Sec-Butyllithium

{{DISPLAYTITLE:''sec''-Butyllithium}} {{Chembox |Watchedfields = changed |verifiedrevid = 464388187 |Name = ''sec''-Butyllithium |ImageFile = Sec Butyllithium structure.svg |ImageClass = skin-invert |ImageFile_Ref = {{chemboximage|correct|??}} |ImageSize = 121 |ImageName = Skeletal formula of sec-butyllithium |ImageFile1 = Sec-butyllithium-2D-skeletal.png |ImageClass1 = skin-invert |ImageFile1_Ref = {{chemboximage|correct|??}} |ImageSize1 = 121 |ImageName1 = Skeletal formula of tetrameric sec-butyllithium |IUPACName = ''sec''-Butyllithium |SystematicName = Butan-2-yllithium |Section1={{Chembox Identifiers |CASNo = 598-30-1 |CASNo_Ref = {{cascite|correct|CAS}} |UNII_Ref = {{fdacite|correct|FDA}} |UNII = 5YV3GII1TB |PubChem = 102446 |ChemSpiderID = 10254345 |ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |EINECS = 209-927-7 |Beilstein = 3587206 |SMILES = [Li]C(C)CC |SMILES1 = CC([Li])CC |StdInChI_Ref = {{stdinchicite|correct|chemspider}} |StdInChI = 1S/C4H9.Li/c1-3-4-2;/h3H,4H2,1-2H3; |InChI = 1/C4H9.Li/c1-3-4-2;/h3H,4H2,1-2H3;/rC4H9Li/c1-3-4(2)5/h4H,3H2,1-2H3 |StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |StdInChIKey = VATDYQWILMGLEW-UHFFFAOYSA-N |InChIKey = VATDYQWILMGLEW-MHILWDCKAX }} |Section2={{Chembox Properties |C=4 | H=9 | Li=1 | Solubility = Reacts |pKa = 51 }} |Section3={{Chembox Hazards | Hazards_ref = <ref>{{cite web |title=Sec-Butyllithium |url=https://pubchem.ncbi.nlm.nih.gov/compound/102446#section=Safety-and-Hazards |website=pubchem.ncbi.nlm.nih.gov |access-date=19 December 2025 |language=en}}</ref> | GHSPictograms = {{GHS02}}{{GHS05}} | GHSSignalWord = Danger | HPhrases = {{HPhrases|H250|H260|H314}} | PPhrases = {{PPhrases|P210|P222|P223|P231|P231+P232|P233|P260|P264|P264+P265|P280|P301+P330+P331|P302+P335+P334|P302+P361+P354|P304+P340|P305+P354+P338|P316|P317|P321|P363|P370+P378|P402+P404|P405|P501}} |ExternalSDS = [https://fscimage.fishersci.com/msds/00217.htm Fisher MSDS] }} |Section4 = {{Chembox Related |OtherFunction_label = organolithium reagents |OtherFunction = ''n''-butyllithium ''tert''-butyllithium }} }}

'''''sec''-Butyllithium''' is an organometallic compound with the formula CH3CHLiCH2CH3, abbreviated ''sec''-BuLi or ''s''-BuLi. This chiral organolithium reagent is used as a source of ''sec''-butyl carbanion in organic synthesis.<ref name=Ovaska>{{cite encyclopedia|author=Ovaska, T. V.|title=s-Butyllithium| encyclopedia =Encyclopedia of Reagents for Organic Synthesis|year=2001|publisher=John Wiley & Sons|location=New York|doi=10.1002/047084289X.rb397| isbn=0471936235 }}.</ref>

==Synthesis== ''sec''-BuLi can be prepared by the reaction of ''sec''-butyl halides with lithium metal:<ref>{{cite journal |author1=Hay, D. R. |author2=Song, Z. |author3=Smith, S. G. |author4=Beak, P. | title = Complex-induced proximity effects and dipole-stabilized carbanions: kinetic evidence for the role of complexes in the α-lithiations of carboxamides | journal = J. Am. Chem. Soc. | year = 1988 | volume = 110 | pages = 8145–8153 | doi = 10.1021/ja00232a029 | issue = 24}}</ref>

