Direct and bromine-atom initiated photodecompositions of N-acetyl-N-bromohexanamide

Abstract

Photolysis of N-acetyl-N-bromohexanamide in the presence of an alkene (which scavenges bromine) gives high yields of N-acetyl-4-bromohexanamide (C₄-bromide) through efficient intramolecular H-atom transfer in the corresponding imidyl radical. Bromine, in a mixture with the N-bromoimide was irradiated selectively to generate bromine atoms that interact with the N-bromoimide to give the imidyl radical and the C₄-bromide. For such a mixture, irradiation of both N-bromoimide and bromine generates both bromine atoms and the imidyl radical and gives a product distribution similar to that obtained by a bromine-atom initiated reaction. These observations are best explained in terms of an equilibrium involving a bromine atom, an imidyl radical, and a bromine–radical complex. Possible reactions of such a radical complex are discussed.