Solvent effects on hydrogen abstraction reactions from lactones with antioxidant properties.

Solvent effects on the kinetics for hydrogen abstraction from a lactone antioxidant were determined for alkoxyl and nitroxyl radicals; their reactivity differ by about 7 orders of magnitude. A decrease by approximately 12 and approximately 35 were determined for H-abstraction by tert-butoxyl and nitroxyl radicals, respectively, upon changing the solvent from hexane to acetonitrile. Results of solvent and isotope studies indicate that the antioxidant properties of lactone antioxidants should be attributed to the enol, not the lactone. [reaction: see text]