| 词条 | Sodium ethyl xanthate |
| 释义 |
| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 422175173 | Name = Sodium ethyl xanthate | ImageFile = Sodium-ethylxanthate-2D-skeletal.png | ImageSize = | ImageName = | ImageFile1 = Sodium ethyl xanthate 3D ball.png | ImageAlt1 = Ball-and-stick model of the component ions of sodium ethyl xanthate | IUPACName = sodium O-ethylcarbonodithioate | OtherNames = Sodium ethylxanthogenate Sodium-O-ethyl dithiocarbonate |Section1={{Chembox Identifiers | CASNo = 140-90-9 | CASNo_Ref = {{cascite|correct|??}}= | CASNoOther = | EINECS = 205-440-9 | SMILES = CCOC(=S)[S-].[Na+] | InChI = 1S/C3H6OS2.Na/c1-2-4-3(5)6;/h2H2,1H3,(H,5,6);/q;+1/p-1 | InChIKey = RZFBEFUNINJXRQ-UHFFFAOYSA-M | PubChem = 8824 | ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} | ChemSpiderID = 8493 | MeSHName = }} |Section2={{Chembox Properties | C=3 | H=5 | O=1 | S=2 | Na=1 | Appearance = Pale yellow powder[1] | Density = 1.263 g/cm3[1] | MeltingPtC = 182 to 256 | MeltingPt_ref = [1] | BoilingPt = decomposes | Solubility = 450 g/L (10 °C)[1] | pKa = 1.6[1] | pKb = 12.4[1]}} |Section7={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPtC = 250 | AutoignitionPt_ref = [2] | RPhrases = {{R15}} {{R21}} {{R22}} {{R29}} {{R36}} {{R38}} | SPhrases = {{S3}} {{S9}} {{S35}} {{S36}} {{S37}} {{S38}} {{S39}} {{S16}} {{S23}} {{S51}} }} }} Sodium ethyl xanthate (SEX)[3] is an organosulfur compound with the chemical formula CH3CH2OCS2Na. It is a pale yellow powder, which is usually obtained as the dihydrate. Sodium ethyl xanthate is used in the mining industry as a flotation agent.[4] A closely related potassium ethyl xanthate (KEX) is obtained as the anhydrous salt. ProductionAs with most xanthates, sodium ethyl xanthate can be prepared by treating sodium ethoxide with carbon disulfide:[5] CH3CH2ONa + CS2 → CH3CH2OCS2Na PropertiesSodium ethyl xanthate is a pale yellow powder. It is relatively stable in water at high pH if not heated. It rapidly hydrolyses at pH <9 at 25 °C. It is the conjugate base of the unknown strong acid with pKa of 1.6 and pKb estimated as 12.4 for the conjugate base. Sodium ethyl xanthate easily adsorbs on the surface of solid sulfides.[6] Decomposition in waterXanthate are susceptible to hydrolysis and oxidation:[7]
These reactions require acidic conditions. DetectionSodium ethyl xanthate can be identified through optical absorption peaks in the infrared (1179, 1160, 1115, 1085 cm−1) and ultraviolet (300 nm) ranges. There are at least six chemical detection methods:
Sodium ethyl xanthate can also be quantified using gravimetry, by weighing the lead xanthate residue obtained after reacting SEX with 10% solution of lead nitrate. There are also several electrochemical detection methods, which can be combined with some of the above chemical techniques.[9] ApplicationsSodium ethyl xanthate is predominantly used in the mining industry as flotation agent for recovery of metals, such as copper, nickel, silver or gold, as well as solid metal sulfides or oxides from ore slurries. This application was introduced by Cornelius H. Keller in 1925. Other applications include defoliant, herbicide and an additive to rubber to protect it against oxygen and ozone.[10] The mechanism of flotation enhancement is as follows. The polar part of xanthate molecule attaches to the ore particles with the non-polar hydrocarbon part sticking out and forming a hydrophobic layer. Then the particles are brought to the water surface by air bubbles. Only a small amount of about 300 g/tonne of ore is required for efficient separation. The efficiency of the hydrophobic action increases, but the selectivity to ore type decreases with increasing length of the hydrocarbon chain in xanthates. The chain is shortest in sodium ethyl xanthate that makes it highly selective to copper, nickel, lead, gold and zinc ores. Aqueous solutions (10%) with pH=7–11 are normally used in the process.