Potassium ethyl xanthate

Potassium ethyl xanthate (KEX) is an organosulfur compound with the chemical formula CH₃CH₂OCS₂K. It is a pale yellow powder that is used in the mining industry for the separation of ores. It is a potassium salt of ethyl xanthic acid.

Potassium ethyl xanthate

Names
Preferred IUPAC name Potassium O-ethylcarbonodithioate
Other names Potassium ethylxanthogenate Potassium ethylxanthate Potassium-O-ethyl dithiocarbonate
Identifiers
CAS Number	140-89-6 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL2380738
ChemSpider	8491 Y
ECHA InfoCard	100.004.946
EC Number	205-439-3
PubChem CID	2735045
UNII	1A6K3Y576K Y
CompTox Dashboard (EPA)	DTXSID6042315
InChI InChI=1S/C3H6OS2.K/c1-2-4-3(5)6;/h2H2,1H3,(H,5,6);/q;+1/p-1 Y Key: JCBJVAJGLKENNC-UHFFFAOYSA-M Y InChI=1S/C3H6OS2.K/c1-2-4-3(5)6;/h2H2,1H3,(H,5,6);/q;+1/p-1
SMILES [K+].[S-]C(=S)OCC
Properties
Chemical formula	CH3CH2OCS2K
Molar mass	160.29 g·mol−1
Appearance	Pale yellow powder
Density	1.263 g/cm3[1]
Melting point	225 to 226 °C (437 to 439 °F; 498 to 499 K)
Boiling point	decomposes
Acidity (pKa)	approximately 1.6
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H228, H302, H315, H319, H332, H335
Precautionary statements	P210, P240, P241, P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P370+P378, P403+P233, P405, P501
Related compounds
Other cations	Sodium ethyl xanthate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Production and properties

Xanthate salts are prepared by the action of alkoxides on carbon disulfide. The alkoxide is often generated in situ from potassium hydroxide:^[2]

CH₃CH₂OH + CS₂ + KOH → CH₃CH₂OCS₂K + H₂O

Potassium ethyl xanthate is a pale yellow powder that is stable at high pH, but rapidly hydrolyses below pH = 9:

CH₃CH₂OCS₂K + H⁺ → CH₃CH₂OH + CS₂ + K⁺

Oxidation gives diethyl dixanthogen disulfide:

4 CH₃CH₂OCS₂K + 2 H₂O + O₂ → 2 (CH₃CH₂OCS₂)₂ + 4 KOH

KEX is a source of ethylxanthate coordination complexes. For example (CH₃CH₂OCS₂)₃M have been prepared from KEX for M = Cr, In, Co.^{[clarification needed][3]}

Applications

Potassium ethyl xanthate is used in the mining industry as flotation agent for extraction of the ores of copper, nickel, and silver.^[4] The method exploits the affinity of these "soft" metals for the organosulfur ligand.

Potassium xanthate is a useful reagent for preparing xanthate esters from alkyl and aryl halides. The resulting xanthate esters are useful intermediates in organic synthesis.^[5]

Safety

The LD₅₀ is 103 mg/kg (oral, rats) for potassium ethyl xanthate.^[4]

References

1. Report 5 (1995) p. 5
2. This report gives a detailed recipe for potassium ethyl xanthate: Charles C. Price, Gardner W. Stacy (1948). "p-Nitrophenyl) Sulfide". Organic Syntheses. 28: 82. doi:10.15227/orgsyn.028.0082.
3. Galsbøl, F.; Schäffer, C. E. (1967). "Tris ( O -Ethyldithiocarbonato) Complexes of Tripositive Chromium, Indium, and Cobalt". Tris (O-Ethyldithiocarbonato) Complexes of Tripositive Chromium, Indium, and Cobalt. Inorganic Syntheses. Vol. 10. pp. 42–49. doi:10.1002/9780470132418.ch6. ISBN 978-0-470-13169-5.
4. Kathrin-Maria Roy (2005). "Xanthates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a28_423. ISBN 3527306730.
5. One of several procedures using xanthate esters: Fabien Gagosz and Samir Z. Zard (1948). "A Xanthate-Transfer Approach to α-Trifluoromethylamines". Organic Syntheses. 84: 32; Collected Volumes, vol. 11, p. 212.