Sodium tetrasulfide

Sodium tetrasulfide

Names
IUPAC name Sodium tetrasulfide
Other names disodiumtetrasulphide, sodium sulfide
Identifiers
CAS Number	12034-39-8^Y
3D model (JSmol)	Interactive image
ChemSpider	74748^Y
ECHA InfoCard	100.031.628
EC Number	234-805-5
PubChem CID	82835
UNII	11J35Y83VX^Y
CompTox Dashboard (EPA)	DTXSID1065186
InChI InChI=1S/2Na.H2S4/c;;1-3-4-2/h;;1-2H/q2*+1;/p-2 Key: ZLCCLBKPLLUIJC-UHFFFAOYSA-L
SMILES [Na+].[Na+].[S-]SS[S-]
Properties
Chemical formula	Na2S4
Molar mass	174.24g/mol
Appearance	Dark red, slightly viscous liquid or yellow crystalline powder
Density	1.268 g/cm^3 at 15.5 °C
Melting point	275 °C (527 °F; 548 K)
Solubility in water	Soluble in water
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Stable at room temperature, but can be explosive when heated. Reactions with acids or oxidative agents will create gaseous byproducts that would be hazardous if inhaled.
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H228, H301, H311, H314, H400
Precautionary statements	P210, P240, P241, P260, P264, P270, P273, P280, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P361, P363, P370+P378, P391, P405, P501
NFPA 704 (fire diamond)	3 1 1
Autoignition temperature	Not applicable
Safety data sheet (SDS)	[1] [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Sodium tetrasulfide is an inorganic compound with the formula Na₂S₄. It is a yellow-orange solid that dissolves via hydrolysis in water.[2] 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:[3]

2NaSH + 4 S → Na₂S₄ + H₂S

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°.[4]

Reactions and applications

Upon treatment with acid, it is converted to hydrogen sulfide and elemental sulfur. Treatment with alkylating agents gives organic polysulfides. In one commercial application, it is used to produce the cross-linking agent bis(triethoxysilylpropyl)tetrasulfide:[5]

Na₂S₄ + 2 ClC₃H₆Si(OEt)₃ → S₄[C₃H₆Si(OEt)₃]₂ + 2 NaCl

Sometimes as a mixture with other polysulfides, sodium tetrasulfide is used to produce the polymer called thiokol. The reaction involves alkylation with ethylene chloride:

Na₂S₄ + C₂H₄Cl₂ → 1/n (C₂H₄)S_x]_n + 2 NaCl

These materials, which have the approximate formula (C₂H₄)S_x]_n (x ~ 4), are highly resistant to degradation by solvents and acids.[6]

References

1. "Safety Data Sheet, Sodium Tetrasulfide" (PDF). Pfaltz & Bauer. Archived from the original (PDF) on 2016-03-03. Retrieved 2013-11-17.
2. Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 365.
3. D. R. Brush (2000). "Sodium Sulfides". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.1915040902211908.a01. ISBN 0471238961.
4. R. Tegman "The crystal structure of sodium tetrasulphide, Na₂S₄" Acta Crystallogr. (1973). B29, 1463-1469 doi:10.1107/S0567740873004735
5. Thurn, Friedrich; Meyer-Simon, Eugen; Michel, Rudolf "Verfahren zur Herstellung von Organosiliziumverbindungen (Continuous manufacture of bis[3-(triethoxysilyl)propyl] tetrasulfide)" Ger. Offen. (1973), DE 2212239 A1 19731004.
6. Sulfides, Polysulfides, and Sulfanes" in Ullmann's Encyclopedia of Industrial Chemistry Ludwig Lange and Wolfgang Triebel, 2000, Wiley-VCH, Weinheim. doi:10.1002/14356007.a25_443