338 
On  Monobromated  Camphor. 
J  Am.  Jour.  Phaem. 
\  August!,  1872. 
camphor,  which,  however,  has  been  refuted  by  Perkin.  I  can  confirm 
this  observation  of  the  latter,  and  have  also  satisfied  myself  that  Lau- 
rent's statement,  that  camphor  crystallizes  unaltered  from  its  warm 
solution  in  bromine,  is  incorrect,  as  the  copious  evolution  of  hydro- 
bromic  acid  already  proves. 
Monobromated  camphor  is  formed  according  to  the  following  equa- 
tion :  C20H16O2+2Br=C20H15BrO2+RBr.  If  prepared  in  a  closed 
tube,  it  is  evident  that  at  all  stages  of  the  process  the  pressure  must 
be  very  considerable,  at  first  in  consequence  of  the  volatile  nature  of 
both  camphor  and  bromine,  and  subsequently  on  account  of  the  pres- 
ence of  the  gaseous  hydrobromic  acid.  When  operating  on  a  small 
scale,  with  suitable  precautions,  there  was  little  difficulty  in  obtaining 
the  compound.  But  when  using  several  ounces  of  bromine  at  once, 
the  tubes  were  usually  shattered,  and  it  became  evident  that  this  pro- 
cess could  not  be  used  with  advantage  on  a  large  scale.  The  obser- 
vation that  on  slightly  heating  the  mixed  camphor  and  bromine,  the 
heat  increases  after  the  withdrawal  of  the  fire,  and  the  vessel  con- 
tains considerable  quantities  of  hydrobromic  acid,  suggested  the  idea 
that  the  camphor  might  be  bromated  without  using  closed  tubes,  simply 
by  digesting  the  bibromide  at  an  elevated  temperature,  or  by  allowing 
bromine  to  act  upon  camphor  at  a  higher  temperature,  with  the  pre- 
caution to  return  into  the  retort  any  bromine  and  bromide  of  cam- 
phor which  might  be  volatilized,  while  the  disengaged  hydrobromic 
acid  might  be  absorbed  by  a  solution  of  an  alkali. 
The  neck  of  the  retort  was  raised  and  connected  with  a  reversed 
Liebig's  condenser,  which  being  found  unnecessary,  was  afterwards  sub- 
stituted by  a  glass  tube.  If  the  reaction  was  not  allowed  to  become 
too  violent  in  the  beginning,  no  bromine  volatilized,  but  a  yellowish- 
brown  substance  condensed  in  the  neck,  flowing  back  into  the  retort, 
like  oil ;  gradually  this  became  lighter  in  color,  and  golden-yellow 
needles  were  observed  in  the  upper  part  and  neck  of  the  retort  after 
cooling.  Whether  these  needles  are  a  bromide  of  camphor  or  a  hy- 
drobromate  of  monobromated  camphor,  has  not  been  determined. 
The  heat  was  raised  after  the  first  reaction  was  over  to  a  tempera- 
ture varying  in  the  different  experiments  between  100°  and  132°  C. 
(212  and  270°  F.)  The  higher  temperatures  were  found  better 
adapted  for  rapidly  generating  the  monobromated  camphor ;  but  in 
all  cases  a  considerable  quantity  of  an  oily  compound  was  found  in 
the  mother  liquor  from  which  the  monobromated  camphor  had  crys- 
