POLAROGRAPHIC AND ELECTROCHEMICAL STUDIES OF SOME AROMATIC NITRO-COMPOUNDS .7. POLAROGRAPHIC, VOLTAMMETRIC, AND CONTROLLED POTENTIAL ELECTROLYTIC REDUCTION OF META-NITROBENZALDEHYDE AND PARA-NITROBENZALDEHYDE

In acidic media, at pH < 7, the nitro groups in both meta- and para-nitrobenzaldehyde are reduced in a four-electron process and form corresponding formylhydroxylamines. These species are reduced in protonated forms to corresponding formylanilines, which are further reduced in two-electron steps to alcohols. At pH > 7, the formylhydroxylamine condenses rapidly to form a nitrone, which is further reduced to two two-electron steps, for the derivative of meta-nitrobenzaldehyde overlap. The addition of ortho- to para-nitrobenzaldehyde results in cross-condensation.