LIQUID-LIQUID EXTRACTION OF TRANSITION METAL CATIONS BY CALIXARENE-BASED CYCLIC LIGANDS

ABSTRACT

The selective liquid-liquid extraction of various alkali and transition metal cations from the aqueous phase to the organic phase was carried out by using p-tert-butylcalix[4]arene (L1), p-tert-butylcalix[6]arene (L2), tetra-ethyl p-tert-butylcalix[4]arene-tetra-acetate (L3), tetra-methyl-p-tert-butyl-calix[4]arene-tetra-ketone (L4), calix[n]arenes (n=4 and 6) bearing oxime groups on the lower rim (L5, L6 ) and a polymeric calix[4]arene. It was found that compounds L5 and L6, showed selectivity towards Ag⁺, Hg⁺, Hg²⁺, Cu²⁺, and Cr3³⁺ and the order of the extractability was Hg⁺>Hg²⁺>Ag⁺>Cu²⁺>Cr³⁺. The polymeric calix[4]arene (L8) was selective for Ag+, Hg+ and Hg2+, unlike its monomeric analog.