Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6679416 | Proceedings of the Combustion Institute | 2009 | 8 Pages |
Abstract
Benzyl is a resonantly stabilized radical that commonly occurs as an intermediate in the combustion of aromatic compounds. The bimolecular reaction of benzyl with HO2 is important in the oxidation of toluene, especially at low to moderate temperatures, where unimolecular decomposition of the benzyl radical is slow. We show that the addition of HO2 to the methylene site in benzyl produces a vibrationally excited benzylhydroperoxide adduct, with over 60 kcal molâ1 (251 kJ molâ1) of excess energy above the ground state. RRKM simulations are performed on the benzyl + HO2 reaction, using thermochemical and kinetic parameters obtained from ab initio calculations, with variational transition state theory (VTST) for treatment of barrierless radical + radical reaction kinetics. Our results reveal that the benzyl + HO2 reaction proceeds predominantly to the benzoxyl radical + OH at temperatures of around 800 K and above, with the production of stabilized benzylhydroperoxide molecules dominating at lower temperatures. The heat of formation of the benzyl radical is calculated as 52.5 kcal molâ1 (219.7 kJ molâ1) at the G3B3 level of theory, in relative agreement with other recent determinations of this value.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Chemical Engineering (General)
Authors
Gabriel da Silva, Joseph W. Bozzelli,