Spectrophotometric study of the complexation equilibria of cobalt(II) with 4-(5′-methyl-3′-isoxazolylazo)-resorcinol and determination of cobalt(II)

Abstract

The reaction of cobalt(II) with 4-(5′-methyl-3′-isoxazolylazo)-resorcinol (MIAR) in 4% v/v ethanol-water medium at I = 0.1 M (NaClO4) was investigated spectrophotometrically. Graphical and numerical calculation methods were used to establish the equilibria in solution and to evaluate the stability constant of the complexes formed (log β101 = 7.48±0.06, log β111 = 12.77 max 12.99, log β102 = 16.41±0.07). The optimum conditions for the spectrophotometric determination of Co(II) with MIAR were established and the method applied to its determination in some low alloy steels and hydrofining catalysts.