Sodium hydride

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Sodium hydride
Names
IUPAC name
Sodium hydride
Other names
Sodium monohydride
Properties
NaH
Molar mass 23.99771 g/mol
Appearance White or gray solid
Odor Odorless
Density 1.396 g/cm3
Melting point 300 °C (572 °F; 573 K)
Boiling point 300–500 °C (572–932 °F; 573–773 K) Decomposes
Reacts
Solubility Reacts with alcohols, aldehydes, carboxylic acids, halocarbons, ketones
Soluble in NaK, molten NaOH
Insoluble in most solvents
Vapor pressure ~0 mmHg
Thermochemistry
-56.366 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Related compounds
Related compounds
 Lithium 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

Sodium hydride is the chemical compound with the chemical formula NaH. It is a strong base.

Properties

Chemical

Sodium hydride will react with water to release hydrogen.

Reaction with aluminium metal and hydrogen will give sodium aluminium hydride.

Physical

Sodium hydride is a white solid, which reacts with water.

Availability

It is sold by chemical suppliers, usually kept under mineral oil or argon.

Preparation

Sodium hydride can be prepared by passing dry and air-free hydrogen over molten sodium metal, at 700-750 °C. The molten sodium sits in a steel crucible or boat, inside a quartz or refractory glass tube. Adding small amounts of calcium metal will accelerate the process.[1] At room temperature, sodium reacts very slow with hydrogen to form sodium hydride.

Heating sodium metal and hydrogen in THF at 250-350 °C, at a pressure rising from 7 to 35 atm will give sodium hydride with a yield of 98%.[2]

Thermal decomposition of sodium aluminium hydride above 250 °C will give hydrogen, aluminium and sodium hydride.

NaAlH4 → NaH + Al + 2 H2

Heating the powdered sodium carbide in an autoclave in the presence of hydrogen at 500 atm and 650°C will give sodium hydride. Yield of this process is 86%.[3]

Thermal decomposition of sodium amide, in a hydrogen atmosphere at 300 °C will give sodium hydride.[4]

Reduction of sodium hydroxide with a mixture of H2-N2 at 750 °C will give sodium hydride. Iron or manganese is used as catalyst.[5]

Hydrogenation of sodium azide at 120 °C in gaseous phase, without a solvent gives sodium hydride and ammonia.[6][7]

Sodium hydride is also produced, along with sodium carbide by reacting molten sodium metal with methane, at 300-500 °C.[8] Reaction of molten sodium metal with acetylene at 100-550 °C is another route.[9]

Projects

Handling

Safety

Sodium hydride is water and air sensitive and must be handled with care and proper protection. In finely divided form it may be pyrophoric.

Storage

Sodium hydride must be kept in an air-tight container under inert atmosphere or inert solvent, like mineral oil.

Disposal

Adding it in a large volume of base, water or alcohol will suffice.

References

  1. ↑ Ephraim; Michel, E.; Helvetica Chimica Acta; vol. 4; (1921); p. 765
  2. ↑ http://www.google.com/patents/US2898195
  3. ↑ Patent; Goerrig, D.; Farbenfabriken Bayer A.-G.; DE953523; (1956); C. A.; (1959); p. 7526
  4. ↑ Guntz; Benoit; Bulletin de la Societe Chimique de France; vol. 41; (1927); p. 434 - 434
  5. ↑ Villard, P.; Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences; vol. 193; (1931); p. 681 - 685
  6. ↑ Wattenberg, H.; Ber. Dtsch. Chem. Ges.; vol. 63; (1930); p. 1667 - 1672
  7. ↑ Patent; Tiede, E.; DE417508; (1925)
  8. ↑ Kovalev; Journal of applied chemistry of the USSR; vol. 57; nb. 7 pt 1; (1984); p. 1368 - 1371
  9. ↑ Walker; Journal of Physical Chemistry; vol. 31; (1927); p. 982 - 982

Relevant Sciencemadness threads

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