Organolithiumföreningar

Organolithium reagents are a class of organometallic compounds containing a carbon-lithium bond. They are widely used in organic synthesis as strong bases and nucleophiles. The polarity of the carbon-lithium bond is significant, with the carbon atom bearing a partial negative charge and the lithium atom a partial positive charge. This polarity makes the carbon atom highly reactive towards electrophiles.

The synthesis of organolithium reagents typically involves the reaction of an alkyl or aryl halide with lithium metal. For example, n-butyllithium, a common organolithium reagent, is prepared by reacting n-butyl chloride with lithium metal in a suitable solvent such as diethyl ether or hexane. Alternatively, transmetallation reactions, where a metal-organic compound is reacted with a lithium halide, can also be employed.

Organolithium reagents are highly reactive and often pyrophoric, meaning they can ignite spontaneously in air. Therefore, they must be handled under an inert atmosphere, such as nitrogen or argon, and in anhydrous conditions to prevent decomposition by reaction with moisture or oxygen. Their strong basicity allows them to deprotonate a wide range of acidic protons, including those in alcohols, amines, and even relatively weak carbon acids. As nucleophiles, they readily attack electrophilic centers such as carbonyl groups, epoxides, and alkyl halides, forming new carbon-carbon bonds. This versatility makes them indispensable tools in the construction of complex organic molecules.