Chemistry:Sulfur dichloride

Sulfur dichloride

Ball-and-stick model of sulfur dichloride Space-filling model of sulfur dichloride
Names
IUPAC name Dichlorosulfane Sulfur dichloride Sulfur(II) chloride
Other names Chloro thiohypochlorite Dichloro sulfide Sulphur chloride
Identifiers
CAS Number	10545-99-0 Y
3D model (JSmol)	Interactive image
ChemSpider	23682
EC Number	234-129-0
PubChem CID	25353
RTECS number	WS4500000
UNII	8Q6684WQ9H Y
UN number	1828
InChI InChI=1S/Cl2S/c1-3-2 Key: FWMUJAIKEJWSSY-UHFFFAOYSA-N InChI=1/Cl2S/c1-3-2 Key: FWMUJAIKEJWSSY-UHFFFAOYAS
SMILES ClSCl
Properties
Chemical formula	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)
Solubility in water	Insoluble, reacts slowly
Magnetic susceptibility (χ)	−49.4·10−6 cm3/mol
Refractive index (nD)	1.5570
Structure
Coordination geometry	C2v
Molecular shape	Bent
Hazards
Safety data sheet	ICSC 1661
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H314, H335, H400
GHS precautionary statements	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)	1 3 1
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 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 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. 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 a 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. Sulfur dichloride loses chlorine slowly at room temperature, converting to disulfur dichloride and eventually higher sulfanes. 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 A well tested method for the production of the mustard gas bis(2-chloroethyl)sulfide, is the addition of ethylene to sulfur dichloride:

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. SO
3 oxidizes SCl
2 to SOCl
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.

Safety considerations

SCl
2 hydrolyzes with release of HCl. Old samples contain Cl
2.