Mechanistic investigation of the catalytic system based on N-hydroxy-phthalimide with vanadium co-catalysts for aerobic oxidation of alcohols with dioxygen

[n-Bu4N]VO3 or a combination of vanadium complexes with some additives. as chloride salts or amines, are attractive and effective co-catalysts for aerobic oxidation of alcohols with dioxygen catalyzed by N-hydroxyphthalimide (NHPI). The role of the additives relates to the formation of more labile six co-ordinate vanadium complexes. A mechanism for the aerobic oxidation of alcohols with dioxygen is proposed and its essential steps are the formation Of oxotrialkoxyvanadium(V) complexes and generation of a phthalimide-N-oxyl (PINO center dot) radical as result of reaction of NHPI with oxovanadium(V) compounds. The oxidation of alcohols concerns to both radical and molecular pathways. (C) 2009 Elsevier Inc. All rights reserved.