Mechanisms for aromatic photocyanation: naphthalene and biphenyl

Abstract

Photocyanation of naphthalene and biphenyl has been studied in the systems ArH–KCN–aqueous CH₃CN and ArH–NaCN–CH₃OH. The reaction is first order in CN^– and in ground state ArH as well as in excited ArH. The proposed mechanism involves the formation of a singlet excimer, which dissociates into radical ions before the attack of cyanide ion. Photocyanations in the presence of oxidants such as p-dicyanobenzene and persulphate ion proceed by oxidation of the singlet excited hydrocarbon to form a radical cation directly.