View source for Lithium aluminium hydride

{{chembox
| Name = Lithium aluminium hydride
| IUPACName = Lithium tetrahydridoaluminate(1−)
| Section1 = {{Chembox Identifiers
|   CASNo = 16853-85-3
|    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
  }}
| Section2 = {{Chembox Properties
|   Reference = <ref>{{RubberBible62nd|page=B-113}}.</ref>
|   Formula = LiAlH<sub>4</sub>
|   MolarMass = 37.954 g&thinsp;mol<sup>–1</sup>
|   Appearance = white or grey solid
|   Density = 0.917 g&thinsp;cm<sup>–3</sup>
|   Solubility = reacts
|   Solubility1 = ''approx.'' 300 g&thinsp;dm<sup>–3</sup>
|    Solvent1 = diethyl ether
|   MeltingPt = 125 °C ''decomp.''
  }}
| Section3 = {{Chembox Structure
|   Reference = <ref>{{citation | last1 = Løvvik | first1 = O. M. | last2 = Opalka | first2 = Susanne M. | last3 = Brinks | first3 = Hendrik W. | last4 = Hauback | first4 = Bjørn C. | title = Crystal structure and thermodynamic stability of the lithium alanates LiAlH<sub>4</sub> and Li<sub>3</sub>AlH<sub>6</sub> | year = 2004 | journal = Phys. Rev. B | volume = 69 | issue = 13 | pages = 134117 | doi = 10.1103/PhysRevB.69.134117}}.</ref>
|   Coordination = tetrahedral (Al)
|   CrystalStruct = [[monoclinic]]
|   SpaceGroup = P2<sub>1</sub>/''c'' (No. 14)
  }}
| 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&thinsp;mol<sup>–1</sup>
|   Entropy = 87.90 J&thinsp;K<sup>–1</sup>&thinsp;mol<sup>–1</sup>
  }}
| Section7 = {{Chembox Hazards
|   Reference = <ref>{{CLP Regulation|index=001-002-00-4|page=340}}</ref>
|   EUIndex = 001-002-00-4
|   GHSPictograms = {{GHS02|Water-react. 1}}
|   GHSSignalWord = DANGER
|   HPhrases = {{H-phrases|260}}
  }}
| Section8 = {{Chembox Related
|   Function = [[hydride]]s
|   OtherFunctn = [[aluminium hydride]]<br/>[[sodium borohydride]]<br/>[[sodium hydride]]
  }}
}}
'''Lithium aluminium hydride''', LiAlH<sub>4</sub>, 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]]:<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
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>

LAH is then prepared by [[metathesis reaction]] according to:
:NaAlH<sub>4</sub> + LiCl → LiAlH<sub>4</sub> + NaCl

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==
{{reflist}}

==External links==
{{wikipedia|Lithium aluminium hydride}}
*{{OrgSynth preps|id=36257|name=Lithium aluminium hydride}}

[[Category:Lithium compounds]]
[[Category:Aluminium compounds]]
[[Category:Hydrides]]
[[Category:Reagents for organic chemistry]]