Ab initio and direct dynamics study on the hydrogen abstraction reaction C2H3 + CH3CHO

The mechanism for the hydrogen abstraction reaction C2H3 + CH3CHO has been investigated by the CCSD (T)/cc-pVTZ method based on the geometries of stationary points optimized at the B3LYP/6-311++G(d,p) level of theory. Two abstraction channels have been identified for the production of C2H4 + CH2CHO and C2H4 + CH3CO. The potential barrier heights of the corresponding transition states TSR/P1 and TSR/P2 were predicted to be 9.47 and 5.95 kcal/mol at the CCSD(T)//B3LYP level of theory, respectively. The rate constants and branching ratios for the two H-abstraction channels were calculated using conventional transition state theory with Eckart tunneling correction at the temperature range 300-2500 K. The predicted rate constants have been compared with available literature data. Both the forward and reverse rate constants have positive temperature dependence and the tunneling effect is only important at low temperatures. The branching ratio calculation shows that the channel producing C2H4 + CH3CO remains predominant throughout the entire studied temperature range. (C) 2015 Elsevier B.V. All rights reserved.