3o6 
On  Copaibic  Acid. 
J  Am.  Jour.  Pharm* 
t       June,  1879. 
the  alcohol  there  is  left  behind  some  of  the  acid  resin,  and  may  be 
obtained  by  treatment  with  hot  alcohol,  and  adding  the  filtrate  to  the 
first. 
The  neutral  resin  is  a  yellowish  powder,  without  taste  or  odor,  neutral 
to  test  paper,  softens  in  hot  alcohol  and  is  soluble  in  ten  times  its  weight 
of  hot  chloroform. 
After  crystals  have  formed  in  the  alcoholic  liquid,  filter,  and  dry 
on  the  filter  paper  under  glass.  On  distilling  off  the  alcohol  from  the 
filtrate,  the  soft  resin  is  left  behind.  Copaivic  acid  may  also  be  obtained 
from  the  resin  by  dissolving  it  in  benzin,  filtering  and  evaporating.  The 
residue  is  heated  to  200°F.,  dissolved  in  pure  naphtha,  filtered  while 
warm  and  set  aside  to  crystallize,  after  which  the  crystals  are  dried 
tinder  glass. 
Of  the  other  processes  which  have  been  tried,  the  following  deserve 
to  be  briefly  mentioned  : 
Dissolve  the  oleo-resin  in  caustic  ammonia  (sp.  gr.  95),  and  expose 
this  in  a  shallow  dish  at  a  temperature  below  6o°F.,  until  hardened  ; 
then  dissolve  in  wood  naphtha,  crystallize  and  filter.  Expose  copaiva  to 
the  air  in  shallow  dishes  until  it  has  become  hard  and  brittle,  dissolve 
it  in  ammonia  water  and  leave  to  evaporate  in  a  cool  place  ;  then  dis- 
solve in  hot  alcohol,  filter  and  set  aside  to  crystallize.  Dissolve  the 
resins  left  after  the  distillation  of  volatile  oil  in  caustic  ammonia,  let 
evaporate,  dissolve  in  hot  alcohol,  filter  and  set  aside  to  crystallize. 
The  alcohol  may  be  partly  recovered  in  these  different  processes  by 
distillation. 
The  crystals  cannot  be  easily  obtained  without  the  previous  separa- 
tion of  the  volatile  oil,  the  acid  being  soluble  in  fixed  and  volatile  oils. 
Doubtless  the  copaiva  yielding  the  largest  amount  of  resins  will  pro- 
duce the  most  acid. 
Copaibic  acid  forms  soft  prismatic  crystals,  which  are  soluble  in  strong 
alcohol,  ether,  fixed  and  volatile  oils.  Its  alcoholic  solution  reddens 
litmus,  is  not  precipitated  by  potassa  or  soda,  yields  with  an  alcoholic 
solution  of  acetate  of  lead  a  crystalline  precipitate  ;  but,  on  adding  it 
to  an  alcoholic  solution  of  nitrate  of  silver,  no  precipitate  is  occasioned 
until  a  little  ammonia  is  added.  A  white  crystalline  powder  falls,  which 
is  with  difficulty  soluble  in  alcohol  but  readily  soluble  in  ammonia. 
