Observation and interpretation of an apparent inverse secondary isotope effect on the electron impact-induced loss of a methyl radical from methyl isobutyrate

Abstract

The loss of CD₃· from the molecular ion of methyl [²H₃]isobutyrate (4) is 2·2 times faster than the loss of CH₃· at 70 eV; the unusual direction and magnitude of the isotope effect are explained by a two-step mechanism, in which a rate-determining hydrogen or deuterium atom transfer precedes the loss of CD₃· or CH₃·.