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== Properties == === Physical properties === ''sec''-Butyllithium is a colorless viscous liquid.<ref name=Ovaska/><ref name=":0">{{Citation |last1=Wietelmann |first1=Ulrich |title=Lithium and Lithium Compounds |date=2000-06-15 |url=https://onlinelibrary.wiley.com/doi/10.1002/14356007.a15_393 |encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry |pages=a15_393 |editor-last=Wiley-VCH Verlag GmbH & Co. KGaA |place=Weinheim, Germany |publisher=Wiley-VCH Verlag GmbH & Co. KGaA |language=en |doi=10.1002/14356007.a15_393 |isbn=978-3-527-30673-2 |access-date=2022-05-07 |last2=Bauer |first2=Richard J.|url-access=subscription }}</ref> Using mass spectrometry, it was determined that the pure compound has a tetrameric structure.<ref>{{Cite journal |last1=Plavsic |first1=D. |last2=Srzic |first2=D. |last3=Klasinc |first3=Leo |date=1986 |title=Mass spectrometric investigations of alkyllithium compounds in the gas phase |url=https://pubs.acs.org/doi/abs/10.1021/j100401a020 |journal=The Journal of Physical Chemistry |language=en |volume=90 |issue=10 |pages=2075–2080 |doi=10.1021/j100401a020 |issn=0022-3654|url-access=subscription }}</ref> It also exists as tetramers when dissolved in organic solvents such as benzene, cyclohexane or cyclopentane.<ref name=":0" /> The cyclopentane solution has been detected with 6Li-NMR spectroscopy to have a hexameric structure at temperatures below −41 °C.<ref>{{Cite journal |last1=Fraenkel |first1=Gideon |last2=Henrichs |first2=Mark |last3=Hewitt |first3=Michael |last4=Su |first4=Biing Ming |date=1984 |title=Structure and dynamic behavior of a chiral alkyllithium compound: carbon-13 and lithium-6 NMR of sec-butyllithium |url=https://pubs.acs.org/doi/abs/10.1021/ja00313a052 |journal=Journal of the American Chemical Society |language=en |volume=106 |issue=1 |pages=255–256 |doi=10.1021/ja00313a052 |issn=0002-7863|url-access=subscription }}</ref> In electron-donating solvents such as tetrahydrofuran, there exists an equilibrium between monomeric and dimeric forms.<ref>{{Cite journal |last1=Bauer |first1=Walter. |last2=Winchester |first2=William R. |last3=Schleyer |first3=Paul von R. |date=1987-11-01 |title=Monomeric organolithium compounds in tetrahydrofuran: tert-butyllithium, sec-butyllithium, supermesityllithium, mesityllithium, and phenyllithium. Carbon-lithium coupling constants and the nature of carbon-lithium bonding |url=https://pubs.acs.org/doi/abs/10.1021/om00154a017 |journal=Organometallics |language=en |volume=6 |issue=11 |pages=2371–2379 |doi=10.1021/om00154a017 |issn=0276-7333|url-access=subscription }}</ref>

=== Chemical properties === The carbon-lithium bond is highly polar, rendering the carbon basic, as in other organolithium reagents. ''Sec''-butyllithium is more basic than the primary organolithium reagent, ''n''-butyllithium. It is also more sterically hindered. ''sec''-BuLi is employed for deprotonations of particularly weak carbon acids where the more conventional reagent ''n''-BuLi is unsatisfactory. It is, however, so basic that its use requires greater care than for ''n''-BuLi. For example diethyl ether is attacked by ''sec''-BuLi at room temperature in minutes, whereas ether solutions of ''n''-BuLi are stable.<ref name="Ovaska"/>

The compound decomposes slowly at room temperature and more rapidly at higher temperatures, giving lithium hydride and a mixture of butenes.<ref>{{Cite journal |last1=Glaze |first1=William H. |last2=Lin |first2=Jacob |last3=Felton |first3=E. G. |date=1965 |title=The Thermal Decomposition of sec-Butyllithium |url=https://pubs.acs.org/doi/abs/10.1021/jo01015a514 |journal=The Journal of Organic Chemistry |language=en |volume=30 |issue=4 |pages=1258–1259 |doi=10.1021/jo01015a514 |issn=0022-3263|url-access=subscription }}</ref><ref>{{Cite journal |last1=Glaze |first1=William H. |last2=Lin |first2=Jacob |last3=Felton |first3=E. G. |date=1966 |title=The Pyrolysis of Unsolvated Alkyllithium Compounds |url=https://pubs.acs.org/doi/abs/10.1021/jo01346a044 |journal=The Journal of Organic Chemistry |language=en |volume=31 |issue=8 |pages=2643–2645 |doi=10.1021/jo01346a044 |issn=0022-3263|url-access=subscription }}</ref>

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==Applications== Many transformations involving ''sec''-butyllithium are similar to those involving other organolithium reagents.

In combination with sparteine as a chiral auxiliary, sec-butyllithium is useful in enantioselective deprototonations.<ref>{{cite journal |doi=10.15227/orgsyn.082.0022| title=Preparation of (S,S)-1,2-bis(''tert''-Butylmethylphosphino)ethane ((''S,S'')-t-bu-bisp*) as a Rhodium Complex | journal=Organic Syntheses | year=2005 | volume=82 | page=22|first1=Karen V. L.|last1=Crépy|first2= Tsuneo|last2=Imamoto |doi-access=free}}</ref> It is also effective for lithiation of arenes.<ref>{{cite journal |doi=10.15227/orgsyn.072.0163|first1=X.|last1=Wang|first2=S. O.|last2=de Silva|first3=J. N.|last3=Reed|first4=R.|last4=Billadeau|first5=E. J.|last5=Griffen|first6=A.|last6=Chan|first7=V.|last7=Snieckus|title=7-Methoxyphthalide|journal=Org. Synth.|year=1995|volume=72|page=163}}</ref>

==References== {{reflist}}

Category:Organolithium compounds Category:Sec-Butyl compounds Category:Pyrophoric materials