Rate constant estimation for C₁ to C₄ alkyl and alkoxyl radical decomposition

Abstract

Rate coefficients for alkyl and alkoxy radical decomposition are important in combustion, biological, and atmospheric processes. In this paper, rate constant expressions for C 1 C 4 alkyl and alkoxy radicals decomposition via β-scission are recommended based on the reverse, exothermic reaction, the addition of a hydrogen atom or an alkyl radical to an olefin or carbonyl species with the decomposition reaction calculated using microscopic reversibility. The rate expressions have been estimated based on a wide-range study of available experimental data. Rate coefficients for hydrogen atom and alkyl radical addition to an olefin show a strong temperature curvature. In addition, it is found that there is a correlation between the activation energy for addition and (i) the type of atom undergoing addition and (ii) whether this radical adds to the internal or terminal carbon atom of the olefin. Rate coefficients for alkoxy radical decomposition show a strong correlation to the ionization potential of the alkyl radical leaving group and on the enthalpy of reaction. It is shown that the activation energy for alkyl radical addition to a carbonyl species can be estimated as a function of the alkyl radical ionization potential and enthalpy of reaction.

Kinetic modeling of gasoline surrogate components and mixtures under engine conditions

“…The decomposition rates of the alkyl radicals and alkoxy radicals were also updated on the basis of the rules reported in [7].…”

“…The decomposition rates were derived by [7], while the thermal properties of the radicals were evaluated using the THERM program developed by Ritter and Bozzelli [3]. The abstraction reactions of H atoms from iso-octane by HO 2 and CH 3 O 2 were updated according the same rules used for the linear alkanes.…”

Experimental and kinetic modeling study of 1-hexanol combustion in an opposed-flow diffusion flame

“…The A-factor proposed in Togbé et al [12] for reaction PC4H9 + M ↔ C2H5 + C2H4 + M is 1.9 x 10 55 s -1 . A study by Curran [87] proposed an A-factor for the reaction as 4.92 x 10 13 , which is much smaller. Other A-factors for the reaction in the NIST Chemical Kinetic Database [68] are within the same magnitude of the A-factor proposed by Curran.…”

Experimental and kinetic modeling study of extinction and ignition of methyl decanoate in laminar non-premixed flows

“…Kinetic parameters are based on a recent review by Curran for the alkyl radicals [13] and from the methyl butanoate mechanism [2] for reactions involving atoms of the ester group. The kinetic parameters for addition of radicals to the oxygen of the C=O bond have been updated from the study of methyl radical addition to the C=O bond by Henry et al [14].…”