Kinetic study of the reaction of chlorine atoms with dichloromethane and D-dichloromethane in the gas phase

Abstract

The kinetics of the gas-phase reactions of chlorine atoms with dichloromethane (CH2Cl2) and D-dichloromethane (CD2Cl2) was studied using the relative rate method with Cl+CH3Br as the reference reaction. The rate constants for H-abstraction from CH2Cl2 (kH) and D-abstraction from CD2Cl2 (kD) were measured in the temperature range of 298–527K and at a total pressure of 100Torr using N2 as a diluent. The temperature dependencies of the rate constants (with the 2σ error limits) are described by the expressions: kH=(8.69±0.82)×10−12×exp(−955±20/T) and kD=(6.98±0.91)×10−12×exp(−1285±25/T)cm3molecule−1s−1. The kinetic isotope effect, described by the ratio kH/kD, was found of 3.8±0.2 at room temperature.