SPECTROPHOTOMETRIC AND POLAROGRAPHIC STUDIES OF DI-2-PYRIDYL KETONE 2-THIENOYLHYDRAZONE

The spectral and differential pulse polarographic (DPP) behaviour of di-2-pyridyl ketone 2-thienoylhydrazone (DPKTH) has been investigated in 30% (v/v) ethanol-buffer mixtures over a wide range of pH (2.0-12.0). The spectral bands located at 325, 276. 230 and 208 nm of the DPKTH in ethanol are assigned to the possible electronic transitions of the molecule. The spectral data at various pH values indicates that the molecule characterized by the keto = enol tautomerization and the pK(a) value for the enolic form of the compound is determined in aqueous ethanol and was found to be 10.6. The effect of various operational parameters on the reduction current and the mechanism of the electrode reaction of DPKTH at the DME are discussed. The main reduction peaks are attributed to the reduction of C=N centre of both the keto and enol forms. This behaviour is compared with the DPP behaviour of the other related acid hydrazone compounds. The applicability of DPP technique for the trace determination of DPKTH was tested under the optimum experimental conditions and the detection limit is found to be 0.09 mu m.