Rate constants and vibrational distributions for water‐forming reactions of OH and OD radicals with thioacetic acid, 1,2‐ethanedithiol and tert‐butanethiol

Abstract

AbstractReactions of OH and OD radicals with CH3C(O)SH, HSCH2CH2SH, and (CH3)3CSH were studied at 298 K in a fast‐flow reactor by infrared emission spectroscopy of the water product molecules. The rate constants (1.3 ± 0.2) × 10−11 cm3 molecule−1 s−1 for the OD + CH3C(O)SH reaction and (3.8 ± 0.7) × 10−11 cm3 molecule−1 s−1 for the OD + HSCH2CH2SH reaction were determined by comparing the HOD emission intensity to that from the OD reaction with H2S, and this is the first measurement of these rate constants. In the same manner, using the OD + (C2H5)2S reference reaction, the rate constant for the OD + (CH3)3CSH reaction was estimated to be (3.6 ± 0.7) × 10−11 cm3 molecule−1 s−1. Vibrational distributions of the H2O and HOD molecules from the title reactions are typical for H‐atom abstraction reactions by OH radicals with release of about 50% of the available energy as vibrational energy to the water molecule in a 2:1 ratio of stretch and bend modes.