Am.  Jour.  Pharrn. ) 
March,  1886.  f 
Cupreine  and  Homoquinine. 
135 
cupreine,  C19H20(C2H3O)2N2O2.  The  crystals  of  this  substance  are 
anhydrous;  it  melts  at  88°  C,  dissolves  with  moderate  ease  in  alcohol 
and  ether,  very  readily  in  chloroform.  The  spirit  solution  has  a 
strong  alkaline  reaction;  it  gives  no  color  with  ferric  chloride,  but 
with  chlorine  and  ammonia  it  becomes  dark  green.  The  base  is  dis- 
solved by  dilute  acids,  and  is  precipitated  on  addition  of  ammonia  or 
soda;  by  contact  with  caustic  soda  it  is  converted  in  a  few  minutes 
into  acetic  acid  and  cupreine." 
Diacetylcupreine  Hydrochlorate  (C19H20(C2H3O)2N2O2HCl).  —  This 
salt  has  the  form  of  hexagonal  plates;  it  is  very  soluble  in  water  or 
alcohol;  the  solution  gives  no  color  with  ferric  chloride.  With  plati- 
num chloride  an  amorphous  precipitate  is  formed  that  is  very  sparingly 
soluble  in  cold  water. 
The  previous  observation  that  homoquinine  when  heated  to  140°  C. 
with  hydrochloric  acid  (1*125  specific  gravity)  in  a  closed  tube  is  con- 
verted into  methyl  chloride  and  apoquinine  led  t)r.  Hesse  to  expect 
apoquinine  only  would  be  formed  by  acting  upon  cupreine  in  the 
same  way.    He  found  that  to  be  the  case. 
By  comparing  the  formulae  representing  the  composition  of  cupreine 
and  of  quinine  it  is  evident  that  quinine  stands  in  the  relation  of  a 
methyl  ether  of  cupreine,  or  that  it  differs  from  cupreine  by  containing 
the  elements  of  methyl  in  place  of  hydrogen,  as  shown  by  the  following : 
Cupreine.  Quinine. 
r\  Tj  IV    I  OH  p  u  \r    1  OCH3 
^19X120i>2  J  OH  ^19J7120LN2   j  QJJ 
It  is  therefore  conceivable  that  cupreine  might  be  convertible  into 
quinine  by  a  substitution  of  methyl  for  hydrogen,  according  to  the 
following  equation : 
C19H21MN202  -I-  C3HI=MI + C19H21(CH3)N202. 
The  experiments  made  to  effect  this  substitution  were  not  successful 
in  producing  quinine,  though  repeated  with  various  modifications 
several  times.  In  one  instance  cupreine  was  dissolved  in  water  with 
a  molecular  proportion  of  caustic  soda  and  then  mixed  with  silver 
nitrate.  Cupreine  silver  was  thus  formed  and  precipitated  in  yellow 
flocks.  A  molecular  proportion  of  methyl  iodide  dissolved  in  alcohol 
was  then  added  and  the  mixture  heated  in  a  closed  vessel.  Reaction 
soon  took  place  and  silver  iodide  was  formed,  the  solution  becoming- 
deep  yellow.    After  twelve  hour-  the  liquid  was  filtered  and  evaporated 
