View source for Disulfur dichloride

{{Chembox
| Verifiedfields = changed
| Watchedfields  = changed
| verifiedrevid  = 476993527
| ImageFile      = Disulfur-dichloride-2D-dimensions.png
| ImageName      = Wireframe model of disulfur dichloride
| ImageFileL1    = Disulfur-dichloride-3D-balls.png
| ImageNameL1    = Ball and stick model of disulfur dichloride
| ImageCaptionL1 = {{color box|yellow}} Sulfur, S;<br>{{color box|lime}} Chlorine, Cl
| ImageFileR1    = Disulfur-dichloride-3D-vdW.png
| ImageNameR1    = Spacefill model of disulfur dichloride
| ImageFile2     = Дитиодихлорид.jpg
| IUPACName      = Disulfur dichloride<br>Dichlorodisulfane
| SystematicName = Chlorosulfanyl thiohypochlorite
| OtherNames     = {{ubl|Bis[chloridosulfur](''S''–''S'')|Dimeric sulfenic chloride|Sulfur monochloride (incorrect name)}}
| Section1       = {{Chembox Identifiers
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Cl2S2/c1-3-4-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = PXJJSXABGXMUSU-UHFFFAOYSA-N
| CASNo = 10025-67-9
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo1_Ref = {{cascite|changed|??}}
| CASNo1 = 85408-26-0
| CASNo1_Comment = (isobutenate)
| DrugBank = DB14647
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = NJ7YR2EV0D
| PubChem = 24807
| ChemSpiderID = 23192
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID1_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID1 = 19158348
| ChemSpiderID1_Comment = (isobutenate)
| EINECS = 233-036-2
| UNNumber = 3390
| MeSHName = Sulfur+monochloride
| RTECS = WS4300000
| SMILES = ClSSCl
| InChI = 1/Cl2S2/c1-3-4-2
| InChIKey = PXJJSXABGXMUSU-UHFFFAOYAK
 }}
| Section2       = {{Chembox Properties
| Formula = {{chem2|S2Cl2}}
| S=2|Cl=2
| Appearance = Light-amber to yellow-red, oily liquid<ref name=PGCH/>
| Odor = pungent, nauseating, irritating<ref name=PGCH/>
| Density = 1.688&nbsp;g/cm<sup>3</sup>
| Solubility = Decomposes, with loss of [[hydrogen Chloride|HCl]]
| SolubleOther = Soluble in [[ethanol]], [[benzene]], [[diethyl ether|ether]], [[tetrahydrofuran|THF]], [[chloroform]], [[carbon tetrachloride|{{chem2|CCl4}}]]<ref name="Patnaik">Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, {{ISBN|0-07-049439-8}}</ref>
| MeltingPtC = −80
| BoilingPtC = 137.1
| RefractIndex = 1.658
| VaporPressure = 7 mmHg (20&nbsp;°C)<ref name=PGCH/>
<!--| Dielectric Constant = 4.79<ref name=Ullmann></ref>-->
| MagSus = &minus;62.2·10<sup>−6</sup> cm<sup>3</sup>/mol
 }}
| Section3       = {{Chembox Structure
| Coordination = 2 at [[sulfur]] atoms
| MolShape = [[Conformational isomerism|gauche]]
| PointGroup = [[Molecular symmetry#Common point groups|C<sub>2</sub>]]
| Dipole = 1.60 [[Debye|D]]<ref name="Patnaik"/> }}
| Section7       = {{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0958.htm ICSC 0958]
| NFPA-H = 2
| NFPA-R = 1
| NFPA-F = 1
| GHSPictograms = {{GHS02}}{{GHS06}}{{GHS07}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|301|314|332|400}}
| PPhrases = {{P-phrases|260|261|264|270|271|273|280|301+310|301+330+331|303+361+353|304+312|304+340|305+351+338|310|312|321|330|363|391|405|501}}
| FlashPtC = 118.5
| AutoignitionPtC = 234
| IDLH = 5 ppm<ref name=PGCH>{{PGCH|0578}}</ref> (1 ppm = 5.52 mg/m<sup>3</sup>)
| REL = C 1 ppm (5.52 mg/m<sup>3</sup>)<ref name=PGCH/>
| PEL = TWA 1 ppm (5.52 mg/m<sup>3</sup>)<ref name=PGCH/>
| LCLo = 150 [[Parts-per notation|ppm]] (mouse, 1 min) (1 ppm = 5.52 mg/m<sup>3</sup>)<ref>{{IDLH|10025679|Sulfur monochloride}}</ref> 
 }}
| Section8       = {{Chembox Related
| OtherFunction = {{ubl|[[Sulfur dichloride]]|[[Thionyl chloride]]|[[Sulfuryl chloride]]}}
| OtherFunction_label = sulfur chlorides/oxychlorides
| OtherCompounds = {{ubl|[[Hydrogen disulfide]]|[[Disulfur difluoride]]|[[Disulfur dibromide]]|[[Disulfur diiodide]]|[[Dimethyl disulfide]]|[[Diphenyl disulfide]]|[[Diselenium dichloride]]}}
 }}
}}

