Solvent Extraction of Fe3+ Cation by Diazo-Coupling Calix[4]arenes

The solvent extraction of Fe3+ cations from the aqueous to the organic (chloroform) phase was car-ried out using p-tert-butyl calix[4]arene(1), calix[4]arene(2), diazo-coupling calix[4]arenes [p-(4-n-butyl-phenylazo)calix[4]arene (3), p-(4-phenylazophenylazo)calix[4]arene(4), p-(4-acetanilidazo)calix[4]arene(5), p-(N’-2-thyazol-2ylsulphanylazo)calix[4]arene(6) and p-(2-thyazolazo)calix[4]arene(8) and the derivatives of phenol [2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(8) (Bromo-PADAP) and 2-hydroxy-5-methyl-phenylazonapthol(9) (HMPAN)]. It was found that the compounds (1-9) showed the highest extractability toward Fe3+ at pH 4.5-5.4 Compound 5 shows strong binding ability to Fe3+ ion. Based on the method of continuous variation, calixarene 5 formed a 1:1 complex with Fe3+ ion. 1