A two-center model of the concerted molecular decomposition of unsaturated compounds

A semiempirical model of the concerted decomposition of unsaturated compounds (olefins, alcohols, acids, and ethers) and aliphatic esters into two molecules is suggested. The model considers the decomposition reaction as a single-step transfer of the hydrogen atom in one reaction center and the dissociation of a C-C or C-O bond in the other accompanied by a shift of π electrons in the cyclic six-membered transition state. Each elementary event in such a concerted reaction is characterized by its own activation energy, E _abs for the transfer of H, E _>d for bond dissociation, and E _π for the shift of π bonds. The E _abs and E _d activation energies were calculated by the method of intersecting parabolas. The spectrum of activation energies (sets of the E _abs, E _d , and E _π values) for each of 45 decomposition reactions was calculated with the use of experimental data. The contribution of enthalpy to the activation energy of each event was estimated.