Sodium aluminium hydride
| Names | |
|---|---|
| IUPAC name
Sodium aluminium hydride
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| 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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CompTox Dashboard (EPA)
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| Properties | |
| AlH4Na | |
| Molar mass | 54.003 g·mol−1 |
| Appearance | White crystalline solid |
| Density | 1.24 g/cm3 |
| Melting point | 183 °C (361 °F; 456 K) |
| Solubility | soluble in THF |
| Hazards | |
| Flash point | -7 °F (-22 °C) |
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 (NaAlH4) or sodium alanate is a chemical compound used as a reducing agent. It is similar to lithium aluminium hydride.
It is used for hydrogen storage in hydrogen tanks,[1] the sodium tetrahydroaluminate can absorb up to 7.4 wt % of hydrogen, with hydrogen released when heated at 200 °C (392 °F). absorption can be slow and take up to 15 minutes to fill a tank.
Sodium aluminium hydride is a strong reducing agent, similar in reactivity to lithium aluminum hydride. It may react violently with oxidizing agents. Its action is similar to DIBAL in organic reactions.
- RCOOR' + H2 + NaAlH4 (reducing agent) → RCOOH + R'OH
LAH is a more powerful reducing agent than sodium borohydride due to the weaker Al-H bond compared to the B-H bond. The reactivity of sodium borohydride can be modified by addition of iodine or methanol in BH3 · THF to reduce esters into the corresponding alcohols, like the reaction of benzyl benzoate to benzyl alcohol
NaH can be used to efficiently produce sodium aluminium hydride (NaAlH4) by metathesis in THF:
- LiAlH4 + NaH → NaAlH4 + LiH
By adding titanium the kinetics of hydrogen release and recharge are improved.[2]
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 or moist air.
See also
References
- ^ Zaluska, A.; Zaluski, L.; Ström-Olsen, J. O. (2000). "Sodium Alanates for Reversible Hydrogen Storage". Journal of Alloys and Compounds. 298 (1–2): 125–134. doi:10.1016/S0925-8388(99)00666-0.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "Researchers Solve Decade-Old Mystery of Hydrogen Storage Material". Phys.Org. 2008-02-27.
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