4-TERT-BUTYLCALIX[4]ARENE TETRAHYDROXAMATE CHELATORS FOR THE SELECTIVE EXTRACTION OF ACTINIDE IONS - SYNTHESIS AND PRELIMINARY METAL-ION EXTRACTION STUDIES

Organic extractants capable of selective and efficient removal of acti nides such as plutonium and americium from aqueous process waste strea ms are potentially useful in radioactive waste remediation. In this co ntext, with the help of molecular modelling, the 4-tert-butylcalix[4]a rene tetrahydroxamate chelators 1 and 2 have been identified as struct ures capable of achieving the selective solvent extraction of actinide (iv) ions from aqueous solutions. The syntheses of 1 and 2 from 4-tert -butylcalix[4]arene have been accomplished in moderate yields using sh ort synthetic sequences. Some extraction studies have been performed u sing Th4+ (as a surrogate for Pu4+), Fe3+, UO22+ and Cu2+ to estimate the metal ion selectivity and extraction efficacy of these chelators. Our preliminary results show these ligands are capable of extracting t horium(IV) efficiently but that they may not be selective for its extr action in the presence of iron(III).