Predicting rate constants of hydroxyl radical reactions with alkenes and aromatics

The radicals obtained from the additions of alkenes with the hydroxyl radical (•OH) and from the H-atom abstraction of aromatics initiated by the OH radical were, respectively, used to calculate quantum chemical descriptors for quantitative structure-activity relationship (QSAR) models for the rate constants (kOH) of the reactions of alkenes and aromatics with the OH radical in the troposphere. Quantum chemical descriptors used as the inputs for the support vector machine (SVM) models were calculated with the unrestricted hybrid density functional theory (DFT), at the UB3LYP level of theory with 6-31G(d) basis set. The average root-mean-square errors (RMSE) for 70 alkenes and 80 aromatics are 0.101 and 0.236 log units, respectively, which show the SVM models in this paper are accuracy and acceptable. To develop QSAR models for kOH, calculating quantum chemical descriptors from the reaction radicals of alkenes and from aromatic radicals formed by the H-atom abstraction is feasible.