Oxyradical reactions: from bond-dissociation energies to reduction potentials.

Destructive radical reactions involve alkyl, alkoxyl and alkylperoxyl radicals, as well as alkylhydroperoxides. From bond energies the following reduction potentials vs NHE at neutral pH are derived: E0'(RO./ROH) = 1.6 V, E0'(ROO./ROOH) = 1.0 V, E0(ROOH/RO., H2O) = 1.9 V, and the two-electron reduction potential E0'(ROOH/ROH, H2O) = 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, delta G0' = -14 kcal/mol.