Photolytic Decomposition of Polyhalogenocyclohexanes - A Pathway to the Formation of Substituted Halogenobenzenes

Liquid phalle photohalogenation of benzene/halogenobenzenes give polyhalogeno­c!,clohexane adducts; these adducts are accompanied by substituted products ego mono- and di­halogenobenzenes. Photochemical decomposition of adducts like C6H6Br6 and C6HsClBr6 later gave the same products, ie. bromobenzene, and dibromobenzenes or bromochlorobenzenes. The distrIbution of the dihalogenobenzene isomers was found markedly different from the reported ratio for such isomers in the heterolytic reactions; meta-isomers are found to a significant extent. Evidence adduced suggests an addition-elimination mechanism as a pOlmble pathway to the bromo­substituted arenes in these photochemical reactions. 

M I BHANGER ,G H WILLIAMS ,R BOLTON ,