Wikipedia

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
Ball-and-stick model of the component ions of potassium ethyl xanthate
Names
Preferred IUPAC name
Potassium O-ethylcarbonodithioate
Other names
  • Potassium ethylxanthogenate
  • Potassium ethylxanthate
  • Potassium-O-ethyl dithiocarbonate
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.004.946 Edit this at Wikidata
EC Number
  • 205-439-3
UNII
  • InChI=1S/C3H6OS2.K/c1-2-4-3(5)6;/h2H2,1H3,(H,5,6);/q;+1/p-1 checkY
    Key: JCBJVAJGLKENNC-UHFFFAOYSA-M checkY
  • InChI=1S/C3H6OS2.K/c1-2-4-3(5)6;/h2H2,1H3,(H,5,6);/q;+1/p-1
  • [K+].[S-]C(=S)OCC
Properties
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:
GHS02: FlammableGHS07: Exclamation mark
Warning
H228, H302, H315, H319, H332, H335
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).
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Production and properties

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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

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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

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

References

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  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. ^ a b 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.
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