Correlation of activation energies of radical–molecule metathesis reactions with enthalpic,polar, and steric parameters

It is shown that the activation energies E oF chlorine atom abstraction by cyclohexyl radicals and hydrogen atom abstraction by Cl atoms from polychloroalkanes can be correlated with the bond dissociation energies D and the Taft polar and steric substituent constants σ* and E_s by the expression: where ΔE and ΔD represent the differences between the E and D values of a given substrate and those of a reference compound (CH₃ substituted substrate) and α, ρ, and δ are the corresponding correlation coefficients. The use of this expression allows quantitative evaluation of the relative contribution of the various factors affecting the activation energies of these reactions and estimation of related thermochemical data.