The photosubstitution (electron transfer) reaction between 1, 4-dicyanobenzene (1) and 2, 3- dimethyl-2-butene (2), which gives 1-(4-cyanophenyl)-2, 3-dimethyl-2-butene (3) and 3-(4- cyanophenyl)-2, 3-dimethyl-1-butene (4), has been extended to other dicyanobenzene- olefin mixtures. Substitution of a cyano group occurs when both 1 or 1, 2-dicyanobenzene (5) are irradiated in acetonitrile solution, in the presence of 2 or cyclohexene (16). Under ...