French
DeutschPotassium ethyl xanthate
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| Names | |
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| Preferred IUPAC name Potassium O-ethylcarbonodithioate | |
Other names
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| Identifiers | |
3D model (JSmol) | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.004.946 |
| EC Number |
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PubChem CID | |
| UNII | |
CompTox Dashboard (EPA) | |
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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: | |
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| 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). | |
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
[edit]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
[edit]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
[edit]The LD50 is 103 mg/kg (oral, rats) for potassium ethyl xanthate.[5]
References
[edit]- ^ 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". Inorganic Syntheses. 10: 42. doi:10.1002/9780470132418.ch6.
- ^ 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.