Abstract

M Zaky². W. G. Hanna¹, A. L. Ansary³, M. M. Moawad¹ and Shaker Labib Stefan⁴

The complexation of R-acid azo dyes with some trivalent lanthanide ions such as La(IlI), Pr(III), Nd(III) and Sm(III) has been studied potentiometrically using Calvin - Bjerrum titration technique as employed by Irving and Rossotti. Protonation constant of the ligand and stability constants of the respective metal complexes have been determined at constant temperature (25°C) and ionic strength (0.1 μ KnO3) in aqueous medium. Solid complexes of R-acid azo dyes derivatives with La(III), Pr(III), Nd(III) and Sm(III) have also been prepared and characterized on the basis of 1. R. spectral data. Also conductometric titrations have been made to characterize the composition of complexes formed. The effect of para-substituent of R-acid azo dye complexes oo the reaction constant (ρ) using Hammett substitution constant (ρ) have been investigated and was found a small positive value.

Complexation; R-Acid; Lanthanide

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