The polarography of cyclohexanone and cyclohex-2-en-1-one

Abstract

Cyclohex-2-en-1-one gives a total of five polarographic waves, in aqueous buffer solutions, over the pH range 0–14 at 25°. One of the three waves observed in acid solutions is due to an inhibition of the hydrogen discharge, and is also observed for cyclohexanone solutions at these pH′s. The remaining two are a diffusion-controlled one-electron wave and an adsorption prewave to this. The combined wave falls from pH 5 to 8 to be replaced by a second wave at a more negative potential; this is also diffusion-controlled, involving a one-electron reduction. These two waves are related by a protonation process occurring in the diffusion layer but not in the bulk solution. In some tetramethylammonium buffer solutions a further wave can be discerned at very negative potentials, but this is not identical with the cyclohexanone reduction wave which is studied in these solutions.