A combination of tetrachlorosilane (TCS) and sodium sulfide in acetonitrile is found to be an efficient thionating reagent for aromatic aldehydes in the absence of catalysis to give the corresponding thioaldehydes as trimers in good yields. Under cobalt (II) chloride catalysis, α, β-unsaturated ketones react with TCS–Na2S to give the respective disulfides in good yields via the intermediacy of β-mercaptoketones at ambient temperature.
