Hydrogenation of amides to amines by heterogeneous catalysis: a review

Abstract

Amines are pivotal building blocks for a range of applications, including pharmaceuticals, polymers, agrochemicals, and organic synthesis. The hydrogenation of amides using molecular hydrogen via heterogeneous catalysis is considered a promising method for producing amines with considerably high atom efficiency, environmental friendliness, and eonomic viability. Continued developments have occurred in this area, with milestones reached in the hydrogenation of various amides to amines via heterogeneous catalysis. At present, no systematic analysis of the influence of amide structures on their reactivity and the required type of catalyst has been reported. This review describes the most recent advances in catalytic amide hydrogenation, paying special attention to the influence of structural features (cyclic amides and aliphatic acyclic amides) on catalyst performance. Structural features endow amides with specific reactivities, reflected in considerable differences in the ease of hydrogenation and diverse product selectivity. In addition, insights into the conversion of polyamides, fatty acids, and triglycerides to amines are provided. This review provides new perspectives for designing and applying heterogeneous catalysts adapted to specific conditions and amide structures.