Sulfur dichloride
| Sulfur dichloride | |
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Sulphur dichloride |
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Other names
Sulphur chloride |
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| Identifiers | |
| CAS number | 10545-99-0  |
| EC number | 234-129-0 |
| UN number | 1828 |
| RTECS number | WS4500000 |
| Jmol-3D images | Image 1 |
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| 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, 152.2 K, -185.8 °F |
| Boiling point |
59 °C, 332 K, 138 °F (decomp.) |
| 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 |
 1
3
1
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| Autoignition temperature |
234 °C |
| Related compounds | |
| Related | Disulfur dichloride Thionyl chloride Sulfuryl chloride |
| Related compounds | Sulfur difluoride Sulfur tetrafluoride Sulfur hexafluoride Disulfur dibromide |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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]
Contents |
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:
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- 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 used in organic synthesis. It adds to alkenes to give chloride-substituted thioethers. Illustrative applications are its addition to 1,5-cyclooctadiene to give a bicyclic thioether[3] and ethylene to give sulfur mustard S(CH2CH2Cl)2.[4]
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]
- ^ Schmidt, M.; Siebert, W. "Sulphur" Comprehensive Inorganic Chemistry Vol. 2, ed. A.F. Trotman-Dickenson. 1973.
- ^ F. Fehér "Dichloromonosulfane" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 370.
- ^ Bishop, Roger (1992), "9-Thiabicyclo[3.3.1]nonane-2,6-dione", Org. Synth. 70: 120; Coll. Vol. 9: 692
- ^ R. J. Cremlyn “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). ISBN 0-471-95512-4.
