374  Conversion  of  Phenol  into  Salicylic  Acid.       { ju^y.^Ss*''"'* 
CONVERSION  OF  PHENYL  ETHERS  OF  CARBONIC 
ACID  INTO  SALICYLIC  ACID. 
By  W.  Hentschel. 
The  author  shows  that  when  sodium-phenol  is  acted  on  by  carbonic 
anhydride^  sodium  phenyl  carbonate  is  first  formed  ;  and  in  presence 
of  another  molecule  of  sodium-phenol  this  is  decomposed  with  forma- 
tion of  the  sodium  salt  of  salicylic  acid.  The  intermediate  product  is 
best  prepared  by  passing  dry  carbonic  anhydride  into  a  solution  of 
sodium-phenol  in  absolute  alcohol ;  the  resulting  body  is  a  mixture  of 
equal  parts  of  ethyl  and  phenyl  sodium  carbonate.  When  heated 
with  sodium-phenol  it  yields  salicylic  acid. 
The  author  has  prepared  phenyl  sodium  carbonate  in  large  quan- 
tities by  passing  carbonyl  chloride  into  an  aqueous  solution  of  sodium- 
phenol.  After  purification,  it  was  obtained  as  a  white  crystalline  mass 
which  distilled  at  301 — 302°.  The  mode  of  preparation  is  of  general 
application.  The  author  has  likewise  ])repared  the  orthonitrophenyl- 
compound,  which  crystallizes  from  alcohol  in  silky  rhombic  plates. 
Ethyl  phenyl  carbonate  obtained  by  the  action  of  ethyl  chlorofor- 
mate  on  potassium-phenol,  can  also  be  converted  into  salicylic  acid. 
Analogous  methods  of  preparation  yield  a  series  of  substituted  ethyl 
ethers  of  phenyl  carbonate.  A  ^^arachlorophenyl,  a  tribrominated,  an 
orthonitro-ether  of  phenyl  carbonate,  and  finally  the  corresponding 
thymol  compounds,  have  been  obtained. 
Conversion  of  Ethyl  Phenyl  Carbonate  into  Salicylic  Acid. — On 
heating  ethyl  phenyl  carbonate  with  sodium-phenol  in  equivalent  pro- 
porti(ms,  the  following  reaction  takes  place:  — 
HO.CcH,.COOEt  +  CeH.ONa     OH.CgH^.COONa  +  CgH^.OEt. 
The  author  considers  that  carbonic  anhydride  in  this  case  exerts 
first  an  etherifying  action  on  sodium-phenol,  and  that  the  phenyl 
sodium  carbonate  thus  formed  only  yields  salicylic  acid  on  coming  into 
contact  with  a  second  mol.  of  sodium-phenol.  In  Kolbe's  process,  it 
is  possible  that  the  conversion  of  the  phenyl  salt  into  salicylic  acid 
might  be  produced  by  some  other  method  such  as  warming.  The 
author  was  unable  to  obtain  salicylic  acid  by  digesting  ethyl  phenyl 
carbonate,  or  diphenyl  carbonate,  with  sodium  or  an  alcoholic  solution 
of  sodium. 
The  Conversion  of  Diphenyl  Carbonate  into  Salicylic  Acid  is  best 
