Role of hyperconjugation in determining carbon-oxygen bond dissociation enthalpies in alkylperoxyl radicals.
[reaction: see text] Theoretical calculations of carbon-oxygen bond dissociation enthalpies in substituted methylperoxyl radicals (YCH(2)OO*) reveal that bond strengths are not governed solely by the stability of YCH2* radicals but are largely affected by hyperconjugation when Y is electron-donating or conjugating. In many cases, this hyperconjugative effect is greater than stabilization of the methyl radical by Y. All electron-withdrawing Y exert small destabilizing effects via inductive withdrawal of electrons from the polarized C-OO* bond.
Pratt
Derek A
DA
Department of Chemistry and Center for Molecular Toxicology, Vanderbilt University, Nashville, Tennessee 37235, USA.
Porter
Ned A
NA
D005609:Free Radicals / Q000737:chemistry; D008958:Models, Molecular; D010545:Peroxides / Q000737:chemistry*; D013816:Thermodynamics
D005609:Free Radicals; D010545:Peroxides; C049375:perhydroxyl radical