Reactions of HOCl + HCl + nH2O and HOCl + HBr + nH2O

Abstract

We present reaction rates for the conversion of HOCl by HCl and HBr into Cl2 and BrCl, respectively, supported by n = 0, 1, 2, and 3 water molecules. The reaction rates were determined using canonical, variational transition-state theory including tunneling corrections for motion along the reaction coordinate. Whereas the potential energy surface between reactants, transition state, and products was generated with the hybrid density functional theory B3LYP/6-31+G(d), the reaction barrier was determined with the recently developed MPW1K/6-31+G(d,p) hybrid density functional theory, a method that was especially designed to evaluate reaction barriers. Within the used density functional theory framework, the reaction rates of HOCl with HBr are several orders of magnitude higher than the reaction rates with HCl. On ice-like clusters, both types of reactions proceed faster by several orders of magnitude than in the gas phase or when supported by only one or two water molecules. Knowledge of the reaction rates i...