Theoretical study of reaction mechanism for CH2CHX(X==H, F, Cl) with ozone

In this work, we study the reaction mechanism of the CH2CHX(X=H, F, Cl) with ozone reactions, using ab initio MP2 method at 6-311 + + g** basis set level. The geometric configurations of reactants, intermediates, transition states, and products were optimized, and the energies were obtained at the QCISD(T) / 6-311 + + G** level. The transition states and intermediates of the reactions were verified by the vibrational analysis. The results show that the ozonolysis of ethylene and its derivatives is reasonable and believable along the Criegee mechanism. The results also show that the activation energies of the controlling steps along the fluoroethylene and chloroethylene with ozone reaction pathways were lower than that along the ethylene with ozone reaction pathway. That is to say, the derivatives of ethylene have the higher activity to react with ozone and deplete the ozone layer. (C) 2004 Wiley Periodicals, Inc.