Hydrogen abstraction from CH3NH2, (CH3) 2 NH, and (CH3) 3 N by H O ̇ 2 radicals: A theoretical study

Highlights: • Rate constants for hydrogen abstraction reactions by HO₂ radical on CH₃NH₂, (CH₃)${}_2$NH, and (CH₃)₃N are calculated. • Thermodynamic properties of selected reactants and products are determined. • Bond dissociation energies of CH and NH bonds, and reaction enthalpies are obtained. • Branching ratio analyses of all reaction sites for CH₃NH₂, (CH₃)${}_2$NH, and (CH₃)${}_3$N are performed. Hydrogen abstraction from CH₃NH₂, (CH₃)${}_2$NH, and (CH₃)${}_3$N by H${\dot{\text{O}}}_2$ radicals, is investigated via quantum chemistry calculations.The B3LYP/6-31G(2df, p) method is employed in geometry optimizations, frequencies, and intrinsic reaction coordinate calculations. The G4 method is applied in energy and thermodynamical property calculations. Rate constants are obtained from variation transition state theory and conventional transition state theory calculations with one-dimensional hindered rotor treatment and Eckart tunneling correction. A branching ratio analysis for each reaction system is further performed.