过氧仲丁基自由基内氢转移及解离机理的理论计算研究

Theoretic Study of Intra-molecular Hydrogen Atom Transfer and Decomposition Mechanism for Peroxy sec-Butyl Radical

采用量子化学从头算MP2方法在6-31G(d)基组水平上系统地研究了过氧仲丁基自由基内三个不同碳位上的氢原子向O—O基的端O转移的过渡态结构,讨论了这些氢转移反应过程中相关化学键的变化,并在此基础上进一步研究了氢转移产物解离的过渡态结构.结果表明具有四元环、五元环、六元环结构的三个氢转移过渡态对应的氢转移反应位垒分别是195.86,176.43,122.49kJ-mol-1;相应的氢转移产物进一步解离的反应位垒分别是3.53,126.23,154.2kJ-mol-1,对应的最终产物分别为HO自由基和丁酮,HO2自由基和丁烯,HOOCHCH3和乙烯.

Using ab initio MP2 method, at basis level of 6-31G（d）, the transition states of intramolecular hydrogen transfer to O-atom of peroxy secbutyl radical were studied systematically.Three transfer transition states, including four-, five-and six-membered ring structures, were obtained, and confirmed by fre-quency analysis.Based on these results, the change of the main chemical bonds in these Hatom transfer reaction processes and the further decomposition reactions of H-transfer products have been discussed.The results show that the H-transfer reaction potential barriers corresponding to the four-, five-, six-membered ring-like transition states are 195.86, 176.43, 122.49 kJ-mol-1, respectively, and corresponding decomposition reaction potential barriers of the H transfer products are 3.53, 126.23, 154.20 kJ-mol-1;and final products are HO and butanone, HO2 and butylene, HOOCHCH3 and ethylene.