Liquid-Liquid Distribution Behavior of Ion Association Complexes of Dihalogenocuprate(I) Anions with Azo-Dye Cations as Counter Ions

The solvent extraction of ion association complexes of dihalogenocuprate(I) ions CuX(2)(-)(X-=chlorideb,r omide and iodide ions), with 4-(4-diethylaminophenylazo)-N-alkylpyridiniumc ations (azo-dye cations) is described: the alkyl groups of the azo-dye cations were methyl, ethyl and propyl groups. The extraction constants (K(ex)) for the ion association complexes of CuX(2)(-) and X(-) with these three azo-dye cations between an aqueous phase and several organic phases (chloroform, chlorobenzene, benzene and toluene) were determined. The extractabilities of CuX2 and X(-) were in the orders CuCl(2)(-)chlorobenzene>benzene>toluene. The difference in the value of log K(ex) between chloroform and chlorobenzene for CuX(2)(-) was much smaller than that for X(-) while between other solvents the differences in log K(ex) values for CuX(2)(-) and t were almost the same. From the extraction constants obtained, some possible extraction systems for a spectrophotometry for copper are predicted: they include one using chlorobenzene, the methyl derivative of the azo-dye, and iodide ion and one using chlorobenzene, the propyl derivative of the azo-dye and bromide ion.