PdCu Bimetallic Catalysts for Selective Synthesis of Secondary Amines from Aldehydes and Ammonia

Secondary amines are highly useful in the pharmaceutical and environmental fields. Reductive amination is an effective method for converting aldehydes and ketones into amines. In this study, we employed a Pd1Cu0.2/SiO2 bimetallic catalyst to synthesize secondary amines directly from aldehydes and ammonia. A 97% yield of dibenzylamine is obtained under 30 °C, 1 MPa H2 within the reaction time of 3.5 min. Moreover, various aromatic and aliphatic aldehydes are converted into the corresponding secondary amines with yields ranging from 74 to 99%. Our findings show that the hydrogenation rate of secondary imine relative to primary imine plays a key role in determining the selectivity for secondary amines. The introduction of Cu leads to lower activation energy and faster reaction rates for the hydrogenation of secondary imines, ultimately leading to high selectivity and catalytic efficiency.