Kinetics and anomalous temperature dependence of the kinetic isotope effect of reactions of cycloalkanes C5H10, C6H12 and C6D12 with OH radicals in aqueous solutions

Abstract

The temperature effect of the c-C6H12/c-C6D12 kinetic isotope effect (KIE) and the rate constant ratio c-C6H12/c-C5D10 (k6/k5) in the reactions of cycloalkanes with OH radicals in aqueous solution and in the gas phase has opposite signs. Values for the KIE and k6/k5 decrease with increasing temperature from 5 to 55 °C in the gas phase, while these values increase in solution. We propose that this phenomenon is a consequence of a solvent cage effect.