Vinyllithium

{{Chembox | ImageFile = Vinyllithium.png | ImageSize = 140 px | ImageAlt = | IUPACName = | OtherNames = |Section1={{Chembox Identifiers | CASNo = 917-57-7 | Beilstein = 3587231 | ChEBI = 51472 | Gmelin = 723 | PubChem = 637931 | ChemSpiderID = 10254403 | EC_number = 213-028-5 | SMILES = [Li]C=C | StdInChI = 1S/C2H3.Li/c1-2;/h1H,2H2; | StdInChIKey = PGOLTJPQCISRTO-UHFFFAOYSA-N}} |Section2={{Chembox Properties | C=2|H=3|Li=1 | MolarMass = | Appearance = white solid | Density = | MeltingPt = | BoilingPt = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = pyrophoric | FlashPt = | AutoignitionPt = }} }}

'''Vinyllithium''' is an organolithium compound with the formula LiC₂H₃. A colorless or white solid, it is encountered mainly as a solution in tetrahydrofuran (THF). It is a reagent in synthesis of organic compounds, especially for vinylations.<ref name=eEROS>{{cite book|chapter=Vinyllithium|author1=Eisenhart, Eric K. |author2=Bessieres, Bernard |title=E-EROS Encyclopedia of Reagents for Organic Synthesis|year=2007|doi=10.1002/047084289X.rv015.pub2|isbn= 978-0-471-93623-7 }}.</ref>

==Preparation and structure== Solutions of vinyllithium are prepared by lithium-halogen exchange reactions. A halide-free route entails reaction of tetravinyltin with butyllithium: :Sn(CH=CH₂)₄ + 4 BuLi → SnBu₄ + 4 LiCH=CH₂ The reaction of ethylene and lithium affords vinyl lithium and lithium hydride, together with other organolithium compounds,<ref name=eEROS/>

Like most organolithium compounds, vinyllithium crystallizes from THF as a cluster compound as a cubane-type cluster.<ref>{{cite journal|title=X-Ray crystal structure of a vinyllithium–tetrahydrofuran solvate (C2H3Li–thf)4. Quantitative estimation of Li–H distances by 6Li–1H HOESY|author=Walter Bauer |author2=Frank Hampel |journal=J. Chem. Soc., Chem. Commun.|year=1992|issue=12|pages=903–905|doi=10.1039/C39920000903}}</ref>

[[File:PAFCEE.png|thumb|left|Structure of [LiC₂H₃(THF)]₄.]]

==Reactions== Vinyllithium is used to install vinyl groups on metal-based reagents, i.e., vinylations. It is a precursor to vinylsilanes, vinylcuprates, and vinylstannanes.<ref>{{cite journal|title=Mixed Higher-order Cyanocuprate-induced Epoxide Openings: 1-benzyloxy-4-penten-2-ol|first1=Bruce H. |last1=Lipshutz|first2=Robert|last2=Moretti|first3=Robert|last3=Crow |journal=Org. Synth.|year=1990|volume=69|page=80|doi=10.15227/orgsyn.069.0080}}</ref> It adds to ketones compounds to give allylic alcohols. Vinylmagnesium bromide is often used in place of vinyllithium.<ref>{{cite journal|title=Di-''n''-butyldivinyltin|author=Dietmar Seyferth|journal=Org. Synth. |year=1959|volume=39|page=10|doi=10.15227/orgsyn.039.0010}}</ref>

==Alternative reagents== Vinyl magnesium bromide, a Grignard reagent, is in many ways easier to generate in the laboratory and behaves similarly to vinyllithium.<ref>{{cite journal |doi=10.15227/orgsyn.068.0116|title=Palladium-catalyzed Coupling of Vinyl Triflates with Organostannanes: 4-''tert''-Butyl-1-Vinylcyclohexene and 1-(4-''tert''-Butylcyclohexen-1-yl)-2-propen-1-one |journal=Organic Syntheses |year=1990 |volume=68 |page=116|author=William J. Scott, G. T. Crisp, J. K. Stille }}</ref>

==References== <references />

{{Lithium compounds}}

Category:Organolithium compounds Category:Vinyl compounds