552 
Synthetic  Camphor. 
/Am.  Jour.  Pharm. 
\   December,  1907. 
CH3 
I 
CH2  C  
CH, 
H90 
H3-C-CH3 
I 
CH2  C(OH)-CH5 
Isoborneol. 
 — > 
Oxidation. 
CH, 
CH, 
CH3 
i 
-C— 
I 
-c- 
I 
CH2 
CHa 
CH2  CH  CO 
Camphor. 
The  first  criticism  that  may  be  made  regarding  the  above  formulae 
is  that  the  one  assigned  to  camphor  is  incorrect.  It  has  been  shown, 
namely,  by  Bredt  {Ber.  d.  deutsch.  chejn.  Ges.,  1893,  26>  3°47)  an(J 
subsequent  workers,  that  this  ketone  is  represented  as  follows : 
CH2— 
CH3- 
CH, — 
-CO 
CH, 
C— 
I 
-C-CH3 
I 
-CH  CH2 
In  the  second  place,  the  formula  given  for  isoborneol  is  obviously 
impossible,  for  this  substance  is  represented  as  a  tertiary  alcohol, 
and  could  not,  therefore,  afford  camphor  on  oxidation.  The  correct 
structural  formula  for  isoborneol,  and  also  for  borneol,  since  the 
latter  only  differs  from  the  former  stereochemical^,  is  obtained  by 
substituting  for  the  oxygen  atom  in  Bredt's  camphor  formula  the 
elements  HOH.  Camphene  and  bornyl  chloride  are  correctly 
represented,  but  the  structure  assigned  to  pinene  is  not  that  which 
is  at  present  accepted.  The  formula  by  which  Mr.  Kebler  represents 
this  terpene  is  that  which  was  suggested  by  Bredt  in  1893  (Joe.  eit)} 
but  the  more  recent  work  of  Wagner  [Ber.  d.  deutsch.  chem.  Ges., 
1894,  27,  1636)  and  of  Baeyer  (Ibid.,  1896,  29,  3,  326,  1907,  1923, 
and  2775)  indicates  that  pinene  possesses  the  following  structure  : 
CHf, 
CH 
CH2 
This  formula  is  now  generally  accepted  as  the  correct  representa- 
tion of  the  constitution  of  pinene.  It  consequently  follows  that  the 
conversion  of  this  terpene  into  bornyl  chloride  is  not  brought  about 
by  the  simple  addition  of  hydrogen  chloride,  but  involves  the  change 
of  the  dimethyltetramethylene  into  a  trimethylpentamethylene  ring. 
