Potassium ethyl xanthate
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| Preferred IUPAC name
Potassium O-ethylcarbonodithioate | |
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3D model (JSmol)
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| ECHA InfoCard | 100.004.946 |
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| 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: | |
| 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
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Sodium ethyl xanthate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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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. Many xanthates are known.
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
The salt KS2COC5H11, prepared from potassium pentanolate and carbon disulfide has been characterized by X-ray crystallography. The COCS2 portion of the anion is planar. The C-S bond lengths are both 1.65 Å, and the C-O distance is 1.38 Å.[3]
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 of xanthate salts gives diethyl dixanthogen disulfide:
- 4 CH3CH2OCS2K + 2 H2O + O2 → 2 (CH3CH2OCS2)2 + 4 KOH
KEX is a source of ethylxanthate coordination complexes. For example, the octahedral complexes (CH3CH2OCS2)3Cr, (CH3CH2OCS2)3In, and (CH3CH2OCS2)3Co have been prepared from KEX.[4]
Applications
Potassium ethyl xanthate is used in the mining industry as flotation agent for extraction of the ores of copper, nickel, and silver.[5] The method exploits the affinity of these "soft" metals for the organosulfur ligand.
Potassium ethyl xanthate is a useful reagent for preparing xanthate esters from alkyl and aryl halides. The resulting xanthate esters are useful intermediates in organic synthesis.[6]
Safety
The LD50 is 103 mg/kg (oral, rats) for potassium ethyl xanthate.[5]
References
- ^ Report 5 (1995) p. 5
- ^ 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.
- ^ N. A. Frolova, T. I. Malinovskii, V. Kh. Kravtsov, Yu. M. Chumakov, S. B. Leonov (1991). "КРИСТАЛЛИЧЕСКАЯ И МОЛЕКУЛЯРНАЯ СТРУКТУРА АМИЛКСАНТОГЕНАТА КАЛИЯ" [Crystal and Molecular Structure of Potassium Amylxanthate]. Dokl.Akad.Nauk SSSR (Proc.Nat.Acad.Sci.USSR) (in Russian). 316 (2): 371.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ 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. p. 42. doi:10.1002/9780470132418.ch6. ISBN 978-0-470-13169-5.
- ^ a b Kathrin-Maria Roy (2005). "Xanthates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a28_423. ISBN 3527306730.
- ^ One of several procedures using xanthate esters: Fabien Gagosz, Samir Z. Zard (1948). "A Xanthate-Transfer Approach to α-Trifluoromethylamines". Organic Syntheses. 84: 32. doi:10.15227/orgsyn.084.0032.