Liquid-Liquid Distribution of Ion Associates of Tetrahalogenothallate(III) with Quaternary Ammonium Ions

Abstract

The distribution behavior of the ion-association complexes of tetrahalogenothallate(III) ions (TlX₄^-(X^-=chloride, bromide and iodide ions)) with quaternary ammonium cations (Q⁺) between three organic phases (chloroform (CF), chlorobenzene (Cl-B) and benzene (B)) and an aqueous phase was examined, and the extraction constants (log K_ex) were determined. The extractability of TlX₄^- was TlCl₄^-<TlBr₄^-<TlI₄^-; the differences in log K_ex between two successive ions were 2.1±0.8 and 2.2±1.5. Among the ion associates examined, the extractability of the extracting solvents was generally in the order B<Cl-B_??_CF; the differences in log K_ex between two successive solvents in this order were 0.4±0.8 and 0.0±1.4. A linear relationship was found between log K_ex and the total number of carbon atoms in Q⁺; from the slope of the line, the contribution of a methylene group in Q⁺ to log K_ex was calculated to be 0.5±0.2. From the obtained extraction constants, a highly sensitive extraction-spectrophotometric method of thallium was developed.