Sodium aluminum hydride

Structural formula
General
Surname	Sodium aluminum hydride
other names	Sodium alanate Sodium tetrahydridoaluminate
Molecular formula	NaAlH 4
Brief description	white solid
External identifiers / databases
CAS number 13770-96-2 EC number 237-400-1 ECHA InfoCard 100,033,986 PubChem 26266 Wikidata Q1961048
properties
Molar mass	54.00 g mol −1
Physical state	firmly
density	1.27 g cm −3
Melting point	183 ° C (decomposition)
solubility	soluble in tetrahydrofuran and polyglycol ethers reacts violently with water
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 261-302-314 EUH: 014 P: 231 + 232-280-305 + 351 + 338-310-422
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sodium aluminum hydride is an inorganic-chemical compound of sodium from the group of hydrides .

Extraction and presentation

Sodium aluminum hydride can be obtained directly from the elements. The reaction has a very high yield if it is carried out at a temperature of 140 ° C. and a pressure of 350  bar in toluene with triethylaluminum as a catalyst .

${\displaystyle \mathrm {Na+Al+2\ H_{2}\longrightarrow NaAlH_{4}} }$

It can also be made by reacting sodium hydride with aluminum chloride in tetrahydrofuran . In the reaction, triethylaluminum is used as a catalyst, which serves to form a soluble intermediate product.

${\displaystyle \mathrm {NaH+(C_{2}H_{5})_{3}Al\longrightarrow NaAl(C_{2}H_{5})_{3}H} }$

${\displaystyle \mathrm {4\ NaAl(C_{2}H_{5})_{3}H+AlCl_{3}\longrightarrow NaAlH_{4}+3\ NaCl+3\ (C_{2}H_{5})_{3}Al} }$

The first synthesis was achieved in 1951 by Schlesinger and Finholt by reacting sodium hydride with aluminum bromide in dimethyl ether , with a yield of 60%.

${\displaystyle \mathrm {4\ NaH+AlBr_{3}\longrightarrow NaAlH_{4}+3\ NaBr} }$

Later they improved the structure by making it with aluminum hydride and sodium hydride in tetrahydrofuran.

${\displaystyle \mathrm {AlH_{3}+NaH\longrightarrow NaAlH_{4}} }$

It is also possible to display it by reacting lithium aluminum hydride or sodium tetrachloroaluminate with sodium hydride.

${\displaystyle \mathrm {LiAlH_{4}+NaH\longrightarrow NaAlH_{4}+LiH} }$

${\displaystyle \mathrm {NaAlCl_{4}+4\ NaH\longrightarrow NaAlH_{4}+4\ NaCl} }$

properties

Sodium aluminum hydride is a white crystalline solid that reacts violently with water. It decomposes when heated, producing hydrogen , among other things . Like lithium aluminum hydride, it is an effective reducing agent, reducing, among other things, carboxylic acid esters to aldehydes and lactones to hydroxyaldehydes .

use

In addition to being used as a reducing agent , sodium aluminum hydride is also used to determine small amounts of water in ethers, olefins and hydrocarbons .

It is also being studied as a storage medium for hydrogen in the vehicle industry.

safety instructions

There is a risk of explosion in contact with water and halogenated hydrocarbons .

Individual evidence

1. ↑ ^{a b c d} Entry on sodium alanate in the GESTIS substance database of the IFA , accessed on January 27, 2020(JavaScript required) .
2. ↑ ^{a b c d e f g h i} Entry on sodium aluminum hydride. In: Römpp Online . Georg Thieme Verlag, accessed on January 26, 2015.
3. ↑ ^{a b c d e} H.J. Emeléus & AG Sharpe: ADVANCES IN INORGANIC CHEMISTRY AND RADIOCHEMISTRY . Academic Press, 1966, ISBN 978-0-08-057857-6 , pp. 319 ( limited preview in Google Book search).
4. ↑ Entry on sodium aluminum hydride in the Hazardous Substances Data Bank , accessed January 26, 2015.
5. ↑ Sven Geitmann: Energiewende 3.0: with hydrogen and fuel cells . Hydrogeit Verlag, 2012, ISBN 978-3-937863-16-0 , p. 105 ( limited preview in Google Book search).
6. ↑ Vitalie Stavila, Raghunandan K. Bhakta, Todd M. Alam, Eric H. Majzoub, Mark D. Allendorf: Reversible Hydrogen Storage by NaAlH Confined within a Titanium-Functionalized MOF-74 (Mg) Nanoreactor. In: ACS Nano . 6, 2012, pp. 9807-9817, doi : 10.1021 / nn304514c .