Formic anhydride, also called methanoic anhydride, is an organic compound with the chemical formula and a structural formula of (H(C=O)−)2O. It can be viewed as the anhydride of formic acid (HCOOH).
Preparation
Formic anhydride can be obtained by reaction of
formyl fluoride with excess
sodium formate 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 of acetic formic anhydride.
[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 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.]
The decomposition of formic anhydride may be catalyzed by formic acid.[
]
Formic anhydride can be detected in the gas-phase reaction of ozone 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.[
]
See also
