Lithium amide

Lithium Amide

Lithium amide is an inorganic compound with the chemical formula LiNH₂. It is a white solid that is highly reactive and is used primarily in organic synthesis as a strong base. Lithium amide is a member of the amide family, which are compounds containing the NH₂⁻ ion.

Structure and Properties

Lithium amide crystallizes in a tetragonal structure, similar to that of sodium amide. The compound consists of lithium ions (Li⁺) and amide ions (NH₂⁻). The amide ion is a strong base due to the presence of the lone pair of electrons on the nitrogen atom, which can readily accept protons.

The compound is highly hygroscopic and reacts vigorously with water to form lithium hydroxide and ammonia:

LiNH₂ + H₂O → LiOH + NH₃

Lithium amide is also sensitive to air and should be handled under an inert atmosphere, such as nitrogen or argon, to prevent decomposition.

Synthesis

Lithium amide can be synthesized by the direct reaction of lithium metal with ammonia gas:

2 Li + 2 NH₃ → 2 LiNH₂ + H₂

This reaction is typically carried out at low temperatures to control the reactivity of lithium metal.

Applications

Lithium amide is primarily used as a strong base in organic synthesis. It is particularly useful in deprotonation reactions, where it can remove a proton from a carbon atom adjacent to a functional group, generating a carbanion. This property makes it valuable in the formation of enolates and other reactive intermediates.

In addition to its role as a base, lithium amide is used in the preparation of lithium diisopropylamide (LDA), another strong base that is widely used in organic chemistry.

Safety and Handling

Due to its reactivity with water and air, lithium amide must be handled with care. It should be stored in a dry, inert atmosphere and handled using appropriate personal protective equipment. Contact with skin or eyes can cause severe irritation, and inhalation of dust or fumes should be avoided.

Also see

• Amide
• Lithium diisopropylamide
• Lithium hydroxide
• Sodium amide