Theoretical studies on the mechanism and kinetic for CH3CH2O + HO2 and CH3CHOH + HO2 reactions

摘要

The singlet and triplet reaction mechanisms and rate constants for CH3CH2O + HO2 and CH3CHOH + HO2 reactions were investigated by employing the high-level quantum chemical calculations with CBS-QB3 theoretical method and conventional transition state theory with the Wigner tunneling correction. For CH3CH2O + HO2 reaction, four direct hydrogen abstraction processes and five addition-elimination channels were identified, while two direct hydrogen abstraction routes and nine addition-elimination channels were found in CH3CHOH + HO2 reaction. The results show that the triplet addition-elimination channels of CH3CH2OH + O-3(2) and CH3COOH + H2O are, respectively, the most favorable channels for CH3CH2O + HO2 and CH3CHOH + HO2 reactions. This is because that they have lower energy barrier and their contribution to the overall rate constants are, respectively, 57% to 86% and 44% to 80%. This work may lead to a better understanding of the mechanism and the kinetic for the singlet and triplet reactions of CH3CH2O + HO2 and CH3CHOH + HO2.