Thermochemical and kinetic study of the recombination and dissociation reactions R + Br (+M) ⇄ RBr (+M) (R = CH3, CH2Cl, CHCl2, CHClBr, CH2Br and CHBr2)

Abstract

The kinetics of the recombination and thermal dissociation reactions R + Br (+ M) ⇄ RBr (+ M) with R = CH3, CH2Cl, CHCl2, CHClBr, CH2Br and CHBr2 were theoretically studied over wide temperature and pressure ranges employing unimolecular reaction rate theory combined with potential energy surfaces derived at the ab initio G4//B3LYP/6-311++G(3df,3pd) level. The resulting rate constants are in good agreement with the available experimental information. Rate constant values for the reactions of CH2Cl, CHCl2, CHClBr, CH2Br and CHBr2 radicals with Br atoms are for a first time reported. Standard enthalpies of formation for the above and related molecules have been calculated.