'''Disulfur dichloride''' (or '''disulphur dichloride''' by the [[British English]] spelling) is the [[inorganic compound]] of [[sulfur]] and [[chlorine]] with the [[Chemical formula|formula]] {{chem2|S2Cl2}}.<ref>Holleman, A. F.; Wiberg, E. ''Inorganic Chemistry'' Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}.</ref><ref>{{OrgSynth | first1 = W. W. | last1 = Hartman | first2 = L. A. | last2 = Smith | first3 = J. B. | last3 = Dickey | title = Diphenylsulfide | collvol = 2 | collvolpages = 242 | volume = 14 | pages = 36 | year = 1934 | prep=cv2p0242}}</ref><ref>R. J. Cremlyn ''An Introduction to Organosulfur Chemistry'' John Wiley and Sons: Chichester (1996). {{ISBN|0-471-95512-4}}</ref><ref>{{cite journal| author=Garcia-Valverde M., Torroba T.|title= Heterocyclic chemistry of sulfur chlorides – Fast ways to complex heterocycles |journal= European Journal of Organic Chemistry|volume=2006| pages= 849–861|year= 2006|doi= 10.1002/ejoc.200500786| issue=4}}</ref> It is an amber oily liquid.

Sometimes, this compound is incorrectly named ''sulfur monochloride'' (or ''sulphur monochloride'' by the British English spelling), the name implied by its [[empirical formula]] SCl.

{{chem2|S2Cl2}} has the structure implied by the formula {{chem2|Cl\sS\sS\sCl}}, wherein the [[dihedral angle]] between the {{chem2|Cl^{''a''}\sS\sS}} and {{chem2|S\sS\sCl^{''b''}|}} planes is 85.2°. This structure is referred to as [[Conformational isomerism|gauche]], and is akin to that for [[Hydrogen peroxide|{{chem2|H2O2}}]]. A rare [[isomer]] of {{chem2|S2Cl2}} is {{chem2|S\dSCl2}} (thiothionyl chloride); this isomer forms transiently when {{chem2|S2Cl2}} is exposed to [[UV-radiation]] (see [[thiosulfoxide]]s).

==Synthesis, basic properties, reactions==
Disulfur dichloride is a yellow liquid that fumes in moist air due to reaction with water:
:{{chem2|16 S2Cl2 + 16 H2O → 8 SO2 + 32 HCl + 3 S8}}

It is produced by partial chlorination of elemental [[sulfur]]. The reaction proceeds at usable rates at room temperature. In the laboratory, chlorine gas is led into a flask containing elemental sulfur. As disulfur dichloride is formed, the contents become a golden yellow liquid:<ref>F. Fehér "Dichlorodisulfane" in ''Handbook of Preparative Inorganic Chemistry'', 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 371.</ref>
:{{chem2|S8 + 4 Cl2 → 4 S2Cl2}}, ''ΔH'' = −58.2&nbsp;kJ/mol
Excess chlorine produces [[sulfur dichloride]], which causes the liquid to become less yellow and more orange-red:
:{{chem2|S2Cl2 + Cl2 ⇌ 2 SCl2}}, ''ΔH'' = −40.6&nbsp;kJ/mol
The reaction is reversible, and upon standing, {{chem2|SCl2}} releases chlorine to revert to the disulfur dichloride. Disulfur dichloride has the ability to dissolve large quantities of sulfur, which reflects in part the formation of [[polysulfane|dichloropolysulfanes]]:
:{{chem2|8 S2Cl2 + ''n'' S8 → 8 S_{''n''+2}Cl2}}
Disulfur dichloride can be purified by distillation from excess elemental sulfur.

{{chem2|S2Cl2}} also arises from the chlorination of [[Carbon disulfide|{{chem2|CS2}}]] as in the synthesis of [[thiophosgene]] or [[carbon tetrachloride]].

