A quantitative structure-property relationship (QSPR) study on the kinetic parameters of the gas-phase homolysis for 287 different C-X bonds was carried out using the CODESSA program. Successful five-, four-, and three-parameter models were developed for the prediction of the log k (891 K) values. These respective multiple linear correlations were obtained by automatic selection of appropriate molecular descriptors for reagents and products, using only the information encoded in the chemical structure.

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The abstraction of hydrogen by general radicals has a wide role in environmental and also in technological processes because it results in reactive free radicals that play a vital role in atmospheric chemistry and also in biochemical processes. In addition to experimental studies, the theoretical modelling of this elementary reaction has been important for understanding and predicting respective rate constants. In this paper, molecular descriptors in the context of a QSAR approach are used to codify the relationship between molecular structure and rate constants. Unique experimental data is collected from the literature for the reaction R(i)• + R(j)H → R(i)H + R(j)•, where R(i)• = H• and R(j)• are diverse radicals. The four-parameter QSAR model (n = 34, r(2) = 0.81, r(2)(CV) = 0.74, r(2)(scr) = 0.12, s(2) = 0.19) is presented for the bimolecular rate constants, accompanied with model diagnostics and analysis of descriptors in the model.