Abstract
<jats:p>Computational methods of quantum chemistry were used to study the reactions of intermolecular transitions of hydrogen atoms in the reaction systems C2H4+HO2 and C2H4+CH3O2. The enthalpies of these reactions were calculated, transition states were found, and potential barriers of the reactions were determined. It was established that the abstraction of an H atom from ethylene in the systems C2H4+HO2 and C2H4+CH3O2 requires the same activation energy of 27.6 kcal/mol, while the enthalpies of these reactions are 23.8 and 24.7 kcal/mol, respectively. It was shown that pre- and post-reaction Van der Waals complexes are formed in this case, and their structures were determined. The enthalpies of 6.7 and 36.1 kcal/mol were determined for the reactions of H atom abstraction by ethylene from HO2 and CH3O2, respectively.</jats:p>