Thermodynamic properties of the species resulting from the phenyl radical with O2 reaction system

Phenyl radicals are formed in combustion and oxidation systems by abstraction of the phenyl-hydrogen from benzene or aromatics by active radical species and by oxidation and thermal reactions of the benzylic carbon on alkyl-substituted aromatics. The reaction of phenyl with 02 leads to chain-branching reactions and a number of unsaturated oxygenated hydrocarbon intermediates that may need to be included in detailed combustion models. Thermochemical parameters and structures on important species resulting from the phenyl radical + O-2 association and reaction are reported in this study. Enthalpies, Delta(f) H-298(0) of a series of stable molecules, radicals, and transition state structures are calculated using ab initio (G3MP2B3 and G3) and density functional (DFT, B3LYP/6-31 lg(d,p) calculations, group additivity (GA), and literature data. The ab initio and density functional calculations are combined with isodesmic reaction analysis, whenever possible, to improve the accuracy of the enthalpy values. Entropies, S-f298(0), and heat capacities, C-pf (298) (T), are calculated using density functional calculations, group additivity, and literature data. (c) 2008 Wiley Periodicals, Inc.