5-Thiation of 1,2-dithiole-3-thiones

5-Thiols are prepared from 4-substituted 1,2-dithiole-3-thiones (I) by the action of sulphur and dimethylamine in hot dimethylformamide or dimethylsulphoxide, or by the action of sodium polysulphide in aqueous alcohols. Some properties of the 5-thiols are described.