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.
