The photochemical reaction of 1,2-naphthoquinone with hydrogen donors. An explanation of the coupling sites of alkyl and acyl radicals to 1,2-naphthosemiquinone radical

Abstract

The photoinduced addition reactions of toluene, diphenylmethane, phenylacetaldehyde, and diphenylacetaldehyde to 1,2-naphthoquinones have been investigated. Benzyl and diphenylmethyl radicals attack the 4-position of 1,2-naphthosemiquinone radical, whereas phenylacetyl radical attacks both the 3-position and the oxygen atoms of the semiquinone radical. The different attacking patterns of alkyl and acyl radicals to the semiquinone radical are successfully interpreted by taking into consideration the charge densities of the radicals concerned.