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 carried out using p-tert-butyl calix[4]arene((1) under bar), calix[4]arene((2) under bar), diazo-coupling calix[4]arenes [p-(4-n-butylphenylazo)calix[4]arene ((3) under bar), p-(4-phenylazophenylazo)calix[4]arene((4) under bar), p-(4-acetanilidazo)calix[4]arene((5) under bar), p-(N'-2-thyazol-2ylsulphanylazo)calix[4]arene((6) under bar) and p-(2-thyazolazo)calix[4]arene((8) under bar) and the derivatives of phenol [2-(5-bromo-2-pyridylazo)-5-diethylaminophenol((8) under bar) (Bromo-PADAP) and 2-hydroxy-5-methylphenylazonapthol((9) under bar) (HMPAN)]. It was found that the compounds ((1) under bar-(9) under bar) showed the highest extractability toward Fe3+ at pH 4.5-5.4 Compound (5) under bar shows strong binding ability to Fe3+ ion. Based on the method of continuous variation, calixarene 5 formed a 1:1 complex with Fe3+ ion