2-PHOTON CLEAVAGE OF BENZIL IN THE LASER-JET - INTERMOLECULAR REACTIONS OF TRANSIENT BENZOYL AND TERT-BUTOXY RADICALS IN THE PHOTOLYSIS OF TERT-BUTYL PEROXIDE MIXTURES

Normal irradiation of benzaldehyde in tert-butyl peroxide as solvent afforded benzil and minor amounts of tert-butyl benzoate (1), whereas in the laser-jet mode exclusively ester 1 was observed. On photolysis of benzaldehyde in a 1:1 mixture of tert-butyl peroxide and CCl4 as solvent, only benzoyl chloride was found on normal irradiation. However, in the laser-jet mode also ester 1, chlorobenzene, and hexachloroethane were observed. Chlorobenzene arises from decarbonylation of the intermediary benzoyl radicals and subsequent chlorine abstraction from CCl4 by the resulting phenyl radicals. Benzil was cleaved in the laser-jet through a two-photon process and afforded the same benzoyl radical-derived products as in the photolysis of benzaldehyde, except that also alpha,alpha,alpha-trichloroacetophenone (2) was formed by an in-cage reaction.