Disulfur dichloride

Disulfur dichloride
Ball and stick model of disulfur dichloride	Spacefill model of disulfur dichloride Sulfur, S Chlorine, Cl
Names
	IUPAC names Disulfur dichloride; Dichlorodisulfane
	Systematic IUPAC name Chlorosulfanyl thiohypochlorite
	Other names Bis[chloridosulfur](S–S); Dimeric sulfenic chloride; Sulfur monochloride (incorrect name);
Identifiers
CAS Number	10025-67-9 ; 85408-26-0 (isobutenate) ;
3D model (JSmol)	Interactive image;
ChemSpider	23192 ; 19158348 (isobutenate) ;
DrugBank	DB14647;
ECHA InfoCard	100.030.021
EC Number	233-036-2;
MeSH	Sulfur+monochloride
PubChem CID	24807;
RTECS number	WS4300000;
UNII	NJ7YR2EV0D ;
UN number	3390
CompTox Dashboard (EPA)	DTXSID3042427 ;
	InChI InChI=1S/Cl2S2/c1-3-4-2 Key: PXJJSXABGXMUSU-UHFFFAOYSA-N ; InChI=1/Cl2S2/c1-3-4-2 Key: PXJJSXABGXMUSU-UHFFFAOYAK;
	SMILES ClSSCl;
Properties
Chemical formula	S2Cl2
Molar mass	135.02 g·mol−1
Appearance	Light-amber to yellow-red, oily liquid
Odor	pungent, nauseating, irritating
Density	1.688 g/cm3
Melting point	−80 °C (−112 °F; 193 K)
Boiling point	137.1 °C (278.8 °F; 410.2 K)
Solubility in water	Decomposes, with loss of HCl
Solubility	Soluble in ethanol, benzene, ether, THF, chloroform, CCl4
Vapor pressure	7 mmHg (20 °C)
Magnetic susceptibility (χ)	−62.2·10−6 cm3/mol
Refractive index (nD)	1.658
Structure
Point group	C2
Coordination geometry	2 at sulfur atoms
Molecular shape	gauche
Dipole moment	1.60 D
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H314, H332, H400
Precautionary statements	P260, P261, P264, P270, P271, P273, P280, P301+P310, P301+P330+P331, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P321, P330, P363, P391, P405, P501
NFPA 704 (fire diamond)	2 1 1
Flash point	118.5 °C (245.3 °F; 391.6 K)
Autoignition; temperature	234 °C (453 °F; 507 K)
	Lethal dose or concentration (LD, LC):
LCLo (lowest published)	150 ppm (mouse, 1 min) (1 ppm = 5.52 mg/m3)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 1 ppm (5.52 mg/m3)
REL (Recommended)	C 1 ppm (5.52 mg/m3)
IDLH (Immediate danger)	5 ppm (1 ppm = 5.52 mg/m3)
Safety data sheet (SDS)	ICSC 0958
Related compounds
Related sulfur chlorides/oxychlorides	Sulfur dichloride; Thionyl chloride; Sulfuryl chloride;
Related compounds	Hydrogen disulfide; Disulfur difluoride; Disulfur dibromide; Disulfur diiodide; Dimethyl disulfide; Diphenyl disulfide; Diselenium dichloride;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Disulfur dichloride (or disulphur dichloride by the British English spelling) is the inorganic compound of sulfur and chlorine with the formula S₂Cl₂.^[4]^[5]^[6]^[7] 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.

S₂Cl₂ has the structure implied by the formula Cl−S−S−Cl, wherein the dihedral angle between the Cl^a−S−S and S−S−Cl^b planes is 85.2°. This structure is referred to as gauche, and is akin to that for H₂O₂. A rare isomer of S₂Cl₂ is S=SCl₂ (thiothionyl chloride); this isomer forms transiently when S₂Cl₂ is exposed to UV-radiation (see thiosulfoxides).

