Ab initio kinetics of hydrogen abstraction reactions of iso-propylamine.

Kinetics of amine-based biofuels in the atmosphere and combustion are mainly initiated by hydrogen abstraction reactions with small radicals, which are crucial in understanding their atmospheric and combustion chemistry. However, the kinetics of hydrogen abstraction reactions of iso-propylamine (IPA) with small radicals are still unclear. In the present study, hydrogen abstractions from IPA by seven radicals (H, O( 3 P), OH, O 2 ( 3 P), HO 2 , NH 2 , and CH 3) are theoretically investigated. By comparing the electronic energies determined by several cost-effective density functional theory methods to those determined by the high-level method CCSD(T)/CBS(T-Q), the M06-2X/def2-TZVP combination with a mean unsigned deviation of 0.85 kcal mol−1 is selected to investigate the kinetics and thermodynamic data at 298–2500 K. High pressure limit rate constants are calculated with the canonical variational transition-state theory (CVT), combined with multi-structural torsional anharmonicity and small-curvature tunneling. Hydrogen abstraction reactions at the C site adhering to the NH 2 group dominant in the low-to-mediate temperature range. Furthermore, the effect of the calculated thermodynamic and kinetics data on the previous IPA model is examined. • Rate constants are theoretically determined. • Site-specific reactivities are theoretically investigated. • Multi-structural torsional anharmonicity effects are theoretically examined. • Multidimensional tunneling coefficients are theoretically determined. • Reliable thermochemical data are provided. [ABSTRACT FROM AUTHOR]