Enthalpies of formation of alkyl radicals

The data on the enthalpies of formation (ΔfH°) for alkyl radicals (R·) were examined. Taking into account the values of enthalpies of C-X bond dissociation (X = H, Cl) in alkanes and their monochlorosubstituted derivatives, ΔfH° of fifteen R· were determined for the first time. The values of ΔfH°(R·) were analyzed on the basis of quantitative structure—property relationships in terms of the additive groups model with the new extended set of fragments introduced according to the quantum theory “Atoms in Molecule.” The parameters for prediction of ΔfH° of radicals for of the considered class were determined. The renewed and extended by more than 25% database on ΔfH° of alkyl radicals was proposed.