Selective Oxidation of Acetophenones Bearing Various Functional Groups to Benzoic Acid Derivatives with Molecular Oxygen

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)] anese(II) acetate and THICA/Co(OAc)(2)/manganese(II) [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),, 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 Oil 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.