Kinetics and mechanism of the oxidative regeneration of carbonyl compounds from phenylhydrazones by [bis(trifluoroacetoxy)iodo]benzene

Abstract

The oxidation of several aldo- and keto-phenylhydrazones by [bis(trifluoroacetoxy)iodo]benzene (TFAIB), in aqueous acetic acid leads to the regeneration of the parent carbonyl compounds. The reaction exhibits a first order dependence on both the phenylhydrazone and TFIAB. The oxidation of ketoximes is slower than that of aldoximes. The oxidation of aliphatic phenylhydrazones correlates well in terms of Pavelich–Taft dual substituent-parameter equation. The low positive value of the polar reaction constant indicates a nucleophilic attack by TFIAB on the carbonyl carbon. The reaction is subject to steric hindrance by the alkyl group. A mechanism involving the formation of a cyclic activated complex in the rate-determining step is proposed.