Electroreduction mechanism of N-phenylhydroxylamines in aprotic solvents: N-(2-nitrophenyl)- and N-(3-nitrophenyl) hydroxylamines

In continuation of our previous studies on N-(4-nitrophenyl) hydroxylamine (1), we investigated the electroreduction of N-(2- (2) and N-(3-nitrophenyl) hydroxylamines (3) in N, N-dimethylformamide/ Bu4NClO4, using chronoamperometry, cyclic voltammetry, digital simulation and quantum chemical calculations. It was shown that anion radical 3 is rather stable and does not eliminate a hydroxide anion, unlike 2 whose electroreduction mechanism is similar to that previously observed for 1. At the same time, the elimination reaction is observed for dianion of 3 formed at potentials of the first electron transfer by disproportionation of anion radicals. Results of quantum-chemical calculations show that the high stability of anion radical 3 results from the absence of unpaired electron density on its hydroxylamine group. (C) 2017 Elsevier Ltd. All rights reserved.