Kinetic Study on the H-Abstraction Reactions from 1-Nitropropane by H and OH Radicals

To improve the comprehension of the combustion kinetics of 1-nitropropane (1-NP), the H-abstraction reactions from 1-NP by H and OH radicals are theoretically explored using the canonical variational transition-state theory combined with the multistructural torsional anharmonicity and small-curvature tunneling corrections (MS-CVT/SCT). The M08-HX/cc-pVTZ method is adopted for geometry optimizations and frequency calculations due to its effective performance in describing the current reaction systems with an average mean unsigned deviation of 0.95 kcal mol^-1 against the benchmark by the high-level DLPNO-CCSD(T)/CBS(T-Q) method. The rate constants for the investigated reactions are calculated using the MS-CVT/SCT method at 200-2000 K, and a good agreement is achieved by comparing our calculations with the available literature data. The rate constant calculations show that the multistructural torsional anharmonicity, variational effect, and tunneling effect have different influences on the H-abstraction reactions 1-NP + H/OH, and the reaction channel at the C_β position is the most important above the room temperature. With our calculations, a literature combustion kinetic model of 1-NP is revised, and the new model demonstrates improved performance across most conditions. Sensitivity analysis demonstrates that the H-abstraction reaction channel, 1-NP + OH = CH₃CHCH₂NO₂ + H₂O, alters the combustion kinetics of 1-NP and plays an important role in controlling its ignition process.