Indirect electrolysis involving an ex-cell two-phase process. Reduction of nitrobenzenes with a titanium complex as mediator

Indirect electrolysis of nitrobenzenes, in organic solvent (dichloromethane, toluene), with a titanium complex (C5H5Ti+ used as mediator in aqueous acidic medium, is performed by phase transfer reaction in a reactor located out of the electrolytic cell. Nitrocompounds are selectively reduced to aminoderivatives and the resulting oxidized form of complex (C5H5)(2)TiOH+ is reduced at a graphite felt cathode by continuous recycling of the aqueous solution until the complete reduction of nitrocompounds. Dinitrocompounds are directly reduced to diamino derivatives. Advantages and limitations of the procedure are shown. Formation of an intermediate between the nitrocompound and the reduced form of the mediator is postulated to explain the selectivity of the reduction. Copyright (C) 1996 Elsevier Science Ltd