SEARCH

SEARCH BY CITATION

Keywords:

  • acetophenones;
  • aerobic oxidation;
  • benzoic acids;
  • N-hydroxyphthalimide;
  • N,N′,N′′-trihydroxyisocyanuric acid

Abstract

Acetophenones substituted by alkyl, alkoxy, acetoxy, and halogen groups were selectively oxidized with molecular oxygen to the corresponding benzoic acids by using the N,N′,N′′-trihydroxyisocyanuric acid (THICA)/cobalt(II) acetate [Co(OAc)2] and THICA/Co(OAc)2/manganese(II) acetate [Mn(OAc)2]. For example, 4-methylacetophenone was selectively oxidized with molecular oxygen to 4-acetylbenzoic acid (85%) by THICA/Co(OAc)2 and to 4-methylbenzoic acid (93%) by Mn(OAc)2, while terephthalic acid was obtained in 93% with the THICA/Co(OAc)2/Mn(OAc)2 catalytic system. It is interesting that the acetyl group on the aromatic ring is efficiently converted by a very small amount of Mn(OAc)2 to the corresponding carboxylic acid, and that the present method provides a versatile route to acetylbenzoic acids which are difficult to prepare by conventional methods.