  Pharm. 
I      Sept.,  1880. 
QUINIC  ACID,  QUINONE  AND  THEIR  DERIVATIVES.^ 
By  O.  Hesse. 
^inic  Acid. — The  quinic  acid  employed  in  this  investigation  was 
chemically  pure,  and  was  prepared  from  the  calcium  salt  by  decompo- 
sition with  oxalic  acid,  according  to  the  method  which  has  been  previ- 
ously described  by  the  author.  By  evaporation  of  an  aqueous  solution 
of  quinic  acid,  the  greater  part  of  the  acid  quickly  separates  in  a  crys- 
talline form,  but  the  mother  liquor  still  contains  amorphous  quinic  acid^ 
and  the  author  states  that  the  presence  of  a  very  small  quantity  of  a 
foreign  substance  is  sufficient  to  hinder  the  crystallization.  The  amor- 
phous acid  can  easily  be  converted  into  the  crystalline  form  by  purifying 
its  calcium  salt  with  animal  charcodl,  then  proceeding  as  before 
described.  Quinic  acid  contains  no  water  of  crystallization,  and  the 
author  draws  attention  to  this  fact  because  from  a  misconception  of  his 
earlier  statement  on  the  subject  Graebe  has  assumed  the  formula  of 
quinic  acid  to  be  Q^^^fi^  -f  H2O. 
Tetracetyl  quinide^  p.  124°  (uncorr.),  is  obtained 
as  an  amorphous  mass  which  becomes  vitreous  on  cooling  by  the  action 
of  acetic  anhydride  on  quinic  acid  in  a  sealed  tube  at  170°.  It  is 
purified  by  melting  it  repeatedly  in  hot  water  and  finally  washing  it  with 
cold  water.  On  being  dried  in  the  air  it  is  obtained  as  a  white  powder^ 
which  is  insoluble  in  cold  water  and  soluble  with  difficulty  in  hot  water. 
It  melts  in  boiling  water  and  is  gradually  decomposed  by  longer  heating 
its  aqueous  solution,  which  then  becomes  acid.  Its  aqueous  or  alco- 
holic solution  becomes  turbid  on  being  cooled,  and  the  anhydride  sepa- 
rates in  granular  crystals.  The  formula  as  above  assigned  to  this  body 
was  confirmed  by  it  yielding  the  anhydride  (quinide)  C^H^o^s  when 
boiled  with  magnesia,  and  quinic  acid  when  decomposed  with  lime,  the 
author  having  previously  shown  that  quinide  is  converted  by  the  action 
of  lime  into  quinic  acid. 
Action  of  Bromine  on  ^inic  Acid. — By  the  action  of  bromine  on  an 
aqueous  solution  of  quinic  acid  an  acid  is  obtained  which  the  author 
had  named  carbohydroquinonic  acid,  on  the  supposition  that  it  yielded 
hydroquinone  when  heated.  But  it  was  afterwards  shown  that  the 
black  precipitate  which  this  decomposition  product  gave  with  ferric 
chloride  was  a  pyrocatechin  compound  ;  hence  the  name  of  the  acid 
was  altered  to  carbopyrocatechuic  acid.    Strecker  subsequently  obtained 
^  Abstract  of  a  paper  in  "  Liebig's  Annalen  "  [200],  232 — 255. 
\ 
