Reactions of methyl radicals. I. Hydrogen abstraction from dimethyl sulphide

Abstract

Hydrogen abstraction from (CH₃)_,S and CH₃COCH₃ by CH₃ radicals CH₃+CH₃SCH₃ → CH₄+CH₃SCH₂ CH₃ + CH₃COCH₃ → CH₄ + CH₃COCH₂ has been studied in the temperature range 120-245º. The rate constants, based on the value of 10^13.34cm³ mol^-l s^-1 for the recombination of CH₃ radicals, are given by (k in cm³ mol^-1 s^-1, E in kJ mol^-1, R = 0.008314 kJ K-1 mol^-1): logk₁ = (11.62 ± 0.08) ? (38.35 ± 0.68)/2.303RT logk₃ = (11.61 ± 0.05) ? (40.48 ± 0.46)/2.303RT Combination of the results for (1) with thermochemical data gives a calculated value of Logk_-1 = (11.8 -63.7/2.303RT for the rate constant of the reverse reaction. The results for CH₃+(CH₃)₂S are compared with all of the available data for hydrogen abstraction by free radicals from both sulphur-containing compounds, and molecules of the type (CH₃)_xM.