Dilithium acetylide

Dilithium acetylide is an organolithium compound with the chemical formula C₂Li₂. It is a white solid that is highly reactive and is used primarily in organic synthesis. This compound is the lithium salt of acetylene and is a member of the acetylide family of compounds.

Structure and Properties

Dilithium acetylide consists of a carbon-carbon triple bond, characteristic of acetylides, with each carbon atom bonded to a lithium ion. The compound is typically found in a polymeric form, where the acetylide anions are linked by lithium cations. This polymeric structure is stabilized by the electrostatic interactions between the negatively charged acetylide ions and the positively charged lithium ions.

The compound is highly reactive due to the presence of the carbon-carbon triple bond and the strong basicity of the acetylide ion. It is sensitive to moisture and air, requiring storage under an inert atmosphere, such as nitrogen or argon.

Synthesis

Dilithium acetylide is typically synthesized by the reaction of acetylene with an excess of butyllithium in a non-polar solvent such as hexane or pentane. The reaction proceeds as follows:

<math>2 \, \text{BuLi} + \text{HC} \equiv \text{CH} \rightarrow \text{LiC} \equiv \text{CLi} + 2 \, \text{BuH}</math>

This reaction must be carried out under an inert atmosphere to prevent the highly reactive acetylide from reacting with moisture or oxygen.

Applications

Dilithium acetylide is used in organic synthesis as a nucleophile in various coupling reactions. It can react with carbonyl compounds to form propargylic alcohols, which are valuable intermediates in the synthesis of complex organic molecules. The compound is also used in the preparation of alkynes and other acetylide derivatives.

Safety and Handling

Due to its high reactivity, dilithium acetylide must be handled with care. It is highly flammable and can react violently with water, releasing acetylene gas. Proper protective equipment, such as gloves and goggles, should be used when handling this compound. It should be stored in a cool, dry place under an inert atmosphere to prevent degradation.

Related pages

• Acetylide
• Organolithium chemistry
• Alkyne
• Butyllithium