Solvent extraction diphenylthiocarbazone

The nature of the donor atoms in the chelating agent. Ligands which contain donor atoms of the soft-base type form their most stable complexes with the relatively small group of Class B metal ions (i.e. soft acids) and are thus more selective reagents. This is illustrated by the reagent diphenylthiocarbazone (dithizone) used for the solvent extraction of metal ions such as Pd2+, Ag+, Hg2+, Cu2+, Bi3+, Pb2+, and Zn2 +. ... 

Due to their relevance in solvent extraction and metal recovery, the facilitated transfer of transition metal ions has been investigated by the type of electrochemical methodology described above. This electrochemical approach has in fact proven to be a valuable tool for the study of the mechanism of solvent extraction processes. Wendt et al studied the transfer of Fe, Ni, and Zn assisted by bidentate nitrogen bases, such as phenanthroline and bipyridine. Similar studies were carried out by Wang et al and by Doe and Freiser, who also studied the transfer of cadmium assisted by diphenylthiocarbazone, a weak monobasic acid. Solomon et studied terpyridine as an extractant for transition metals. An interesting result from this type of work is... 

Haddock has shown that the yellow bismuth compound formed with potassium iodide can be quantitatively extracted by organic solvents, and in the presence of considerable quantities of highly coloured ions and other interfering metals it is possible to determine very small amounts of bismuth by this method. Lead and thallium in quantities greater than 0 5 mg are the only two elements which interfere seriously other interfering metals (antimony, copper, silver, mercury, tin), especially those which react with soluble iodides, are removed by extracting the bismuth with diphenylthiocarbazone in chloroform before proceeding to the colorimetric determination. 

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