Abstract: At the theoretical level of M06-2X/SMD/6-311+G(d,p), we studied  the reaction mechanism between Edaravone (Eda) keto isomers and superoxide hydrogen radical ·HO₂  in aqueous liquid phase at 1 atmospheric pressure and 310.15 K temperature. The results show  that there are three processes in the reaction of Eda keto isomers with ·HO₂:  H extraction,  addition and single electron transfer.  The H extraction reaction is mainly achieved through ·HO₂ extraction of heterocyclic H and methyl H,  and the free energy barrier of the reaction is  77.1—78.7 kJ/mol. The addition reaction can be realized by the process of ·HO₂ addition to unsaturated C,  and the free energy barrier of addition is 48.2—95.0 kJ/mol. The most advantageous exothermic reaction is the addition of C atoms connected to methyl groups on heterocycles,  with a free energy barrier of 48.2 kJ/mol. The free energy barrier of single electron transfer is 141.1 kJ/mol,  which is impossible.Therefore,  the  Eda  keto isomer in aqueous liquid phase can eliminate ·HO₂ by H extraction and addition reactions.

Key words: Eda keto isomer,  , superoxide hydrogen radical,  , density functional theory,  , transition state,  , Marcus theory,  , electron transfer,  , free energy barrier