Oxyradical reactions: from bond-dissociation energies to reduction potentials

Abstract

Destructive radical reactions involve alkykl, alkoxyl and alkylperoxyl radicals, as well as alkylhydroperoxides. From bond energies the following reduction potentials vs NHE at neutral pH are derived: Esuo'(RO./ROH) = 1.6 V, E o'(ROO./ROOH) = 1.0 V, E o'(ROOH/RO., H 2;0) = 1.9 V, and the two-electron reduction potential E o'(ROOH/ROH, H 2O) = 1.7 V. Hydrogen abstraction from a bis-allylic methylene group by alkoxyl and alkylperoxyl radicals is favourable with Gibbs energies of −23 and −9 kcal mol , respectively. Similarly, alkoxyl radicals can oxidize alkylhydroperoxides, ΔG o' = −14 kcal mol .