2S  Benzoic  Acid  prepared  from  Benzoin.        |  '^""  /an"'^i8^5^^°^' 
odor  is  stronger  than  that  of  the  Turkish  oil  (chiefly,  perhaps,  because 
it  is  pure),  and  its  freezing  point  higher.  Turkish  oil  freezes  at  21  °C., 
while  the  German  freezes  already  at  32°C. — Ibid.,  x,  p.  676. 
SUBSTANCES  ACCOMPANYING  BENZOIC  ACID  PRE- 
PARED FROM  BENZOIN. 
By  O.  Jacobsen. 
On  treating  benzoic  acid  from  gum  benzoin  with  sodium  car- 
bonate solution,  an  oil  is  left  undissolved,  smelling  of  vanillin  and  also 
of  ])henol.  By  fractionation,  it  may  be  separated  into  three  principal 
portions,  boiling  at  200-210°,  235-245°,  and  280-330°,  and  a  pitch- 
like residue  not  further  examined.  The  first  fraction  consists  of 
methyl  benzoate  and  guaiacol,  which  can  be  separated  by  treatment 
with  cold  dilute  caustic  soda.  The  second  and  smaller  fraction,  when 
shaken  with  water,  gives  up  catechol  in  the  acqueous  solution  ;  the 
portion  insoluble  in  water  and  dilute  alkalis  is  acetyl  guaiacol.  The 
thir'J  and  largest  portion  consists  of  an  oil,  insoluble  in  dilute  alkalis, 
which  by  saponification  with  alcoholic  potash,  and  subsequent  treat- 
ment with  water  and  ether,  yields  benzyl  alcohol,  and  benzophenone, 
Avhilst  the  aqueous  solution  contains  guaiacol  and  benzoic  acid ;  this 
fraction  therefore  contains  benzyl  benzoate,  benzophenone,  and  benzoyl- 
guaiacol.  The  oil  also  contains  vanillin,  but  in  minute  quantity  only. 
The  medicinal  value  of  sublimed  benzoic  acid  is  attributed  to  the  cate- 
chol and  guaiacol;  it  is  believed  that  of  the  above  bodies  only  vanillin 
and  benzyl  benzoate  exist  ready  formed  in  the  gum.  Benzaldehyde 
may  be  formed  by  the  oxidation  of  the  contained  benzyl  benzoate,  so 
that  the  production  of  the  former  cannot  be  considered  as  a  proof  of 
adulteration  with  cinnamic  acid.  Schlickum  and  Schneider  have 
tested  the  genuine  nature  of  natural  benzoic  acid  by  its  reducing 
boiling  ammoniacal  silver  solution;  but  catechol  will  reduce  the  solu- 
tion in  the  cold,  and  the  author  therefore  suggests  the  following  method 
of  testing  : — Convert  the  benzoic  acid  into  the  sodium  salt,  and,  after 
drying,  shake  with  ether;  after  removal  of  the  ether,  the  residue  may 
be  dissolved  in  water,  and  the  above  or  any  other  tests  for  catechol 
applied. — Arch.  Pharm.  [3],  xxii,  pp.  366-374  ;  Jour.  Chem.  Soc,  Nov. 
1884,  p.  1168. 
