New functional form to describe the temperature dependence of liquid phase reaction rates

Abstract

Chemical reactions in subcritical or near-critical solvents hold significant promise for numerous industrial and environmental applications. The Arrhenius equation is typically used to describe the temperature dependence of reaction rates, yet it often falls short in capturing the behavior of liquid phase reaction rates near critical points of solvents. To address this limitation, we propose a novel functional form that can correctly describe the temperature trends of liquid phase rate constants from room temperature up to the critical temperature of a solvent. The proposed scheme uses four kinetic parameters with physical implications, two accounting for the gas phase contribution and the other two accounting for the solvation effect on reactions. The new functional form can accurately reproduce the anomalous temperature dependence of liquid phase rate constants in subcritical and near-critical regimes that the Arrhenius equation fails to capture. Furthermore, our preliminary finding suggests that the kinetic parameters associated with the solvation terms can be computed with ab initio approaches to estimate the temperature-dependent rate constants of liquid phase reactions based on their corresponding rate constants in gas phase. The proposed functional form provides an alternative approach to describe the non-Arrhenius behavior of diverse liquid phase reactions across a wide range of temperature.