Abstract
AbstractMacrocyclic ligands were designed according to the principle of ion recognition, synthesized and tested in their capability to extract AuIII. Different from other complexants which require ligand exchange prior to complexation, the reported ligands bind the complexes AuCl3 and AuCl4−. With a sufficiently sized macrocyclic cavity, hydrophobic calix[6]arenes derivatized at the “lower rim’ were employed for that purpose. Their ligating functionalities contain pyridino, amide or thioamide groups in order to achieve electron donor‐acceptor and electrostatic host‐guest interactions. We report the synthesis route and results on extraction, selectivity, kinetics and back‐extraction and compare with commercial extractants. Quantitative extraction from hydrochloric acid solutions was achieved as well as over 99% recovery in back‐extraction in one step each. Data on the selectivity over base metals, which are representative for the matrix in gold ores are provided. The ligands are powerful extractants for AuIII and show fast complexation kinetics. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
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