Sodium hydride

Crystal structure
__ Na +      __ H -
General
Surname	Sodium hydride
Ratio formula	Close
Brief description	gray-white crystals
External identifiers / databases
CAS number 7646-69-7 EC number 231-587-3 ECHA InfoCard 100.028.716 PubChem 24758 Wikidata Q407924
properties
Molar mass	23.99 g mol −1
Physical state	firmly
density	1.396 g cm −3
Melting point	Decomposition from 425 ° C
solubility	reacts violently with water
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 228-260-314 P: 210-223-231 + 232-280-370 + 378-422
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sodium hydride (NaH) is the hydride of sodium , i.e. an ionic compound in which hydrogen is negatively charged and sodium is positive.

Extraction and presentation

It is produced technically at 250-300 ° C by passing pure hydrogen gas over molten sodium . Neither water nor oxygen may be present.

${\displaystyle \mathrm {2\ Na+H_{2}\longrightarrow 2\ NaH} }$

properties

Sodium hydride

Sodium hydride is an ionic , salt-like compound : It has the structure of an ion lattice , which is similar to the structure of sodium chloride . When it comes into contact with water , it reacts violently to form caustic soda and molecular hydrogen, which is highly flammable. As protection against humidity , sodium hydride is usually sold as a mixture of 60% NaH in paraffin oil or petroleum ether .

It shows all the typical properties of a salt-like hydride . With all acids there is an immediate, often explosive formation of elemental hydrogen . This applies e.g. B. for the reaction with water , alcohols , ammonia and hydrogen halides :

${\displaystyle \mathrm {NaH+H_{2}O\longrightarrow NaOH+H_{2}} }$

Reacts with water to form sodium hydroxide and hydrogen

${\displaystyle \mathrm {NaH+CH_{3}CH_{2}OH\longrightarrow CH_{3}CH_{2}ONa+H_{2}} }$

Reaction with ethanol to form sodium ethoxide and hydrogen

${\displaystyle \mathrm {NaH+NH_{3}\longrightarrow NaNH_{2}+H_{2}} }$

Reaction with ammonia to form sodium amide and hydrogen

${\displaystyle \mathrm {NaH+HCl\longrightarrow NaCl+H_{2}} }$

Reaction with hydrogen chloride to form sodium chloride and hydrogen

The basic effect of the hydride - ion also utilized for the condensation Claisen . In addition, sodium hydride is a powerful reducing agent and is used to reduce organic compounds .

use

Sodium hydride is a strong base (according to Brønsted , the hydride ion is the base), which is mainly used in organic synthesis because it is able to also react weak acids such as. B. to deprotonate alcohols . Furthermore, sodium hydride can be used as a reducing agent , e.g. B. to obtain thiols from disulfides .

literature

• AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 .

Individual evidence

1. ↑ ^{a b c d e f} Entry on sodium hydride in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
2. ↑ Entry on Sodium hydride in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
3. ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 949.
4. ↑ Spectrum of Science Verlagsgesellschaft mbH: Sodium hydride