Sodium polysulfide
[CAS# 1344-08-7]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal sulfides and sulfates
• Name: Sodium polysulfide
• Molecular Formula: Na2(S)_x
• CAS Registry Number: 1344-08-7
• EC Number: 215-686-9
• SMILES: [Na+].[Na+].[S-]S[S-]

Safety Data

• Hazard Symbols: GHS05;GHS06;GHS09 Danger
• Hazard Statements: H301-H314-H400
• Precautionary Statements: P260-P264-P270-P273-P280-P301+P316-P301+P330+P331-P302+P361+P354-P304+P340-P305+P354+P338-P316-P321-P330-P363-P391-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Acute toxicity	Acute Tox.	3	H301
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Serious eye damage	Eye Dam.	1	H318
Self-heating substances or mixtures	Self-heat.	1	H251
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Acute toxicity	Acute Tox.	3	H311

Discovory and Applicatios

Sodium polysulfide (Na₂S_x, where x = 2–5) is an inorganic compound that has been known since the 19th century through studies of sulfur chemistry and alkali metal reactions. It is typically prepared by the reaction of elemental sulfur with aqueous sodium sulfide. The compound exists as a mixture of chain-length polysulfides, and the sulfur atoms in the chains provide redox activity and nucleophilicity, making it highly reactive in chemical processes. Sodium polysulfide appears as an orange to yellow solid or solution, and it readily dissolves in water to give strongly alkaline solutions.

Historically, sodium polysulfide was first investigated for its ability to react with various metals and organic compounds. Its early applications were associated with rubber vulcanization, where it functions as a sulfur donor, and with the production of dyes and pigments, particularly for textile applications. The reactive sulfur chains in polysulfides allow the formation of thiosulfates, sulfides, and sulfur-containing dyes when treated with organic halides or other electrophiles.

In industry, sodium polysulfide is widely used in the manufacture of sulfur dyes, particularly in the production of “sulfur blacks” and other insoluble pigments. It acts as a reducing agent and a nucleophile, facilitating the introduction of sulfur into organic molecules to form stable colored compounds. These dyes are notable for their strong colorfastness and suitability for cotton and other cellulosic fibers. Sodium polysulfide is also used in leather processing and textile finishing, where it participates in deliming, dehairing, and bleaching operations.

The compound has applications in environmental and chemical processes as well. It is employed in mining and metallurgy to precipitate heavy metals as metal sulfides, aiding in the treatment of effluents. Its reducing properties make it useful for removing oxygen or oxidizing species in various industrial streams. In the rubber industry, it continues to be used as a vulcanization accelerator, contributing sulfur atoms that crosslink polymer chains, enhancing elasticity and strength.

Sodium polysulfide also finds use in organic synthesis. It can react with alkyl halides, epoxides, and other electrophiles to produce organosulfur compounds such as thiols, thioethers, and polysulfide derivatives. These reactions exploit its nucleophilic sulfur chains, making it a versatile reagent in laboratories and industrial processes.

Safety considerations are critical when handling sodium polysulfide. It is highly alkaline and can release hydrogen sulfide gas upon acidification, which is toxic and has a characteristic odor. Appropriate protective equipment, ventilation, and chemical handling procedures are required in industrial and laboratory contexts. Environmental precautions are taken to manage sulfide-containing effluents, as they can contribute to oxygen depletion and toxicity in aquatic systems.

The discovery and development of sodium polysulfide have enabled its extensive use across multiple industries, including textiles, leather, rubber, and chemical synthesis. Its combination of nucleophilicity, reducing power, and sulfur donation continues to make it an important reagent in both industrial and research applications.

References

2014. Cytoprotective effects of hydrogen sulfide-releasing N-methyl-d-aspartate receptor antagonists mediated by intracellular sulfane sulfur. MedChemComm, 5(10).
DOI: 10.1039/c4md00180j

Compound: Sodium polysulfide. .
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https://www.epa.gov/chemical-data-reporting. .
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