Preparative Electrochemical Reduction of Fluorinated Benzonitriles

Electrochemical reduction of fluorinated benzonitriles in aprotic media is accompanied by concurrent processes of dimerization and fragmentation of the corresponding anion-radicals. With 2-fluoro- and 3,4,5-trifluorobenzonitriles the defluorinated products can be obtained at direct electrochemical reduction; for the other compounds studied have been found mediators providing a possibility to obtain in high yield defluorinated products at preparative electrochemical reduction. A fundamental possibility was demonstrated of providing products by nucleophilic fluorine substitution by S_BN mechanism at electrochemical reduction of fluorinated benzonitriles in aprotic solvents in the presence of mediators.