Typically, two main classes of compounds, chelates and macrocycles, have been used commercially for the removal of toxic heavy metals such as lead, mercury, and chromium from a variety of industrial processes. Chelates, while inexpensive and easy to synthesize, are not selective enough for many applications. Macrocycles, while more selective for particular ions or compounds, are usually more expensive and difficult to synthesize The preparation and characterization of a series of compounds belonging to each of these classes have been described, and their extractive properties were examined. The chelating compounds are long chain alkyl substituted xanthates while the macrocyclic compounds are amine or carbamoyl substituted calix (4) arenes The complexes of cadmium(II) with the xanthate anions have also been synthesized, and the stoichiometry of the complexes in aqueous solution has been confirmed as 1:2 for cadmium: xanthate by the mole ratio method. While the aqueous solubility of the complexes decreases with increasing alkyl chain length, the addition of ionic detergents increases the aqueous solubility of the cadmium xanthates by some 20 percent. In addition the choline substituted xanthate ligand can be used for the electrokinetic extraction of cadmium ions from soils where its efficiency is approximately 10 percent that of EDTA The calix (4) arene amides have been prepared by reacting the precursor calix (4) arene with either 2-bromoacetamide or 2-chloro-N,N-diethylacetamide. The calix (4) arene amines have been synthesized by the borane reduction of either the precursor amide or cyanomethoxy derivative. As observed by UV-vis spectroscopy, the protonated calix (4) arene alkylamines are effective extractants for transferring chromate and dichromate anions from aqueous solution into a chloroform layer. Deprotonation of the calix (4) arene alkylammonium cations results in the reverse migration of the chromate and dichromate anions back into the aqueous layer. The amine and carbamoyl substituted calix (4) arenes have been investigated as extractants for several other anions also. Measurement of the remaining metal content by ICP has been used to obtain the distribution coefficient and percentage extraction into chloroform from aqueous solutions having a pH of both 0.85 and 7.0
