Quantum chemical study on the reaction mechanism for the C2H3 radical with O2(a1Δg)

Ab initio UMP2 (full) method has been used to study the reaction mechanism Of C2H3 radical with O-2(a(1)Delta(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 CH2O and CHO are the main products. At the same time, the C2H3 + O-2(a(1)Delta(g)) reaction may form CH3 + CO2, CH2CO2 + H, C2H2 + O2H, C2H3O + O and COHCOH + H. The probabilities gradually decrease. The reaction heat gained in our study along the four pathways (C2H3 + O-2(a(1)Delta(g)) --> CH2O + CHO, C2H3 + O-2(a(1)Delta(g)) --> CH3 + CO2, C2H3 + O-2(a(1)Delta(g)) --> C2H2 + O2H and C2H3 + O-2(a(1)Delta(g)) --> COHCOH + H) are in good agreement with those of experiments. (C) 2002 Elsevier Science B.V. All rights reserved.