Effects of aliphatic substituents on the reduction of nitroanilines. II. Studies by modulated-potential polarography

The reduction of 2-methyl-5-nitroaniline (A) and 2,4-di-t-butyl-6-methyl-5-nitroaniline (B) in 1/1 water-ethanol mixture was studied by a.c.- and pulse-polarog. At the time-scale of these methods, the reduction of the above compounds in strongly alk. solutions shows the characteristics of a reversible process in the potential-range of the first DC wave. The first electron uptake by the non-protonated reactant in alk. media is followed either by disproportionation (first wave) or a sequence of electron transfers (second wave) giving the same final product, RNHO-. The steric- and charge distribution effects induce some peculiar features in the polarog. behavior of B.