Gold(III) chloride
Ball-and-stick model of AuCl3
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Crystal structure of AuCl3
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Names | |
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IUPAC name
Gold(III) trichloride
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Other names
Auric chloride
Gold trichloride | |
Identifiers | |
3D model (
JSmol ) |
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ChEBI | |
ChemSpider | |
ECHA InfoCard
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100.033.280 |
PubChem CID
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RTECS number
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
AuCl3 (exists as Au2Cl6) | |
Molar mass | 606.6511 g/mol |
Appearance | Red crystals (anhydrous); golden, yellow crystals (monohydrate)[1] |
Density | 4.7 g/cm3 |
Melting point | 160 °C (320 °F; 433 K) (decomposes) |
68 g/100 ml (20 °C) | |
Solubility | soluble in ether and ethanol, slightly soluble in liquid ammonia, insoluble in benzene |
−112·10−6 cm3/mol | |
Structure | |
monoclinic
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P21/C | |
a = 6.57 Å, b = 11.04 Å, c = 6.44 Å α = 90°, β = 113.3°, γ = 90°[2]
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Square planar | |
Thermochemistry | |
Std enthalpy of (ΔfH⦵298)formation |
−117.6 kJ/mol[3] |
Hazards[4] | |
Occupational safety and health (OHS/OSH): | |
Main hazards
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Irritant |
GHS labelling: | |
Warning | |
H315, H319, H335 | |
P261, P264, P271, P280, P302+P352, P305+P351+P338 | |
Related compounds | |
Other anions
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Gold(III) fluoride Gold(III) bromide |
Other cations
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Supplementary data page | |
Gold(III) chloride (data page) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Gold(III) chloride, traditionally called auric chloride, is an
Structure
AuCl3 exists as a
Each gold center is
Properties
Gold(III) chloride is a
Preparation
Gold(III) chloride was first prepared in 1666 by Robert Boyle by the reaction of metallic gold and chlorine gas at 180 °C:[1][6][7]
- 2 Au + 3 Cl2 → Au2Cl6
This method is the most common method of preparing gold(III) chloride. It can also be prepared by reacting gold powder with iodine monochloride:[5]
- 2 Au + 6 ICl → 2 AuCl3 + 3 I2
The
Another method of preparation is via chloroauric acid, which is obtained by first dissolving the gold powder in aqua regia to give chloroauric acid:[9]
- Au + HNO3 + 4 HCl → H[AuCl4] + 2 H2O + NO
The resulting chloroauric acid is subsequently heated in an inert atmosphere at around 100 °C to give Au2Cl6:[10][11]
- 2 H[AuCl4] → Au2Cl6 + 2 HCl
Reactions
Decomposition
Anhydrous AuCl3 begins to decompose to AuCl (gold(I) chloride) at around 160 °C (320 °F), however, this, in turn, undergoes disproportionation at higher temperatures to give gold metal and AuCl3:[5][10]
- AuCl3 → AuCl + Cl2 (160 °C)
- 3 AuCl → AuCl3 + 2 Au (>210 °C)
Due to the disproportionation of AuCl, above 210 °C, most of the gold is in the form of elemental gold.[12][11]
Gold(III) chloride is more stable in a chlorine atmosphere and can sublime at around 200 °C without any decomposition. In a chlorine atmosphere, AuCl3 decomposes at 254 °C yielding AuCl which in turn decomposes at 282 °C to elemental gold.[2][13] This fact that no gold chlorides can exist above 400 °C is used in the Miller process.[14]
Other reactions
AuCl3 is a
- HCl + AuCl3 → H+ + [AuCl4]−
Chloroauric acid is the product formed when gold dissolves in aqua regia.[15]
On contact with water, AuCl3 forms
Other chloride sources, such as
Gold(III) chloride is the starting point for the chemical synthesis of many other gold compounds. For example, the reaction with potassium cyanide produces the water-soluble complex, K[Au(CN)4]:[20]
