Electron Spin Resonance Detection of Radical Intermediates During Photo-oxidation by Metal Ions in Solution

Abstract

Irradiation of fluid solutions of ceric and uranyl ions in various organic media in the temperature range 140–290 K gives rise in many cases to well-resolved e.s.r. spectra of solvent-derived radicals, enabling characterisation of the photolytic process. Whilst UO2+2 photo-oxidises predominantly, but not exclusively, by means of abstracting a hydrogen atom from carbon adjacent to an activating site such as —OH or —CO2H, Ce(IV) attacks by a process of C—C fission; for example RCO2H yields R˙ and R′CH2OH yields, not R′ĊHOH as is customarily found at 77 K, but R′˙.