Sulfur dichloride
{{Chembox
| Watchedfields = changed
| verifiedrevid = 408467094
| Name = Sulfur dichloride
| ImageFile = Sulfur-dichloride-2D-dimensions.png
| ImageSize = 160px
| ImageName = Structure and dimensions of the sulfur dichloride molecule
| ImageFileL1 = Sulfur-dichloride-3D-balls.png
| ImageSizeL1 = 120px
| ImageNameL1 = Ball-and-stick model of sulfur dichloride
| ImageFileR1 = Sulfur-dichloride-3D-vdW.png
| ImageSizeR1 = 110px
| ImageNameR1 = Space-filling model of sulfur dichloride
| IUPACName = {{ubl|Dichlorosulfane|Sulfur dichloride|Sulfur(II) chloride}}
| OtherNames = {{ubl|Chloro thiohypochlorite|Dichloro sulfide|Sulphur chloride}}
|Section1={{Chembox Identifiers
| CASNo = 10545-99-0
| CASNo_Ref = {{cascite|correct|CAS}}
| ChemSpiderID = 23682
| RTECS = WS4500000
| EINECS = 234-129-0
| UNNumber = 1828
| PubChem = 25353
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 8Q6684WQ9H
| SMILES = ClSCl
| InChI = 1/Cl2S/c1-3-2
| InChIKey = FWMUJAIKEJWSSY-UHFFFAOYAS
| StdInChI = 1S/Cl2S/c1-3-2
| StdInChIKey = FWMUJAIKEJWSSY-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
| Formula = {{chem2|SCl2}}
| S=1|Cl=2
| Appearance = Cherry-red liquid
| Odour = Pungent
| Density = 1.621 g/cm3
| Solubility = Insoluble, reacts slowly
| MeltingPtC = −121.0
| BoilingPtC = 59
| BoilingPt_notes = (decomposes)
| RefractIndex = 1.5570
| MagSus = −49.4·10−6 cm3/mol
}}
|Section3={{Chembox Structure
| Coordination = C2v
| MolShape = Bent
| Dipole =
}}
|Section7={{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics1661.htm ICSC 1661]
| GHSPictograms = {{GHS05}}{{GHS07}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|314|335|400}}
| PPhrases = {{P-phrases|260|261|264|271|273|280|301+330+331|303+361+353|304+340|305+351+338|310|312|321|363|391|403+233|405|501}}
| NFPA-H = 3
| NFPA-F = 1
| NFPA-R = 1
| NFPA-S =
| AutoignitionPtC = 234
| PEL =
}}
|Section8={{Chembox Related
| OtherFunction = {{ubl|Disulfur dichloride|Thionyl chloride|Sulfuryl chloride}}
| OtherCompounds = {{ubl|Sulfur difluoride|Sulfur tetrafluoride|Sulfur hexafluoride|Disulfur dibromide}}
}}
}}
Sulfur dichloride is the chemical compound with the formula {{chem2|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
{{chem2|SCl2}} is produced by the chlorination of either elemental sulfur or disulfur dichloride. The process occurs in a series of steps, some of which are:
:{{chem2|S8 + 4 Cl2 → 4 S2Cl2}}; ΔH = −58.2 kJ/mol
:{{chem2|S2Cl2 + Cl2 ⇌ 2 SCl2}}; ΔH = −40.6 kJ/mol
The addition of chlorine to {{chem2|S2Cl2}} has been proposed to proceed via a mixed valence intermediate {{chem2|Cl3S\sSCl}}. {{chem2|SCl2}} undergoes even further chlorination to give SCl4, but this species is unstable at near room temperature. It is likely that several {{chem2|S_{n}Cl2}} exist where n > 2.
Disulfur dichloride, {{chem2|S2Cl2}}, is a common impurity in {{chem2|SCl2}}.{{cite book|author=F. Fehèr|chapter=Dichloromonosulfane|title=Handbook of Preparative Inorganic Chemistry, 2nd Ed. |editor=G. Brauer|publisher=Academic Press|year=1963|place=NY, NY|volume=1|page=370}} Separation of {{chem2|SCl2}} from {{chem2|S2Cl2}} is possible via distillation with Phosphorus trichloride 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 {{chem2|SCl2}} in chemical synthesis
{{chem2|SCl2}} 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{{OrgSynth | last = Bishop | first = Roger | title = 9-Thiabicyclo[3.3.1]nonane-2,6-dione | volume = 70 | pages = 120 | collvol = 9 | collvolpages = 692 | year = 1992 | prep = cv9p0692}} A well tested method for the production of the mustard gas bis(2-chloroethyl)sulfide, is the addition of ethylene to sulfur dichloride:R. J. Cremlyn “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). {{ISBN|0-471-95512-4}}.
:{{chem2|SCl2 + 2 C2H4 -> (ClC2H4)2S}}
{{chem2|SCl2}} is also a precursor to several inorganic sulfur compounds. Treatment with fluoride salts gives Sulfur tetrafluoride via the decomposition of the intermediate sulfur difluoride. With {{chem2|H2S}}, {{chem2|SCl2}} reacts to give "lower" sulfanes such as {{chem2|S3H2}}. {{chem2|SO3}} oxidizes {{chem2|SCl2}} to {{chem2|SOCl2|link=thionyl chloride}}.
Reaction with ammonia affords sulfur nitrides related to tetrasulfur tetranitride. Treatment of {{chem2|SCl2}} with primary amines gives sulfur diimides. One example is di-t-butylsulfurdiimide.{{cite journal | doi = 10.1002/anie.196701491| pmid = 4962859| title = New Methods of Preparative Organic Chemistry V: Organic Syntheses with Imides of Sulfur Dioxide| journal = Angewandte Chemie International Edition in English| volume = 6| issue = 2| pages = 149–167| year = 1967| last1 = Kresze| first1 = G.| last2 = Wucherpfennig| first2 = W.}}
Safety considerations
{{chem2|SCl2}} hydrolyzes with release of HCl. Old samples contain {{chem2|Cl2}}.
References
{{reflist}}
{{sulfur compounds}}
{{Chlorides}}