Synthesis of benzothioamide derivatives from benzonitriles and H2S-based salts in supercritical CO2

A novel and efficient method has been developed for synthesizing benzothioamide from benzonitrile in supercritical CO₂, which could be used to synthesize various benzothioamide derivatives efficiently with yields of up to 98% without the need for organic solvent. Notably, some H₂S-based salts were designed and prepared, and they were found to be effective catalysts in promoting the thiolysis of benzonitrile to produce benzothioamide in an excellent yield. Furthermore, the utilization of supercritical CO₂ as a solvent has demonstrated a remarkable increase in the yield of the desired product compared to conventional solvents for promoting benzonitrile thiolysis. Additionally, the investigation of the reaction mechanism has revealed that the acid–base properties of the reaction solution played a crucial role in the thiolysis of benzonitrile mediated by the H₂S-based salts.