Am.  Jour.  Pharm.  ) 
June,  1879.  / 
On  Copaibic  Acid. 
305 
ON  COPAIBIC  ACID. 
By  Warren  B.  Rush,  Ph.G. 
{Abstract  from  a  Thesis.) 
In  preparing  copaibic  acid  the  volatile  oil  must  first  be  removed, 
which  is  usually  done  by  distillation  with  steam.  The  oil  is,  however, 
much  more  readily  separated  on  a  small  scale  by  one  of  the  following 
processes  :  First,  by  dissolving  ten  parts  of  copaiva  in  ten  parts  of 
benzin,  adding  an  equal  part  of  caustic  soda  solution,  sp.  gr.  1*30,  and 
agitating  well  ;  or,  secondly,  by  mixing  ten  parts  of  copaiba,  ten  parts 
of  alcohol  and  four  parts  of  soda  solution,  when  the  mixture  wiil 
separate  into  three  layers.  A  third  and  most  economical  way  for  sepa- 
rating the  volatile  oil  is  to  shake  together  three  parts  of  the  soda  solu- 
tion with  one  of  the  copaiva.  After  separation,  pour  off  the  volatile 
oil,  decant  the  alkali  solution,  pass  a  stream  of  water  over  the  resin,  to 
wash  off"  adhering  particles  of  alkali,  and  let  it  dry.  Next,  dissolve  the 
resins  in  benzin,  and  agitate  the  solution  with  very  diluted  hydrochloric 
acid  until  the  aqueous  liquid  remains  slightly  acid  to  litmus.  Let  the 
mixture  rest  until  the  resin  and  water  have  separated,  decant  the  water 
and  evaporate  the  benzin  solution  to  a  thick  syrupy  mass,  and  let  cool. 
The  same  resins  are  thus  obtained  which  are  left  on  the  distillation  of 
the  volatile  oil. 
I  have  observed  that  if  the  percentage  of  oil  is  below  55  then  the 
oil  does  not  separate,  there  being  sufficient  resin  to  hold  the'volatile 
oil  combined,  and  in  this  condition  some  of  the  latter  is  oxidified  or 
altered.  It  may  be  separated  from  the  resin  by  dissolving  in  benzin  or 
alcohol  and  treating  as  above. 
The  resinous  residue  left  after  the  separation  of  the  oil  contains  an 
acid,  a  neutral  and  a  soft  resin.  The  following  are  among  the  processes 
for  the  isolation  of  the  different  resins  of  copaiva  :  Liquefy  the  resins 
by  the  heat  of  a  water-bath,  pour  into  about  twice  the  weight  of  petro- 
leum benzin,  stir  until  dissolved,  filter,  and  let  evaporate  spontaneously.  A 
few  particles  will  remain  on  the  filter,  consisting  of  the  usual  impurities. 
Warm  the  residue  left  by  evaporation  over  a  water-bath  and  pour  it  into 
three  times  its  quantity  of  alcohol  ;  or  heat  the  alcohol  to  boiling,  mix 
thoroughly,  and  while  hot  filter.  The  portion  left  on  the  filter  is  the 
neutral  resin.  Set  the  filtrate  aside  for  several  days  to  crystallize. 
Treat  a  portion  of  the  neutral  resin  with  hot  alcohol,  and  if  it  colors 
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