Chemistry:Sulfur dichloride
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UN number | 1828 | ||
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Properties | |||
SCl 2 | |||
Molar mass | 102.96 g·mol−1 | ||
Appearance | Cherry-red liquid | ||
Odor | Pungent | ||
Density | 1.621 g/cm3 | ||
Melting point | −121.0 °C (−185.8 °F; 152.2 K) | ||
Boiling point | 59 °C (138 °F; 332 K) (decomposes) | ||
Insoluble, reacts slowly | |||
−49.4·10−6 cm3/mol | |||
Refractive index (nD)
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1.5570 | ||
Structure | |||
C2v | |||
Bent | |||
Hazards | |||
Safety data sheet | ICSC 1661 | ||
GHS pictograms | |||
GHS Signal word | Danger | ||
H314, H335, H400 | |||
P260, P261, P264, P271, P273, P280, P301+330+331, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P363, P391, P403+233, P405, P501 | |||
NFPA 704 (fire diamond) | |||
234 °C (453 °F; 507 K) | |||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
verify (what is ?) | |||
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Sulfur dichloride is the chemical compound with the formula SCl
2. This cherry-red liquid is the simplest sulfur chloride and one of the most common, and it is used as a precursor to organosulfur compounds. It is a highly corrosive and toxic substance, and it reacts on contact with water to form chlorine-containing acids.
Chlorination of sulfur
SCl
2 is produced by the chlorination of either elemental sulfur or disulfur dichloride.[1] The process occurs in a series of steps, some of which are:
- S
8 + 4 Cl
2 → 4 S
2Cl
2; ΔH = −58.2 kJ/mol - S
2Cl
2 + Cl
2 ↔ 2 SCl
2; ΔH = −40.6 kJ/mol
The addition of Cl
2 to S
2Cl
2 has been proposed to proceed via a mixed valence intermediate Cl
3S–SCl. SCl
2 undergoes even further chlorination to give SCl
4, but this species is unstable at near room temperature. It is likely that several S
nCl
2 exist where n > 2.
Disulfur dichloride, S
2Cl
2, is the most common impurity in SCl
2. Separation of SCl
2 from S
2Cl
2 is possible via distillation with PCl
3 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 SCl
2 in chemical synthesis
SCl
2 is used in organic synthesis. It adds to alkenes to give chloride-substituted thioethers. Illustrative is its addition to 1,5-cyclooctadiene to give a bicyclic thioether[2] A well tested method for the production of the mustard gas bis(2-chloroethyl)sulfide, is the addition of ethylene to sulfur dichloride:[3]
- SCl
2 + 2 C
2H
4 → (ClC
2H
4)
2S
SCl
2 is also a precursor to several inorganic sulfur compounds. Treatment with fluoride salts gives SF
4 via the decomposition of the intermediate sulfur difluoride. With H
2S, SCl
2 reacts to give "lower" sulfanes such as S
3H
2.
Reaction with ammonia affords sulfur nitrides related to S
4N
4. Treatment of SCl
2 with primary amines gives sulfur diimides. One example is di-t-butylsulfurdiimide.[4]
Safety considerations
References
- ↑ 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". Organic Syntheses 70: 120. http://www.orgsyn.org/demo.aspx?prep=cv9p0692.; Collective Volume, 9, pp. 692
- ↑ R. J. Cremlyn “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). ISBN:0-471-95512-4.
- ↑ Kresze, G.; Wucherpfennig, W. (1967). "New Methods of Preparative Organic Chemistry V: Organic Syntheses with Imides of Sulfur Dioxide". Angewandte Chemie International Edition in English 6 (2): 149–167. doi:10.1002/anie.196701491. PMID 4962859.
Original source: https://en.wikipedia.org/wiki/Sulfur dichloride.
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