C2-Transformation of calcium carbide trigered by hydrogen sulfide

Calcium carbide, a bulky and cheap raw chemical, is traditionally depolymerized by water to release acetylene, allowing the downstream organic transformation. In this study, hydrogen sulfide (H₂S), an industrial waste gas, has been exploited to depolymerize calcium carbide, which represents a strategy for the comprehensive utilization of both hydrogen sulfide and calcium carbide. As a proof of concept, a three-component condensation reaction was established to prepare thioamides directly from hydrogen sulfide and calcium carbide in high yields. Leveraging the unique properties of thioamides that possess both nucleophilic sulfur and electrophilic carbon sites, a series of novel tandem reactions were further developed to construct structurally diverse heterocyclic compounds. Our strategy not only provides a new chemical pathway for calcium carbide depolymerization, but also offers a solution for the utilization of hazardous hydrogen sulfide gas. More importantly, this approach facilitates the comprehensive and sustainable utilization of the calcium carbide resource.