Dissolution of copper and gold in the donor-acceptor systems DMSO-NH4Xaq (X = Cl, Br, and I) and NH4Iaq-O2

Shirshova, L. V.; Lavrentiev, Igor P.

doi:10.1007/s11172-012-0144-0

“…The alternative system DMSO−NH 4 X aq can dissolve copper as well. 74 The mechanism for the formation of intermediates active for metal dissolution shown in Scheme 12 is similar to that for the system DMSO−-HX.…”

Section: Dmso With Halide Acids or Saltsmentioning

confidence: 99%

Oxidative Dissolution of Metals in Organic Solvents

Li

¹

,

Binnemans

²

2021

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Dissolution of metals in organic solvents is relevant to various application fields, such as metal extraction from ores or secondary resources, surface etching or polishing of metals, direct synthesis of organometallic compounds, and separation of metals from other compounds. Organic solvents for dissolution of metals can offer a solution when aqueous systems fail, such as separation of metals from metal oxides, because both the metal and metal oxide could codissolve in aqueous acidic solutions. This review critically discusses organic media (conventional molecular organic solvents, ionic liquids, deep-eutectic solvents and supercritical carbon dioxide) for oxidative dissolution of metals in different application areas. The reaction mechanisms of dissolution processes are discussed for various lixiviant systems which generally consist of oxidizing agents, chelating agents, and solvents. Different oxidizing agents for dissolution of metals are reviewed such as halogens, halogenated organics, donor–acceptor electron-transfer systems, polyhalide ionic liquids, and others. Both chemical and electrochemical processes are included. The review can guide researchers to develop more efficient, economic, and environmentally friendly processes for dissolution of metals in their elemental state.

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“…Commonly, halogens are coupled in a charge‐complex[ 34 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ] (Figure 1 , c) with various S ‐donor ligands, in particular, dithiooxamides,[ 38 , 39 , 40 , 41 , 42 ] dithiocarbamates,[ 42 , 43 , 44 ] thiourea[ 44 , 45 ] and thioimidophosphinic acid [46] compounds. The latter then stabilize Au III and Au I centres in THF,[ 38 , 39 , 40 , 41 ] MeCN,[ 41 , 47 , 48 ] DCM,[ 45 , 48 ] chloroform, [39] DMSO, [49] acetone,[ 41 , 42 , 43 ] MEK, [41] Et 2 O,[ 44 , 46 ] ionic liquids,[ 50 , 51 ] deep eutectic solvent, [52] or even in water. [34] Similar to aqueous iodine‐iodine leaching, over stoichiometric amounts of halogen are needed for quantitative dissolution of Au.…”

Section: Introductionmentioning

confidence: 99%

Iodine‐Catalysed Dissolution of Elemental Gold in Ethanol

Zupanc

¹

,

Heliövaara

²

,

Moslova

³

et al. 2022

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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-mercaptobenzimidazole 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 [Au I I 2 ] À species, which undergoes subsequent ligand-exchange reactions and forms a stable bis-ligand Au I complex. H 2 O 2 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.

show abstract

“…Commonly, halogens are coupled in a charge-complex [34,[38][39][40][41][42][43][44][45][46] (Figure 1, c) with various S-donor ligands, in particular, dithiooxamides, [38][39][40][41][42] dithiocarbamates, [42][43][44] thiourea [44,45] and thioimidophosphinic acid [46] compounds. The latter then stabilize Au III and Au I centres in THF, [38][39][40][41] MeCN, [41,47,48] DCM, [45,48] chloroform, [39] DMSO, [49] acetone, [41][42][43] MEK, [41] Et 2 O, [44,46] ionic liquids, [50,51] deep eutectic solvent, [52] or even in water. [34] Similar to aqueous iodine-iodine leaching, over stoichiometric amounts of halogen are needed for quantitative dissolution of Au.…”

Section: Introductionmentioning

confidence: 99%

Iodine‐Catalysed Dissolution of Elemental Gold in Ethanol

Zupanc

¹

,

Heliövaara

²

,

Moslova

³

et al. 2022

View full text Add to dashboard Cite

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-mercaptobenzimidazole 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 [Au I I 2 ] À species, which undergoes subsequent ligand-exchange reactions and forms a stable bis-ligand Au I complex. H 2 O 2 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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Dissolution of copper and gold in the donor-acceptor systems DMSO-NH4Xaq (X = Cl, Br, and I) and NH4Iaq-O2

Cited by 3 publications

References 4 publications

Oxidative Dissolution of Metals in Organic Solvents

Oxidative Dissolution of Metals in Organic Solvents

Iodine‐Catalysed Dissolution of Elemental Gold in Ethanol

Iodine‐Catalysed Dissolution of Elemental Gold in Ethanol

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