INVESTIGATION OF COBALT(II) COMPLEXING WITH 2-HYDROXY-5- NITROTHIOPHENOL AND AMINOPHENOLS

Abstract

The complex formation of cobalt(II) with 2-hydroxy-5-nitrothiophenol (НNTP) and aminophenols (AP) was studied by physicochemical methods. Of the aminophenols, 2(N, N-dimethylaminomethyl)-4- ethylphenol (AР1) and 2(N, N-dimethylaminomethyl)-4-iodophenol (AР2) were used. Mixed-ligand complexes are formed in a slightly acidic medium (рНopt 5.5–6.4). For one extraction, Co(II) is extracted with chloroform by 98.8–99.3% in the form of a mixed ligand complex (МLC). The optimal condition for the formation and extraction of these compounds is (1.2-2.0)×10-3 mol/l НNTP concentration and (2.0-2.5)×10-3 mol/l AP. The ratio of the reacting components in the МLC corresponds to Co(II) : HNTF : AP = 1:2:2. The maximum light absorption is observed at λ = 520–530 nm. The molar light absorption coefficients are (3.78–3.95)×104. Based on the obtained data, photometric methods for the determination of cobalt in various industrial and natural objects have been developed.