With special regard to the synthesis of β-thioketoesters, the acid catalysed reactions of 36 differently substituted β-keto esters with H2S have been studied under various conditions in order to determine the influence of the substituents on reaction course. gem-Dithiols may also be obtained in good yields by this reaction. Treatment of T1 (I)-salts of β-thioketo esters with alkyl halides results exclusively in S-alkylation. A slow cis-trans isomerization of S- ...