Thermal Decomposition Mechanism for Ethanethiol.

The thermal decomposition of ethanethiol was studied using a 1 mm × 2 cm pulsed silicon carbide microtubular reactor, CH3CH2SH + Δ → Products. Unlike previous studies these experiments were able to identify the initial ethanethiol decomposition products. Ethanethiol was entrained in either an Ar or a He carrier gas, passed through a heated (300-1700 K) SiC microtubular reactor (roughly ≤100 μs residence time) and exited into a vacuum chamber. Within one reactor diameter the gas cools to less than 50 K rotationally, and all reactions cease. The resultant molecular beam was probed by photoionization mass spectroscopy and IR spectroscopy. Ethanethiol was found to undergo unimolecular decomposition by three pathways: CH3CH2SH → (1) CH3CH2 + SH, (2) CH3 + H2C═S, and (3) H2C═CH2 + H2S. The experimental findings are in good agreement with electronic structure calculations.