Mechanistic study on the oxidative coupling of amines to imines on K-10 montmorillonite

A mechanistic study of the K-10 montmorillonite-catalyzed microwave-assisted oxidative self-coupling of benzylamine and cross coupling of benzylamines with anilines and aliphatic amines is described. The coupling of benzylamines readily produced benzylidene benzylamines, while reactions of benzylamine with aliphatic amines and anilines resulted in benzylidene alkylamines and benzylidene anilines. The mechanism of the reaction has been investigated by varying reaction conditions, kinetic studies, thermogravimetric analysis and DRIFT spectroscopy. The data obtained clarified the steps of this multistep reaction sequence and a mechanistic scheme has been proposed.

Research Highlights
► K-10 montmorillonite catalyzes the oxidative self-coupling of amines.
► The self-coupling is initiated by an oxidation and formation of benzaldehyde.
► Anilines and aliphatic amines form benzilidene-amines with benzylamines.