CATHODIC REDUCTION OF ISATIN-3-OXIME

The molecule of isatin-3-oxime was studied polarographically over the region of pH 1 to 13. Cathodic reduction within the region of pH 1 to 10.5 gives rise to a single four-electron polarographic wave due to th e reduction of the oxime group, whereas two polarographic waves are ob served at pH 10.5 to 13: one is due to the reduction of the isatin-3-o xime anion, the other, more negative wave is associated with the reduc tion of the oxime group in the alpha-oxime isatinic acid anion, which is the product of hydrolytic cleavage of the isatin ring in the basic pH region. The experimental results give evidence that the substance c an exist as seven ionic and molecular species in dependence on pH. The species have been confirmed polarographically, by IR and electronic s pectroscopy, potentiometrically and by paper electrophoresis.