Synthesis and Binding Studies of a Novel Highly Selective Ag(I) Ligand

Ligands bearing S- and N- donors are an important class of extractants with demonstrated efficiency and selectivity for Ag+ extraction over metals with similar chemistries. However, the synthesis of some of these ligands can be complicated and low yielding. Here, we report the synthesis of a novel ligand - N-(2-((4-vinylbenzyl)thio)ethyl)acetamide, over two simple steps and in a good yield. The extractant was observed to demonstrate excellent selectivity for Ag+, extracting only Ag+ from an aqueous solution also containing Cu2+ and Pb2+. Moderate extraction efficiencies of 36 % for Ag+ and 0% each for Cu2+ and Pb2+ were observed. From mass spectrometry and proton NMR titration data, the extractant was found to form both the 1:1 and 1:2 (Ag+:ligand) complexes with Ag+ indicating that ligand forms bent linear and tetrahedral coordination complexes with Ag+. Overall, the results indicate that the novel amide-based ligand is highly selective for Ag+ removal from aqueous solutions containing Cu2+ and Pb2+. These results indicate the ligand could be easily synthesized and applied for selective silver recovery from low grade ores.