Sustainable Hydrogenation of Nitroarenes to Anilines with Highly Active In-Situ Generated Copper Nanoparticles

Abstract

Metal nanoparticles (NPs) are usually stabilized by a capping agent, a surfactant, or a support material, to maintain their integrity. However, these strategies can impact their intrinsic catalytic activity. Here, we demonstrate that the in-situ formation of copper NPs (Cu 0 NPs) upon the reduction of the earth-abundant Jacquesdietrichite mineral with ammonia borane (NH 3 BH 3 , AB) can provide an alternative solution for stability issues. During the formation of Cu 0 NPs, hydrogen gas is released from AB, and utilized for the reduction of nitroarenes to their corresponding anilines, at room temperature and under ambient pressure. After the nitroarene-to-aniline conversion is completed, regeneration of the mineral occurs upon the exposure of Cu 0 NPs to air. Thus, the hydrogenation reaction can be performed multiple times without the loss of the Cu 0 NPs' activity. As a proof-of-concept, the hydrogenation of drug molecules "flutamide" and "nimesulide" was also performed and their corresponding amino-compounds were isolated in high selectivity and yield.[a] F.