The photoreactions of a number of biphenyl derivatives, in particular nitrobiphenyl derivatives, with cyanide ion have been investigated. Photosubstitution by cyanide ion has been found to predominate; photoreduction is not observed. In some cases (4-nitrobiphenyl, 4, 4′-dinitrobiphenyl, 3-nitrobiphenyl and similar compounds) the behaviour can be rationalized on the basis of analogy to the pattern of photocyanation of biphenyl itself ( ...