Quantitative structure-activity relationship for the ozonation of phenols

Ozonation rates of twenty-three phenols were measured. Their Quantitative Structure Activity Relationship (QSAR) models were developed by the method of genetic algorithm (GA) combining with Partial Least Squares (PLS) and Artificial Neural Networks (ANN), respectively. The degradation rate of phenols can be described by the pseudo-first-order reaction rate model. The capacity of releasing or taking electron of the substitution group in the ring has obvious effect on the ozonation rate of the phenols. The QSAR model developed by GA-PLS is lgk=3.439-0.206lgP (the logarithm of octanol-water partition coefficients)+0.122×pKa (dissociation constant)-0.3464χpc (four order path/cluster molecular connectivity index)-0.0236qC- (the maximum negative charge of carbon atom). The QSAR model developed by GA-ANN model has the descriptors of lgP, 4χpc, pKa and α (molecular average polarizability). Based on leave-one-out cross validation, the QSAR model constructed by GA-ANN has better robustness than that by GA-PLS. The study of QSAR shows that the ozonation rate of phenols has a close relationship with electron cloud distribution and the properties of substitution groups in benzene ring. It also shows that the solvent effect of water obviously influences the ozonation rate of phenols.