56  Camphor — Natural  and  Synthetic.  {^f^^l^m^' 
2.  Heating  with  caustic  soda  and  a  salt  of  a  higher  fatty  acid, 
such  as  stearates  of  sodium,  lead,  or  copper. 
3.  Heating  with  phenolates  or  naphtholates  of  sodium,  potassium, 
calcium,  magnesium,  etc. 
4.  Heating  with  glacial  acetic  acid  and  anhydrous  acetates  of  lead, 
zinc,  or  alkaline  earth  metals. 
5.  Treatment  with  magnesium  as  used  in  the  Grignard  reaction. 
It  is  worthy  of  note  that  camphene  is  the  only  solid  terpene  hydro- 
carbon.   It  is  a  white  solid  melting  at  500  C. 
The  next  stage  in  the  process  is  the  conversion  of  camphene  to 
bornyl  acetate.11  This  is  accomplished,  as  Bertram  and  Walbaum  12 
showed,  by  treating  the  solution  of  the  camphene  in  glacial  acetic 
acid  with  about  5  per  cent,  of  sulphuric  acid  at  a  slightly  elevated 
temperature.  Acetic  acid  is  added  on,  in  accordance  with  the  formula 
below.  Bornyl  acetate  is  an  oil  boiling  with  some  decomposition 
at  about  225 0  C.   It  is  readily  volatile  in  steam. 
The  final  steps  in  the  camphor  synthesis  consist  in  the  saponi- 
fication of  the  bornyl  acetate  to  borneol,  and  the  oxidation  of  the 
borneol  to  camphor. 
CH2  CH  CH2  CH2  CH  CH2        CH2  CH  CH2 
I 
CH3— C— CH3 
I 
I 
CH3— C— CH3 
I 
I 
CH3-C-CH3 
I 
C  H2  C  C  HOOC  -C  H3  C  H2  C  C  HO  H   C  H2  C  CO 
CH3  CH3  CH3 
(XIII)  Bornyl  acetate  (XIV)  Borneol  (XV)  Camphor 
The  saponification  is  accomplished  with  alcoholic  caustic  soda, 
yielding  sodium  acetate  as  a  by-product.  The  borneol  so  obtained 
is,  with  the  exception  of  its  optical  inactivity,  identical  with  the 
Borneo  camphor  occurring  in  nature. 
The  oxidation  of  borneol  to  camphor  can  be  accomplished  by  a 
great  variety  of  oxidizing  agents — air,  ozone,  chlorine,  nitric  acid, 
potassium  permanganate,  potassium  bichromate,  and  sulphuric  acid, 
and  finely  divided  metals  such  as  nickel  and  cobalt.13    When  potas- 
11  The  term  bornyl  acetate  and  borneol  are  used  for  simplicity.  In  reality 
wo-bornyl  acetate  and  uo-borneol  are  produced.  The  nature  of  the  isomerism 
is  not  clearly  understood. 
12  Jour.  f.  prak.  Chem.,  NF.,  49,  1. 
13  Schering,  German  patents  271 147  and  271 157.  Also  patent  of  Port 
Chester  Chemical  Company,  New  York  (1911). 
