Kinetic modeling of the benzyl + HO2 reaction

Document Type

Article

Publication Date

1-1-2009

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 mol-1 (251 Mmol-1) 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 mol-1 (219.7 kJ mol-1) at the G3B3 level of theory, in relative agreement with other recent determinations of this value. © 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Identifier

61849176918 (Scopus)

Publication Title

Proceedings of the Combustion Institute

External Full Text Location

https://doi.org/10.1016/j.proci.2008.05.040

ISSN

15407489

First Page

287

Last Page

294

Issue

1

Volume

32 I

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