Journal
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
Volume 61, Issue 14, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/anie.202117587
Keywords
Catalysis; Gold; Iodine; Recycling; Sustainable Chemistry
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Funding
- University of Helsinki, Slovenian Research Agency [P1-0230, P1-0201]
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This article describes a simple, inexpensive, and environmentally friendly method for dissolving gold which uses 2-mercaptoben-zimidazole as a ligand and a catalytic amount of iodine in ethanol. This method has the potential to open a new pathway for more sustainable metal recycling.
Gold is a scarce element in the Earth's crust but indispensable in modern electronic devices. New, sustainable methods of gold recycling are essential to meet the growing eco-social demand of gold. Here, we describe a simple, inexpensive, and environmentally benign dissolution of gold under mild conditions. Gold dissolves quantitatively in ethanol using 2-mercaptoben-zimidazole as a ligand in the presence of a catalytic amount of iodine. Mechanistically, the dissolution of gold begins when I-2 oxidizes Au-0 and forms a [(AuI2)-I-1](-) species, which undergoes subsequent ligand-exchange reactions and forms a stable bis-ligand Au-1 complex. H2O2 oxidizes free iodide and regenerated I-2 returns back to the catalytic cycle. Addition of a reductant to the reaction mixture precipitates gold quantitatively and partially regenerates the ligand. We anticipate our work will open a new pathway to more sustainable metal recycling with the utilization of just catalytic amounts of reagents and green solvents.
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