Formic anhydride
Formic anhydride, also called methanoic anhydride, is a chemical compound with formula or (H(C=O)-)2O. It can be viewed as the anhydride of formic acid
Formic acid
Formic acid is the simplest carboxylic acid. Its chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant, formica, referring to its early...


Formic anhydride is a liquid with boiling point 24 °C at 20 mmHg. It is stable in diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...

 solution. It can be isolated by low-temperature, low-pressure distillation, but decomposes on heating above room temperature. It decomposes into formic acid and carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...


Formic anhydride can be obtained by reaction of formyl fluoride
Formyl fluoride
Formyl fluoride is the organic compound with the formula FCH.-Preparation:FCH was first reported in the 1934. Among the many preparations, a typical one involves the reaction of sodium formate with benzoyl fluoride :-Reactions:HCF decomposes autocatalytically near room temperature to carbon...

 with sodium formate
Sodium formate
Sodium formate, HCOONa, is the sodium salt of formic acid, HCOOH. It usually appears as a white deliquescent powder.-Uses:Sodium formate is used in several fabric dyeing and printing processes...

 in ether at −78 °C. It can also be produced by reacting formic acid with N,N′-dicyclohexylcarbodiimide ((-N=)2C) in ether at -10 °C. It can also be obtained by disproportionation
Disproportionation, also known as dismutation is used to describe a specific type of redox reaction in which a species is simultaneously reduced and oxidized so as to form two different products....

 of acetic formic anhydride
Acetic formic anhydride
Acetic formic anhydride, or ethanoic methanoic anhydride is a chemical compound with formula , or --O-H. It can be viewed as the mixed anhydride of acetic acid and formic acid by removal of a molecule of water....


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 a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

 with ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...

. The molecule is planar in the gas phase.
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