organolithiums

Organolithiums are organometallic compounds characterized by a polar carbon–lithium bond (R-Li). They are among the most versatile and reactive reagents in organic synthesis, functioning primarily as strong bases and powerful nucleophiles. Common examples include n-butyllithium, sec- and tert-butyllithium, and phenyllithium. They enable carbon–carbon bond formation by deprotonating substrates to generate carbanions or by adding to electrophiles such as carbonyl compounds and epoxides.

Preparation and handling: Organolithiums are typically prepared by metal-halogen exchange or direct metallation of organic halides with lithium metal. They are highly reactive toward air and moisture and are normally used under inert atmosphere in dry, aprotic solvents such as THF or diethyl ether. In solution they exist as aggregates whose structure depends on solvent, temperature, and concentration, a factor that influences reactivity.

Applications and scope: They are used to generate carbanions for alkylation and acylation reactions, to perform directed metallations, and to initiate anionic polymerizations. They also serve in the formation of complex building blocks through nucleophilic additions to aldehydes or ketones, followed by workup to give alcohols after protonation. Transmetalation to other metals broadens their utility, for example to give less reactive organocuprates.

Safety and handling: Organolithiums are highly reactive and frequently pyrophoric, reacting vigorously with air and water. They require dry glassware, inert atmosphere, and meticulous exclusion of moisture. Proper storage, handling procedures, and appropriate fire suppression methods are essential in laboratories, and exposure can cause severe chemical burns.