A CONTRIBUTION TO THE ELECTRODE-REACTION OF OXIMES - A STUDY OF THE INTERMEDIATE IMINE ON THE ELECTROREDUCTION OF PYRIDINE-4-ALDOXIME

The electroreduction of the pyridine-4-aldoxime is revisited and its f our-electron exchange process is analysed by means of classical polaro graphy, differential pulse polarography, linear cyclic voltammetry, ex haustive electrolysis and W-visible spectroscopy on a wide pH interval covering the four acid-base species of the oxime. The acid-base prope rties of both oxime and its four electron reduction product are charac terized in buffered aqueous solution. From polarographic and voltammet ric parameters, the electrode process is analysed in different pH inte rvals, in particular, the process causing the first-wave which corresp onds to the electroreduction of the conjugate acid and free base oxime . The observation of a second two-electron process at more negative po tentials and the comparison with the electrochemical behaviour of the imine derived from pyridine-4-aldehyde and n-hexylamine and the proper pyridine-4-aldehyde are discussed in dealing with the four electron p rocess.