sec -Butyllithium

Structural formula
General
Surname	sec -Butyllithium
other names	s -butyllithium; s -BuLi;
Molecular formula	C 4 H 9 Li
Brief description	colorless liquid
External identifiers / databases
EC number	209-927-7
ECHA InfoCard	100.009.026
PubChem	102446
ChemSpider	92522
Wikidata	Q220108
properties
Molar mass	64.05 g mol −1
Physical state	liquid
boiling point	90 ° C (0.05 Torr)
solubility	soluble in cyclohexane
safety instructions
H and P phrases	H: 225-304-314-336-410
	P: 210-261-273-280-301 + 310-305 + 351 + 338
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

sec -Butyllithium ( s -BuLi) is a secondary organometallic compound of the element lithium ( organolithium compound ). There are also the isomeric forms n -butyllithium and tert -butyllithium . The basicity increases in the series n -Butyllithium < sec -Butyllithium < tert -Butyllithium. s -BuLi is thus the second strongest base in this series. sec -Butyllithium is usually commerciallyavailableas a solution in cyclohexane . A fineprecipitate of lithium hydride can formduring storage; This also leads to a reduction in the concentration of the solutions.

Extraction and presentation

The synthesis can be carried out by reacting 2-chlorobutane with elemental lithium .

properties

Physical Properties

sec -Butyllithium is a colorless, viscous liquid. A tetramer structure was demonstrated for the pure substance by mass spectrometry . In non-polar solvents such as benzene , cyclohexane or cyclopentane , the compound is present as a tetramer. At temperatures of −41 ° C a hexamer could be detected in cyclopentane using ⁶ Li NMR spectroscopy . In solvents with donor properties such as tetrahydrofuran there is a balance between dimeric and monomeric structures.

Chemical properties

s -BuLi can be used for lithium-halogen exchange on halogenated aromatics or for deprotonation , for example of amines or alcohols . Lithium di- sec butyl cuprates are formed with copper (I) iodide . Compared to n -BuLi, s -BuLi reacts faster with diethyl ether and THF at room temperature . The compound decomposes slowly at room temperature or more rapidly at elevated temperature into lithium hydride and a butene mixture of 1-butene, cis-2-butene and trans-2-butene.

Pure s -butyllithium is pyrophoric and burns in the air with a typical red flame .

use

The carbon-lithium bond is highly polarized, which means that the carbon is very nucleophilic and basic. s -Buli is more basic than n -Buli and also more sterically hindered. These two properties can be used in various syntheses. It is z. B. used when there is only a weak CH acidity and n -BuLi does not give satisfactory results. In addition, s- Butyllithium is used as a catalyst for technical polymerizations of isoprene , butadiene and styrene .

safety instructions

s -BuLi is self-igniting in the air and also reacts violently with water. The reagent must therefore always be stored and handled under protective gas (e.g. argon ).

