# Fluorine perchlorate

Fluorine perchlorate
Identifiers
CAS number 10049-03-3
Jmol-3D images Image 1
Properties
Molecular formula FClO
4
Melting point -167.3 °C
Boiling point -16 °C
Thermochemistry
Std enthalpy of
formation
ΔfHo298
9 kcal/mol[1]
Hazards
Main hazards Highly explosive gas
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Fluorine perchlorate is the rarely encountered chemical compound of fluorine, chlorine, and oxygen with the chemical formula FClO
4
or FOClO
3
. It is an extremely unstable gas that explodes spontaneously[2] and has a penetrating odor.[3]

## Synthesis

One synthesis uses fluorine and perchloric acid,[4] though the action of ClF5 on water is another method[citation needed].

$\rm \ F_2 + HClO_4 \rightarrow FClO_4 + HF$

Another method of synthesis involves the thermal decomposition of tetrafluoroammonium perchlorate, NF
4
ClO
4
, which yields very pure FClO
4
that may be manipulated and frozen without explosions.[5]

$\rm \ NF_4ClO_4 \xrightarrow{\Delta} NF_3 + FClO_4$

## Structure

Fluorine perchlorate is not analogous to perchloric acid because the fluorine atom does not exist as a positive ion. It contains an oxygen atom in a rare oxidation state of 0, due to the electronegativity of oxygen, which is higher than that of chlorine but lower than that of fluorine.

## Safety

FClO4 has a very dangerous and unpredictable series of reactions associated with it, as a covalent perchlorate (chlorine in the +7 oxidation state) and a compound featuring a very sensitive O-F single bond. Small amounts of reducing agent, such as organic compounds, can trigger explosive detonation. Products of these decomposition reactions could include oxygen halides, interhalogen compounds, and other hazardous substances.

Accidental synthesis is possible if precursors are carelessly mixed. Like similar covalent fluorides and perchlorates, it needs to be handled with extreme caution.

## Reaction

FClO4 is a strong oxidant and it reacts with iodide ion:

FOClO3 + 2I- → ClO4- + F- + I2

FClO4 can also react with tetrafluoroethylene:[6]

CF2=CF2 + FOClO3 → CF3CF2OClO3