Methyl and trifluoromethyl radical reactions with methyl fluoroformate and methyl trifluoroacetate : fluorine substituent effects

Abstract

The influence of fluorinated substituents on the reactivity of methoxyl groups in methyl formate and methyl acetate has been studied. Rate constants and Arrhenius parameters for hydrogen atom abstraction by CH₃ and CF₃ radicals from methyl fluoroformate and methyl trifluoroacetate are [graphic omitted] In general, fluorinated acyl substituents activate methoxyl sites to both CH₃ and CF₃ radical attack. Activation is directly caused by reduction of activation energies which is off-set in some cases by anomalously low A-factors. The latter are explained in terms of intramolecular hydrogen bonding in the fluoro-esters.