Radical addition to the vinyl C=C bond: quantum chemistry model of the reaction

摘要

Transition states of radical addition of C and O centered radicals to vinyl monomers were studied by MNDO UHF. Linear relationships between activation barriers and the enthalpies of addition were found in all reaction series. To expose factors of reactivity, calculated activation barriers were subjected to energy partitioning procedure, and an attempt was made to correlate those parts with monomolecular and bimolecular indexes of reactivity (such as deformation energies of monomers, CT-energies, etc). Shown that a satisfactory 2-parameter linear correlation can be built. Problems of PMO theory application to considered class of reactions were discussed and alternative method of calculation of CT-energies by using monomolecullar parameters proposed. Resulting scheme of reactivity applied to existing experimental data on reactivity in radical addition reactions, optimized parameters of large group of reagents tabulated.