Lithium hydride

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Lithium hydride
Names
IUPAC name
Lithium hydride
Other names
Lithium monohydride
Properties
LiH
Molar mass 7.95 g/mol
Appearance White or light gray samples
Odor Odorless
Density 0.78 g/cm3
Melting point 688.7 °C (1,271.7 °F; 961.9 K)
Boiling point 900 °C (1,650 °F; 1,170 K) (decomposes)
Reacts
Solubility Reacts with alcohols, aldehydes, amines, ammonia, carboxylic acids, DMSO, esters, ethers, halocarbons, ketones
Soluble in molten lithium borohydride, lithium fluoride and sodium hydride
Slightly soluble in dimethylformamide
Insoluble in hydrocarbons
Vapor pressure ~0 mmHg
Thermochemistry
170.8 J·mol-1K-1
-90.65 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Related compounds
Related compounds
Sodium hydride
Calcium hydride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Lithium hydride is an inorganic compound with the formula LiH.

Properties

Chemical

Lithium hydride reacts with water to release hydrogen.

LiH + H2O → LiOH + H2

Physical

Lithium hydride is a white or slight grayish solid, which reacts with most solvents.

Availability

Lithium hydride is sold by chemical suppliers.

Preparation

Can be prepared by reacting molten lithium metal with hydrogen. The reaction takes place in a nickel crucible, between 450-500 °C, and the hydrogen used must be air and water-free. The yield of this reaction is 95%.[1]

However, the reaction can proceed at temperatures as low as 29 °C. The yield is 60% at 99 °C and 85% at 125 °C, and the rate depends significantly on the surface condition of LiH.

Hydrogenolysis of n-butyllithium at normal temperature and atmospheric pressure in the absence of catalyst will yield LiH.[2]

Projects

Handling

Safety

Lithium hydride is very reactive towards most common solvents, it will even slowly attack ethers. It may spontaneously ignite in moist air.

Storage

Lithium hydride must be kept in air-tight containers, in an inert atmosphere, away from moisture. Schlenk flasks are good storage containers.

Disposal

Lithium hydride can be safely neutralized by slowly adding it in a large volume of alcohol, followed by slow addition of water.

References

  1. Brandt, P.; Acta Chemica Scandinavica (1947-1973); vol. 3; (1949); p. 1050 - 1057
  2. Gilman, H.; Jacoby, A. L.; Ludeman, H.; Journal of the American Chemical Society; vol. 60; (1938); p. 2336 - 2338

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