Atom-economical insertion of hydrogen and sulfur into carbon–nitrogen triple bonds using H2S via synergistic C–N sites†

Abstract

Developing efficient strategies that convert industrial waste hydrogen sulfide (H₂S) into value-added products is meaningful for both applied environmental science and industrial chemistry. Here we report a series of heterogeneous N-doped carbon catalysts with synergistic C–N sites that enable the nucleophilic addition of H₂S into aromatic nitrile compounds (PhCN) under mild conditions to produce thiobenzamide (PhCSNH₂). The as-designed C–N sites achieve a high thioamide production rate of 26 400 μmol_PhCSNH2 L⁻¹ h⁻¹ and a notable selectivity of ca. 80% at 60 °C within a short 2-hour timeframe. Additionally, the catalyst exhibits easy recyclability and maintains high stability over ten cycles during a 6-month period. Systematic microscopic and in situ spectroscopic characterization, combined with theoretical calculations, reveal that C-pyridinic N coordination sites effectively lower the adsorption energy barrier of the crucial intermediate *PhCSHNH, offering a dynamically favorable pathway for PhCSNH₂ production. Furthermore, the protocol demonstrates excellent compatibility with various substituted substrates, providing access to a diverse range of thioamides.