Organic photochemistry. Part VII. The photolytic reactions of α-halogeno-ketones in solutions of olefins

Abstract

Irradiation of mixtures of chloroacetone and cyclohexene with light (λ > 280 mµ) gave acetone, chlorocyclohexane, bicyclohex-2-enyl (II), cyclohexylacetone, and cyclohex-2-enylacetone. Similar mixtures of saturated and unsaturated ketonic adducts were derived from the illumination of mixtures of chloroacetone and pent-1-ene p-menth-1-ene, the trimethylstyrene (XVIII) and 2,3-dihydropyran. 2-Chlorocyclohexanone and bromoacetone behaved similarly, but iodoacetone in cyclohexene gave mainly trans-2-iodocyclohexylacetone and iodocyclohexene. The effects of dilution and of adding carbon tetrachloride and thiols to some of these systems were investigated.

The results seem to require the postulates (a) that the primary photochemical reaction is a homolysis: [graphic omitted] + X·, and (b) that the fate of the ketonyl radical is intimately linked with the fate of the halogen atom.