Tert-Butyllithium

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IUPACName = 2-Lithio-2-methylpropane
OtherNames = tert-Butyllithium
Section1 = Chembox Identifiers
CASNo = 594-19-4
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Section2 = Chembox Properties
Formula = C₄H₉Li
MolarMass = 64.05 g/mol
Appearance = colorless solid
Density = 0.66 g·cm^-3
MeltingPt = 36-40 °C
BoilingPt =
Solubility = decomp by water
SolubleOther = alkanes
Section3 = Chembox Hazards
MainHazards = flammable
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OtherCpds = N-Butyllithium, sec-Butyllithium

"tert"-Butyllithium is the chemical compound with the formula (CH₃)₃CLi. This organolithium compound is used as an extremely strong base in certain applications of organic synthesis. The compound exists as a cluster, is capable of deprotonating many carbon acids, including benzene.

"tert"-Butyllithium is extremely flammable and ignites spontaneously in air. It must be kept and handled under a dry nitrogen atmosphere. Even with standard dry nitrogen conditions (such as a Schlenk line), this presents a hazard - if the ^tBuLi is drawn into a syringe through a septum, when the needle is removed the tip of the needle will catch fire - while this is not always a problem, the combustion can block the tube, leaving the chemist holding a tube of very dangerous solution with no means of delivering it back to the nitrogen atmosphere. The solution is to keep the tip of the needle in an inert atmosphere. A short glass tube, with a septum in each end, flushed with inert gas, is pierced with the needle and then the tip is drawn into the tube after the liquid has been drawn.

Chemical properties

The lithium carbon bond in "tert"-Butyllithium is strongly polarised. Chemically, it behaves like a carbanion, which can be shown by the resonance structures: [K. P. C. Vollhardt, N. E. Schore: "Organische Chemie". 3. Auflage. Wiley-VCH, 2005, ISBN 978-3527298198] :

Similar to "n"-Butyllithium, "tert"-Butyllithium can be used for the exchange of lithium with halogenes and for the deprotonation of amines and activated C-H compounds. "tert"-Butyllithium can attack the alpha position of ethers. In the following example this is shown for tetrahydrofuran that decomposes within a few minutes at room temperature:

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References