Substituent and Ring-Number Effects on the Kinetics of PAH + OH Reactions: A QSAR–DOE Approach with Tunneling Corrections

The reactions of hydrogen transfer by hydroxyl radicals involving polycyclic aromatic hydrocarbons (PAH) are important, because these compounds contribute to environmental pollution and negatively affect human health. Hydroxyl radicals play a key role in atmospheric processes. This study analyzed the influence of the substituent and the number of aromatic rings in the compound on the kinetics of the hydrogen-transfer reaction. This work proposes for the first time a quantitative structure-activity relationship-based statistical framework combining design of experiments and tunneling corrections to predict PAH + ·OH kinetics. The main objective of this research was to identify which molecular features and substituent effects most strongly govern tunneling and reactivity, thereby enabling the rational prediction of PAH behavior in atmospheric and combustion environments. For this purpose, a quantitative structure-activity relationship model was developed using 22 descriptors, and their relationship with the kinetic parameters of the reaction was determined using statistical tools such as design of experiments and partial least squares.