- AuCl3 + 4 KCN → K[Au(CN)4] + 3 KCl
Gold(III) fluoride can be also produced from gold(III) chloride by reacting it with bromine trifluoride.[15]
Gold(III) chloride reacts with
- 2 PhH + Au2Cl6 → [PhAuCl2]2 + 2 HCl
Gold(III) chloride reacts with carbon monoxide in a variety of ways. For example, the reaction of anhydrous AuCl3 and carbon monoxide under SOCl2 produces gold(I,III) chloride with Au(CO)Cl as an intermediate:[22][23]
- 2 AuCl3 + 2 CO → Au4Cl8 + 2 COCl2
If carbon monoxide is in excess, Au(CO)Cl is produced instead.[24][25]
However, under tetrachloroethylene and at 120 °C, gold(III) chloride is first reduced to gold(I) chloride, which further reacts to form Au(CO)Cl. AuCl3 is also known to catalyze the production of phosgene.[25][26]
Applications
Although gold(III) chloride has no commercial uses, it has many uses in the laboratory.[5]
Organic synthesis
Since 2003, AuCl3 has attracted the interest of organic chemists as a mild acid catalyst for various reactions,
Gold catalyses the
The efficiency of this
This reaction involves a rearrangement that gives a new aromatic ring.[30]
Another example of an AuCl3 catalyzed reaction is a hydroarylation, which is basically a
Gold(III) chloride can be used for the direct oxidation of primary
This reaction is pH sensitive, requiring a mildly acidic pH to proceed, however, it does not require any additional steps.[5]
In the production of organogold(III) compounds, AuCl3 is used as a source of gold. A main example of this is the production of monoarylgold(III) complexes, which are produced by direct
Gold nanoparticles
Gold(III) chloride is used in the synthesis of gold nanoparticles, which are extensively studied for their unique size-dependent properties and applications in fields such as electronics, optics, and biomedicine. Gold nanoparticles can be prepared by reducing gold(III) chloride with a reducing agent such as sodium tetrafluoroborate, followed by stabilization with a capping agent.[33]
Photography
Gold(III) chloride has been used historically in the photography industry as a sensitizer in the production of photographic films and papers. However, with the advent of digital photography, its use in this field has diminished.[34]
Natural occurrence
This compound does not occur naturally; however, a similar compound with the formula AuO(OH,Cl)·nH2O is known as a product of natural gold oxidation.[35][36]
References
- ^ ISBN 978-0-12-352651-9.
- ^ . Retrieved 2010-05-21.
- )
- ^ "Gold Chloride". American Elements. Retrieved July 22, 2019.
- ^ ISBN 9780470842898.
- ^ Robert Boyle (1666). The origine of formes and qualities. p. 370.
- .
- doi:10.1071/C97029.
- ISBN 9780470132357.
- ^ a b Ya-jie Zheng; Wei Guo; Meng Bai; Xing-wen Yang (2006). "Preparation of chloroauric acid and its thermal decomposition". The Chinese Journal of Nonferrous Metals (in Chinese). 16 (11): 1976–1982. Archived from the original on March 27, 2024.
- ^ .
- PMID 25463171.
- .
- ISBN 978-3-527-30673-2.
- ^ ISBN 9780750633659.
- ^ Cotton, F.A.; Wilkinson, G.; Murillo, C.A.; Bochmann, M. Advanced Inorganic Chemistry; John Wiley & Sons: New York, 1999; pp. 1101-1102
- ISBN 978-0-911910-00-1.
- McGraw-Hill, New York, 1968, p. 222
- ^ A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984, p. 909
- ^ Henry K. Lutz (1961). "Synthesis and Analyses of KAu(CN)4". Honors Theses. Union Digital Works.
- PMID 18613729.
- .
- .
- ISBN 9780470132555.
- ^ ISBN 9780080538808.
- .
- ^ G. Dyker, An Eldorado for Homogeneous Catalysis?, in Organic Synthesis Highlights V, H.-G. Schmaltz, T. Wirth (eds.), pp 48–55, Wiley-VCH, Weinheim, 2003
- .
- ^ .
- PMID 15806608.
- .
- ISSN 0002-7863.
- .
- S2CID 136538890.
- ^ "UM1995-16-O:AuClH". mindat.org. Retrieved 27 April 2023.
- ^ John L. Jambor; Nikolai N. Pertsev; Andrew C. Roberts (1996). "New Mineral Names" (PDF). American Mineralogist. 81: 768.
External links
- Media related to Gold trichloride at Wikimedia Commons