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 (Cu0NPs) 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 Cu0NPs, 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 Cu0NPs to air. Thus, the hydrogenation reaction can be performed multiple times without the loss of the Cu0NPs’ 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. The in‐situ formation of Cu0NPs from Jacquesdietrichite mineral is demonstrated. In‐situ generated Cu0NPs selectively hydrogenated nitro compounds to anilines at room temperature using ammonia borane (AB). The activity remained the same for at least five consecutive runs and synthetic mineral is fully recovered at the end of each cycle. Drug molecules “flutamide” and “nimesulide” could be successfully hydrogenated at ambient conditions.