Lithium amide or lithium azanide is an
inorganic compound with the chemical formula . It is a white solid with a tetragonal crystal structure. Lithium amide can be made by treating
lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ...
metal with liquid
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
:
:
Other lithium amides
The conjugate bases of amines are known as amides. Thus, a ''lithium amide'' may also refer to any compound in the class of the lithium salt of an
amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen
Hydrogen is the chemical element wi ...
. These compounds have the general form , with the chemical lithium amide itself as the
parent structure
In chemistry, a parent structure is the structure of an unadorned ion or molecule from which derivatives can be visualized. Parent structures underpin systematic nomenclature and facilitate classification. Fundamental parent structures have one ...
. Common lithium amides include
lithium diisopropylamide
Lithium diisopropylamide (commonly abbreviated LDA) is a chemical compound with the molecular formula . It is used as a strong base and has been widely utilized due to its good solubility in non-polar organic solvents and non-nucleophilic nature ...
(LDA),
lithium tetramethylpiperidide
Lithium tetramethylpiperidide (often abbreviated LiTMP or LTMP) is a chemical compound with the molecular formula . It is used as a non-nucleophilic base, being comparable to LiHMDS in terms of steric hindrance.
Synthesis
It is synthesised by the ...
(LiTMP), and
lithium hexamethyldisilazide (LiHMDS). They are produced by the reaction of Li metal with the appropriate amine:
:
Lithium amides are very reactive compounds. Specifically, they are strong
bases.
Examples
Lithium tetramethylpiperidide has been crystallised as a tetramer. On the other hand, the lithium derivative of bis(1-phenylethyl)amine crystallises as a trimer:
It is also possible to make mixed oligomers of metal
alkoxides and amides.
These are related to the
superbases which are mixtures of metal alkoxides and alkyls. The cyclic oligomers form when the nitrogen of the amide forms a
sigma bond
In chemistry, sigma bonds (σ bonds) are the strongest type of covalent chemical bond. They are formed by head-on overlapping between atomic orbitals. Sigma bonding is most simply defined for diatomic molecules using the language and tools of s ...
to a lithium while the nitrogen
lone pair binds to another metal centre.
Other organolithium compounds (such as
BuLi) are generally considered to exist in and function via high-order, aggregated species.
See also
*
Sodium amide
Sodium amide, commonly called sodamide (systematic name sodium azanide), is the inorganic compound with the formula . It is a salt composed of the sodium cation and the azanide anion. This solid, which is dangerously reactive toward water, is white ...
*
Butyllithium Butyllithium may refer to one of 5 isomeric organolithium reagents of which 3 are commonly used in chemical synthesis:
* ''n''-Butyllithium, abbreviated BuLi or nBuLi
* ''sec''-Butyllithium, abbreviated ''sec''-BuLi or sBuLi, has 2 stereoisomers, ...
References
* ''
Merck Index
''The Merck Index'' is an encyclopedia of chemicals, drugs and biologicals with over 10,000 monograph on single substances or groups of related compounds published online by the Royal Society of Chemistry.
History
The first edition of the Mer ...
'', 11th Edition, 5398.
External links
{{Lithium compounds
Lithium salts
Metal amides