Tertbutyllithium

tert-Butyllithium (t-BuLi) is an organolithium reagent known for being a very strong base and, to a lesser extent, a nucleophile in organic synthesis. It is widely used to generate reactive carbanions and to perform halogen–lithium exchange, enabling the in situ preparation of other organolithium species. Because of its extreme reactivity, t-BuLi is handled under strictly anhydrous, inert conditions and is typically used in dry hydrocarbon solvents.

Preparation and availability

tert-Butyllithium is commonly prepared by metallation of tert-butyl halides (usually tert-butyl chloride or bromide) with lithium metal in dry ether solvents such as diethyl ether or THF. It is usually supplied as a solution in hydrocarbon solvents (for example hexane or cyclohexane) with typical commercial concentrations ranging from around 0.5 to 2 M.

Properties and handling

t-BuLi is highly reactive and pyrophoric, reacting vigorously with air and moisture to form hydrocarbons and lithium salts. It can ignite upon exposure to air or water, and contact with moisture or oxygen must be strictly avoided. Storage and use require inert atmosphere techniques (glovebox or Schlenk line), dry solvents, and appropriate fire suppression methods for pyrophoric materials.

Reactions and applications

In practice, t-BuLi is employed as a non-nucleophilic, extremely strong base to deprotonate substrates with very high pKa values, or to generate other organolithium reagents via halogen–lithium exchange. It can initiate formation of reactive carbanions that participate in subsequent additions to electrophiles, cross-couplings, or metalations. Because of safety concerns, its use is typically confined to well-equipped laboratories and experienced personnel.

See also

Organolithium reagents; lithium-halogen exchange; strong bases in organic synthesis.