Chemistry:Sec-Butyllithium
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| Names | |
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| IUPAC name
sec-Butyllithium
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| Systematic IUPAC name
Butan-2-yllithium | |
| Identifiers | |
3D model (JSmol)
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| 3587206 | |
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PubChem CID
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| Properties | |
| C4H9Li | |
| Molar mass | 64.06 g·mol−1 |
| Acidity (pKa) | 51 |
| Hazards | |
| Safety data sheet | Fisher MSDS |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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| Infobox references | |
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
- ↑ 1.0 1.1 1.2 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.
- ↑ 3.0 3.1 Wietelmann, Ulrich; Bauer, Richard J. (2000-06-15), Wiley-VCH Verlag GmbH & Co. KGaA, ed. (in en), Lithium and Lithium Compounds, Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, pp. a15_393, doi:10.1002/14356007.a15_393, ISBN 978-3-527-30673-2, https://onlinelibrary.wiley.com/doi/10.1002/14356007.a15_393, retrieved 2022-05-07
- ↑ Plavsic, D.; Srzic, D.; Klasinc, Leo (1986). "Mass spectrometric investigations of alkyllithium compounds in the gas phase" (in en). The Journal of Physical Chemistry 90 (10): 2075–2080. doi:10.1021/j100401a020. ISSN 0022-3654. https://pubs.acs.org/doi/abs/10.1021/j100401a020.
- ↑ 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" (in en). Journal of the American Chemical Society 106 (1): 255–256. doi:10.1021/ja00313a052. ISSN 0002-7863. https://pubs.acs.org/doi/abs/10.1021/ja00313a052.
- ↑ 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" (in en). Organometallics 6 (11): 2371–2379. doi:10.1021/om00154a017. ISSN 0276-7333. https://pubs.acs.org/doi/abs/10.1021/om00154a017.
- ↑ Glaze, William H.; Lin, Jacob; Felton, E. G. (1965). "The Thermal Decomposition of sec-Butyllithium" (in en). The Journal of Organic Chemistry 30 (4): 1258–1259. doi:10.1021/jo01015a514. ISSN 0022-3263. https://pubs.acs.org/doi/abs/10.1021/jo01015a514.
- ↑ Glaze, William H.; Lin, Jacob; Felton, E. G. (1966). "The Pyrolysis of Unsolvated Alkyllithium Compounds" (in en). The Journal of Organic Chemistry 31 (8): 2643–2645. doi:10.1021/jo01346a044. ISSN 0022-3263. https://pubs.acs.org/doi/abs/10.1021/jo01346a044.
- ↑ 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.
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