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Abstract

We have studied the reaction mechanism for both the NO3- and OH-initiated atmospheric oxidation of three cresol isomers, p-cresol, m-cresol, and o-cresol, in the presence of high NO2 concentration. We have focused on the reaction mechanism leading to ring-retaining products. Geometries of the reactants, intermediates, transition states, and products have been optimized at DFT-BB1K level of theory with the 6-311+G(d,p) basis set. The single point energy calculations have been carried out at the CCSD(T) level of theory with the cc-pVDZ basis set. Several energetically favorable reaction pathways were revealed for the first time. In the NO3-initiated reaction, the NO3 radical is added to the carbon atom with the OH group, then the NO2 radical is added to one of the neighboring carbon atoms, and finally HNO3 is eliminated, leading to a methylnitrophenol isomer. In the OH-initiated reaction, the OH radical is added to the carbon atom adjacent to the carbon atom with the OH group; second, the NO2 radical is added to the carbon atom with the original OH group, and, finally, HNO2 is eliminated, leading to a dihydroxymethylbenzene isomer. The calculated results were compared with available experimental observations. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 165–178, 2012