(2-MERCAPTOETHYL)TRIMETHYLSILANE

bp 144–146 °C [52–54 °C (25 Torr)]; d 0.850.

2-(Trimethylsilyl)ethanethiol is a reagent used as a monoprotected sulfide dianion equivalent for the two-step installation of a divalent sulfur atom into organic molecules. It participates in the reactions of Thiol Substitution Reactions, Source of Sulfur Acid Derivatives, etc.

The high commercial cost of 2-(trimethylsilyl)ethanethiol necessitates methods for its lab scale synthesis. The radical addition of thiolacetic acid to vinyltrimethylsilane occurs thermally to afford a 9:1 ratio of regioisomers, the 1- and 2-(trimethylsilyl)ethyl thiolesters of acetic acid (eq 1). Photochemical initiation may improve the ratio of regioisomers obtained. Purification of the thiolacetate by careful fractional distillation should be performed prior to conversion to the thiol in order to ensure high purity. The conversion to thiol is best performed with LAH3 or methanolic K2CO3, but ammonolysis may also be suitable. Saponification with KOH in water/ethanol is slightly less efficient. Direct radical addition of liquid H2S to vinyl trimethylsilane has been demonstrated, but the procedure is low-yielding and inconvenient.