Wavelength dependent oxygen mediated electron- transfer reactions within M⁺Y zeolites: photo oxidation and reduction of 1,1-diarylethylenes

Abstract

Radical cations of 1,1-diarylethylenes have been generated by direct excitation of the parent olefins within zeolites. The radical cation generated by short wavelength irradiation of the olefin reacts with the solvent hexane while the one generated by long wavelength excitation of the diarylethylene/oxygen complex reacts with the counteranion radical (superoxide anion). While in solution the preferred reaction of the 1,1-diarylethylene radical cation is in addition to another ground-state olefin, no products derived from such a reaction were detected within zeolites. Within zeolites, the 1,1-diarylethylene radical cations undergo abstraction of a hydrogen atom and reaction with superoxide anion, the least-favored reactions in solution. The results show that reactive organic radical cations can be generated within zeolites by lamp irradiation in the absence of a sensitizer.