Difference between revisions of "Lithium aluminium hydride"
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| CASNo = 16853-85-3 | | CASNo = 16853-85-3 | ||
| CASNo_Ref = {{cascite}} | | CASNo_Ref = {{cascite}} | ||
| + | | EINECS = 240-877-9 | ||
| + | | ChemSpiderID = 26150 | ||
| + | | InChI=1/Al.Li.4H/q-1;+1;;;;/rAlH4.Li/h1H4;/q-1;+1 | ||
| + | | InChIkey = OCZDCIYGECBNKL-PDCCDREHAZ | ||
| + | | StdInChI = 1S/Al.Li.4H/q-1;+1;;;; | ||
| + | | StdInChIkey = OCZDCIYGECBNKL-UHFFFAOYSA-N | ||
| RTECS = BD0100000 | | RTECS = BD0100000 | ||
}} | }} | ||
| Section2 = {{Chembox Properties | | Section2 = {{Chembox Properties | ||
| Formula = LiAlH<sub>4</sub> | | Formula = LiAlH<sub>4</sub> | ||
| − | | MolarMass = 37. | + | | MolarMass = 37.954 g mol<sup>–1</sup> |
| − | | Appearance = white | + | | Appearance = white or grey solid |
| − | | Density = 0.917 g | + | | Density = 0.917 g cm<sup>–3</sup> |
| − | | Solubility = | + | | Solubility = reacts |
| MeltingPt = 150 °C (423 K), decomposing | | MeltingPt = 150 °C (423 K), decomposing | ||
}} | }} | ||
| Line 20: | Line 26: | ||
| CrystalStruct = [[monoclinic]] | | CrystalStruct = [[monoclinic]] | ||
| SpaceGroup = P2<sub>1</sub>c | | SpaceGroup = P2<sub>1</sub>c | ||
| + | }} | ||
| + | | Section4 = {{Chembox Thermochemistry | ||
| + | | Reference = <ref name="NIST">{{NIST chemistry|id=1S/Al.Li.4H/q-1;+1;;;;|name=Lithium tetrahydroaluminate|accessdate=2010-06-20}}.</ref><ref>{{citation | last1 = Smith | first1 = Martin B. | last2 = Bass | first2 = George E., Jr. | title = Heats and Free Energies of Formation of the Alkali Aluminum Hydrides and of Cesium Hydride | journal = J. Chem. Eng. Data | year = 1963 | volume = 8 | issue = 3 | pages = 342–46 | doi = 10.1021/je60018a020}}.</ref> | ||
| + | | DeltaHf = –117.15 kJ/mol | ||
| + | | Entropy = 87.90 J K<sup>–1</sup> mol<sup>–1</sup> | ||
}} | }} | ||
| Section7 = {{Chembox Hazards | | Section7 = {{Chembox Hazards | ||
| Line 40: | Line 51: | ||
It was first prepared from the reaction between [[lithium hydride]] (LiH) and [[aluminium chloride]]:<ref>{{citation | last1 = Finholt | first1 = A. E. | last2 = Bond | first2 = A. C. | last3 = Schlesinger | first3 = H. I.| title = Lithium Aluminum Hydride, Aluminum Hydride and Lithium Gallium Hydride, and Some of their Applications in Organic and Inorganic Chemistry | journal = J. Am. Chem. Soc. | year = 1947 | volume = 69 | issue = 5 | pages = 1199–1203 | doi = 10.1021/ja01197a061}}.</ref> | It was first prepared from the reaction between [[lithium hydride]] (LiH) and [[aluminium chloride]]:<ref>{{citation | last1 = Finholt | first1 = A. E. | last2 = Bond | first2 = A. C. | last3 = Schlesinger | first3 = H. I.| title = Lithium Aluminum Hydride, Aluminum Hydride and Lithium Gallium Hydride, and Some of their Applications in Organic and Inorganic Chemistry | journal = J. Am. Chem. Soc. | year = 1947 | volume = 69 | issue = 5 | pages = 1199–1203 | doi = 10.1021/ja01197a061}}.</ref> | ||
:4 LiH + AlCl<sub>3</sub> → LiAlH<sub>4</sub> + 3 LiCl | :4 LiH + AlCl<sub>3</sub> → LiAlH<sub>4</sub> + 3 LiCl | ||
| − | + | The modern industrial synthesis involves the initial preparation of sodium aluminium hydride from the elements under high pressure and temperature:<ref name="H&W">{{Holleman&Wiberg102nd}}.</ref> | |
:Na + Al + 2 H<sub>2</sub> → NaAlH<sub>4</sub> | :Na + Al + 2 H<sub>2</sub> → NaAlH<sub>4</sub> | ||
| Line 46: | Line 57: | ||
:NaAlH<sub>4</sub> + LiCl → LiAlH<sub>4</sub> + NaCl | :NaAlH<sub>4</sub> + LiCl → LiAlH<sub>4</sub> + NaCl | ||
