Sustainable Hydrogenation of Nitroarenes to Anilines with Highly Active in-situ Generated Copper Nanoparticles

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 (NH3BH3, 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.