Disulfur decafluoride
{{Chembox
| Watchedfields = changed
| ImageFile = Disulfur-decafluoride-2D-dimensions.png
| ImageSize = 210px
| ImageName = Wireframe model of disulfur decafluoride
| ImageFileR1 = Disulfur-decafluoride-3D-vdW.png
| ImageSizeR1 = 110px
| ImageNameR1 = Space-filling model of disulfur decafluoride
| ImageFileL1 = Disulfur-decafluoride-3D-balls.png
| ImageSizeL1 = 130px
| ImageNameL1 = Ball-and-stick model of disulfur decafluoride
| PIN = Disulfur decafluoride
| SystematicName = Decafluoro-1λ6,2λ6-disulfane
| OtherNames = Sulfur pentafluoride
TL-70
Agent Z
|Section1={{Chembox Identifiers
| CASNo = 5714-22-7
| PubChem = 62586
| ChemSpiderID = 56348
| EINECS = 227-204-4
| MeSHName = Disulfur+decafluoride
| RTECS = WS4480000
| UNNumber = 3287
| UNII = 5XG19I842O
| SMILES = FS(F)(F)(F)(F)S(F)(F)(F)(F)F
| InChI = 1S/F10S2/c1-11(2,3,4,5)12(6,7,8,9)10
| InChIKey = BPFZRKQDXVZTFD-UHFFFAOYSA-N}}
|Section2={{Chembox Properties
| Formula = {{chem2|S2F10}}
| S=2|F=10
| Density = 2.08 g/cm3
| MeltingPtC = -53
| BoilingPtC = 30.1691
| Appearance = colorless liquid
| Odor = like sulfur dioxide{{PGCH|0579}}
| Solubility = insoluble{{Cite web|url=http://www.chemicalbook.com/ChemicalProductProperty_EN_CB0751782.htm|title = Disulphur Decafluoride | 5714-22-7}}
| VaporPressure = 561 mmHg (20 °C)
}}
|Section3={{Chembox Hazards
| MainHazards = Poisonous
| NFPA-H = 4
| NFPA-F = 0
| NFPA-R = 0
| NFPA-S = OX
| LC50 = 2000 mg/m3 (rat, 10 min)
1000 mg/m3 (mouse, 10 min)
4000 mg/m3 (rabbit, 10 min)
4000 mg/m3 (guinea pig, 10 min)
4000 mg/m3 (dog, 10 min){{IDLH|5714227|Sulfur pentafluoride}}
| REL = C 0.01 ppm (0.1 mg/m3)
| PEL = TWA 0.025 ppm (0.25 mg/m3)
}}
}}
Disulfur decafluoride is a chemical compound with the formula {{chem2|S2F10}}. It was discovered in 1934 by Denbigh and Whytlaw-Gray.{{cite journal |last1=Denbigh |first1=K. G. |last2=Whytlaw-Gray |first2=R. | title = The Preparation and Properties of Disulphur Decafluoride | journal = Journal of the Chemical Society | year = 1934 | volume = 1934 | pages = 1346–1352 | doi = 10.1039/JR9340001346 }} Each sulfur atom of the {{chem2|S2F10}} molecule is octahedral, and surrounded by five fluorine atoms{{Cite journal| first1 = R. B.| first2 = S. H.| title = An Electron Diffraction Study of Disulfur Decafluoride | journal = Journal of the American Chemical Society | volume = 75| issue = 12| pages = 2840–2846 | date=June 1953 | last1 = Harvey | doi = 10.1021/ja01108a015| last2 = Bauer}} and one sulfur atom. The two sulfur atoms are connected by a single bond. In the {{chem2|S2F10}} molecule, the oxidation state of each sulfur atoms is +5, but their valency is 6 (they are hexavalent). {{chem2|S2F10}} is highly toxic, with toxicity four times that of phosgene.
It is a colorless liquid with a burnt match smell similar to sulfur dioxide.{{PGCH|0579}}
Production
Disulfur decafluoride is produced by photolysis of {{chem2|SF5Br}}:{{cite journal |doi=10.1016/S0022-1139(97)00096-1|title=A new preparation of disulfur decafluoride|year=1998|last1=Winter|first1=R.|last2=Nixon|first2=P.G.|last3=Gard|first3=G.L.|journal=Journal of Fluorine Chemistry|volume=87|issue=1|pages=85–86|bibcode=1998JFluC..87...85W }}
:{{chem2|2 SF5Br → S2F10 + Br2}}
Disulfur decafluoride arises by the decomposition of sulfur hexafluoride. It is produced by the electrical decomposition of sulfur hexafluoride ({{chem2|SF6}})—an essentially inert insulator used in high voltage systems such as transmission lines, substations and switchgear. {{chem2|S2F10}} is also made during the production of {{chem2|SF6}}.
