Prediction of reactive sites in the hydroxyl radical-mediated oxidation pathway of phenol by using quantum chemical calculation

Abstract

 In this study, we carried out quantum chemical calculations using Gaussian for the oxidative decomposition reaction of phenol by OH•, and investigated the reaction sites of the oxidizing agent in radical reaction and electrophilic reaction. As a result of calculating and comparing the Fukui index at different theoretical levels of HF, B3LYP and M062X, the calculation accuracy of reaction point was found to be high in the order of B3LYP > M062X > HF for the OH• addition to phenol. In addition, the estimation of the reaction point by Fukui index was consistent with the experimental observation for the reactions of intermediate products. In addition to the prediction of reactive sites, we also performed the estimation of reaction rate constants by optimizing the reaction pathway (transition state structure). In this study, we focused on the initial oxidation process in which phenol is converted to catechol (or hydroquinone), but the same method to the other organic trace contaminants can be applicable to theoretically estimate the reaction sites during the oxidative degradation.