===Reactions===
{{chem2|S2Cl2}} [[hydrolyze]]s to [[sulfur dioxide]] and elemental [[sulfur]]. When treated with [[hydrogen sulfide]], [[polysulfane]]s are formed as indicated in the following idealized formula:
:{{chem2|2 H2S + S2Cl2 → [[Hydrogen tetrasulfide|H2S4]] + 2 HCl}}
It reacts with [[ammonia]] to give [[tetrasulfur tetranitride]] as well as [[heptasulfur imide]] ({{chem2|S7NH}}) and related S−N rings {{chem2|S_{8−''n''}(NH)_{''n''}|}} (''n'' = 2, 3).<ref name=Tyree>{{cite book |doi=10.1002/9780470132401 |chapter= Chapter VI |title=Inorganic Syntheses |year=1967 |last1=Tyree Jr. |first1=S. Y.|volume= 9 |isbn=9780470131688}}</ref>
:{{chem2|16 NH3 + 6 S2Cl2 → S4N4 + S8 + 12 NH4Cl}}
With primary and secondary [[alkoxide]] equivalents, it forms disulfoxylate esters:
:2&nbsp;ROH&nbsp;+ S<sub>2</sub>Cl<sub>2</sub>&nbsp;+ 2&nbsp;NEt<sub>3</sub>&nbsp;→ (R&ndash;O&ndash;S)<sub>2</sub>&nbsp;+ 2&nbsp;[HNEt<sub>3</sub>]Cl
In principle the subsequent addition of base should give [[sulfoxylate]] esters, but typically induces disproportionation to aldehydes and alcohols instead.<ref>{{unbulleted list citebundle|{{cite journal|doi=10.1021/jo01019a044|journal= The Journal of Organic Chemistry|volume=30|number=8|date=1 Aug 1965|orig-date=11 Jan 1965|title=    Organic Esters of Bivalent Sulfur. I. Dialkoxy Disulfides|first1=Q.&nbsp;E.|last1=Thompson|first2=M.&nbsp;M.|last2=Crutchfield|first3=M.&nbsp;W.|last3=Dietrich|first4=E.|last4=Pierron|pages= 2692–2696}}|{{cite journal |doi=10.1021/jo01019a046 |title=Organic Esters of Bivalent Sulfur. III. Sulfoxylates |date=1965 |last1=Thompson |first1=Q. E. |journal=The Journal of Organic Chemistry |volume=30 |issue=8 |pages=2703–2707 }}}}</ref>

==Applications==
{{chem2|S2Cl2}} has been used to introduce [[Organosulfur chemistry|C−S bonds]]. In the presence of [[aluminium chloride]] ({{chem2|AlCl3}}), {{chem2|S2Cl2}} reacts with [[benzene]] to give diphenyl sulfide:
:{{chem2|8 S2Cl2 + 16 [[Benzene|C6H6]] → 8 [[Diphenyl sulfide|(C6H5)2S]] + 16 [[Hydrogen chloride|HCl]] + [[Octasulfur|S8]]}}
[[Aniline]]s (1) react with {{chem2|S2Cl2}} in the presence of [[Sodium hydroxide|NaOH]] to give 1,2,3-benzodithiazolium chloride (2) ([[Herz reaction]]) which can be transformed into ''ortho''-aminothiophenolates (3), these species are precursors to [[thioindigo]] [[dye]]s. 
:[[File:Herzrxn.png|700px]]
It is also used to prepare [[Bis(2-chloroethyl) sulfide|mustard gas]] via [[ethylene]] at 60&nbsp;°C (the Levinstein process):
:{{chem2|8 S2Cl2 + 16 [[ethylene|H2C\dCH2]] → 8 (ClCH2CH2)2S + S8}}
If the reaction is performed at a temperature under 30 °C, the sulfur stays in "pseudo-solution" and avoids the problems associated with the sulfur that is formed during the reaction.

Other uses of {{chem2|S2Cl2}} include the manufacture of [[sulfur dye]]s, [[insecticides]], and [[synthetic rubber]]s. It is also used in cold [[vulcanization]] of [[rubbers]], as a [[polymerization]] [[catalyst]] for [[vegetable oils]] and for hardening [[soft wood]]s.<ref name=Ullmann>{{cite book |doi=10.1002/14356007.a25_623 |chapter=Sulfur Halides |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2000 |last1=Lauss |first1=Hans-Dietrich |last2=Steffens |first2=Wilfried |isbn=3527306730}}</ref>

==Safety and regulation==
{{chem2|S2Cl2}} can be used to produce [[bis(2-chloroethyl)sulfide]] {{chem2|S(CH2CH2Cl)2}}, known as the mustard gas:<ref name = Ullmann/>
:{{chem2|S2Cl2 + 2 [[Ethylene|H2C\dCH2]] → S(CH2CH2Cl)2 + [[Sulfur|"S"]]}}
Consequently, it is listed in Schedule 3 of the [[Chemical Weapons Convention]]. Facilities that produce and/or process and/or consume scheduled chemicals may be subject to control, reporting mechanisms and inspection by the [[Organisation for the Prohibition of Chemical Weapons]].

==References==
{{reflist}}
{{Commons category|Disulfur dichloride}}

{{sulfur compounds}}
{{Chlorides}}

[[Category:Disulfides]]
[[Category:Sulfur chlorides]]