| 词条 | Lithium carbide |
| 释义 |
| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 450703945 | ImageFile = lithium carbide.png | ImageSize = 120px | ImageName = Wireframe model of lithium carbide | PIN = Lithium carbide | SystematicName = Dilithium(1+) ethyne | OtherNames = Dilithium acetylide Lithium dicarbon Lithium percarbide | Section1 = {{Chembox Identifiers | InChI1 = 1/C2.2Li/c1-2;;/q-2;2*+1 | InChIKey1 = ARNWQMJQALNBBV-UHFFFAOYAB | CASNo_Ref = {{cascite|correct|??}} | CASNo = 1070-75-3 | ChemSpiderID = 59503 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | EINECS = 213-980-1 | PubChem = 66115 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C2.2Li/c1-2;;/q-2;2*+1 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = ARNWQMJQALNBBV-UHFFFAOYSA-N | SMILES = [Li+].[Li+].[C-]#[C-] | InChI = 1S/C2.2Li/c1-2;;/q-2;2*+1 | InChIKey = ARNWQMJQALNBBV-UHFFFAOYSA-N}} | Section2 = {{Chembox Properties | Formula = {{chem|Li|2|C|2}} | MolarMass = 37.9034 g/mol | Density = 1.3 g/cm³[1] | Solubility = Reacts | SolubleOther = insoluble in organic solvents | MeltingPt = > 550°C | BoilingPt = }} }} Lithium carbide, {{chem|Li|2|C|2}}, often known as dilithium acetylide, is a chemical compound of lithium and carbon, an acetylide. It is an intermediate compound produced during radiocarbon dating procedures. {{chem|Li|2|C|2}} is one of an extensive range of lithium-carbon compounds which include the lithium-rich {{chem|Li|4|C}}, {{chem|Li|6|C|2}}, {{chem|Li|8|C|3}}, {{chem|Li|6|C|3}}, {{chem|Li|4|C|3}}, {{chem|Li|4|C|5}}, and the graphite intercalation compounds {{chem|LiC|6}}, {{chem|LiC|12}}, and {{chem|LiC|18}}. The other lithium-rich compounds are produced by reacting lithium vapor with chlorinated hydrocarbons, e.g. CCl4. Lithium carbide is sometimes confused with the drug lithium carbonate, {{chem|Li|2|CO|3}}, because of the similarity of its name. Preparation and chemistryIn the laboratory samples may be prepared by treating acetylene with a solution of lithium in ammonia, on −40°C, with creation of addition compound of Li2C2 • C2H2 • 2NH3 that decomposes in stream of hydrogen at room temperature giving white powder of Li2C2. Samples prepared in this manner generally are poorly crystalline. Crystalline samples may be prepared by a reaction between molten lithium and graphite at over 1000 °C.[2] Li2C2 can also be prepared by reacting CO2 with molten lithium. Other method for production of Li2C2 is heating of metallic lithium in atmosphere of ethylene. Lithium carbide hydrolyzes readily to form acetylene: Lithium hydride reacts with graphite at 400°C forming lithium carbide. Also Li2C2 can be formed when organometallic compound n-Buthyllithium reacts with ethyne in THF or Et2O used as a solvent, reaction is rapid and highly exothermic. Structure{{chem|Li|2|C|2}} is a Zintl phase compound and exists as a salt, {{chem|2Li|+|C|2||2−}}. Its reactivity, combined with the difficulty in growing suitable single crystals, has made the determination of its crystal structure difficult. It adopts a distorted anti-fluorite crystal structure, similar to that of rubidium peroxide ({{chem|Rb|2|O|2}}) and caesium peroxide ({{chem|Cs|2|O|2}}). Each Li atom is surrounded by six carbon atoms from 4 different acetylides, with two acetylides co-ordinating side -on and the other two end-on.[2][4] The observed C-C distance of 120 pm indicates the presence of a C≡C triple bond.At high temperatures {{chem|Li|2|C|2|}} transforms reversibly to a cubic anti-fluorite structure.[5] Use in radiocarbon dating{{main|Radiocarbon dating}}There are a number of procedures employed, some that burn the sample producing CO2 that is then reacted with lithium, and others where the carbon containing sample is reacted directly with lithium metal.[6] The outcome is the same: Li2C2 is produced, which can then be used to create species easy to use in mass spectroscopy, like acetylene and benzene.[7] Note that lithium nitride may be formed and this produces ammonia when hydrolyzed, which contaminates the acetylene gas. References1. ^{{cite journal | title = Zur Kenntnis des Lithiumacetylids |author1=R. Juza |author2=V. Wehle |author3=H.-U. Schuster | journal = Zeitschrift für anorganische und allgemeine Chemie | year = 1967 | volume = 352 | pages = 252 | doi = 10.1002/zaac.19673520506 | issue = 5–6}} {{Lithium compounds}}2. ^1 2 {{cite journal|last1=Ruschewitz|first1=Uwe|title=Binary and ternary carbides of alkali and alkaline-earth metals|journal=Coordination Chemistry Reviews|date=September 2003|volume=244|issue=1-2|pages=115–136|doi=10.1016/S0010-8545(03)00102-4}} 3. ^H. Moissan Comptes Rendus hebd. Seances Acad. Sci. 122, 362 (1896) 4. ^{{cite journal|last1=Juza|first1=Robert|last2=Opp|first2=Karl|title=Metallamide und Metallnitride, 24. Mitteilung. Die Kristallstruktur des Lithiumamides|journal=Zeitschrift für anorganische und allgemeine Chemie|date=November 1951|volume=266|issue=6|pages=313–324|doi=10.1002/zaac.19512660606|language=German}} 5. ^{{cite journal |author1=U. Ruschewitz |author2=R. Pöttgen | title = Structural Phase Transition in {{chem|Li|2|C|2}} | journal = Zeitschrift für anorganische und allgemeine Chemie | volume = 625 | issue = 10 | pages = 1599–1603 | doi = 10.1002/(SICI)1521-3749(199910)625:10<1599::AID-ZAAC1599>3.0.CO;2-J | year = 1999}} 6. ^{{cite journal | author = Swart E.R. | title = The direct conversion of wood charcoal to lithium carbide in the production of acetylene for radiocarbon dating | journal = Cellular and Molecular Life Sciences | doi = 10.1007/BF02146038 | year = 1964 | volume = 20 | pages = 47}} 7. ^University of Zurich Radiocarbon Laboratory webpage {{webarchive|url=https://web.archive.org/web/20090801100716/http://www.geo.unizh.ch/c14/ |date=2009-08-01 }} 3 : Lithium compounds|Acetylides|Carbides |
| 随便看 |
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。