Perchloryl fluoride is a reactive gas with the chemical formula ClO
3F. It has a characteristic sweet odor that resembles gasoline and kerosene. It is toxic and is a powerful oxidizing and fluorinating agent. It is the acid fluoride of perchloric acid.
Chlorine oxyfluoride, Perchlorofluoride, Chlorine fluorine oxide, Trioxychlorofluoride, Perchloric acid fluoride
3D model (JSmol)
|Molar mass||102.4496 g/mol|
|Melting point||−147.8 °C (−234.0 °F; 125.3 K)|
|Boiling point||−46.7 °C (−52.1 °F; 226.5 K)|
|0.06 g/100 ml (20 °C)|
|Vapor pressure||10.5 atm (20°C)|
|Viscosity||3.91 x 10−3 Pa.s (@ melting point)|
Std enthalpy of
|-21.42 kJ/mol :380|
|Main hazards||Corrosive, oxidizing, toxic|
|NFPA 704 (fire diamond)|
Threshold limit value (TLV)
|Lethal dose or concentration (LD, LC):|
LC50 (median concentration)
|385 ppm (rat, 4 hr)|
451 ppm (dog, 4 hr)
LCLo (lowest published)
|2000 ppm (rat, 40 min)|
451 ppm (dog, 4 hr)
|NIOSH (US health exposure limits):|
|TWA 3 ppm (13.5 mg/m3)|
|TWA 3 ppm (14 mg/m3) ST 6 ppm (28 mg/m3)|
IDLH (Immediate danger)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
In spite of its small enthalpy of formation (ΔHf° = −5.2 kcal/mol), it is kinetically stable, decomposing only at 400 °C.:380 It is quite reactive towards reducing agents and anions, however, with the chlorine atom acting as an electrophile.:382 It reacts explosively with reducing agents such as metal amides, metals, hydrides, etc. Its hydrolysis in water occurs very slowly, unlike that of chloryl fluoride.
Synthesis and chemistry
4 + 3 HF + 2 SbF
5 → ClO
3F + H
+ 2 SbF−
3F reacts with alcohols to produce alkyl perchlorates, which are extremely shock-sensitive explosives. In the presence of a Lewis acid, it can be used for introducing the –ClO
3 group into aromatic rings via electrophilic aromatic substitution.
Perchloryl fluoride is used in organic chemistry as a mild fluorinating agent.:383 It was the first industrially relevant electrophilic fluorinating agent, used since the 1960s for producing fluorinated steroids. In the presence of aluminum trichloride, it has also been used as a electrophilic perchlorylation reagent for aromatic compounds.
Perchloryl fluoride was investigated as a high performance liquid rocket fuel oxidizer. In comparison with chlorine pentafluoride and bromine pentafluoride, it has significantly lower specific impulse, but does not tend to corrode tanks. It does not require cryogenic storage. Rocket fuel chemist John Drury Clark reported in his book Ignition! that perchloryl fluoride is completely miscible with all-halogen oxidizers such as chlorine trifluoride and chlorine pentafluoride, and such a mixture provides the needed oxygen to properly burn carbon-containing fuels.
It can also be used in flame photometry as an excitation source.
Perchloryl fluoride is toxic, with a TLV of 3 ppm. It is a strong lung- and eye-irritant capable of producing burns on exposed skin. Its IDLH level is 100 ppm. Symptoms of exposure include dizziness, headaches, syncope, and cyanosis. Exposure to toxic levels causes severe respiratory tract inflammation and pulmonary edema.
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- Inman, C. E.; Oesterling, R. E.; Tyczkowski, E. A. (1958-10-01). "Reactions of Perchloryl Fluoride with Organic Compounds. I. Perchlorylation of Aromatic Compounds1". Journal of the American Chemical Society. 80 (19): 5286–5288. doi:10.1021/ja01552a069. ISSN 0002-7863.
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- Schmauch, G. E.; Serfass, E. J. (1958). "The Use of Perchloryl Fluoride in Flame Photometry". Applied Spectroscopy. 12 (3): 98–102. Bibcode:1958ApSpe..12...98S. doi:10.1366/000370258774615483.
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