2,2,2-Tri(aryl and alkyl)ethyl Xanthatesの熱分解反応

Abstract

Pyrolysis of 2, 2, 2-tri (aryl and alkyl) ethyl S-methyl xanthates (RCH2OCSSCH3) afforded olefins accompanying 1, 2-shift of the aryl group. To elucidate this reaction mechanism, kinetic studies were made. The first-order rate constants for pyrolysis of xanthates in a variety of solvents were determined. Judging from the solvent effect estimated on the basis of ET-value, the solvent effect on the reaction rate of VIII (R=CH3-(C6H5)2C) and IX (R=C6H5(CH3)2C) appears too small to attribute the reaction mechanism to the one via an ion pair which has been already proposed. However, in the case of V (R=(C6H5)3C), the solvent effect, Hammatt parameter, ρ=+1.35, and also kinetic isotope effect, kH/kD=1.21, indicate that the reaction may have an ionic character.