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The pyrolysis of dimethyl sulfide, kinetics and mechanism
Author(s) -
Shum Lilian G. S.,
Benson Sidney W.
Publication year - 1985
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550170705
Subject(s) - chemistry , kinetics , pyrolysis , isomerization , rate equation , dimethyl sulfide , reaction rate constant , reaction mechanism , sulfide , chemical kinetics , thermodynamics , photochemistry , organic chemistry , catalysis , sulfur , physics , quantum mechanics
The kinetics of the gas phase pyrolysis of dimethyl sulfide (DMS) was studied in a static system at 681–723 K by monitoring total pressure‐time behavior. Analysis showed the pressure increase to follow DMS loss. The reaction follows two concurrent paths:with a slow, minor, secondary reaction:In a seasoned reactor the reaction follows a 3/2 order rate law with rate coefficient given by\documentclass{article}\pagestyle{empty}\begin{document}$$ \log [k({\rm L}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} /{\rm mol}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} {\rm s})] = 13.84 \pm 0.21 - (51.4 \pm 0.7)/\theta $$\end{document}with θ = 2.303 RT in kcal/mol. A free radical mechanism is proposed to account for the data and a theoretical rate coefficient is derived from independent data:\documentclass{article}\pagestyle{empty}\begin{document}$$\log [k({\rm L}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} /{\rm mol}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} {\rm s})] = 12.8 \pm 0.3 - (47 \pm 1.5)/\theta $$\end{document}which agrees well with the experimental one over the range studied. The reaction is initiated by Me 2 S → Me + MeS⋅ and propagated by metathetical radical attack on Me 2 S. C 2 H 4 is formed by an isomerization reaction which may in part be due to a hot radical:Thermochemical data are listed, many from estimations, for both molecular and radical species of interest in the present system.