132 
Cupreine  and  Homoquinine. 
f  Am.  Jour.  Pharm. 
\      March,  1886. 
would  be  impossible  to  investigate  its  composition  inasmuch  as  it  very 
soon  turns  red  as  in  the  case  of  the  mydriatic  alkaloids. 
Thus,  mercuric  chloride  as  well  as  phenolphtalei'n  are  to  be  con- 
sidered as  very  valuable  tests  for  alkaloids. — Strassburg,  Germany. — 
Pharm.  Jour,  and  Trans.,  January  16,  1886,  p.  601. 
CUPREINE  AND  HOMOQUININE. 
By  Dr.  O.  Hesse. 
Dr.  Hesse,  in  repeating  the  experiments  published  in  this  Journal 
by  Paul  and  Cownley,1  found  that  caustic  lime  acts  upon  homoquinine 
salts  in  the  same  way  as  caustic  soda,  but  that  it  was  advantageous  to 
boil  the  precipitated  alkaloid  with  excess  of  caustic  lime  in  order  to 
extract  the  whole  of  the  cupreine.  By  boiling  a  suitable  bark  with 
caustic  lime  the  cupreine  could  be  also  extracted  at  once,  but  it  was 
then  associated  with  another  alkaloid,  from  which  the  cupreine  had  to 
be  separated  in  the  form  of  neutral  sulphate.  The  yield  thus  obtained 
was  very  small,  and  for  that  reason  Dr.  Hesse  preferred  to  prepare 
cupreine  by  operating  upon  the  quinine  sulphate  obtained  in  the  ordi- 
nary way  from  cuprea  bark.  This  was  dissolved  with  dilute  sulphuric 
acid,  an  excess  of  caustic  soda  added,  and  the  quinine  separated  by 
ether.  The  alkaline  liquor  was  then  heated  and  neutralized  with  sul- 
phuric acid,  and  the  cupreine  sulphate  crystallized  out.  The  sulphate 
was  treated  with  ammonia  and  hot  ether,  and  as  the  solution  cooled 
the  cupreine  crystallized  out.  The  crystals  were  then  digested  with 
chloroform  to  remove  a  remaining  trace  of  quinine,  and  the  undis- 
solved portion  recrystallized  from  boiling  alcohol  or  dissolved  with 
dilute  sulphuric  acid,  excess  of  ammonia  added,  and  the  mixture  shaken 
with  ether  sufficient  to  dissolve  the  alkaloid.  After  a  time  cupreine 
separates  from  the  ether  solution  in  groups  of  concentric  prisms,  which 
contain  two  molecules  of  water,  while  the  crystals  obtained  from  an  alcohol 
solution  generally  contain  somewhat  less  water.  Analysis  gave  results 
agreeing  with  the  formula  C19H22N202.  The  crystallized  alkaloid  does 
not  lose  all  its  water  at  100°,  but  only  when  heated  to  120°  or  125° 
C.  In  a  perfectly  dry  state  cupreine  melts  at  198°  C.  It  is  but 
sparingly  soluble  in  ether  or  chloroform,  more  so  in  alcohol.  An 
alcohol  solution  has  a  strong  basic  reaction ;  it  acquires  a  dark  reddish- 
brown  color  with  ferric  chloride,  and  an  intense  dark  green  color  on 
1  Pharm.  Jour.,  [3],  xv,  221.  See  Amer.  Jour.  Phar.  (1884),  p.  575,  and  (1885), 
p.  249. 
