Kinetics of the Acid Hydrolysis of Potassium Trans-dioxalatobis(Ethylnicotinate) Chromium(iii)

Abstract

The kinetics of the aquation of trans-Cr(ox)2(py.3COOEt)2 - has been studied spectrophotometrically in aqueous HClO4-NaClO4 media. The results indicate a first-order reaction proceeding through the trans-Cr(ox)2(OH2)2 - intermediate with subsequent isomerisation to give cis-Cr(ox)2(OH2)2 - ion. The intermediate(s) and the final product have been identified by their spectral properties. The reaction was also found to be independent of the ionic strength. The activation enthalpy ( . H*) and entropy ( . S*) values are 17.6¡¾0.8 kcal/mol and -17.5¡¾1.2 cal/deg.mol respectively, suggesting the dissociation of the Cr(III)-oxalato bond in the transition process.

(Af. J. of Science and Technology: 2002 3(1): 109-113)