354 
Synthetic  Camphor. 
f  Am.  Jour.  Phariu. 
I      August,  1907. 
results  are  obtained.  The  inventor  of  the  present  process,  however, 
states  that  not  more  than  a  yield  of  10  per  cent,  can  be  secured  by 
the  operation,  but  claims  that  from  95  to  100  per  cent,  can  be  secured 
when  isoborneol,  either  in  powdered  form  or  when  dissolved  in  such 
solvents  as  benzin  or  benzol,  is  oxidized  with  an  aqueous  solution 
of  potassium  permanganate.  The  oxidization  takes  place  in  an 
alkaline  medium,  but  not  in  an  acid  or  neutral  one  ;  for  example, 
10  kilos  of  isoborneol,  either  finely  powdered  or  dissolved  in  10 
kilos  of  benzol,  are  well  stirred  with  a  solution  of  10  kilos  of 
potassium  permanganate  in  1  cubic  meter  of  water  at  the  ordinary 
temperature  until  the  color  of  the  permanganate  has  vanished.  The 
mixture  is  distilled  with  steam,  and  the  resulting  product  crystallized 
from  petroleum  ether,  whereby  the  camphor  is  obtained  in  a  pure 
state.  It  is  claimed  that  by  this  process  a  very  superior  camphor 
is  produced  because  by-products  are  "  wholly  avoided." 
U.  S.  patent  No.  790,601, issued  May  23,  1905,  embodies  a  process 
by  means  of  which  camphor  is  produced  by  the  direct  oxidation  of 
isoborneol  esters  in  place  of  isoborneol  itself,  by  such  agents  as 
chromic  acid,  nitric  acid,  permanganate,  sulphuric  acid,  manganese, 
Caro's  acid,  etc.,  working  either  in  solution  or  in  suspension. 
Various  esters  may  be  employed,  such  as  the  acetate,  benzoate, 
formate,  etc.,  but  the  one  generally  preferred  is  borneol  acetate,  on 
account  of  its  greater  accessibility.  Glacial  acetic  acid  may  be  em- 
ployed as  a  solvent  of  the  ester.  The  oxidation  may  also  be 
accomplished  in  water. 
It  is  stated  in  U.  S.  patent  No.  801,483,  issued  October  10,  1905, 
on  a  process  for  manufacturing  of  camphor,  that  it  is  well  known 
that  borneol  and  isoborneol  can  be  transformed  into  camphor  by  the 
usual  oxidizing  agents,  such  as  chromic  acid,  permanganate  and  the 
like,  but  they  possess  the  drawback  of  contaminating  the  camphor 
with  by-products  which  materially  hinder  the  subsequent  purifica- 
tion of  the  camphor.  This  difficulty  is  overcome  in  this  patent  by 
the  use  of  ozone.  It  was  at  first  believed  that  the  use  of  this  oxi- 
dizing agent  would  be  impossible  or  impracticable  because  of  the 
possibility  of  forming  ''additive  products  which,  by  reason  of  their 
tendency  to  explode,  would  have  rendered  the  process  technically 
impossible."  Experience,  however,  has  shown  that  this  apprehen- 
sion was  entirely  without  foundation.  It  should  also  be  stated  that 
ozone  does  not  produce  camphor,  as  do  other  oxidizing  agents, 
