Sec-Butyllithium

sec-Butyllithium (s-BuLi) is an organolithium reagent with the chemical formula C₄H₉Li. It is commonly used in organic synthesis as a strong base and nucleophile. sec-Butyllithium is a member of the alkyllithium family, which includes other reagents such as n-butyllithium and tert-butyllithium.

Structure and Properties

sec-Butyllithium is typically encountered as a colorless to pale yellow solution in hydrocarbon solvents such as hexane or heptane. The compound exists as a tetramer or hexamer in solution, similar to other alkyllithium reagents. The structure of sec-butyllithium in the solid state is often described as a cluster of lithium atoms coordinated by butyl groups.

Preparation

sec-Butyllithium can be prepared by the reaction of sec-butyl chloride with lithium metal in an inert atmosphere such as argon or nitrogen. The reaction is typically carried out in a hydrocarbon solvent:

<math> \text{C}_4\text{H}_9\text{Cl} + 2\text{Li} \rightarrow \text{C}_4\text{H}_9\text{Li} + \text{LiCl} </math>

Applications

sec-Butyllithium is widely used in organic synthesis for various applications:

• As a strong base in deprotonation reactions.
• As a nucleophile in nucleophilic addition and nucleophilic substitution reactions.
• In the preparation of other organolithium reagents through transmetalation reactions.

Safety and Handling

sec-Butyllithium is highly reactive and can ignite spontaneously upon exposure to air. It reacts violently with water, producing butane and lithium hydroxide. Proper safety precautions, including the use of glove boxes or Schlenk lines, are necessary when handling this reagent.

See Also

• n-Butyllithium
• tert-Butyllithium
• Organolithium reagent
• Deprotonation
• Nucleophilic addition
• Nucleophilic substitution