Overwhelming decomposition of 4-bromo-4′-cyanomethylbiphenylyl radical anion without electron transfer to 4,4′-dibromobiphenyl

Dibromobiphenyl reacted with cynomethyl anion in ammonia under irradiation to form nucleophilic bis-substituted product in high yield without substantial monosubstituted product. Quantum yields far the formations of bis- and monosubstituted products were found to be 85.6 and 2.3×10−5 respectively while the corresponding pseudo-first-order rates were 6.9×10−3 and 5.2×10−10 mol·L−1·S−1. Block up the possible electron transfer of 4-brome-4′-cyanomethyl-biphenylyl radical anion to 4-cyanomethyl-biphenylyl radical and bromine ion.