Theoretical studies for reaction kinetics of cy-C6H11CH2 radical with O2

The oxidation mechanism of cyclohexylmethyl radical (cy-C6H11CH2), a prototypical alkyl-substituted cycloalkyl radical, has been investigated by high level quantum chemical calculations, and the chemical kinetics was studied by the variational transition state theory and the Rice-Ramsperger-Kassel-Marcus/Master-Equation theory. The relationship between molecular structure and reactivity was explored for the cyclohexylmethyl peroxy radical, which was also compared with chain-like alkyl peroxy radicals. It is shown that the 1,5 H-shift reaction is more competitive than the 1,6 H-shift for the cy-C6H11CH2OO radical, and at high temperatures the concerted elimination reaction channel forming HO2 and methylenecyclohexane bimolecular products becomes more important. Comparing with cyclohexane, the presence of a methyl group in cyclic alkanes prompts the 1,5-H shift of the corresponding peroxy radical and accelerates the overall low temperature chain branching reaction rate. The current study extends kinetic data involved in cy-C6H11CH2 oxidation including cy-C6H11CH2 and O2 recombination, subsequent isomerization and dissociation of the cy-C6H11CH2OO radical over wide pressure and temperature range.