| Summary: | 碩士 === 中國文化大學 === 化學系應用化學碩士班 === 103 === The olefins were synthesis by deoxygenation of ethylene oxide is an important method. Various reagents have been employed for this purpose in the last several decades.In principle, the reaction pathways depended on the nature of the reagent and substrate. However, the deoxygenation of oxiranes with carbenes has been investigations widely.In our study,high level ab initio calculations have been performed to study the mechanisms and Kinetics of the CR2 (where R=H, F, Cl, Br, CH3, NH2) reacted with ethylene oxide. The reactant, intermediates, transition states, and products have been optimized at the B3LYP/6-311++G(3df,2p) level and their corresponding single-point energies also calculated with B3LYP/6-311++G(3df,2p) level. From the calculated potentail energy surface, we have predicted that H2C-OC2H4 complex (IM) formed via passing transition state (TS1), and the deoxygenation process occurs to form ethylene. The substituent group would be effect the reaction barrier and the rate-determing step (RDS). Futermore, we investigated the rate constant by transitionstate thoery and microcanonical Rice-Ramsperger-Kassel-Marcus RRKM with CHEMRATE program. The predicted total rate constant, ktotal, at the 760 torr Ar pressure can be represented by the equations: k=3.07×1022 T3.01exp(-11.19 kcal/mol-1/RT) and k=4.86×1022T3.07exp(-20.62 kcal/mol-1/RT) at T=298-3000Kfor CF2 and C(CH3)2, respectively. In addition, the rate constants for key individual product channels are provided in a table for different temperature and pressure conditions.
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