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Benzyl  Alcohol. 
Am.  Tour.  Pharm. 
May,  1919. 
acter  is  already  indicated  by  this  formula.  The  cresols  are  phenols, 
the  hydroxyl  group  being  attached  to  the  carbon  ring  C6H4OHCHs. 
Benzyl  alcohol  is  a  derivative  of  toluene  C6H5CH3,  one  hydroxyl 
group  replacing  hydrogen  in  the  methyl  group.  When  oxidized  it 
follows  the  general  reaction  for  primary  alcohols,  being  converted 
into  an  aldehyde  (benzaldehyde  C6H5CHO)  and  on  further  oxida- 
tion into  an  acid  (benzoic  acid  C6H5COOH). 
It  occurs  naturally  free,  and  combined  with  anisic  and  benzoic 
acid  in  certain  resins,  storax,  balsam  of  Tolu  and  balsam  of  Peru. 
When  benzaldehyde  is  reduced  by  nascent  hydrogen  (sodium 
amalgam)  benzyl  alcohol  is  produced. 
C6H5CHO  +  2H  =  C6H5CH2OH. 
It  is  also  formed  when  benzyl  chloride  is  boiled  with  a  solution 
of  sodium  carbonate :  hydrolysis  takes  place,  and  the  hydrochloric 
acid  set  free  is  neutralized  by  the  carbonate. 
C6H5CHX1  +  H20  =  C6H5CH2OH  +  HQ. 
Preparation. 
A  very  convenient  and  practical  way  of  preparing  pure  benzyl 
alcohol  is  by  means  of  potassium  hydroxide  on  benzaldehyde. 
2C6H5CHO  +  KOK  =  C6H5CH2OH  +  C6H5COOK. 
It  will  be  seen  from  the  equation  that  two  molecules  of  benzalde- 
hyde are  required  to  produce  one  molecule  of  the  alcohol,  in  other 
words  212  Gm.  of  benzaldehyde  will  theoretically  yield  108  Gm.  of 
alcohol,  and  by  the  practical  method  given  below  90  per  cent,  of  this 
theoretical  yield  may  be  obtained.  If  necessary  the  benzoic  acid  can 
be  recovered  from  the  potassium  benzoate. 
Dissolve  90  Gm.  of  solid  potassium  hydroxide  in  60  mils,  of 
water,  cool  to  air  temperature  (150  C.)  and  transfer  to  a  500-600 
mil.  stoppered  bottle,  add  100  Gm.  benzaldehyde,  and  shake  well 
until  a  permanent  emulsion  is  formed. 
Allow  to  stand  until  the  following  day  (15-20  hours),  during 
which  time  the  mixture  solidifies  owing  to  the  separation  of  a  mass 
of  white  crystals — potassium  benzoate.  Water  is  added  with  shak- 
ing until  all  the  crystals  have  dissolved. 
The  mixture  is  next  agitated  with  ether  to  remove  the  benzyl 
alcohol.  Allow  the  ethereal  layer  to  separate ;  repeat  the  extrac- 
tion three  or  four  times. 
