Development of a model for predicting reaction rate constants of organic chemicals with ozone at different temperatures

To assess the persistence and fate of volatile organic compounds in the troposphere, the rate constants for the reaction with ozone (k(O3)) are needed. As k(O3) values are only available for hundreds of compounds, and experimental determination of k(O3) is costly and time-consuming, it is of importance to develop predictive models on k(O3). In this study, a total of 379 log k(O3) values at different temperatures were used to develop and validate a model for the prediction of k(O3), based on quantum chemical descriptors, Dragon descriptors and structural fragments. Molecular descriptors were screened by stepwise multiple linear regression, and the model was constructed by partial least-squares regression. The cross validation coefficient Q(CUM)(2) of the model is 0.836, and the external validation coefficient Q(ext)(2) is 0.811, indicating that the model has high robustness and good predictive performance. The most significant descriptor explaining log k(O3) is the BELm2 descriptor with connectivity information weighted atomic masses. k(O3) increases with increasing BELm2, and decreases with increasing ionization potential. The applicability domain of the proposed model was visualized by the Williams plot. The developed model can be used to predict k(O3) at different temperatures for a wide range of organic chemicals, including alkenes, cycloalkenes, haloalkenes, alkynes, oxygen-containing compounds, nitrogen-containing compounds (except primary amines) and aromatic compounds. (C) 2013 Elsevier Ltd. All rights reserved.