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. Unlike the related sodium ethyl xanthate, the potassium salt exists as an anhydrous salt.

Potassium ethyl xanthate

Names
IUPAC name potassium O-ethylcarbonodithioate
Other names potassium ethylxanthogenate potassium-O-ethyl dithiocarbonate
Identifiers
CAS Number	140-89-6
3D model (JSmol)	Interactive image
ChemSpider	8491
ECHA InfoCard	100.004.946
PubChem CID	2735045
UNII	1A6K3Y576K
CompTox Dashboard (EPA)	DTXSID6042315
InChI InChI=1S/C3H6OS2.K/c1-2-4-3(5)6;/h2H2,1H3,(H,5,6);/q;+1/p-1 Key: JCBJVAJGLKENNC-UHFFFAOYSA-M 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	C3H5KOS2
Molar mass	160.29 g·mol^−1
Appearance	Pale yellow powder
Density	1.263 g/cm^3[1]
Melting point	225 to 226 °C (437 to 439 °F; 498 to 499 K)
Boiling point	decomposes
Acidity (pKa)	approximately 1.6
Hazards
R-phrases (outdated)	R15 R21 R22 R29 R36 R38
S-phrases (outdated)	S3 S9 S35 S36 S37 S38 S39 S16 S23 S51
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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 at pH <9 at 25 °C. Unlike the sodium derivative, potassium xanthate crystallizes as the anhydrous salt and is non-hygroscopic.

Applications

Potassium ethyl xanthate is used in the mining industry as flotation agent for extraction of the ores of copper, nickel, and silver.[3] 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.[4]

Safety

The ${\displaystyle {\text{LD}}_{50}}$ is 683 mg/kg (oral, rats) for potassium ethyl xanthate.[3]

References

1. Report 5 (1995) p. 5
2. This report gives a detailed procedure Charles C. Price and Gardner W. Stacy (1948). "p-nitrophenyl) sulfide". Organic Syntheses. 28: 82.; Collective Volume, 3, p. 667
3. Kathrin-Maria Roy (2005). "Xanthates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a28_423. ISBN 3527306730.
4. 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.; Collective Volume, 11, p. 212