ENERGETICS, KINETICS, AND PRODUCT DISTRIBUTIONS OF THE REACTIONS OF OZONE WITH ETHENE AND 2,3-DIMETHYL-2-BUTENE

A detailed kinetic analysis of the complex reaction systems arising fr om the ozonolysis of C2H4 and (CH3)(2)C=C(CH3)(2) (TME), respectively, is carried out, using master equations and statistical rate theory. T he thermochemical as well as the molecular data required are obtained from CCSD(T)/TZ2P and B3LYP/DZP calculations. It is shown that the pri mary ozonides are not collisionally stabilized under atmospheric condi tions. In the reaction sequence for O-3 + TME, the same is true for CH 2=C(CH3)OOH formed from (CH3)(2)COO, which completely dissociates to g ive OH radicals. However, in this system, a pressure dependence is pre dicted for the relative branching fractions of the reactions of the Cr iegee intermediate. Under atmospheric conditions, for both examples, t he product yields obtained are in reasonable agreement with experiment al results.