Am.  Jour.  Pharm.  \ 
Sept.,  191S.  i 
Chemistry  of  Gossypol. 
655 
boiling  point  was  abnormally  small,  indicating  a  much  greater 
molecular  weight.  The  freezing-point  method  with  benzene  was 
unreliable,  owing  to  the  slight  solubility  of  the  substance  in  cold 
benzene.  These  results  led  to  suspecting  the  presence  of  solvent  of 
crystallization.  This  was  found  to  be  the  case  as  previously  de- 
scribed. Further  molecular-weight  determinations  with  the  McCoy 
apparatus  of  the  gossypol  freed  from  acetic  acid  gave  the  following 
results : 
(1)  Ether  as  solvent.  Gossypol  1.002  G.  Ether  17.73  ^-  Elevation  0.200. 
Molecular  weight  found :  595. 
(2)  Acetone  as  solvent.  Gossypol  1.008  G.  Acetone  25.6  G.  Elevation 
0.1210.    Molecular  weight  found :  553. 
(3)  Gossypol  "acetate"  in  ether  as  solvent.  Gossypol  "acetate"  0.994 
G.    Ether  200  G.   Elevation  0.291.   Apparent  molecular  weight  found:  352. 
These  data  indicate  that  the  gossypol  "  acetate  "  dissociates  in 
solution  into  free  gossypol  and  acetic  acid,  causing  the  previously 
mentioned  anomalous  results. 
After  it  was  found  that  gossypol  "acetate"  crystallized  from 
ether-acetic  acid  contained  uniformly  about  10.1  per  cent,  acetic 
acid  or  somewhat  more  than  that  prepared  in  Marchlewski's  way, 
the  latter's  method  was  abandoned.  Since  the  determination  of 
acetic  acid  is  easily  and  accurately  made,  the  method  offers  a  reliable 
method  for  the  determination  of  the  molecular  weight. 
Gossypol  "  acetate "  recrystallized  4  times  from  ether-glacial 
acetic  acid  mixture  was  dissolved  in  ether.  Warm  water  was  then 
added  and  the  ether  driven  off.  The  water  was  then  separated 
from  the  brittle  crusts  of  gossypol  which  remained,  the  latter  dis- 
solved in  ether,  and  the  previous  treatment  repeated.  The  water 
containing  the  acetic  acid  was  then  titrated  with  alkali  using  phe- 
noltetrachlorophthalein  as  indicator. 
Subst.,  (I)  0.5326,  (II)  05057;  Cc.  0.1  N  NaOH,  (I),  8.98,  (II)  8.57. 
Acetic  acid  found:  (I)  10.12,  (II)  10.17. 
Acetic  acid  calc.  for : 
(1)  Mol.  wt.  592  C3oH2S09-C2HX>2   10.18 
(2)  Mol.  wt.  594  CsoHsoOo •  C^HiO?   10.10 
Hence  "  free  "  gossypol  has  a  molecular  weight  of  530  if  C30H28O9, 
or  532  if  C30H30O9. 
The  above  values  for  the  molecular  weight  of  gossypol  stand  in 
agreement  with  the  values  obtained  by  direct  titration  of  the  residual 
