Formic anhydride, also called methanoic anhydride, is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

and a structural formula of (H(C=O)−)₂O. It can be viewed as the

anhydride An organic acid anhydride is an acid anhydride that is an organic compound. An acid anhydride is a compound that has two acyl groups bonded to the same oxygen atom. A common type of organic acid anhydride is a carboxylic anhydride, where the pa ...

of formic acid (HCOOH).

Preparation

Formic anhydride can be obtained by reaction of formyl fluoride with excess

sodium formate Sodium formate, HCOONa, is the sodium salt of formic acid, HCOOH. It usually appears as a white deliquescent powder. Preparation For commercial use, sodium formate is produced by absorbing carbon monoxide under pressure in solid sodium hydroxide ...

and a catalytic amount of formic acid in ether at −78 °C.George A. Olah, Yashwant D. Vankar; Massoud Arvanaghi; Jean Sommer (1979), ''Formic Anhydride''. Angewandte Chemie International Edition Engl., volume 18, issue = 8, page = 614. . It can also be produced by reacting formic acid with ''N'','-dicyclohexylcarbodiimide ((−N=)₂C) in ether at −10 °C.G. Wu, S. Shlykov, F. S. Van Alseny, H. J. Geise, E. Sluyts, B. J. Van der Veken (1995), ''Formic Anhydride in the Gas Phase, Studied by Electron Diffraction and Microwave and Infrared Spectroscopy, Supplemented with Ab-Initio Calculations of Geometries and Force Fields''. J. Phys. Chem., volume 99, issue 21, pages 8589–8598 It can also be obtained by

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can ...

acetic formic anhydride Acetic formic anhydride is an organic compound with the chemical formula and a structural formula of -(C=O)-O-(C=O)H. It can be viewed as the mixed anhydride of acetic acid and formic acid. Preparation Acetic formic anhydride can be produced by ...

.R. Schijf, J. W. Scheeren, A. van Es, W. Stevens (1965) ''Mixed carboxylic acid anhydrides: IV. formic anhydride''. Recueil des Travaux Chimiques des Pays-Bas, volume 84, issue 5, pages 594–596.

Properties

Formic anhydride is a liquid with boiling point 24 °C at 20 mmHg. It is stable in

diethyl ether Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable li ...

solution. It can be isolated by low-temperature, low-pressure distillation, but decomposes on heating above room temperature. At room temperature and higher, it decomposes through a decarbonylation reaction into formic acid and

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

. Due to its instability, formic anhydride is not commercially available and must be prepared fresh and used promptly. The decomposition of formic anhydride may be catalyzed by formic acid. Formic anhydride can be detected in the gas-phase reaction of

ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...

with ethylene.A. Vaccani, A. Bauder and Hs. H. Günthar (1975), ''The Microwave Spectrum of Formic Anhydride''. Abstracts of OSU International Symposium on Molecular Spectroscopy 1970-1979 The molecule is planar in the gas phase.

References

{{reflist Carboxylic anhydrides

Preparation

Properties

See also

References