Using ab initio MP2 method, at basis level of 6-31G(d), the transition states of intramolecular hydrogen transfer to O-atom of peroxy sec-butyl radical were studied systematically. Three transfer transition states, including four-, five- and six-membered ring structures, were obtained, and confirmed by frequency analysis. Based on these results, the change of the main chemical bonds in these H-atom 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.

Key words: peroxy sec-butyl radical, transition state, reaction mechanism