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Formyl fluoride

Formyl fluoride
IUPAC name Formyl fluoride
Other names Formic acid fluoride
CAS number 1493-02-3
Molecular formula CHFO
Molar mass 48.02 g/mol
Appearance Colourless gas
Melting point

-142 °C

Boiling point

–29 °C

Solubility in water decomposes
Solubility in other solvents chlorocarbons,
Dipole moment 2.02 D[1]
Main hazards toxic
Related Compounds
Related compounds Formic acid
Hydrogen fluoride
Carbonyl fluoride
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Formyl fluoride is the organic compound with the formula FC(O)H. It is the only verified acyl halide of formic acid.



FC(O)H was first reported in the 1934.[2] Among the many preparations, a typical one involves the reaction of sodium formate with benzoyl fluoride (generated in situ from KHF2 and benzoyl chloride):[3]

NaOC(O)H + C6H5C(O)F → FC(O)H + C6H5CO2Na


The molecule is planar; C-O and C-F distances are 1.18 and 1.34 A, respectively.[1]


HC(O)F decomposes autocatalytically near room temperature to carbon monoxide and hydrogen fluoride:

HC(O)F → HF + CO

Because of the compound’s sensitivity, reactions are conducted at low temperatures and samples are often stored over anhydrous alkali metal fluorides, e.g. KF which absorbs HF.

Benzene (and other arenes) react with formyl fluoride in the presence of boron trifluoride to give benzaldehyde. In a related reaction, formyl chloride is implicated in Gattermann-Koch formylation reaction. The reaction of formyl fluoride/BF3 with perdeuteriobenzene (C6D6) exhibits a kinetic isotope effect of 2.68, similar to the isotope effect observed in Friedel-Crafts acetylation of benzene. Formylation of benzene with a mixture of CO and hexafluoroantinomic acid however, exhibits no isotope effect (C6H6 and C6D6 react at the same rate), indicating that this reaction involves a more reactive formylating agent, possibly CHO+.[3]

Formyl fluoride undergoes the reactions expected of an acyl halide: alcohols and carboxylic acids are converted to formate esters and mixed acid anhydrides, respectively.[4]


  1. ^ a b LeBlanc, Jr., O. H.; Laurie, V. W.; Gwinn, W. D. “Microwave Spectrum, Structure, and Dipole Moment of Formyl Fluoride” The Journal of Chemical Physics 1960, volume 33, pp. 598-600.
  2. ^ Nesmejanow, A. N.; Kahn, E. J. “Über die unmittelbare Synthese von Säure-fluoriden aus Säuren und die Herstellung von Formylfluorid” Chemische Berichte. 1934, volume 67, page 370-373. DOI: 10.1002/cber.19340670303
  3. ^ a b Olah, G. A.; Ohannesian, L.; Arvanaghi, M, ”Formylating Agents” Chemical Reviews, 1987, volume 87, pp 671 - 686. DOI: 10.1021/cr00080a001
  4. ^ Olah, G. A.; Prakash, G. K. S.; Wang, Q.; Li, X. "Formyl Fluoride" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Formyl_fluoride". A list of authors is available in Wikipedia.
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