EVIDENCE OF PROTONATION DURING THE OXIDATION OF SOME ARYL ALCOHOLS BYPERMANGANATE IN PERCHLORIC-ACID MEDIUM AND MECHANISM OF THE OXIDATIONPROCESSES

The oxidation of benzyl alcohol and methoxy-, chloro-, and nitro- subs tituted benzyl alcohols by permanganate has been studied in aqueous an d acetic acid medium in presence of perchloric acid. The reaction is f irst-order in [MnO4-] and [XC(6)H(4)CH(2)OH], but the order is complex with respect to [H+]. Different thermodynamic parameters have been ev aluated. The reaction occurs through the protonation of alcohol in a f ast preequilibrium followed by a slow rate-determining oxidation step. A two-electron transfer oxidation step has been suggested for benzyl alcohol and chloro- and nitro- substituted alcohols, while the oxidati on of methoxy compounds involves a one-electron transfer via a free-ra dical mechanism. (C) 1995 John Wiley and Sons, Inc.