Polarographic Behaviour of Salicylaldehyde-2-Pyridylhydrazone and Its Copper(ll) Complex*

The polarographic behaviour of salicylaldehyde-2-pyridylhydrazone (SAPH) has been studied in aqueous buffer solution containing 40% ethanol using DC and DP polarographic methods. In the pH range 1.8--7.5 the observed single irreversible reduction wave is assigned to the splitting of the N N bond and reduction of C = N centre. In alkaline medium, a second wave appears at a more negative potential due to the reduction of the salicylaldehyde which is formed by hydrolytic decomposition of the SAPH molecule. The effect of pH on the limiting current and E1/2 as well as the reduction mechanism are discussed and compared with similar compounds. The kinetic parameters of the electrode reaction have been calculated. The analytical properties of the copper(II)-SAPH system is described. The complex gave rise to a single irreversible well-defined wave (E1/2---0.58 V at pH--5.2). The reaction process is diffusion controlled. A method is suggested for the determination of Cu(II) in presence of different metal ions as the difference in their E1/2 values is sufficient for the purpose.