Theoretical Study on the Mechanism and Kinetics for the Self-Reaction of C2H5O2 Radicals

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• 作者：Pei Zhang ; Wenliang Wang ; Tianlei Zhang ; Long Chen ; Yongmei Du ; Chunying Li ; Jian L眉
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：May 10, 2012
• 年：2012
• 卷：116
• 期：18
• 页码：4610-4620
• 全文大小：712K
• 年卷期：v.116,no.18(May 10, 2012)
• ISSN：1520-5215

文摘

Oxygen-to-oxygen coupling, direct H-abstraction and oxygen-to-(伪)carbon nucleophilic substitution processes have been investigated for both the singlet and triplet self-reaction of C₂H₅O₂ radicals at the CCSD(T)/cc-pVDZ//B3LYP/6-311G(2d,2p) level to evaluate the reaction mechanisms, possible products and rate constants. The calculated results show that the title reaction mainly occurs through the singlet oxygen-to-oxygen coupling mechanism with the formation of entrance tetroxide intermediates, and the most dominant product is C₂H₅O + HO₂ + CH₃CHO (P5) generated in channel R5. Beginning from the radical products of P5 (C₂H₅O, HO₂) and reactant (C₂H₅O₂), five secondary reactions HO₂ + HO₂ (a), HO₂ + C₂H₅O (b), C₂H₅O + C₂H₅O (c), HO₂ + C₂H₅O₂ (d), and C₂H₅O + C₂H₅O₂ (e) mainly proceed on the triplet potential energy surface. Among these reactions, (a), (b), and (d) are kinetically favorable because of lower barrier heights. The calculated rate constants of channel R5 between 200 and 295 K are almost independent of the temperature, which is in agreement with the experimental report. With regard to the final products distribution, CH₃CHO, C₂H₅OH, C₂H₅OOH, H₂O₂, and ³O₂ are predicted to be major, whereas C₂H₅OOC₂H₅ should be in minor amount.