Individual evidence

↑ ^a ^b ^c Entry on butyllithium. In: Römpp Online . Georg Thieme Verlag, accessed on December 6, 2013.
^ TV Ovaska: s-Butyllithium. In: Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons, New York 2001. doi: 10.1002 / 047084289X.rb397 .
↑ ^a ^b ^c data sheet sec-Butyllithium solution, 1.4 M in cyclohexane from Sigma-Aldrich , accessed on April 23, 2011 ( PDF ).
↑ Parts of the labeling of hazardous substances relate to the hazards caused by the solvent.
^ H. Gilman, FW Moore, O. Baine: Secondary and Tertiary Alkyllithium Compounds and Some Interconversion Reactions with Them. In: J. Am. Chem. Soc. 63, 1941, pp. 2479-2482, doi: 10.1021 / ja01854a046 .
↑ ^a ^b U. Wietelmann, RJ Bauer: lithium and lithium compounds. In: Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag, Weinheim 2005, doi : 10.1002 / 14356007.a15_393
↑ D. Plavsic, D. Srzic, L. Klasinc: Mass spectrometric investigations of alkyllithium compounds in the gas phase. In: J. Phys. Chem. 90, 1986, pp. 2075-2080, doi: 10.1021 / j100401a020 .
↑ S. Bywater, DJ Worsfold: alkyllithium Anionic Polymerization initiator in hydrocarbon Solvents. In: J. Organomet. Chem. 10, 1967, pp. 1-6.
↑ ^a ^b G. Fraenkel, M. Henrichs, M. Hewitt, BM Su: Structure and dynamic behavior of a chiral alkyllithium compound: ¹³ C and ⁶ Li NMR of sec-butyllithium. In: J. Am. Chem. Soc. 106, 1984, pp. 255-256.
↑ W. Bauer, WR Winchester, P. von Schleyer: 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: Organometallics . 6, 1987, pp. 2371-2379, doi: 10.1021 / om00154a017 .
^ WH Glaze, J. Lin, EG Felton: The Thermal Decomposition of sec.-Butyllithium. In: J. Org. Chem. 30, 1965, pp. 1258-1259, doi: 10.1021 / jo01015a514 .
^ WH Glaze, J. Lin, EG Felton: The Pyrolysis of Unsolvated Alkyllithium Compounds. In: J. Org. Chem. 31, 1966, pp. 2643-2645, doi: 10.1021 / jo01346a044 .

literature

Heinz GO Becker among others: Organikum. 21st edition. Wiley-VCH, Weinheim 2001, ISBN 3-527-29985-8 .
Christoph Elschenbroich: Organometallic chemistry. 5th edition. Teubner, Wiesbaden 2005, ISBN 3-519-53501-7 .

[roempp-1] Entry on butyllithium. In: Römpp Online . Georg Thieme Verlag, accessed on December 6, 2013.

[Ovaska-2] TV Ovaska: s-Butyllithium. In: Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons, New York 2001. doi: 10.1002 / 047084289X.rb397 .

[Sigma-3] ta sheet sec-Butyllithium solution, 1.4 M in cyclohexane from Sigma-Aldrich , accessed on April 23, 2011 ( PDF ).

[LM-4] Parts of the labeling of hazardous substances relate to the hazards caused by the solvent.

[5] H. Gilman, FW Moore, O. Baine: Secondary and Tertiary Alkyllithium Compounds and Some Interconversion Reactions with Them. In: J. Am. Chem. Soc. 63, 1941, pp. 2479-2482, doi: 10.1021 / ja01854a046 .

[Ullmann-6] U. Wietelmann, RJ Bauer: lithium and lithium compounds. In: Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag, Weinheim 2005, doi : 10.1002 / 14356007.a15_393

[Plavsic-7] D. Plavsic, D. Srzic, L. Klasinc: Mass spectrometric investigations of alkyllithium compounds in the gas phase. In: J. Phys. Chem. 90, 1986, pp. 2075-2080, doi: 10.1021 / j100401a020 .

[8] S. Bywater, DJ Worsfold: alkyllithium Anionic Polymerization initiator in hydrocarbon Solvents. In: J. Organomet. Chem. 10, 1967, pp. 1-6.

[Fraenkel-9] G. Fraenkel, M. Henrichs, M. Hewitt, BM Su: Structure and dynamic behavior of a chiral alkyllithium compound: ¹³ C and ⁶ Li NMR of sec-butyllithium. In: J. Am. Chem. Soc. 106, 1984, pp. 255-256.

[Bauer-10] W. Bauer, WR Winchester, P. von Schleyer: 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: Organometallics . 6, 1987, pp. 2371-2379, doi: 10.1021 / om00154a017 .

[Glaze-11] WH Glaze, J. Lin, EG Felton: The Thermal Decomposition of sec.-Butyllithium. In: J. Org. Chem. 30, 1965, pp. 1258-1259, doi: 10.1021 / jo01015a514 .

[Glaze2-12] WH Glaze, J. Lin, EG Felton: The Pyrolysis of Unsolvated Alkyllithium Compounds. In: J. Org. Chem. 31, 1966, pp. 2643-2645, doi: 10.1021 / jo01346a044 .