Sodium tetrasulfide

Chemical compound From Wikipedia, the free encyclopedia

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.

Quick facts Names, Identifiers ...
Sodium tetrasulfide
Names
IUPAC name
Sodium tetrasulfide
Other names
disodiumtetrasulphide, sodium sulfide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.628 Edit this at Wikidata
EC Number
  • 234-805-5
UNII
  • InChI=1S/2Na.H2S4/c;;1-3-4-2/h;;1-2H/q2*+1;/p-2
    Key: ZLCCLBKPLLUIJC-UHFFFAOYSA-L
  • [Na+].[Na+].[S-]SS[S-]
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
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:
GHS02: FlammableGHS05: CorrosiveGHS06: ToxicGHS09: Environmental hazard
Danger
H228, H301, H311, H314, H400
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)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
3
1
1
Not applicable
Safety data sheet (SDS) [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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]

Popular culture

In The Simpsons season 2 episode 14, Principal Charming, Bart learns about sodium tetrasulfide in class and then uses its herbicidal properties to vandalize the schoolyard. The compound is illustrated as a white powder, although Principal Skinner refers to the incorrectly-labelled substance as 'sodium tetrasulfate', which does not exist.

References

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