356 
Synthetic  Camphor. 
<  Am.  Jour.  Pbarm. 
I      August,  1907. 
process  for  the  manufacture  of  camphor  by  the  action  of  the  so- 
called  "  gaseous  nitrous  acid  "  on  borneol  or  isoborneol,  either  solid 
or  in  solution.  The  reaction  is  best  brought  about  by  dissolving 
these  several  compounds  in  such  solvents  as  chloroform,  ether  or 
ligroine  and  passing  the  gas  through  the  solution  until  reaction  is 
complete.  For  example  :  "  In  an  enameled  vessel,  which  is  furnished 
with  a  stirring  arrangement  and  a  cooling  apparatus,  10  kilograms 
of  isoborneol  are  subjected  to  the  action  of  well-dried  nitrous  gases 
which  are  passed  in  by  a  tube.  The  escaping  fumes  are  compelled 
to  pass  through  a  reflux  condenser.  As  soon  as  all  the  borneol  is 
liquefied  the  vessel  is  cooled  from  outside  with  water,  and  the  intro- 
duction of  gas  is  continued  until  the  liquid  has  attained  a  bluish 
green  coloration.  The  mixture  is  now  allowed  to  stand,  care  being 
t  .ken  to  prevent  the  temperature  rising  above  6o°  to  yo°  centi- 
grade. During  this  time  nitrous  fumes  are  evolved.  After  about 
our  or  five  hours  the  contents  of  the  vessel  are  poured  slowly  into 
ioo  liters  of  water,  whereupon  the  camphor  at  once  separates  in 
the  pure  state." 
"  My  process  leads  to  a  quantitative  yield  of  camphor  pure  and 
f  ree  from  by-products." 
A  process  for  manufacturing  borneol  from  pinene  hydrochlorid 
was  protected  by  U.  S.  patent  No.  826,165,  August  17,  1906,  based 
on  the  well-known  Grignard  reaction.  It  consists  in  warming  a 
mixture,  with  stirring,  of  ethylbromid,  dry  ether  and  magnesium 
until  a  reaction  ensues.  Just  before  the  reaction  is  completed,  a 
suitable  quantity  of  pinene  hydrochlorid  dissolved  in  dry  ether  is 
gradually  added  to  the  stirring  mixture.  When  the  reaction  ter- 
minates, the  vessel  is  cooled  with  water  and  oxygen,  or  atmospheric 
air  is  passed  through  the  mixture,  until  oxygen  is  no  longer 
absorbed.  Ice  is  then  added,  and  the  mixture  rendered  acid  by 
dilute  acids  which  cause  a  separation  into  two  layers.  The  upper 
ethereal  layer  contains  the  borneol.  The  lower  aqueous  layer  is 
withdrawn,  the  ether  distilled  from  the  borneol,  which  can  be 
purified  by  crystallization  from  such  solvents  as  petroleum  ether, 
benzene  or  alcohol. 
