Abstract: We used density functional theory (DFT) to investigate the reaction mechanisms of the sodium ion valine chelates (Val→Na⁺) with hydroxyl radicals (·OH) in aqueous liquid environment at 310.15 K. We explored the potential energy surfaces of the hydrogen abstraction and addition reactions of Val→Na⁺ and ·OH, and the free energy barriers and free energy changes of the single-electron transfer reactions between them. The calculation results show that thermodynamics allows for the hydrogen abstraction reactions with a reaction energy barrier of 23.3—75.6 kJ/mol for implicit water solvent effects, and 33.8—81.2 kJ/mol for explicit water solvent effects. Most hydrogen abstraction energy barries increase slightly. Thermodynamics and kinetics do not allow for electron transfer under both implicit and explicit solvent effects. It can be seen that Val→Na⁺ can rapidly scavenge ·OH through hydrogen abstraction reaction in aqueous liquid phase, and sodium valine chelate can be used as ·OH scavenger.

Key words: sodium valine, hydroxyl radical, density functional theory, solvent effect, hydrogen bond, free energy barrier