Synthesis, basic properties, reactions

Disulfur dichloride is a yellow liquid that fumes in moist air due to reaction with water:

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:^[8]

S₈ + 4 Cl₂ → 4 S₂Cl₂, ΔH = −58.2 kJ/mol

Excess chlorine produces sulfur dichloride, which causes the liquid to become less yellow and more orange-red:

S₂Cl₂ + Cl₂ ⇌ 2 SCl₂, ΔH = −40.6 kJ/mol

The reaction is reversible, and upon standing, 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 polysulfanes:

8 S₂Cl₂ + n S₈ → 8 S_n+2Cl₂

Disulfur dichloride can be purified by distillation from excess elemental sulfur.

S₂Cl₂ also arises from the chlorination of CS₂ as in the synthesis of thiophosgene or carbon tetrachloride.

Reactions

S₂Cl₂ hydrolyzes to sulfur dioxide and elemental sulfur. When treated with hydrogen sulfide, polysulfanes are formed as indicated in the following idealized formula:

2 H₂S + S₂Cl₂ → H₂S₄ + 2 HCl

It reacts with ammonia to give tetrasulfur tetranitride as well as heptasulfur imide (S₇NH) and related S−N rings S_8−n(NH)_n (n = 2, 3).^[9]

16 NH₃ + 6 S₂Cl₂ → S₄N₄ + S₈ + 12 NH₄Cl

With primary and secondary alkoxide equivalents, it forms disulfoxylate esters:

2 ROH + S₂Cl₂ + 2 NEt₃ → (R–O–S)₂ + 2 [HNEt₃]Cl

In principle the subsequent addition of base should give sulfoxylate esters, but typically induces disproportionation to aldehydes and alcohols instead.^[10]

Applications

S₂Cl₂ has been used to introduce C−S bonds. In the presence of aluminium chloride (AlCl₃), S₂Cl₂ reacts with benzene to give diphenyl sulfide:

8 S₂Cl₂ + 16 C₆H₆ → 8 (C₆H₅)₂S + 16 HCl + S₈

Anilines (1) react with S₂Cl₂ in the presence of 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 dyes.

It is also used to prepare mustard gas via ethylene at 60 °C (the Levinstein process):

8 S₂Cl₂ + 16 H₂C=CH₂ → 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 S₂Cl₂ include the manufacture of sulfur dyes, insecticides, and synthetic rubbers. It is also used in cold vulcanization of rubbers, as a polymerization catalyst for vegetable oils and for hardening soft woods.^[11]

Safety and regulation

S₂Cl₂ can be used to produce bis(2-chloroethyl)sulfide S(CH₂CH₂Cl)₂, known as the mustard gas:^[11]

S₂Cl₂ + 2 H₂C=CH₂ → S(CH₂CH₂Cl)₂ + "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

^ ^a ^b ^c ^d ^e ^f NIOSH Pocket Guide to Chemical Hazards. "#0578". National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
^ "Sulfur monochloride". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ Holleman, A. F.; Wiberg, E. Inorganic Chemistry Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
^ Hartman, W. W.; Smith, L. A.; Dickey, J. B. (1934). "Diphenylsulfide". Organic Syntheses. 14: 36; Collected Volumes, vol. 2, p. 242.
^ R. J. Cremlyn An Introduction to Organosulfur Chemistry John Wiley and Sons: Chichester (1996). ISBN 0-471-95512-4
^ Garcia-Valverde M., Torroba T. (2006). "Heterocyclic chemistry of sulfur chlorides – Fast ways to complex heterocycles". European Journal of Organic Chemistry. 2006 (4): 849–861. doi:10.1002/ejoc.200500786.
^ F. Fehér "Dichlorodisulfane" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 371.
^ Tyree Jr., S. Y. (1967). "Chapter VI". Inorganic Syntheses. doi:10.1002/9780470132401. ISBN 9780470131688.
^
- Thompson, Q. E.; Crutchfield, M. M.; Dietrich, M. W.; Pierron, E. (1 Aug 1965) [11 Jan 1965]. "Organic Esters of Bivalent Sulfur I: Dialkoxy Disulfides". JOC. 30 (8). doi:10.1021/jo01019a044.
- Thompson, Q. E. "——— III: Sulfoxylates". Ibid. doi:10.1021/jo01019a046
^ ^a ^b Lauss, Hans-Dietrich; Steffens, Wilfried (2000). "Sulfur Halides". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a25_623. ISBN 3527306730.