Selective Transfer Hydrogenation and N-Formylation of Nitroarenes by a Facilely Prepared N, S Co-doped Carbon-Encapsulated Cobalt Nanoparticle Catalyst

The N, S co-doped carbon nanotube-encapsulated Co nanoparticle (NP) material was prepared by one-pot pyrolysis of cheap precursor materials. As-prepared Co@NSC-800 exhibited excellent catalytic activity in transfer hydrogenation and N-formylation of nitroarenes, and the solvent and hydrogen source were the critical factors affecting the selectivity of aniline and benzamide. Moreover, the synergistic effect between Co NPs and N, S atoms was beneficial to improve the catalytic efficiency of Co@NSC-800; especially, the incorporation of S atoms greatly boosted the selectivity of N-formylation. Despite the use of HCOONH4 (HCOOH) as a hydrogen donor for hydrogenation and formylation of nitroarenes, the special nanotube structure of the Co@NSC-800 catalyst effectively prevented the corrosion of Co NPs and showed excellent durability under harsh reaction conditions. In addition, the catalyst maintained excellent catalytic activity after six cycles and was easily separated using an external magnet. Thus, this study can provide an effective method for the transfer hydrogenation and formylation of nitroarenes.