Sulfur dichloride

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Sulfur dichloride
Structure and dimensions of the sulfur dichloride molecule
Ball-and-stick model of sulfur dichloride Space-filling model of sulfur dichloride
Identifiers
CAS number 10545-99-0 YesY
EC number 234-129-0
UN number 1828
RTECS number WS4500000
Jmol-3D images Image 1
Properties
Molecular formula SCl2
Molar mass 102.97 g mol−1
Appearance red liquid with pungent odour
Density 1.621 g cm−3, liquid
Melting point −121.0 °C (−185.8 °F; 152.2 K)
Boiling point 59 °C (138 °F; 332 K) (decomposes)
Solubility in water hydrolysis
Refractive index (nD) 1.5570
Structure
Coordination
geometry
C2v
Molecular shape Bent
Hazards
MSDS ICSC 1661
EU Index 016-013-00-X
EU classification Corrosive (C)
Irritant (Xi)
Dangerous for the environment (N)
R-phrases R14, R34, R37, R50
S-phrases (S1/2), S26, S45, S61
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Autoignition temperature 234 °C (453 °F; 507 K)
Related compounds
Related Disulfur dichloride
Thionyl chloride
Sulfuryl chloride
Related compounds Sulfur difluoride
Sulfur tetrafluoride
Sulfur hexafluoride
Disulfur dibromide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Sulfur dichloride is the chemical compound with the formula SCl2. This cherry-red liquid is the simplest sulfur chloride and one of the most common. It is used as a precursor to organosulfur compounds.[1]

Chlorination of sulfur[edit]

SCl2 is produced by the chlorination of either elemental sulfur or disulfur dichloride.[2] The process occurs in a series of steps, some of which are:

S8 + 4 Cl2 → 4 S2Cl2; ΔH = −58.2 kJ/mol
S2Cl2 + Cl2 → 2 SCl2; ΔH = −40.6 kJ/mol

The addition of Cl2 to S2Cl2 has been proposed to proceed via a mixed valence intermediate Cl3S-SCl. SCl2 undergoes even further chlorination to give SCl4, but this species is unstable at near room temperature. It is likely that several SxCl2 exist where x > 2.

Disulfur dichloride, S2Cl2, is the most common impurity in SCl2. Separation of SCl2 from S2Cl2 is possible via distillation with PCl3 to form an azeotrope of 99% purity, however sulfur dichloride loses chlorine slowly at room temperature and reverts to disulfur dichloride. Pure samples may be stored in sealed glass ampules which develop a slight positive pressure of chlorine, halting the decomposition.

Use of SCl2 in chemical synthesis[edit]

SCl2 is also a precursor to several inorganic sulfur compounds. Treatment with fluoride salts gives SF4. Reaction with ammonia affords sulfur nitrides related to S4N4. With H2S, SCl2 reacts to give "lower" sulfanes such as S3H2.

Safety considerations[edit]

SCl2 hydrolyzes with release of HCl. Old samples contain Cl2.

References[edit]

  1. ^ Schmidt, M.; Siebert, W. "Sulphur" Comprehensive Inorganic Chemistry Vol. 2, ed. A.F. Trotman-Dickenson. 1973.
  2. ^ F. Fehér "Dichloromonosulfane" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 370.
  3. ^ Bishop, Roger (1992), "9-Thiabicyclo[3.3.1]nonane-2,6-dione", Org. Synth. 70: 120 ; Coll. Vol. 9: 692 
  4. ^ R. J. Cremlyn “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). ISBN 0-471-95512-4.