Appearance Colorless gas Molar mass 102.4496 g/mol Boiling point -46.7 °C | Formula FClO3 Density 1.4 g/cm³ | |
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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.
Contents
In spite of its small enthalpy of formation (ΔHfO = −5.7), it is stable, decomposing only at 400 °C. It is quite reactive towards reducing agents and anions, however, with the chlorine atom acting as an electrophile. It reacts explosively with reducing agents such as amides, metals, hydrides, etc. Its hydrolysis in water occurs very slowly, unlike that of chloryl fluoride.
Synthesis and chemistry
Perchloryl fluoride is produced primarily by the fluorination of perchlorates. Antimony pentafluoride is a commonly used fluorinating agent:
ClO−4 + 3 HF + 2 SbF
5 → ClO
3F + H
3O+
+ 2 SbF−
6
ClO
3F reacts with alcohols to produce alkyl perchlorates, which are extremely shock-sensitive explosives. Using Friedel-Crafts catalysts, it can be used for introducing the –ClO
3 group into aromatic rings via electrophilic aromatic substitution.
Applications
Perchloryl fluoride is used in organic chemistry as a mild fluorinating agent. 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.
It can also be used in flame photometry as an excitation source.
Safety
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.