Properties
The S-S bond dissociation energy is 305 ± 21 kJ/mol, about 80 kJ/mol stronger than the S-S bond in diphenyldisulfide.
At temperatures above 150 °C, {{chem|S|2|F|10}} decomposes slowly (disproportionation) into {{chem|SF|6}} and {{chem|SF|4}}:
{{chem|S|2|F|10}} reacts with Tetrafluorohydrazine to give Difluoroamino sulfur pentafluoride. It reacts with {{chem|SO|2}} to form {{chem|SF|5|OSO|2|F}} in the presence of ultraviolet radiation.
: {{chem|S|2|F|10}} + {{chem|N|2|F|4}} → 2 {{chem|SF|5|NF|2}}
In the presence of excess chlorine gas, {{chem|S|2|F|10}} reacts to form sulfur chloride pentafluoride ({{chem|SF|5|Cl}}):
: {{chem|S|2|F|10}} + {{chem|Cl|2}} → 2 {{chem|SF|5|Cl}}
The analogous reaction with bromine is reversible and yields {{chem|SF|5|Br}}.{{Cite journal| first1 = B.| first2 = A. G. | title = Chemical Properties of Disulfur Decafluoride | journal = Inorganic Chemistry | volume = 4 | issue = 12| pages = 1782–1785 | date=December 1965 | last1 = Cohen | doi = 10.1021/ic50034a025| last2 = MacDiarmid}} The reversibility of this reaction can be used to synthesize {{chem|S|2|F|10}} from {{chem|SF|5|Br}}.{{Cite journal| first1 = R. | first2 = P. | first3 = G.| last3 = Gard| last1 = Winter| last2 = Nixon| title = A new preparation of disulfur decafluoride | journal = Journal of Fluorine Chemistry | volume = 87| issue = 1| pages = 85–86 | date=January 1998 | doi = 10.1016/S0022-1139(97)00096-1| bibcode = 1998JFluC..87...85W }}
Ammonia is oxidised by {{chem|S|2|F|10}} into Thiazyl trifluoride.{{cite book | title = Biological Interactions of Sulfur Compounds | author = Mitchell, S. | publisher = CRC Press | year = 1996 | isbn = 978-0-7484-0245-8 | page = 14 }}
Toxicity
{{chem|S|2|F|10}} was considered a potential chemical warfare pulmonary agent in World War II because it does not produce lacrimation or skin irritation, thus providing little warning of exposure.
Disulfur decafluoride is a colorless gas or liquid with a SO2-like odor.{{ cite web | url = https://www.cdc.gov/niosh/pel88/5714-22.html | title = Sulfur Pentaflu | work = 1988 OSHA PEL Project | date = 28 February 2020 | publisher = CDC NIOSH }} It is about four times as poisonous as phosgene. Its toxicity is thought to be caused by its disproportionation in the lungs into {{chem|SF|6}}, which is inert, and {{chem|SF|4}}, which reacts with moisture to form sulfurous acid and hydrofluoric acid.{{cite book | title = A Bridge not Attacked: Chemical Warfare Civilian Research During World War II | url = https://archive.org/details/bridgenotattacke00john | url-access = limited | author = Johnston, H. | publisher = World Scientific | year = 2003 | isbn = 978-981-238-153-8 | pages = [https://archive.org/details/bridgenotattacke00john/page/n45 33]–36 }}
See also
References
{{reflist}}
- {{cite book |author1=Christophorou, L. G. |author2=Sauers, I. | title = Gaseous Dielectrics VI | year = 1991 | publisher = Plenum Press | isbn = 978-0-306-43894-3 }}
External links
- {{ cite web | url = https://www.cdc.gov/niosh/pel88/5714-22.html | title = Sulfur Pentaflu | work = 1988 OSHA PEL Project | date = 28 February 2020 | publisher = CDC NIOSH }}
{{Sulfur compounds}}
{{Chemical agents}}