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′˙.