ELECTROREDUCTION OF PORPHYRIN WITH A 4-NITROPHENYL GROUP IN THE MESO POSITION - PREPARATION OF NITROSO AND AMINO DERIVATIVES IN A REDOX CELL

The polarogram of the 544-nitrophenyl)-10,15,20-tris (4-pyridyl) porphyrin (Ia) and the polarogram of the 5,10-bis (4-nitrophenyl)-15,20-bis (4-pyridyl) porphyrin (IIa), in aqueous acidic medium, show several waves corresponding to the reduction of nitro group and porphyrin ring. The electrosyntheses of the corresponding amino (Ib), nitroso (Ic) and dinitroso derivatives (IIc) are carried out in a ''redox'' cell with two consecutive porous electrodes of opposite polarities. Both reduction of the nitro group and reduction of the porphyrin ring occur at the first porous electrode and the immediate reoxidation of the reduced porphyrin at the second porous electrode prevents the chemical rearrangement of the macro-cycle.