Effect of unlimited self-association of a component of a chemical reaction on the equilibrium states of the copper dialkyldithiophosphate systems

Abstract

In this paper, the redox and self-association processes of Cu(II) and Cu(I) dithiophosphates in the organic solutions were investigated by electronic absorption spectroscopy. It was shown that, over a wide concentration range of all components, the system under consideration is well described by the reduction of Cu(II) dithiophosphate with the formation of Cu(I) dithiophosphate and disulfide, followed by the unlimited self-association of the Cu(I) dithiophosphate. The results of this study also showed that the theory of ideal associated solutions can be efficiently applied for the description of this system. Considering that the self-association process is unlimited, we revealed the fundamentally new properties of highly associated compounds that simplify the description of such systems. The data obtained in this study can be useful for analyzing flotation and extraction processes with participation of Cu(II) and thiosubstituted organophosphorus acids, in particular, the commercial reagent CYANEX 301. The constants of the redox and self-association reactions were found to be as follows: Кredox = (7.5 ± 0.2) × 10−4, β = 348.3 ± 0.7.