Sulfur-derivatized calixarenes as selective extractants for heavy and precious metal ions
Description
The compounds 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-N, N-dimethyldithiocarbamoylethoxy) calix (4) arene, 25,26,27,28-tetra-(2-N, N-dimethyldithiocarbamoylethoxy)calix (4) arene, 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-mercaptoethoxy)calix (4) arene, 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-(methylthio)ethoxy)calix lbrack 4) arene, 25,26,27,28-tetra-(2-(methylthio)ethoxy)calix (4) arene, 25,26,27,28-tetra-(2-(2-pyridylthio)ethoxy)calix (4) arene tetra-N-oxide and 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-(2-thiophenecarboxy)ethoxy)calix (4) arene have been synthesized. They have been characterized by proton NMR spectroscopy, carbon-13 NMR spectroscopy, infrared spectroscopy and elemental analysis. In addition, the crystal structures of 25,26,27,28-tetra-(2-hydroxyethoxy)calix (4) arene, 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-bromoethoxy)calix (4) arene, 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-(2-N,N-dimethyldithiocarbamoylethoxy) calix (4) arene, 25,26,27,28-tetra-(2-N,N-dimethyldithiocarbamoylethoxy)calix (4) arene and 25,26,27,28-tetra-(2-(methylthio)ethoxy)calix (4) arene have been determined by single crystal X-ray diffraction. These sulfur derivatized calixarene derivatives have been found to be selective extractants for heavy and precious metal ions such as Hg(II), Ag(I), Pd(II), Au(III) into chloroform from water. The potential of these ligands as extraction agents in environmental cleaning operations and industrial separations are discussed