Coulometric Study of the Reduction of Dinitroaniline Compounds

The authors' d.c.‐polarographic study [ Anal. Chim. Acta. 82 , 29 (1976)] has been extended to include a coulometric investigation of the cathodic reduction of six substituted dinitroanilines: 4‐(trifluoromethyl)‐2,6‐dinitro‐ N,N ‐dipropylaniline (I) was measured in 40% aqueous ethanol buffered at four p H values (1.5, 5.1, 7.4, 9.2), and N ‐butyl‐ N ‐ethyl‐4‐(trifluoromethyl)‐2,6‐dinitroaniline (II), 2,6‐dinitro‐4‐isopropyl‐ N,N ‐dipropylaniline (III), N 1 , N 1 ‐diethyl‐4‐(trifluoromethyl)‐2,6‐dinitro‐ m ‐phenylenediamine (IV), 4‐(methyl‐sulfonyl)‐2,6‐dinitro‐ N,N ‐dipropylaniline (V), and 3,5‐dinitro‐ N 4 , N 4 ‐dipropylsulfanilamide (VI) were measured in 40% aqueous ethanol buffered at one p H value (1.5). Preparative scale runs and product analyses indicate that the electroreduction mechanism is p H dependent, as evidenced by substantial benzimidazole formation at 1.5 p H and little production of this compound at 7.4 p H.