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Usage

Uses

Used in Pharmaceutical Industry:
Lithium amide is used as a reagent in the synthesis of active pharmaceutical ingredients and antioxidants. It aids in the production of anti-inflammatory and pro-resolving protectin D1, chemotype dipeptidyl peptidase IV inhibitors, and sterically congested triarylamines.
Used in Dye Industry:
Lithium amide is used as a reagent for the synthesis of dyes that display large Stokes shifts, which are important for their light absorption and emission properties.
Used in Organic Chemistry:
Lithium amide serves as a reagent in various organic reactions, such as Claisen condensations, alkylation of nitriles and ketones, and the synthesis of ethynyl compounds and acetylenic carbinols.
Used in Polymer Industry:
Lithium amide acts as a catalyst for polymers, facilitating the formation of polymer chains and improving their properties.
Used in Cross-coupling Reactions:
Lithium amide is used as a reagent for cross-coupling of aryl chlorides and amines, which is an important process in the synthesis of various organic compounds and materials.
Used in Synthesis of GM1 Ganglioside Derivatives:
Lithium amide is employed as a reagent in the synthesis of GM1 ganglioside derivatives, which have potential applications in the treatment of certain neurological disorders.

Preparation

Lithium amide is obtained by dissolution of lithium metal in liquid ammonia. The reaction is slow, but may be catalyzed by cobalt nitrate: 2Li + 2NH3 → 2LiNH2 + H2 It also is obtained by passing gaseous ammonia over lithium hydride: LiH + NH3 → LiNH2 + H2

Preparation

Lithium amide, LiNH2 , may be considered the ammonia analogue of lithium hydroxide in the water system. Lithium amide may be prepared from lithium hydride or lithium metal and ammonia. Industrial preparations use lithium hydride as a starting material. The reaction of lithium metal in a stream of ammonia gas at about 400°C may be used successfully as a preparative method. Lithium may also be reacted with liquid ammonia in the presence of an iron compound as a catalyst. Since amide ion is the strongest base which can exist in ammonia, lithium amide is a very strong base. The compound has a low solubility in liquid ammonia. Lithium amide is hydrolyzed by water to yield lithium hydroxide and ammonia. It is readily oxidized. For example, the substance may be oxidized with dinitrogen oxide to yield lithium azide. Amides of the alkali metals in general must be guarded against air oxidation to prevent the formation of potentially explosive substances.

Reactions

Lithium amide decomposes to imide when heated above 400°C: 2LiNH2 → Li2NH + NH3 It is used in several organic syntheses. Some of these synthetic reactions are based on the mechanism that the terminal alkynes react with the stronger base, the anion, forming the weaker conjugate base: It converts vic dibromide to bromoalkene and then alkyne: Ketones can be converted into alkynes:

Reactivity Profile

Powdered Lithium amide is highly reactive. A strong base. Reacts to release toxic ammonia gas with water. Forms explosive peroxide on storage.

Safety Profile

A powerful irritant to skin, eyes, and mucous membranes. Flammable when exposed to heat or flame. Ammonia is liberated and lithmm hydroxide is formed when Lithium amide is exposed to moisture. Reacts violently with water or steam to produce toxic and flammable vapors. Vigorous reaction with oxilzing materials. Exothermic reaction with acid or acid fumes. When heated to decomposition it emits very toxic fumes of LiO, NH3, and NO,. Used in synthesis of drugs, vitamins, steroids, and other organics. See also LITHIUM COMPOUNDS, AMIDES, AMMONIA, and LITHIUM HYDROXIDE.

Purification Methods

Purify it by heating at 400o while NH3 is passed over it in the upper of two crucibles (the upper crucible is perforated). The LiNH2 will drip into the lower crucible through the holes in the upper crucible. The product is cooled in a stream of NH3. Protect it from air and moisture, store it under N2 in a clear glass bottle sealed with paraffin. Store it in small quantities so that all the material is used once the bottle is opened. If the colour of the amide is yellow, it should be destroyed as it is likely to have oxidised and to EXPLODE. On heating above 450o it is decomposed to Li2NH, which is stable up to 750-800o. [Schenk in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 463 1963, Greenlee & Henne Inorg Synth II 135 1953.]

InChI:InChI=1/CH5N.Li/c1-2;/h2H2,1H3;