tert-Butyllithium

• T- butyl
• T -BuLi

Colorless, pyrophoric solid

Fixed

140 ° C ( decomposition)

Soluble in pentane

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Tert-butyllithium (t -BuLi ) is a tertiary organo-metallic compound of the element lithium ( organolithium compound ). There are also the isomeric forms of n- butyllithium and sec -butyllithium. The basicity increases in the order of n-butyllithium < sec -butyl < tert- butyllithium to. t -BuLi is thus the strongest base in the series. t- BuLi, lithium hydride decomposes at room temperature and isobutene. The resulting isobutene is deprotonated by further t -BuLi in the allyl position, resulting in a further reduction of the concentration of t -BuLi.

Representation

The synthesis can be carried out by reaction of t -butyl bromide with lithium ( powder).

Properties

It is commercially available (mostly in pentane or heptane) is only available as a solution in alkanes, with a concentration of 1.7 mol / L is common. Ethers such as THF or diethyl ether as a solvent are not suitable for storage since they are rapidly decomposed. t -BuLi is extremely pyrophoric and in solution and burns in air with a typical red flame.

Reactions

The lithium - carbon bond in the tert- Butyllithiummolekül is strongly polarized. The carbon atom carries a negative here and the lithium atom has a partial positive charge. tert- butyllithium therefore behaves chemically similar to a corresponding carbanion. By formulating a mesomeric structure can illustrate this behavior:

Similar to n-butyl lithium and t -BuLi can be used for the lithium - halogen exchange and deprotonating amines and activated CH - compounds. t -BuLi can also attack the alpha - position of the ether.

This shows the example, tetrahydrofuran which is decomposed even at room temperature within minutes:

This method is used for example when deprotonated acetaldehyde is required.

Use

T -BuLi has gained importance as an ultra- strong base or as Lithiierungsreagenz in modern synthetic organic chemistry. As it is much pyrophoric as n-BuLi, it is less frequently used. In some cases it will because of the higher basicity or steric reasons ( the t- butyl radical is relatively large in size ) were used.

Safety

As mentioned above, t -BuLi extremely pyrophoric and in solution. The handling and storage so it should always be carried out under protective gas. t -BuLi also reacts violently with water to form lithium hydroxide and isobutane. For longer storage, a sediment from also pyrophoric lithium hydride forms ( from the self- decomposition) and lithium hydroxide ( trapped moisture ).

Swell

• Lithium compound
• Organometallic compound