carbon disulfide

 

CS₂, liquid organic compound; it is colorless, foul-smelling, flammable, and poisonous. It can be prepared by direct reaction of carbon, e.g., as charcoal, with sulfur. It is a widely used solvent, e.g., for rubber, and is used to treat alkali cellulose in the viscose process (a source of rayon and cellophane). Carbon disulfide reacts with chlorine in the presence of a catalyst to form carbon tetrachloride.

Carbon disulfide
IUPAC name	Carbon disulfide
Other names	Dithiocarbonic anhydride
Identifiers
CAS number	75-15-0
SMILES	CS(S)
Properties
Molecular formula	CS2
Molar mass	76.1 g/mol
Appearance	colorless liquid impure: light-yellow
Density	1.26 g/cm³
Melting point	-112 °C
Boiling point	46 °C
Solubility in other solvents	0.2 g/100 ml of water (20 °C)
Hazards
MSDS	External MSDS
NFPA 704	4 3 0
R-phrases	R11, R23, R24, R25, R48
S-phrases	S16, S33, , S53
Flash point	-30 °C
Autoignition temperature	90 °C
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Carbon disulfide is a colorless, volatile liquid with the formula, CS₂. The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical solvent. It has an "ether-like" odor, but commercial samples are typically contaminated with foul-smelling impurities.^[1]

Occurrence and manufacture

Small amounts of carbon disulfide are released by volcanic eruptions and marshes. CS₂ once was manufactured by combining carbon (or coke) and sulfur at high temperatures. A lower temperature reaction, requiring only 600 °C utilizes natural gas as the carbon source in the presence of kieselgel or alumina catalysts:^[1]

CH₄ + 1/2 S₈ → CS₂ + 2 H₂S

The reaction is analogous to the combustion of methane. Although it is structurally similar to carbon dioxide, CS₂ is highly flammable:

CS₂ + 3 O₂ → CO₂ + 2 SO₂

Reactions

Compared to CO₂, CS₂ is more reactive toward nucleophiles and more easily reduced. These differences in reactivity can be attributed to the weaker π donor-ability of the sulfido centers, which renders the carbon more electrophilic. It is widely used in the synthesis of organosulfur compounds such as Metham sodium, a soil fumigant.

Addition of nucleophiles

Nucleophiles such as amines afford dithiocarbamates:

2R₂NH + CS₂ → [R₂NH₂⁺][R₂NCS₂^-]

Xanthates form similarly from alkoxides:

RONa + CS₂ → [Na⁺][ROCS₂^-]

This reaction is the basis of the manufacture of regenerated cellulose, the main ingredient of viscose rayon and cellophane. Both xanthates and the related thioxanthates (derived from treatment of CS₂ with sodium thiolates) are used as flotation agents in mineral processing. Sodium sulfide affords trithiocarbonate:

Na₂S + CS₂ → [Na⁺]₂[CS₃^2-]

Reduction

Sodium reduces CS₂ to give the heterocycle "dmit^2-":^[2]

3 CS₂ + 4 Na → Na₂C₃S₅ + Na₂S

Direct electrochemical reduction affords the tetrathiooxalate anion:^[3]

2 CS₂ + 2e^- → C₂S₄^2-

Chlorination

Chlorination of CS₂ is the principal route to carbon tetrachloride:^[1]

CS₂ + 3 Cl₂ → CCl₄ + S₂Cl₂

This conversion proceeds via the intermediacy of thiophosgene, CSCl₂.

Coordination chemistry

CS₂ is a ligand for many metal complexes, forming pi complexes. One example is CpCo(η²-CS₂)(PMe₃).^[4]

Health effects

At very high levels, carbon disulfide may be life-threatening because it affects the nervous system. Significant safety data come from the viscose rayon Industry, where both carbon disulfide as well as small amounts of H₂S may be present.

References

1. ^ ^{a b c} Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
2. ^ Girolami, G. S.; Rauchfuss, T. B. and Angelici, R. J., Synthesis and Technique in Inorganic Chemistry, University Science Books: Mill Valley, CA, 1999.ISBN: 0935702482
3. ^ Jeroschewski, P. "Electrochemical Preparation of Tetraalkylammonium Salts of Tetrathiooxalic Acid" Zeitschrift für Chemie (1981), volume 21, 412.
4. ^ Werner, H. (1982). "Novel Coordination Compounds formed from CS₂ and Heteroallenes". Coordination Chemistry Reviews 43: 165-185. DOI:10.1016/S0010-8545(00)82095-0. 

External links

• National Pollutant Inventory: Carbon disulfide

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