butyllithiums

Butyllithiums are organolithium compounds with the general formula C4H9Li. They are highly reactive compounds commonly used as reagents in organic synthesis. The most common butyllithium reagents are n-butyllithium, sec-butyllithium, and tert-butyllithium. These reagents are typically supplied as solutions in hydrocarbon solvents such as hexanes, heptane, or cyclohexane due to their pyrophoric nature.

The carbon-lithium bond in butyllithiums is highly polar, with the carbon atom bearing a significant partial negative charge. This makes the butyl group a strong nucleophile and a strong base. This basicity is exploited in deprotonation reactions, where butyllithiums can abstract protons from a wide variety of organic molecules, generating carbanions. These carbanions can then react with electrophiles to form new carbon-carbon bonds, which is a fundamental transformation in organic chemistry.

The reactivity of different butyllithium isomers varies. Tert-butyllithium, with its sterically hindered tert-butyl group, is a stronger base and more reactive than n-butyllithium. However, it is also less stable. Butyllithiums are generally handled under an inert atmosphere, such as nitrogen or argon, to prevent reaction with moisture and oxygen. Their pyrophoric nature necessitates careful handling and storage.