New empirical models of radical abstraction reactions

Two physical models of radical abstraction reactions are described: the model of intersecting parabolas and the model of intersecting Morse curves. A systematic account is given of the results of the analysis of a large set of experimental data (rate constants and activation energies) for a wide variety of radical reactions. It is shown that the activation energies for such reactions depend on their enthalpies, on the force constants of the reacting bonds, the strength, length, and polarity of the X–Y bond in the X^• +HY reaction, and also the presence in the reactants of one or several polar groups, π-bonds, and bulky groups adjoining the reaction centre. Solvation plays an important role in processes involving polar reactants. Both methods are compared as instruments for the calculation of the activation energy and bond strengths. The limits of applicability of the methods are examined. The bibliography includes 93 references.