Quantum chemical study on the reaction mechanism for the C_2H_3 radical with O_2(a'Δg)

摘要

Ab initio UMP2 (full) method has been used to study the reaction mechanism of C_2H_3 radical with O_2(a'Δ_g) on the potential energy surface and energies have been calculated at Gaussian-3-G3) level. In this paper, we have optimized the geometry configuration of reactants, products, intermediates and transition states. We have also calculated the activation energies of elementary reactions along the reaction pathways. The results suggest that the reaction mechanism of this reaction involves the formation of three-, four- and five-membered rings and produces different reaction resultants, respectively. According to the calculated activation energies, the CH_2O and CHO are the main products. At the same time, the C_2H_3 + O_2(a~1Δ_g) reaction may form CH_3 + CO_2, CH_2CO_2 + H, C_2H_2 + O_2H, C_2H_3O + O and COHCOH + H. The probabilities gradually decrease. The reaction heat gained in our study along the four pathways (C_2H_3 + O_2(a~1Δ_g) → CH_2O + CHO, C_2H_3 + O_2(a~1Δ_g) → CH_3 + CO_2, C_2H_3 + O_2(a~1Δ_g) → C_2H_2 + O_2H and C_2H_3 + O_2(a~1Δ_g) → COHCOH + H) are in good agreement with those of experiments.