Experimental and Computational Studies of the Kinetics of the Reaction of Atomic Hydrogen with Methanethiol

Abstract

The overall rate constant for H + CH 3 SH has been studied over 296− 1007 K in an Ar bath gas using the laser flash photolysis method at 193 nm. H atoms were generated from CH 3 SH and in some cases NH 3 . They were detected via timeresolved resonance fluorescence. The results are summarized as k = (3.45 ± 0.19) × 10 −11 cm 3 molecule −1 s −1 exp(−6.92 ± 0.16 kJ mol/RT) where the errors in the Arrhenius parameters are the statistical uncertainties at the 2σ level. Overall error limits of ±9% for k are proposed. In the overlapping temperature range there is very good agreement with the resonance fluorescence measurements of Wine et al. Ab initio data and transition state theory yield moderate accord with the total rate constant, but not with prior mass spectrometry measurements of the main product channels leading to CH 3 S + H 2 and CH 3 + H 2 S by Amano et al.

From interstellar carbon monosulfide to methyl mercaptan: paths of least resistance

“…Here, we make use of MPWB1K/def2-TZVP, which was explicitly benchmarked against two high-level theories, namely both CCSD(T)-F12/cc-VTZ-F12 and MRCI(+Q)-F12/VTZ-F12 single-point energies. Moreover, the values provided here are in good agreement with previous work by Kobayashi et al (2011); Kerr et al (2015). Furthermore, the branching ratios given by KIDA were determined solely by the most exothermic reaction channel.…”

“…The current research therefore provides a detailed theoretical investigation of the reaction network involving ten CS-bearing species and 29 reactions with atomic hydrogen, explicitly taking quantum tunnelling into account. This work builds on various computational approaches previously reported in the literature where a part of the reaction network has been considered (Kobayashi et al 2011;Kerr et al 2015;Vidal et al 2017). To the best of our knowledge there are currently no low-temperature experimental data, calculated or measured unimolecular rate constants, or branching ratios available for any of the reactions mentioned below.…”

Theoretical study on the atmospheric reaction of CH3SH with O2

“…As a kind of highly reactive sulfur compound, CH 3 SH (methanethiol or methyl mercaptan) has been drawing long‐term attention because of its critical role in the atmospheric sulfur cycle . Significant amount of recent studies have focused on the reactions of CH 3 SH with series of species, such as H, O( 3 P), S( 3 P), OH, NO x (x = 1, 2, 3), X(X = F, Cl, Br), CN, XO(X = Br, I), O 3 , HOCl, CH 3 SLi, H 2 O 2 , HOO, and so on.…”

A reaction kinetics study and model development to predict the formation and destruction of organosulfur species (carbonyl sulfide and mercaptans) in Claus furnace

“…to find the rate constants for the reactions of OH with COS, CS 2 , and CH 3 SCH 3 and to suggest that the reaction paths leading to H 2 and CH 3 S formation were dominant. Kerr et al . studied the reaction of the H atom with methyl mercaptan (CH 3 SH) over 296–1007 K using laser flash photolysis to determine its rate constant and found that the product channels leading to CH 3 S + H 2 and SH + CH 4 were the dominant ones.…”

“…Theoretical calculations have also been conducted on the reactions of COS with H, OH, and O radicals and on the reactions of mercaptans with H, OH, O, and S . Saheb et al .…”