Reaction branching as a mechanistic alternative to tunneling in explaining anomalous temperature‐dependencies of kinetic isotope effects

The temperature‐dependence of the kinetic isotope effects for branched reactions proceeding via a common intermediate has been simulated by calculations. It is shown that, under certain conditions, anomalously small isotope effects on the Arrhenius preexponential factors, as well as unusually large observed isotope effects, may originate from the branching.