Collect. Czech. Chem. Commun. 1993, 58, 1803-1812

Cathodic Reduction of Isatin-3-oxime

Alexander Hudák, Adam Košturiak, Alexander Hanudeľ and Pavol Meľuch

Department of Physical and Analytical Chemistry, Šafárik University, 041 67 Košice, Slovak Republic


The molecule of isatin-3-oxime was studied polarografically 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 the reduction of the oxime group, whereas two polarographic waves are observed at pH 10.5 to 13: one is due to the reduction of the isatin-3-oxime anion, the other, more negative wave is associated with the reduction of the oxime group in the α-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 can exist as seven ionic and molecular species in dependence on pH. The species have been confirmed polarographically, by IR and electronic spectroscopy, potentiometrically and by paper electrophoresis.