Optimization of reaction conditions in single-stage reductive amination of aldehydes and ketones

This paper is concerned with the optimization of catalyst choice and reaction conditions in several reductive amination processes. The reactions were carried out in a single process stage and the objective was to maximize yield and avoid by-products. The response of selectivity to reaction conditions was also investigated during the course of this work and the results have been interpreted in terms of the reaction mechanism. It is proposed that, under conditions whereby the aldehyde or ketone is introduced gradually, the reactions proceed via hydrogenolysis of intermediate hemi-aminals rather than hydrogenation of intermediate imines. Steric hindrance of N-adsorption or of C-OH bond breakage can affect activity or selectivity in some reactions.