Computational Investigation of the Reaction Kinetics between 2-Hydroxyethyl Radical and Nitrogen Dioxide

The 2-hydroxyethyl (CH₂CH₂OH), a key oxygenated carbon-centered intermediate in ethylene and ethanol oxidation, critically influences combustion chemistry. Nitrogen oxides (NO_x) from hydrocarbon combustion significantly modulate its consumption kinetics by competing with the ĊH₂CH₂OH + O₂ reaction pathway. Current literature models rely on extrapolated rate parameters from limited low-temperature and pressure experimental data, the applicability of which remains unvalidated. This study provides a rigorous theoretical investigation of the ĊH₂CH₂OH + NO₂ reaction kinetics at the CCSD(T)/CBS//M06-2X/aug-cc-pVDZ level. Microcanonical variational transition state theory and Rice-Ramsperger-Kassel-Marcus/Master Equation calculations were performed to obtain temperature- and pressure-dependent rate coefficients. The dominant pathway involves nucleophilic attack by the radical carbon on nitrogen, forming CH₂O + CH₂NOOH. Kinetic modeling reveals that incorporating these results induces negligible perturbation to established reaction mechanisms for predicting major species evolution. However, further refinement of the NO₂ + NO₂ = NO + NO + O₂ kinetics is recommended to enhance model accuracy.