Of Ch <sub> 3 </ Sub> O <sub> 2 </ Sub> Density Functional Theory Study Of Gas Phase Reactions Of Free Radicals,

Recently, the radical reactions related to interstellar and combustion chemistries studies on the formation, structure, thermal stability and reactivity of radicals have been the essential parts of chemistry. While the methyl peroxy radical, CH3O2, is an important intermediate in combustion processes and in the reaction of methane in the troposphere and stratosphere, resulting in the production or destruction of ozone. Therefore the studies of CH3O2 will provide the important theoretical foundation for the ozonosphere and atmosphere protecting.In this thesis, quantum chemical investigations on the potential energy surfaces of some radical reactions related to CH3O2, including the CH3O2+NO and CH3O2+OCl reactions, that are important in interstellar and combustion chemistries have been carried out. Important information of potential energy surfaces such as structures and stability of intermediate isomers, possible reaction channels and reaction mechanisms are obtained from these theoretical investigations. The results presented in this thesis may be very helpful for understanding the related radical reactions in interstellar and combustion chemistries, and may provide some elemental theoretical basis for further experiments on radical reactions. The main results are follows:1. The mechanism of the CHa3O2+NO - CH3O+NO2 reaction in gas phase has been studied at QCISD(T)/6-311G**//B3LYP/6-31G* level by using density functional theory. The possible channel and the potential energy surfaces have been obtained. The results showed that the whole reaction comes through many courses, including 6 intermediates and 4 transition states, and it is an endothermic reaction with 50.93kJ/mol endothermic value calculated.2. The mechanism of the CH3O2+ClO reaction in gas phase has been studied at CCSD(T)/6-311++G**//B3LYP/6-311G* level by using density functional theory. The possible channel leading to the lowest-lying productP1 CH3OC1+O2 and the potential energy surface have obtained. The results showed that the whole reaction comes through many courses, and P1 (1CH3OC1+3O2) and P4 (1CH2O+1HOOC1) are two lowest products. Among the reaction paths proposed, channels la: R -- IM1 -- TS1/3 -IM3-P1, 4a: R-IMl-TSl/P4-P4and4b: R-IM2-TS2/P4 -P4 are the probable paths.