The Formation of Copper(ii) Complexes With Water Soluble N-(Furan-2-Ylmethylidene)hydroxylamine

Abstract

The paper is devoted to the interaction of copper(II) chloride with water soluble β-furfuraldoxime (N-(furan-2-ylmethyliden)hydroxylamine) in hydrochloric solutions. It was been revealed that the degree of copper(II) precipitation from aqueous solutions and hydrochloric solutions with the pH of 4 M HCl by this reagent is not higher than 52% even when the precipitant is used in abundance. These dependencies has been compared to the similar results of palladium(II) precipitation obtained when all other conditions were equal. It has been discovered that various complexes are formed when Cu(II) reacts with a β-furfuraldoxime and that it depends on the acidity of the solution. In weak acid solutions (0.01-0.1 M HCl) the «green» complex of composition [CuL4Cl2] was obtained and in this complex the oxime is coordinated with the central atom by an oxygen atom of the oxime group. The so-called «red» complex of composition [CuL2Cl2] is formed in the pH range of 1-4 M HCl and in ethanol. In this complex the coordination of ligand molecules is realized by the oxygen atom of the furan ring and by the oxygen of the oxime group. Reagent N-(furan-2-ylmethyliden)hydroxylamine can be used for practical quantitative release of palladium from hydrochloric solutions. However, it does not provide the separation of copper and palladium in their joint presence.