Solvent effects on the reduction potentials of nitroanilines

The influence of a number of aprotic solvents on the electrochemical reduction of ortho- and para-nitroanilines and their N-methyl derivatives has been studied. The reduction potentials, depending fundamentally on the acceptor properties of the medium, decrease with increasing solvent acceptor number. A similar effect is produced by intramolecular hydrogen-bonding interactions in ortho-derivatives. Intermolecular hydrogen-bonding interactions, occurring with derivatives having ‘free’ N–H protons, are transmitted through the molecule, enhancing the sensitivity of the NO2 group to the acceptor solvent.