Extraction of Alkaline and Alkaline-Earth Metal Cations at Synergistic Action of Bis[undecahydro-7,8-dicarbaundecaborato(2-)]cobaltate(1-) and Substituted Calix[n]arenes in Nitrobenzene

The extraction of alkaline and alkaline-earth metal cations at synergistic action of bis[undecahydro-7,8-dicarbaundecaborato(2-)]cobaltate(1-) and substituted calix[n]arenes (n = 4 and 6) in nitrobenzene was investigated. It was found that the lower-rim-substituted calix[4]arene with four (diethylcarbamoyl)methyl groups extracts calcium, strontium and barium in the systems under study much better than calixarenes which do not contain amide groups. Synergistic factor values log S(Ca) = 7, log S(Sr) = 5.5 and log S(Ba) = 5.4 were found. The competition of K+ and Na+ in the extraction of strontium is much lower than in analogous systems containing crown ethers. The addition of calixarene causes a synergistic effect in the extraction of sodium and an antagonistic effect in the extraction of cesium.