Infrared study of the Beckmann rearrangement catalysed by decationated zeolite

Abstract

The Beckmann rearrangement of cyclopentanone oxime and cyclohexanone oxime to 2-piperidone and ε-caprolactam, respectively, has been studied by i.r. absorption at a catalysing decationated zeolite surface. By comparison of the spectra of the parent oximes, oxime hydrochlorides, lactams, and lactams hydrochlorides with the oximezeolite system it has been possible to show that reaction is initiated by the transfer of a proton from one of the hydroxy-groups associated with the zeolite lattice. The spectra also reveal that rearrangement is substantially complete at 120 °C but that the product is strongly adsorbed at the zeolite surface. This feature of the reaction probably accounts for the limited life of the catalyst which is characteristic of the process.