OXIDATION OF N-BENZYL-N-METHYLHYDROXYLAMINES TO NITRONES - A MECHANISTIC STUDY

Oxidation of various N-(o-, m-, p-substituted benzyl)-N-methylhydroxyl amines has been carried out using mercury(II) oxide and p-benzoquinone (p-BQ) as oxidants, Hammett plots have been obtained with negative rh o values, showing the development of a positive centre in the transiti on state, The unstable E nitrones, which readily isomerize to the more stable Z nitrones, are obtained in appreciable quantities and in some cases as the major product, A considerable deuterium isotope effect i s observed in the oxidation process, The overall picture of the mechan istic pathway involves electron transfer from nitrogen to the oxidant followed by hydrogen abstraction.