Rate constants for reactions of ethylbenzene with hydroperoxyl radical and oxygen molecule

A central step in the low-temperature oxidation of hydrocarbons is the abstraction of H by hydroperoxyl radical (H0₂). In this study, reaction rate constants are derived for H abstraction by H0₂ from the three distinct locations of H in ethylbenzene (primary, secondary and aromatic H, with H on the ortho carbon taken as an example of unreactive aromatic H) as well as for the addition of H at the four possible sites. Rate constants are provided in the simple Arrhenius form. The dominant channel at all temperatures is found to be H abstraction from the secondary C-H bonds of the ethyl chain, whereas abstractions from the primary C-H bonds also contribute significantly at higher temperatures. Reasonable agreement was obtained with the limited literature data. Addition at the four sites of the aromatic ring and abstraction of one of the C-H aromatic bonds are rather unimportant for all temperatures. The results presented herein should be useful in modeling the lower temperature oxidation of alkylbenzenes.