Hydrocarbon radical reactions with oxygen: comparison of allyl, formyl, and vinyl to ethyl

Abstract

The reactions of allyl, formyl, and vinyl radicals with molecular oxygen have been analyzed as addition reactions, in which the energized adduct has several pathways available for further reaction. Rate constants for each of the reaction channels are estimated using a chemical activation formalism based on the Quantum Rice-Ramsperger-Kassel theory, along with thermodynamically consistent input rate constants and falloff parameters. Results show good agreement with the limited experimental data available. The well depth of the initially formed adduct is shown to exert a major influence over the preferred reaction channels. In particular, the shallow (-18 kcal/mol) well for the allyl addition results in very little apparent reaction, and the major channel is simply redissociation to the initial reactants