Am.  Jour.  Pharm.  "I 
August,  1907.  J 
Synthetic  Camphor. 
355 
when  acting  on  camphene,  but  camphenilon  and  formaldehyde.  The 
method  is  applied  in  the  following  manner : 
"Ten  kilos  of  borneol  are  dissolved  in  75  kilos  of  95  per  cent, 
acetic  acid  and  ozone  at  the  ordinary  temperature,  passed  through 
until  the  greatest  part  escapes  practically  unchanged.  The  main 
portion  of  the  acetic  acid  is  then  distilled  off ;  the  residuum  is  diluted 
with  water,  neutralized  with  soda,  and  the  deposited  camphor  puri- 
fied by  known  means," 
Petroleum  ether  can  also  be  used  as  a  solvent  in  which  oxidation 
may  be  effected. 
U.  S.  patent  No.  801,485  covers  a  process  for  converting  borneol 
or  isoborneol  into  camphor  by  means  of  oxygen  or  air.  The  method 
consists  in  vaporizing  borneol  or  isoborneol  and  subjecting  the  vapor 
to  the  action  of  oxygen  either  with  or  without  the  presence  of  so- 
called  "  catalytic 'T  reagents ;  for  example,  isoborneol  is  heated  to 
about  1700  C.  and  volatilized  by  a  current  of  oxygen  or  air.  The 
mixture  vapors  are  slowly  passed  over  copper  wire  or  through  glass 
tubes  filled  with  fragments  of  earthenware  heated  to  a  temperature 
of  from  1 75°  to  1800  C.  The  cooled  product  contains  from  6  to  25 
per  cent,  of  camphor,  depending  upon  the  length  of  oxidation  and 
the  dilution  of  the  oxygen.  "  Other  ketones  or  aldehydes  are  not 
produced." 
According  to  U.  S.  patent  No.  802,792,,  issued  October  24,  1905, 
the  methods  commonly  recommended  for  the  production  of.  camphor 
are  not  satisfactory.  The  author  of  this  patent  found  that  chlorine 
converts  isoborneol  rapidly  and  easily  into  camphor  either  in  a 
gaseous  state  or  in  solution,  using  such  solvents  as  water,  carbon 
tetrachloride,  benzene,  or  chloroform.  When  chlorine  gas  is  passed 
over  finely  powdered  isoborneol,  the  following  reaction  takes  place : 
C10H18O  +  2CI  =  C10H16O  +  2HCI 
Isoborneol  Camphor 
The  oxidation  develops  much  heat,  which  is  controlled  both  by 
external  cooling  and  by  mixing  the  chlorine  gas  with  some  inert 
gas  such  as  air  or  carbon  dioxide.  The  temperature  must  be  kept 
at  or  near  300  C.  An  aqueous  solution  of  the  chlorine  works  very 
satisfactorily.  As  long  as  any  unconverted  isoborneol  is  left  the 
chlorine  does  not  act  on  the  camphor. 
Another  patent  issued  October  .24,  1905,  No.  802,793,  covers  a 
