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N-Butyllithium

n-Butyllithium
N-butyllithium-tetramer-3D-balls.png
n-Butyllithium tetramer
Butyllithium-hexamer-from-xtal-3D-balls-A.png
n-Butyllithium hexamer
Butyllithium-hexamer-from-xtal-3D-balls-C.png
Close-up of the delocalized bonds between butyl and lithium
Names
IUPAC name
butyllithium, tetra-μ3-butyl-tetralithium
Other names
NBL, BuLi,
1-lithiobutane
Identifiers
109-72-8 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:51469 YesY
ChemSpider 10254339 YesY
ECHA InfoCard 100.003.363
PubChem 61028
Properties
C4H9Li
Molar mass 64.06 g·mol−1
Appearance colorless liquid
unstable
usually obtained
as solution
Density 0.68 g/cm3, solvent defined
Melting point −76 °C (−105 °F; 197 K) (<273 K)
Boiling point decomposes
Reaction
Solubility Diethyl ether, cyclohexane
Acidity (pKa) 50
Structure
tetrameric in solution
0 D
Hazards
Main hazards pyrophoric (inflames in air),
decomposes to corrosive LiOH
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g., fluorine Special hazard W: Reacts with water in an unusual or dangerous manner. E.g., cesium, sodiumNFPA 704 four-colored diamond
Related compounds
sec-butyllithium
tert-butyllithium
hexyllithium
methyllithium
Related compounds
 lithium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

n-Butyllithium (abbreviated n-BuLi) is an organolithium reagent. It is widely used as a polymerization initiator in the production of elastomers such as polybutadiene or styrene-butadiene-styrene (SBS). Also, it is broadly employed as a strong base (superbase) in the synthesis of organic compounds as in the pharmaceutical industry.

Butyllithium is commercially available as solutions (15%, 25%,1.5 M, 2 M, 2.5 M, 10 M, etc.) in alkanes such as pentane, hexanes, and heptanes. Solutions in diethyl ether and THF can be prepared, but are not stable enough for storage. Annual worldwide production and consumption of butyllithium and other organolithium compounds is estimated at 1800 tonnes.

Although butyllithium is colorless, n-butyllithium is usually encountered as a pale yellow solution in alkanes. Such solutions are stable indefinitely if properly stored, but in practice, they degrade upon aging. Fine white precipitate (lithium hydride) is deposited and the color changes to orange.

n-BuLi exists as a cluster both in the solid state and in a solution. The tendency to aggregate is common for organolithium compounds. The aggregates are held together by delocalized covalent bonds between lithium and the terminal carbon of the butyl chain. In the case of n-BuLi, the clusters are tetrameric (in ether) or hexameric (in cyclohexane). The cluster is a distorted cubane-type cluster with Li and CH2R groups at alternating vertices. An equivalent description describes the tetramer as a Li4tetrahedron interpenetrated with a tetrahedron [CH2R]4. Bonding within the cluster is related to that used to describe diborane, but more complex since eight atoms are involved. Reflecting its "electron-deficient character," n-butyllithium is highly reactive toward Lewis bases.


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Wikipedia

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