Am.  Jour.  Pharm. 
October,  1915. 
Examination  of  Opium  Alkaloids. 
449 
In  1910  Pictet  and  Kraemers  16  pointed  out  that  most  of  the  color 
reactions  for  papaverine  described  in  the  literature  were  not  due  to 
that  alkaloid,  but  to  cryptopine,  which  at  that  time  was  present  as  an 
impurity  in  commercial  papaverine  to  the  extent  of  as  high  as  4  per 
cent.  These  authors  obtained  pure  papaverine  in  the  form  of  its 
acid  oxalate  by  precipitating  with  oxalic  acid  in  the  presence  of  al- 
cohol. The  cryptopine  was  then  recovered  from  the  filtrate  by  mak- 
ing alkaline  and  shaking  with  appropriate  solvents.  The  papaverine 
was  recovered  from  the  oxalate  by  dissolving  in  hot  water,  making 
alkaline  and  shaking  with  appropriate  solvents. 
Papaverine  is  distinguished  from  codeine  by  its  weak  basic  properties,  its 
scant  solubility  in  water  or  in  ammonia  water,  by  the  production  of  a  deep  rose 
instead  of  a  violet  color  with  Marquis'  reagent  and  a  greenish-blue  instead  of 
a  violet  color  with  potassium  ferricyanide  and  Marquis'  reagent;  from  mor- 
phine by  its  weak  basic  properties,  its  ready  solubility  in  most  of  the  ordinary 
organic  solvents,  its  failure  to  reduce  iodic  acid,  by  the  production  of  a  deep 
rose  instead  of  a  purple  color  with  Marquis'  reagent,  and  a  greenish-blue  in 
stead  of  a  purple  color  with  potassium  ferricyanide  and  Marquis'  reagent; 
from  narceine  by  its  ready  solubility  in  most  of  the  ordinary  organic  solvents, 
by  its  scant  solubility  in  hot  water  or  in  ammonia  water,  by  the  formation  of  a 
reddish-brown  instead  of  a  blue  precipitate  with  very  dilute  iodine  solution, 
by  the  production  of  a  deep  rose  instead  of  a  brown  color  with  Marquis'  re- 
agent, and  a  greenish-blue  instead  of  a  brown  color  with  potassium  ferricyanide 
and  Marquis'  reagent;  from  narcotine  by  the  production  of  a  deep  rose  in- 
stead of  a  fugitive  violet  color  with  Marquis'  reagent,  and  a  greenish-blue 
instead  of  a  dirty,  evanescent  violet  color  with  potassium  ferricyanide  and 
Marquis'  reagent ;  and  from  thebaine  by  its  weak  basic  properties,  by  the 
production  of  a  colorless  instead  of  a  deep  blood-red  solution  with  sulphuric 
acid,  a  deep  rose  instead  of  a  deep  blood-red  color  with  Marquis'  reagent,  and 
a  greenish-blue  instead  of  a  deep  blood-red  color  with  potassium  ferricyanide 
and  Marquis'  reagent. 
In  testing  the  specimens  of  papaverine  hydrochloride  for  traces 
of  cryptopine  salts  it  was  found  desirable  to  remove  the  papaverine 
as  completely  as  possible,  so  as  to  leave  the  cryptopine  in  as  high 
concentration  as  possible.  Precipitation  as  acid  oxalate  was  tried, 
but  was  found  not  to  be  as  satisfactory  as  precipitation  by  potassium 
ferricyanide  to  form  the  acid  papaverine  ferricyanide.  This  was 
collected  in  a  weighed  Gooch  crucible,  washed  with  a  little  water, 
dried  at  ioo°  C,  and  weighed.  The  filtrate  was  made  alkaline  with 
ammonia  water,  the  mixture  shaken  with  chloroform,  the  solvent 
IS 
Ber.}  43,  1329  (1910). 
