Reduction of dinitrobenzenes by electron-carrying catalysts in the electrosynthesis of diaminobenzenes

The interaction of isomeric dinitrobenzenes (DNBs) with titanium(III), tin(II), and vanadium(II) chlorides, which are reducing agents used as electron carriers in the electrosynthesis of diaminobenzenes, has been studied. Rate constants of the reduction of isomeric DNBs and nitrophenylhydroxylamines by SnCl 2 and TiCl 3 in a 2 M water-alcohol solution (10 vol.% C 2 H 5 OH) of HCl were measured, and activation energies of the reduction of isomeric DNBs were determined. The rates of interaction of DNBs with the listed mediators increase in the series SnCl 2 < TiCl 3 < VCl 2 . It is shown that the electrolysis of DNBs in the presence of an excess of these mediators makes it possible to obtain the corresponding diaminobenzenes with a yield of 60–90%.