AFebSy  Pi9ai5m' }  Camphor — Natural  and  Synthetic. 
53 
contains  the  ketonic  group  C— CO  — C  ^>  forming  a  well-de- 
fined oxime,  and  yielding  a  secondary  alcohol  (borneol)  by  reduc- 
tion electrolytically  or  with  sodium  amalgam. 
When  camphor  is  distilled  with  phosphorus  pentoxide  the  hydro- 
carbon cymene  (I)  is  obtained.  Cymene  is  para-methyl-isopropyl- 
benzene,  and  the  same  complex  is  therefore  assumed  to  be  present  in 
camphor. 
CH3-CH-CH3 
CioHieO-H20  =  I 
/\ 
CH3 
Camphor  (I)  Cymene 
On  boiling  with  iodine,  camphor  is  converted  to  carvacrol  (II) 
another  substance  of  known  structure. 
CioHiaO—  H2 
CH3-CH-CHS 
QOH 
I 
CH3 
Camphor  (II)  Carvacrol 
The  reactions  of  camphor  considered  above  are  satisfied  by  the 
formula  (III)  proposed  by  Kekule  in  1873.  This  formula,  however, 
does  not  account  for  the  saturated  character  of  camphor,  nor  for  its 
oxidation  to  camphoronic  acid. 
Formula  (IV)  was  put  forward  by  Kannonikow  in  1883  and 
(V)  by  Bredt  in  1884.  That  Bredt  was  correct  and  Kannonikow 
incorrect  in  the  position  assigned  to  the  carbonyl  group  is  proved 
by  the  conversion  of  camphor  to  carvacrol,  considered  above. 
CH3-CH-CH3  CH3-CH-CH3  CH3-CH-CH3 
I  I 
CH  C 
CH2  ^\  CH2  CH2  f7^  CO 
CH         CO  CH2  CH2 
c  c 
I  I 
CH3  CH3 
(III)  Kekule,  1873  (IV)  Kannonikow,  1883 
