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
IUPAC names
Sulfur dichloride
Sulfur(II) chloride
Other names
Sulphur chloride
3D model (JSmol)
ECHA InfoCard 100.031.014 Edit this at Wikidata
EC Number
  • 234-129-0
RTECS number
  • WS4500000
UN number 1828
  • InChI=1S/Cl2S/c1-3-2
  • InChI=1/Cl2S/c1-3-2
  • ClSCl
Molar mass 102.97 g·mol−1
Appearance Red liquid
Odor Pungent
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)
−49.4·10−6 cm3/mol
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation markGHS09: Environmental hazard
H314, H335, H400
P260, P261, P264, P271, P273, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P363, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)
234 °C (453 °F; 507 K)
Safety data sheet (SDS) ICSC 1661
Related compounds
Disulfur dichloride
Thionyl chloride
Sulfuryl chloride
Related compounds
Sulfur difluoride
Sulfur tetrafluoride
Sulfur hexafluoride
Disulfur dibromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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, 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[edit]

SCl2 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:

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[2] and ethylene to give sulfur mustard S(CH2CH2Cl)2.[3]

SCl2 is also a precursor to several inorganic sulfur compounds. Treatment with fluoride salts gives SF4 via the decomposition of the intermediate sulfur difluoride. With H2S, SCl2 reacts to give "lower" sulfanes such as S3H2.

Reaction with ammonia affords sulfur nitrides related to S4N4. Treatment of SCl2 with primary amines gives sulfur diimides. One example is di-t-butylsulfurdiimide.[4]

Safety considerations[edit]

SCl2 hydrolyzes with release of HCl. Old samples contain Cl2.[citation needed]


  1. ^ F. Fehér "Dichloromonosulfane" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 370.
  2. ^ Bishop, Roger (1992). "9-Thiabicyclo[3.3.1]nonane-2,6-dione". Organic Syntheses. 70: 120.; Collective Volume, vol. 9, p. 692
  3. ^ R. J. Cremlyn “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). ISBN 0-471-95512-4.
  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.