Collect. Czech. Chem. Commun. 1981, 46, 2382-2389

The use of 2-(2-hydroxyphenylazo)-7-oxo-5,5-dimethyl-4,5,6,7-tetrahydrobenzothiazole as an extractant for Cu(II), Ni(II), Co(II), Pb(II) and Cd(II)

Margita Vačková, Emil Kuchár and Viera Šuriková

Department of Analytical Chemistry, Comenius University, 816 50 Bratislava


The heterocyclic azo dye, 2-(2-hydroxy-5-ethylphenylazo)-7-oxo-5,5-dimethyl-4,5,6,7-tetrahydrobenzothiazole (I), was prepared. The acid-base and optical parameters of the azo dye were found spectrophotometrically and the molar absorption coefficients and concentration dissociation constants were determined. The formation of the chelates of compound (I) with Cu(II), Ni(II), Pb(II) and Cd(II) was studied. The molar absorption coefficients and stability constants of the chelates were determined by calculations, graphical and logarithmic analysis, based on data from the A = f(pH) curves. The region of optimal extraction and the extraction constants were found for the chelates of I with Cu(II), Ni(II), Co(II) and Pb(II).