Am.  Joub.  Pharm.  1 
Aug.  1, 1872.  J 
On  Monobromated  Camphor. 
341 
perature  rose,  and  a  little  oil  distilled  over,  which  solidified  after  a 
while  and  turned  red  from  the  liberation  of  some  bromine.  Mean- 
while the  flake-like  sublimate  in  the  neck  of  the  retort  increased  con- 
siderably, and  the  hot  liquid  boiled  actively  between  260  and  261°  C. 
(500  and  502°  F.),  disengaging  considerable  quantities  of  hydrobro- 
mic  acid,  and  separating  also  so  much  charcoal  that  the  retort  cracked. 
8  ounces  of  bromine  had  been  used  in  this  experiment,  the  black  resi- 
due of  which,  when  dissolved  in  alcohol  and  filtered,  yielded  white 
crystals,  requiring  to  be  recrystallized  once,  while  the  mother  liquor 
had  a  strong  acid  reaction,  due  to  free  hydrobromic  acid. 
Although  this  experiment  was  not  very  favorable  for  Perkin's  pro- 
cess, in  its  application  to  the  preparation  of  this  compound  on  a  large 
scale,  it  suggested  a  method  of  utilizing  the  oily  residue  which  had 
accumulated  from  the  mother  liquors  of  the  first  crystallization  of 
monobromated  camphor  prepared  at  a  lower  temperature.  The  grey 
granular  mass,  left  by  expressing  a  portion  of  the  solidified  oil,  as 
stated  above,  was  slowly  heated  to  260°  C.  (500°  F.),  and  after  the 
disengagement  of  most  of  the  hydrobromic  acid,  was  dissolved  in 
petroleum  benzine,  treated  with  marble  and  filtered,  when  monobro- 
mated camphor  crystallized.  The  oily  residue,  containing  some  of  the 
granular  compound,  was  next  treated  in  the  same  way,  with  a  similar 
result.  In  both  cases  some  of  the  oily  mass  was  left  in  the  mother 
liquor,  which  may  undoubtedly  be  utilized  in  a  subsequent  operation. 
To  recapitulate  the  results  of  these  experiments,  before  giving  the 
process  which  in  my  experience  is  best  adapted  to  obtain  monobro- 
mated camphor  on  a  more  extensive  scale  for  medicinal  purposes,  it 
may  be  stated  that  the  process  is  divided  into  three  distinct  opera- 
tions :  1,  the  combination  of  bromine  with  camphor  (bibromide  of 
camphor),  which  takes  place  at  the  ordinary  or  slightly  elevated  tem- 
perature, particularly  in  the  presence  of  a  trace  of  alcohol ;  2,  the 
formation  of  the  substitution  compound  (monobromated  camphor), 
which  may  be  effected  at  a  temperature  of  100°  C.  (212°  F.),  or  in  a 
much  shorter  time  at  132°  C.  (270°  F.) ;  and  3,  the  utilization  of  the 
oily  residue,  the  greatest  part  of  which  is  converted  into  the  substitu- 
tion compound  at  260°  C.  (500°  F.)  The  product  of  the  second  part 
is  at  once  white,  requiring,  if  decomposition  has  been  avoided,  no  fil- 
tration, but  simply  recrystallization.  The  use  of  the  cheap  petro- 
leum benzine  and  naphtha,  in  preference  to  alcohol  and  ether,  will 
also  commend  itself  for  the  sake  of  economy.    The  yield  is  probably 
