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

Abstract

Hydrogen atom abstraction from (CH₃)₂S by CF₃ radicals has been studied in the temperature range 79-167º: (1) CF₃ + CH₃SCH₃ ←→ CF₃H + CH₃SCH₂ (-1) The rate constant, based on Ayscough's value of 10^13.36cm^S mol^-l s^-l for the recombination of CF₃ radicals, is given by (k₁ in cm³ mol^-1 s^-l, E in J mol^-l): Logk₁ = (12.05 ± 0.02)-(28710 ± 130)/2.303RT Combination of these results with thermochemical data gives a calculated value of log k_-1 = 12.2 - 62600/2.303RT for the rate constant of the reverse reaction. ΔHºf(CH₃SCH₂) and Sº(CH₃SCH₂) are estimated to be 155.6 kJ mol^-l and 290 J K^-l mol^-1 respectively.