Photochemical Reactions of Dicyanobenzenes with Aliphatic Amines

Abstract Upon irradiation, p-dicyanobenzene reacted with primary, secondary, and tertiary aliphatic amines to give substitution products in which one of the cyano groups was replaced by the amine at α-CH position or by an alkyl group of the amine. o-Dicyanobenzene reacted similarly, but the meta-isomer did not react under similar conditions. The rates of the fluorescence quenching of p-dicyanobenzene with the amines are close to the diffusioncontrolled rate, but are somewhat dependent on the ionization potentials of the amines. When the substitution product was irradiated, the corresponding alkylation product was obtained. The mechanisms of these reactions have been investigated by the use of such proton donors as MeOH(MeOD); on the basis of those investigations, new photochemical reactions involving charge-transfer, followed by proton-transfer and then addition-elimination, are proposed, as well as a new type of photo-induced Birch reduction.