Chemistry:Disulfur dichloride

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Disulfur dichloride
Wireframe model of disulfur dichloride
Ball and stick model of disulfur dichloride
Spacefill model of disulfur dichloride
  Sulfur, S
  Chlorine, Cl
Names
IUPAC name
Disulfur dichloride
Systematic IUPAC name
Dichlorodisulfane
Other names
  • Bis[chloridosulfur](SS)
  • Dimeric sulfenic chloride
  • Sulfur monochloride (incorrect name)
Identifiers
3D model (JSmol)
ChemSpider
DrugBank
EC Number
  • 233-036-2
MeSH Sulfur+monochloride
RTECS number
  • WS4300000
UNII
UN number 3390
Properties
S
2
Cl
2
Molar mass 135.02 g·mol−1
Appearance Light-amber to yellow-red, oily liquid[1]
Odor pungent, nauseating, irritating[1]
Density 1.688 g/cm3
Melting point −80 °C (−112 °F; 193 K)
Boiling point 137.1 °C (278.8 °F; 410.2 K)
Decomposes, with loss of HCl
Solubility Soluble in ethanol, benzene, ether, THF, chloroform, CCl
4
[2]
Vapor pressure 7 mmHg (20 °C)[1]
−62.2·10−6 cm3/mol
1.658
Structure
C2
2 at sulfur atoms
gauche
1.60 D[2]
Hazards
Safety data sheet ICSC 0958
GHS pictograms GHS02: FlammableGHS06: ToxicGHS07: HarmfulGHS09: Environmental hazard
GHS Signal word Danger
H301, H314, H332, H400
P260, P261, P264, P270, P271, P273, P280, P301+310, P301+330+331, P303+361+353, P304+312, P304+340, P305+351+338, P310, P312, P321, P330, P363, P391, P405, P501
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no codeNFPA 704 four-colored diamond
1
2
1
Flash point 118.5 °C (245.3 °F; 391.6 K)
234 °C (453 °F; 507 K)
Lethal dose or concentration (LD, LC):
150 ppm (mouse, 1 min) (1 ppm = 5.52 mg/m3)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 1 ppm (5.52 mg/m3)[1]
REL (Recommended)
C 1 ppm (5.52 mg/m3)[1]
IDLH (Immediate danger)
5 ppm[1] (1 ppm = 5.52 mg/m3)
Related compounds
Related sulfur chlorides/oxychlorides
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Disulfur dichloride (or disulphur dichloride by the British English spelling) is the inorganic compound of sulfur and chlorine with the formula S
2
Cl
2
.[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.

S
2
Cl
2
has the structure implied by the formula Cl–S–S–Cl, wherein the dihedral angle between the Cla
–S–S
and S–S–Clb
planes is 85.2°. This structure is referred to as gauche, and is akin to that for H
2
O
2
. A rare isomer of S
2
Cl
2
is S=SCl
2
(thiothionyl chloride); this isomer forms transiently when S
2
Cl
2
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 S
2
Cl
2
+ 16 H
2
O → 8 SO
2
+ 32 HCl + 3 S
8

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]

S
8
+ 4 Cl
2
→ 4 S
2
Cl
2
, ΔH = −58.2 kJ/mol

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

S
2
Cl
2
+ Cl
2
⇌ 2 SCl
2
, ΔH = −40.6 kJ/mol

The reaction is reversible, and upon standing, SCl
2
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 S
2
Cl
2
+ n S
8
→ 8 S
n+2
Cl
2

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

S
2
Cl
2
also arises from the chlorination of CS
2
as in the synthesis of thiophosgene or carbon tetrachloride.

Reactions

S
2
Cl
2
hydrolyzes to sulfur dioxide and elemental sulfur. When treated with hydrogen sulfide, polysulfanes are formed as indicated in the following idealized formula:

2 H
2
S + S
2
Cl
2
→ H
2
S
4
+ 2 HCl

It reacts with ammonia to give heptasulfur imide (S
7
NH
) and related S−N rings S
8-n
(NH)
n
(n = 2, 3).

Applications

S
2
Cl
2
has been used to introduce C−S bonds. In the presence of aluminium chloride (AlCl
3
), S
2
Cl
2
reacts with benzene to give diphenyl sulfide:

8 S
2
Cl
2
+ 16 C
6
H
6
→ 8 (C
6
H
5
)
2
S
+ 16 HCl + S
8

Anilines (1) react with S
2
Cl
2
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.

Herzrxn.png

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

8 S
2
Cl
2
+ 16 H
2
C=CH
2
→ 8 (ClCH
2
CH
2
)
2
S + S
8

Other uses of S
2
Cl
2
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.[9]

Safety and regulation

S
2
Cl
2
can be used to produce bis(2-chloroethyl)sulfide S(CH
2
CH
2
Cl)
2
, known as the mustard gas:[9]

S
2
Cl
2
+ 2 H
2
C=CH
2
→ S(CH
2
CH
2
Cl)
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

  1. 1.0 1.1 1.2 1.3 1.4 1.5 NIOSH Pocket Guide to Chemical Hazards. "#0578". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0578.html. 
  2. 2.0 2.1 Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN:0-07-049439-8
  3. "Sulfur monochloride". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/idlh/10025679.html. 
  4. Holleman, A. F.; Wiberg, E. Inorganic Chemistry Academic Press: San Diego, 2001. ISBN:0-12-352651-5.
  5. Hartman, W. W.; Smith, L. A.; Dickey, J. B. (1934). "Diphenylsulfide". Organic Syntheses 14: 36. http://www.orgsyn.org/demo.aspx?prep=cv2p0242. ; Collective Volume, 2, pp. 242 
  6. R. J. Cremlyn An Introduction to Organosulfur Chemistry John Wiley and Sons: Chichester (1996). ISBN:0-471-95512-4
  7. 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. 
  8. F. Fehér "Dichlorodisulfane" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 371.
  9. 9.0 9.1 Lauss, Hans-Dietrich; Steffens, Wilfried (2000). "Sulfur Halides". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a25_623. ISBN 3527306730.