Organolithiumühendeid

Organolithium compounds 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 bearing a partial positive charge. This polarity makes organolithium reagents highly reactive.

Common organolithium reagents include alkyllithiums such as n-butyllithium and methyllithium, and aryllithiums such as phenyllithium. These compounds are typically prepared by reacting an organohalide with lithium metal or by deprotonation of a hydrocarbon with a strong lithium base. Due to their reactivity, organolithium reagents are often prepared and handled under anhydrous and inert atmosphere conditions, such as in a glovebox or using Schlenk techniques, to prevent decomposition by moisture or oxygen.

The reactivity of organolithium compounds stems from the strongly nucleophilic nature of the carbanionic carbon. They readily react with electrophiles such as carbonyl compounds (aldehydes, ketones, esters), epoxides, and alkyl halides, forming new carbon-carbon bonds. Their strong basicity allows them to deprotonate even weak carbon acids, a process known as metalation, which can be used to generate other reactive intermediates. The regioselectivity and stereoselectivity of reactions involving organolithium compounds can often be controlled by careful choice of reaction conditions, solvent, and additives.