Sec-Butyllithium

*sec*-Butyllithium
Names


IUPAC name sec-Butyllithium
Systematic IUPAC name Butan-2-yllithium
Identifiers
CAS Number	598-30-1^Y
3D model (JSmol)	Interactive image Interactive image
Beilstein Reference	3587206
ChemSpider	10254345^Y
ECHA InfoCard	100.009.026
EC Number	209-927-7
PubChem CID	102446
UNII	5YV3GII1TB^Y
CompTox Dashboard (EPA)	DTXSID80883459
InChI InChI=1S/C4H9.Li/c1-3-4-2;/h3H,4H2,1-2H3;^Y Key: VATDYQWILMGLEW-UHFFFAOYSA-N^Y InChI=1/C4H9.Li/c1-3-4-2;/h3H,4H2,1-2H3;/rC4H9Li/c1-3-4(2)5/h4H,3H2,1-2H3 Key: VATDYQWILMGLEW-MHILWDCKAX
SMILES [Li]C(C)CC CC([Li])CC
Properties
Chemical formula	C₄H₉Li
Molar mass	64.06 g·mol⁻¹
Acidity (pK_a)	51
Hazards
Safety data sheet (SDS)	Fisher MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is ^YN ?) Infobox references

Chemical compound

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.^[1]

Synthesis

sec-BuLi can be prepared by the reaction of sec-butyl halides with lithium metal:^[2]

Properties

Physical properties

sec-Butyllithium is a colorless viscous liquid.^[1]^[3] Using mass spectrometry, it was determined that the pure compound has a tetrameric structure.^[4] It also exists as tetramers when dissolved in organic solvents such as benzene, cyclohexane or cyclopentane.^[3] The cyclopentane solution has been detected with ⁶Li-NMR spectroscopy to have a hexameric structure at temperatures below −41 °C.^[5] In electron-donating solvents such as tetrahydrofuran, there exists an equilibrium between monomeric and dimeric forms.^[6]

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.^[1]

The compound decomposes slowly at room temperature and more rapidly at higher temperatures, giving lithium hydride and a mixture of butenes.^[7]^[8]

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.^[9] It is also effective for lithiation of arenes.^[10]

References

^ ^a ^b ^c Ovaska, T. V. (2001). "s-Butyllithium". Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rb397. ISBN 0471936235..
^ Hay, D. R.; Song, Z.; Smith, S. G.; Beak, P. (1988). "Complex-induced proximity effects and dipole-stabilized carbanions: kinetic evidence for the role of complexes in the α-lithiations of carboxamides". J. Am. Chem. Soc. 110 (24): 8145–8153. doi:10.1021/ja00232a029.
^ ^a ^b Wietelmann, Ulrich; Bauer, Richard J. (2000-06-15), "Lithium and Lithium Compounds", in Wiley-VCH Verlag GmbH & Co. KGaA (ed.), Ullmann's Encyclopedia of Industrial Chemistry, Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, pp. a15_393, doi:10.1002/14356007.a15_393, ISBN 978-3-527-30673-2, retrieved 2022-05-07
^ Plavsic, D.; Srzic, D.; Klasinc, Leo (1986). "Mass spectrometric investigations of alkyllithium compounds in the gas phase". The Journal of Physical Chemistry. 90 (10): 2075–2080. doi:10.1021/j100401a020. ISSN 0022-3654.
^ Fraenkel, Gideon; Henrichs, Mark; Hewitt, Michael; Su, Biing Ming (1984). "Structure and dynamic behavior of a chiral alkyllithium compound: carbon-13 and lithium-6 NMR of sec-butyllithium". Journal of the American Chemical Society. 106 (1): 255–256. doi:10.1021/ja00313a052. ISSN 0002-7863.
^ Bauer, Walter.; Winchester, William R.; Schleyer, Paul von R. (1987-11-01). "Monomeric organolithium compounds in tetrahydrofuran: tert-butyllithium, sec-butyllithium, supermesityllithium, mesityllithium, and phenyllithium. Carbon-lithium coupling constants and the nature of carbon-lithium bonding". Organometallics. 6 (11): 2371–2379. doi:10.1021/om00154a017. ISSN 0276-7333.
^ Glaze, William H.; Lin, Jacob; Felton, E. G. (1965). "The Thermal Decomposition of sec-Butyllithium". The Journal of Organic Chemistry. 30 (4): 1258–1259. doi:10.1021/jo01015a514. ISSN 0022-3263.
^ Glaze, William H.; Lin, Jacob; Felton, E. G. (1966). "The Pyrolysis of Unsolvated Alkyllithium Compounds". The Journal of Organic Chemistry. 31 (8): 2643–2645. doi:10.1021/jo01346a044. ISSN 0022-3263.
^ Crépy, Karen V. L.; Imamoto, Tsuneo (2005). "Preparation of (S,S)-1,2-bis(tert-Butylmethylphosphino)ethane ((S,S)-t-bu-bisp*) as a Rhodium Complex". Organic Syntheses. 82: 22. doi:10.15227/orgsyn.082.0022.
^ Wang, X.; de Silva, S. O.; Reed, J. N.; Billadeau, R.; Griffen, E. J.; Chan, A.; Snieckus, V. (1995). "7-Methoxyphthalide". Org. Synth. 72: 163. doi:10.15227/orgsyn.072.0163.