ELECTROCHEMICAL REDUCTION OF IMINES IN DIMETHYLFORMAMIDE

The mechanism of electrochemical reduction of several imines (Schiff bases) has been investigated in dimethylformamide containing tetraethylammonium bromide, using polarography, cyclic voltammetry, coulometry, and comparison of the stereochemistry of the amines produced in preparative-scale electrolysis, catalytic hydrogenation, and sodium-alcohol reduction. Polarography and cyclic voltammetry indicate an irreversible two-electron reduction. It is suggested that a radical anion is formed initially. With the species examined in this investigation, proton abstraction and a second electron transfer are both rapid. This behavior contrasts with the stability of ketyl ions in dimethylformamide; the higher basicity of the nitrogen species presumably enhances proton abstraction rates. A mechanism for sodium-alcohol reductions is suggested, based upon the electrochemical and stereochemical results. © 1969, American Chemical Society. All rights reserved.