 | |||
| |||
| Names | |||
|---|---|---|---|
| Preferred IUPAC name Disulfur decafluoride | |||
| Systematic IUPAC name Decafluoro-1λ6,2λ6-disulfane | |||
| Other names Sulfur pentafluoride TL-70 Agent Z | |||
| Identifiers | |||
3D model (JSmol) | |||
| ChemSpider | |||
| ECHA InfoCard | 100.024.732 | ||
| EC Number |
| ||
| MeSH | Disulfur+decafluoride | ||
| RTECS number |
| ||
| UNII | |||
| UN number | 3287 | ||
| |||
| |||
| Properties | |||
| S2F10 | |||
| Molar mass | 254.10 g·mol−1 | ||
| Appearance | colorless liquid | ||
| Odor | likesulfur dioxide[1] | ||
| Density | 2.08 g/cm3 | ||
| Melting point | −53 °C (−63 °F; 220 K) | ||
| Boiling point | 30.1691 °C (86.3044 °F; 303.3191 K) | ||
| insoluble[2] | |||
| Vapor pressure | 561 mmHg (20 °C)[1] | ||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards | Poisonous | ||
| NFPA 704 (fire diamond) | |||
| Lethal dose or concentration (LD, LC): | |||
LC50 (median concentration) | 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)[3] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 0.025 ppm (0.25 mg/m3)[1] | ||
REL (Recommended) | C 0.01 ppm (0.1 mg/m3)[1] | ||
IDLH (Immediate danger) | 1 ppm[1] | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Disulfur decafluoride is achemical compound with the formulaS2F10. It was discovered in 1934 byDenbigh and Whytlaw-Gray.[4] Eachsulfur atom of theS2F10 molecule isoctahedral, and surrounded by fivefluorine atoms[5] and one sulfur atom. The two sulfur atoms are connected by a single bond. In theS2F10 molecule, the oxidation state of each sulfur atoms is +5, but theirvalency is 6 (they arehexavalent).S2F10 is highlytoxic, with toxicity four times that ofphosgene.
It is a colorless liquid with a burnt match smell similar tosulfur dioxide.[1]
Disulfur decafluoride is produced byphotolysis ofSF5Br,[6] orSF5Cl inH2:[7]
Disulfur decafluoride arises by the decomposition ofsulfur hexafluoride. It is produced by the electrical decomposition ofsulfur hexafluoride (SF6)—an essentially inertinsulator used in high voltage systems such astransmission lines,substations andswitchgear.S2F10 is also made during the production ofSF6.
The S-S bond dissociation energy is 305 ± 21 kJ/mol, about 80 kJ/mol stronger than the S-S bond indiphenyldisulfide.
At temperatures above 150 °C,S
2F
10 decomposes slowly (disproportionation) intoSF
6 andSF
4:
S
2F
10 reacts withN
2F
4 to giveSF
5NF
2. It reacts withSO
2 to formSF
5OSO
2F in the presence of ultraviolet radiation.
In the presence of excesschlorine gas,S
2F
10 reacts to formsulfur chloride pentafluoride (SF
5Cl):
The analogous reaction withbromine is reversible and yieldsSF
5Br.[8] The reversibility of this reaction can be used to synthesizeS
2F
10 fromSF
5Br.[9]
Ammonia is oxidised byS
2F
10 intoNSF
3.[10]
S
2F
10 was considered a potentialchemical warfarepulmonary agent inWorld War II because it does not producelacrimation or skin irritation, thus providing little warning of exposure. Disulfur decafluoride is a colorless gas or liquid with aSO2-like odor.[11] It is about four times as poisonous as phosgene. Its toxicity is thought to be caused by itsdisproportionation in the lungs intoSF
6, which is inert, andSF
4, which reacts with moisture to formsulfurous acid andhydrofluoric acid.[12]
