REACTIVITY IN METHYL TRANSFER-REACTIONS .3. EQUILIBRIA AND RATES IN TRANSFERS BETWEEN SUBSTITUTED THIOPHENOXIDES

Methyl phenyl sulfide methylates substituted thiophenoxide ions reversibly at elevated temperatures. Using a GC analysis, the rates and equilibria for five substituted cases have been measured at several temperatures in the range ca. 110-210°C, and the identity reaction with unsubstituted thiophenoxide has also been measured using a 35S tracer. The Hammett ρ for the forward reaction is close to half that for the equilibrium, suggesting a transition state with a half-transferred methyl group. This represents the first measurement of substituent effect on both rate and equilibrium for a simple organic substitution reaction. © 1979, American Chemical Society. All rights reserved.