Sodium tetrasulfide

Sodium tetrasulfide is an inorganic compound with the formula Na2S4. It is a yellow-orange solid that dissolved with hydrolysis in water.[2] They are precursors to some specialty polymers and intermediates in prototypes of the sodium-sulfur battery.

Sodium tetrasulfide
Names
IUPAC name
Sodium tetrasulfide
Other names
disodiumtetrasulphide, sodium sulfide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.628
EC Number
  • 234-805-5
UNII
Properties
Na2S4
Molar mass 174.24g/mol
Appearance Dark red, slightly viscous liquid or yellow crystalline powder
Density 1.268 g/cm3 at 15.5 °C
Melting point 275 °C (527 °F; 548 K)
Soluble in water
Hazards
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.
Safety data sheet [1]
GHS pictograms
GHS Signal word Danger
H228, H301, H311, H314, H400
P210, P240, P241, P260, P264, P270, P273, P280, P301+310, P301+330+331, P302+352, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P322, P330, P361, P363, P370+378, P391, P405, P501
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
1
3
1
Not applicable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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)Sx]n + 2 NaCl

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

References
  1. "Safety Data Sheet, Sodium Tetrasulfide" (PDF). Pfaltz & Bauer.
  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
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