100 
Phytochemical  Research. 
Am.  Jour.  Pharm. 
March,  19 17 
Chaulmoogric  acid  is  a  beautifully  crystalline  substance,  melting 
at  68°,  and  having  an  optical  rotatory  power  of  [a]n  +560. 
Although  isomeric  with  linolic  acid,  it  combines  directly  with  only 
two  atomic  proportions  of  bromine  or  iodine,  therefore  has  but  one 
ethylenic  linking,  and  must  contain  in  its  structure  a  closed  carbon 
ring. 
Another  crystalline  acid,  which  represents  a  lower  homologue  of 
chaulmoogric  acid,  has  also  been  isolated  from  chaulmoogra  oil. 
This  acid  possesses  the  empirical  formula  C16H2802,  melts  at  6o°, 
and  has  [a]D  +68°.  It  has  been  termed  hydnocarpic  acid,  on  ac- 
count of  having  first  been  obtained  from  a  Hydnocarpus  oil,  to 
which  reference  will  again  be  made. 
A  number  of  derivatives  of  both  chaulmoogric  and  hydnocarpic 
acid  have  been  prepared,  and  their  constitution  has  been  thoroughly 
elucidated.3  They  have  been  shown  to  be  cyclopentene  derivatives, 
containing  an  aliphatic  side  chain,  and  a  consideration  of  their 
behavior  towards  oxidizing  agents  indicates  them  to  exist  in  two 
tautomeric  forms.  In  the  case  of  chaulmoogric  acid  these  two 
forms  may  be  represented  by  the  following  formulae : 
CH  CH2 
//  \  ^\ 
CH     CH[CH2]i2-C02H  CH— C[CH2]i2-C02H 
II  II 
CH2  •  CH2  CH2  •  CH2 
The  simplest  expression  of  the  constitution  of  chaulmoogric 
acid  would  therefore  be  by  the  following  formula,  in  which  the 
dotted  lines  represent  a  state  of  equilibrium  between  a  hydrogen 
atom  and  two  carbon  atoms : 
CH 
CH— H  C  •  [CH2]12  •  C02H 
I  I 
CH2—   — CH2 
Hydnocarpic  acid  possesses  the  same  structure  as  chaulmoogric 
acid,  and  differs  from  it  only  by  containing  ten  methylene  groups  in 
the  side  chain  instead  of  twelve. 
In  addition  to  the  two  acids  already  mentioned,  chaulmoogra 
oil  has  been  found  to  contain  a  relatively  small  proportion  of  palmitic 
acid  or  its  glyceride,  and  a  phytosterol.    The  seeds  contain,  further- 
3  Power  and  Gornall,  Jour.  Chem.  Soc,  1904,  85,  pp.  851-861,  and  Barrow- 
cliff  and  Power,  ibid.,  1907,  01,  pp.  557-578. 
