Potassium dicyanoaurate

Potassium dicyanoaurate
Ball-and-stick model of the aurocyanide or dicyanoaurate(I) complex anion
Ball-and-stick model of the aurocyanide or dicyanoaurate(I) complex anion, [Au(CN)2]−.[1]
Names
Other names
potassium dicyanoaurate(I)
Identifiers
3D model (JSmol)
6235525
ChEBI
ChemSpider
ECHA InfoCard 100.034.303
EC Number 237-748-4
37363
UNII
UN number 1588
Properties
C2AuKN2
Molar mass 288.10 g·mol−1
Appearance white powder
Boiling point decomposes
water-soluble
Hazards
Main hazards toxic
GHS pictograms
GHS signal word Warning
H300, H400, H310, H410, H330, H317, H290, H318, H315
P260, P264, P273, P280, P284, P301+310
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Potassium dicyanoaurate, also potassium dicyanoaurate(I), potassium gold cyanide, potassium gold dicyanide or gold potassium cyanide, is an inorganic compound with formula K[Au(CN)2]. It is a colorless to white crystalline powder, usually prepared by dissolving metallic gold in aqueous solution of potassium cyanide. It is most often used in gold plating applications. It contains 68.2 wt.% of gold. It is soluble in water and slightly soluble in alcohol.

Its CAS number is 13967-50-5 and its EC number number is 237-748-4. Its molar mass is 288.33 g/mol, its density is 3.45 g/cm3.


Potassium gold cyanide can be used for photoreduction of gold ions by nanopowder ZnO, preparation of gold-gold junction electrodes in voltammetric glucose detection,[2] and other reactions where metallic gold is prepared.

A trivalent compound, potassium tetracyanoaurate(III), K[Au(CN)4], also exists, but its use is less common.


The cyanide-gold complex penetrates cells much easier than gold ions alone, facilitating gold toxicity. Gold inhibits activity of many enzymes, hindering detoxification of the cyanide ion to thiocyanate, potentiating the cyanide toxicity.[3]

Gold mining

Potassium dicyanoaurate is produced in the cyanide process variant of gold mining.

Cyanide leaching "heap" at a gold mining operation near Elko, Nevada

The chemical reaction for the dissolution of gold, the "Elsner Equation", follows:

4 Au + 8 KCN + O2 + 2H2O → 4 K[Au(CN)2] + 4 KOH

In this redox process, oxygen removes, via a two-step reaction, one electron from each gold atom to form the complex Au(CN)−
2 ion.[4]

References

  1. ↑ Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
  2. ↑ https://www.alfa.com/en/catalog/012552/
  3. ↑ Wright, I. H.; Vesey, C. J. (September 1986). "Acute poisoning with gold cyanide". Anaesthesia. 41 (9): 936–939. doi:10.1111/j.1365-2044.1986.tb12920.x.
  4. ↑ (Web Archive) Technical Bulletin, https://web.archive.org/web/20091023235047/http://www.multimix.com.au/DOCUMENTS/Technical%20Bulletin1.PDF
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