Sodium tetrasulfide is an
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the formula Na
2S
4. It is a yellow-orange solid that dissolves via hydrolysis in water. It is a precursor to some specialty polymers and intermediates in prototypes of the
sodium-sulfur battery.
Synthesis and structure
It is produced through the reaction between elemental sulfur and sodium hydrosulfide in alcoholic solution:
:2NaSH + 4 S → Na
2S
4 + H
2S
The polysulfide anions adopt zig-zag chains of sulfur atoms. The S-S distances are about 2.05 Å and the S-S-S-S dihedral angles are around 90°.
Reactions and applications
Upon treatment with acid, it is converted to
hydrogen sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The unde ...
and elemental sulfur. Treatment with alkylating agents gives organic polysulfides. In one commercial application, it is used to produce the
cross-link
In chemistry and biology a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural ...
ing agent
bis(triethoxysilylpropyl)tetrasulfide:
:Na
2S
4 + 2 ClC
3H
6Si(OEt)
3 → S
4 3H6Si(OEt)3sub>2 + 2 NaCl
Sometimes as a mixture with other
polysulfide
Polysulfides are a class of chemical compounds containing chains of sulfur atoms. There are two main classes of polysulfides: inorganic and organic. Among the inorganic polysulfides, there are ones which contain anions, which have the general formu ...
s, sodium tetrasulfide is used to produce the polymer called thiokol. The reaction involves alkylation with
ethylene chloride Ethylene chloride is a chemical name that can refer to either of the following compounds:
{{Chemistry index ...
:
:Na
2S
4 + C
2H
4Cl
2 → 1/n (C
2H
4)S
x]
n + 2 NaCl
These materials, which have the approximate formula (C
2H
4)S
x]
n (x ~ 4), are highly resistant to degradation by solvents and acids.
[Sulfides, Polysulfides, and Sulfanes" in Ullmann's Encyclopedia of Industrial Chemistry Ludwig Lange and Wolfgang Triebel, 2000, Wiley-VCH, Weinheim. ]
References
{{Reflist
Polysulfides
Sodium compounds