[11] In 2000, Australia produced up to 10,000 tonnes of sodium ethyl xanthate and imported about 6,000 tonnes, mostly from China.[12] The material produced in Australia is the so-called 'liquid sodium ethyl xanthate' that refers to a 40% aqueous solution of the solid.[13] It is obtained by reacting carbon disulfide with sodium hydroxide and ethanol in a closed process.[24] Its density is 1.2 g/cm3 and the freezing point is −6 °C.[14] SafetySodium ethyl xanthate has moderate oral and dermal toxicity in animals and is irritating to eyes and skin.[15] It is especially toxic to aquatic life and therefore its disposal is strictly controlled.[16] Median lethal dose for (male albino mice, oral, 10% solution at pH~11) is 730 mg/kg of body weight, with most deaths occurring in the first day. The most affected organs were the central nervous system, liver and spleen.[17] Since 1993, sodium ethyl xanthate is classified as a Priority Existing Chemical in Australia, meaning that its manufacture, handling, storage, use or disposal may result in adverse health or environment effects. This decision was justified by the widespread use of the chemical in industry and its decomposition to the toxic and flammable carbon disulfide gas. From two examples of sodium ethyl xanthate spillage in Australia, one resulted in evacuation of 100 people and hospitalization of 6 workers who were exposed to the fumes. In another accident, residents of the spillage area complained of headache, dizziness and nausea.[18] Consequently, during high-risk sodium ethyl xanthate handling operations, workers are required by the Australian regulations to be equipped with protective clothing, anti-static gloves, boots and full-face respirators or self-contained breathing apparatus.[19] References1. ^1 2 3 4 5 Report 5 (1995) p. 5 2. ^Report 5 (1995) p. 6 3. ^{{cite book|author=Caroline Cooper|title=Organic Chemist's Desk Reference|url=https://books.google.com/books?id=ahbUc5M0I5AC&pg=PA123|accessdate=22 February 2011|date=23 July 2010|publisher=CRC Press|isbn=978-1-4398-1164-1|pages=123 (Acronyms and Miscellaneous Terms used in Describing Organic Molecules)}} 4. ^{{cite encyclopedia|author=Kathrin-Maria Roy|title=Xanthates|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|year=2005|publisher= Wiley-VCH|location=Weinheim|doi=10.1002/14356007.a28_423}} 5. ^{{cite journal|authors=Ingram, G.; Toms, B. A.|title=The reactions of sodium ethyl xanthate with ethanol and with water. |journal=Journal of the Chemical Society (Resumed)|year=1961|pages=117-127|doi=10.1039/JR9610000117}} 6. ^Report 5 (1995) p. 6 7. ^Report 5 (1995) pp. 14–16 8. ^Report 5 (1995) p. 8 9. ^1 2 3 4 5 Report 5 (1995) p. 9 10. ^Report 5 (1995), p. 2, citing Rao, R.S., “Xanthates and Related Compounds”, Marcel Dekker, New York, 1971 {{ISBN|0-8247-1563-2}} and Keller, C.H. (1925) {{US Patent|1554216}} "Concentration of gold, sulphide minerals and uranium oxide minerals by flotation from ores and metallurgical plant products" 11. ^Report 5 (1995) p. 13 12. ^Report 5s (2000) p. 1 13. ^Report 5s (2000) p. 3 14. ^Report 5s (2000) p. 7 15. ^1 Report 5s (2000) p. v 16. ^Report 5 (1995) pp. 43–45 17. ^Report 5 (1995) p. 17 18. ^Report 5 (1995) p. 1 19. ^Report 5s (2000) p. vi Bibliography
3 : Salts|Thiocarbonyl compounds|Organic sodium salts |
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