| 摘要： |
The search for active, inexpensive, and stable heterogeneous catalysts for organic transformation still remains challenging in both academia and industry. Herein, we present the facile fabrication of non-noble cobalt nanocomposites on N-doped hierarchical porous carbon derived from naturally renewable biomass together with Earth-abundant and low-cost cobalt salts. The whole preparation process is operationally simple and straightforward, cost-effective and environmentally benign and can be used in mass production for practical applications. The most active cobalt nanocomposite catalyst, that is, CoOx@NC-800, demonstrated outstanding activity and excellent selectivity for the hydrogenation of functionalized nitroarenes to aniline derivatives with molecular hydrogen in water as a green medium. It also showed high activity for the direct and expedient synthesis of imines from the reductive amination of nitroarenes and aldehydes with excellent selectivity and good tolerance to a variety of functional groups. More importantly, a new straightforward one-pot cascade synthesis of benzimidazole was developed from the reductive amination of ortho-amino substituted nitrobenzene with aldehyde followed by sequential cyclization in a green and sustainable manner, further highlighting the utility of the catalyst. In addition, the catalyst can be easily separated for successive reuses without a significant loss in both activity and selectivity. |
