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Names | |
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IUPAC name
Sodium aluminium hydride
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Systematic IUPAC name
Sodium alumanuide | |
Other names
Sodium tetrahydroaluminate
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Identifiers | |
3D model (
JSmol)
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ECHA InfoCard | 100.033.986 |
EC Number |
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PubChem
CID
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UN number | 2835 |
CompTox Dashboard (
EPA)
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Properties | |
AlH4Na | |
Molar mass | 54.003 g·mol−1 |
Appearance | White or gray crystalline solid |
Density | 1.24 g/cm3 |
Melting point | 178 °C (352 °F; 451 K) |
Solubility | soluble in THF (16 g/100 mL at room temperature) |
Hazards | |
GHS labelling: | |
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NFPA 704 (fire diamond) | |
Flash point | −22 °C; −7 °F; 251 K |
185 °C (365 °F; 458 K) | |
Lethal dose or concentration (LD, LC): | |
LD50 (
median dose)
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740 mg/kg (oral, mouse) |
Safety data sheet (SDS) | Fisher Scientific |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
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Sodium aluminium hydride or sodium alumanuide is an
inorganic compound with the
chemical formula NaAlH4. It is a white
pyrophoric solid that dissolves in
tetrahydrofuran (THF), but not in
diethyl ether or hydrocarbons. It has been evaluated as an agent for the reversible storage of hydrogen and it is used as a
reagent for the
chemical synthesis of
organic compounds. Similar to
lithium aluminium hydride, it is a
salt consisting of separated
sodium
cations and tetrahedral AlH−
4
anions.
[1]
Sodium tetrahydroaluminate adopts the structure of (is isostructural with)
calcium tungstate. As such, the tetrahedral AlH−
4 centers are linked with eight-coordinate Na+ cations.
[1]
The compound is prepared from the elements under high pressures of H2 at 200 °C using
triethylaluminium catalyst:
[2]
As a suspension in diethyl ether, it reacts with lithium chloride to give the popular reagent lithium aluminium hydride:
The compound reacts rapidly, even violently, with protic reagents, such as water, as described in this idealized equation:
Sodium alanate [3] has been explored for hydrogen storage in hydrogen tanks. [4] The relevant reactions are:
Sodium tetrahydroaluminate can release up to 7.4 wt % of hydrogen when heated at 200 °C (392 °F). Absorption can be slow, with several minutes being required to fill a tank. Both release and uptake are catalysed by titanium. [5]
Sodium aluminium hydride is a strong reducing agent, very similar in reactivity to lithium aluminium hydride (LAH) and, to some extent, Diisobutylaluminium hydride (DIBAL) in organic reactions. [6] It is much more powerful reducing agent than sodium borohydride due to the weaker and more polar Al-H bond compared to the B-H bond. Like LAH, it reduces esters to alcohols.
Sodium aluminium hydride is highly flammable. It does not react in dry air at room temperature but is very sensitive to moisture. It ignites or explodes on contact with water.