Computational study of the mechanisms for the reaction of O-2((3)Sigma(g))with aromatic radicals

The potential energy surface (PES) of the C6H5. + O-2((3)Sigma(g)) reaction has been studied using the B3LYP method. Several pathways were considered following the formation of the phenylperoxy (C6H5OO.) radical. At low tempe ratures (T < 432 K), the lowest energy pathway was found to go through a di oxiranyl radical. Scission of the O-O bond to form the phenoxy (C6H5O.) rad ical and O(P-3) atom is more favorable at higher temperatures. Transition s tate structures for several steps in the decomposition of the phenylperoxy radical are presented to augment the C6H5. + O-2 PES. For the heteroatomic aromatic hydrocarbon radicals, such as pyridine, furan, and thiophene, only minima on the PES are calculated in analogy with the intermediates obtaine d for the reaction of phenyl radical with O-2. One important result of the proposed decomposition mechanism is that subsequent rearrangements of the h eteroatomic aromatic hydrocarbon peroxy radicals (Ar-OO.) are likely to yie ld intermediates that are of atmospheric interest.