A novel type of free radical reactions: isomerization of a radical with concerted fragmentation

A comparison of experimental data and results of the rate constant calculations by the method of intersecting parabolas (MIP) showed that abstraction of H atom by a peroxyl radical from the C_α-H bond in hydroperoxide is accompanied by concerted fragmentation of the molecule. The complicated character of the elementary event is due to high exothermicity of the reaction. The kinetic parameters of isomerization with fragmentation of peroxyalkyl, peroxyalkoxyl, and peroxyperoxyl radicals were calculated within the framework of the MIP method. The enthalpies, activation energies, and rate constants for a series of isomerization reactions of peroxyl radicals with concerted fragmentation were also obtained from the MIP calculations. Factors influencing these reactions are analyzed.