Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, Shaanxi 710062, China.
J Phys Chem A. 2012 May 10;116(18):4610-20. doi: 10.1021/jp301308u. Epub 2012 Apr 26.
Oxygen-to-oxygen coupling, direct H-abstraction and oxygen-to-(α)carbon nucleophilic substitution processes have been investigated for both the singlet and triplet self-reaction of C(2)H(5)O(2) 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 C(2)H(5)O + HO(2) + CH(3)CHO (P5) generated in channel R5. Beginning from the radical products of P5 (C(2)H(5)O, HO(2)) and reactant (C(2)H(5)O(2)), five secondary reactions HO(2) + HO(2) (a), HO(2) + C(2)H(5)O (b), C(2)H(5)O + C(2)H(5)O (c), HO(2) + C(2)H(5)O(2) (d), and C(2)H(5)O + C(2)H(5)O(2) (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, CH(3)CHO, C(2)H(5)OH, C(2)H(5)OOH, H(2)O(2), and (3)O(2) are predicted to be major, whereas C(2)H(5)OOC(2)H(5) should be in minor amount.
氧-氧偶联、直接 H 提取和氧-（α）碳亲核取代过程已在 CCSD(T)/cc-pVDZ//B3LYP/6-311G(2d,2p)水平上对 C(2)H(5)O(2)自由基的单重态和三重态自反应进行了研究，以评估反应机制、可能的产物和速率常数。计算结果表明，该反应主要通过单重态氧-氧偶联机制发生，形成入口四氧化物中间体，最主要的产物是通过通道 R5 生成的 C(2)H(5)O + HO(2) + CH(3)CHO（P5）。从 P5（C(2)H(5)O、HO(2)）和反应物（C(2)H(5)O(2)）的自由基产物出发，HO(2) + HO(2)（a）、HO(2) + C(2)H(5)O（b）、C(2)H(5)O + C(2)H(5)O（c）、HO(2) + C(2)H(5)O(2)（d）和 C(2)H(5)O + C(2)H(5)O(2)（e）主要在三重态势能面上进行。在这些反应中，（a）、（b）和（d）由于较低的势垒高度而具有动力学优势。通道 R5 在 200 到 295 K 之间的计算速率常数几乎与温度无关，这与实验报告一致。对于最终产物分布，预测 CH(3)CHO、C(2)H(5)OH、C(2)H(5)OOH、H(2)O(2)和（3）O(2)为主要产物，而 C(2)H(5)OOC(2)H(5)应为次要产物。