| − | which proceeds in a high yield of LAH. | + | which proceeds in a high yield of LAH. [[Lithium chloride]] is removed by [[filtration]] from an [[Diethyl ether|ethereal]] solution of LAH, with subsequent precipitation of LAH to yield a product containing around 1% LiCl by mass.<ref name="H&W"/> |
==References== | ==References== | ||
Revision as of 09:31, 20 June 2010
| Lithium aluminium hydride | |
|---|---|
| IUPAC name | Lithium tetrahydridoaluminate(1−) |
| Identifiers | |
| InChI | InChI=1/Al.Li.4H/q-1;+1;;;;/rAlH4.Li/h1H4;/q-1;+1 |
| Standard InChI | InChI=1S/Al.Li.4H/q-1;+1;;;; |
| CAS number | [] |
| EC number | |
| RTECS | BD0100000 |
| ChemSpider | |
| Properties | |
| Chemical formula | LiAlH4 |
| Molar mass | 37.954 g mol–1 |
| Appearance | white or grey solid |
| Density | 0.917 g cm–3 |
| Melting point |
150 °C (423 K), decomposing |
| Solubility in water | reacts |
| Structure[1] | |
| Crystal structure | monoclinic |
| Space group | P21c |
| Coordination geometry | tetrahedral (Al) |
| Thermochemistry[2][3] | |
| Std enthalpy of formation ΔfH |
–117.15 kJ/mol |
| Standard molar entropy S |
87.90 J K–1 mol–1 |
| Hazards[4] | |
| EU index number | 001-002-00-4 |
| GHS pictograms | 
|
| GHS signal word | DANGER |
| GHS hazard statements | H260 |
| Related compounds | |
| Other hydride | aluminium hydride sodium borohydride sodium hydride |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Lithium aluminium hydride, LiAlH4, often abbreviated to LAH or "Lithal", is the lithium salt of the tetrahydridoaluminate(1−) anion. A moderately air-stable white or grey solid, it is widely used as a strong reducing agent in organic synthesis.
It was first prepared from the reaction between lithium hydride (LiH) and aluminium chloride:[5]
- 4 LiH + AlCl3 → LiAlH4 + 3 LiCl
The modern industrial synthesis involves the initial preparation of sodium aluminium hydride from the elements under high pressure and temperature:[6]
- Na + Al + 2 H2 → NaAlH4
LAH is then prepared by metathesis reaction according to:
- NaAlH4 + LiCl → LiAlH4 + NaCl
which proceeds in a high yield of LAH. Lithium chloride is removed by filtration from an ethereal solution of LAH, with subsequent precipitation of LAH to yield a product containing around 1% LiCl by mass.[6]
References
- ↑ Løvvik, O. M.; Opalka, Susanne M.; Brinks, Hendrik W.; Hauback, Bjørn C. Crystal structure and thermodynamic stability of the lithium alanates LiAlH4 and Li3AlH6. Phys. Rev. B 2004, 69 (13), 134117. DOI: 10.1103/PhysRevB.69.134117.
- ↑ Lithium tetrahydroaluminate. In NIST Chemistry WebBook; National Institute for Standards and Technology, <http://webbook.nist.gov/cgi/inchi/InChI%3D1S/Al.Li.4H/q-1;+1;;;;>. (accessed 20 June 2010).
- ↑ Smith, Martin B.; Bass, George E., Jr. Heats and Free Energies of Formation of the Alkali Aluminum Hydrides and of Cesium Hydride. J. Chem. Eng. Data 1963, 8 (3), 342–46. DOI: 10.1021/je60018a020.
- ↑ Index no. 001-002-00-4 of Annex VI, Part 3, to Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006. OJEU L353, 31.12.2008, pp 1–1355 at p 340.
- ↑ Finholt, A. E.; Bond, A. C.; Schlesinger, H. I. Lithium Aluminum Hydride, Aluminum Hydride and Lithium Gallium Hydride, and Some of their Applications in Organic and Inorganic Chemistry. J. Am. Chem. Soc. 1947, 69 (5), 1199–1203. DOI: 10.1021/ja01197a061.
- ↑ 6.0 6.1 Holleman, A. F.; Wiberg, E.; Wiberg, N. Lehrbuch der Anorganischen Chemie, 102nd ed.; de Gruyter, 2007. ISBN 978-3-11-017770-1.
External links
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See also the corresponding article on Wikipedia. |
