Sodium disulfide

Crystal structure
__ Na +      __ S -
General
Surname	Sodium disulfide
other names	Disodium disulfide Disodium disulfane Disodium persulfide Sodium (I) persulfide
Ratio formula	Na 2 S 2
Brief description	yellow solid
External identifiers / databases
CAS number 22868-13-9 12034-38-7 EC number 245-272-3 ECHA InfoCard 100.041.142 PubChem 89870 Wikidata Q1969735
properties
Molar mass	110.11 g mol −1
Physical state	firmly
Melting point	470 ° C
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sodium disulfide is a chemical compound from the group of sulfides .

Extraction and presentation

Sodium disulfide can be obtained by reacting sodium with sulfur .

${\displaystyle \mathrm {8\ Na+S_{8}\longrightarrow 4\ Na_{2}S_{2}} }$

The reaction of sodium tetrasulfide dissolved in alcohol with sodium or tetraphenylphosphonium chloride is also possible .

${\displaystyle \mathrm {Na_{2}S_{4}+2\ Na\longrightarrow 2\ Na_{2}S_{2}} }$

When sodium trisulfide is heated to 100 ° C, it decomposes to a 1: 1 mixture of sodium disulfide and sodium tetrasulfide.

The reaction of sodium sulfide with sulfur is also possible

${\displaystyle \mathrm {Na_{2}S+S\longrightarrow Na_{2}S_{2}} }$

or sodium with sulfur in liquid ammonia .

${\displaystyle \mathrm {2\ Na+2\ S\longrightarrow Na_{2}S_{2}} }$

properties

Sodium disulfide is a light yellow, very hygroscopic solid. When heated, it gradually turns darker in color and is light red-brown at 400 ° C. Above 475 ° C the color deepens towards dark brown, and the substance begins to sinter strongly and from 490 ° C to melt into a deep dark brown liquid. The products made from an alcohol solution are always olive green in color after melting. It occurs in two allotropic forms, with the α-form below 160 ° C and the β-form irreversibly above. Both have a hexagonal crystal system.

use

Sodium disulfide is used to make other chemical compounds (e.g. diallyl disulfide ).

Individual evidence

1. ↑ ^{a b c d e f g} Ralf Steudel : Elemental sulfur and sulfur-rich compounds, Volume 2 . 2003, ISBN 3-540-40378-7 , pp. 130 ( limited preview in Google Book search).
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ↑ ^{a b c d} Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 374.