Kinetics and Mechanism of Pyridinium Chlorochromate Oxidation of Some N-Methyl-2,6-diphenylpiperidin-4-one Oximes

Abstract

The oxidative deoximation of 1-methyl-2,6-diphenyl piperidin-4-one and its 3-alkyl substituted derivatives by pyridinium chlorochromate (PCC) in aqueous acetic acid medium exhibits a first order dependence on both the oxime and PCC. The reactions are catalyzed by hydrogen ions. The rates are accelerated by increasing the dielectric strength of the medium. The activation parameters are computed by performing the reactions at four different temperatures. On the basis of the experimental results a suitable mechanism has been proposed. The reactivity trend observed for the oximes is 1-MePPO > 1,3-diMe2PPO > 1-Me-3-EtPPO > 1,3,3-Me3PPO > 1- Me-3-iprPPO.