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IUPAC name Furan
Other names Oxole, furfuran, divinyl oxide
CAS number 110-00-9
Molecular formula C4H4O
Molar mass 68.07 g/mol
Appearance colorless, volatile liquid
Density 0.936 g/mL
Melting point

-85.6 °C

Boiling point

31.4 °C

Flash point -35 °C
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Furan, also known as furane and furfuran, is a heterocyclic organic compound. It is typically derived by the thermal decomposition of pentose-containing materials, cellulosic solids especially pine-wood. Furan is a colorless, flammable, highly volatile liquid with a boiling point close to room temperature. It is toxic and may be carcinogenic. Catalytic hydrogenation (see redox) of furan with a palladium catalyst gives tetrahydrofuran.

Furan is aromatic because one of the lone pairs of electrons on the oxygen atom is delocalized into the ring, creating a 4n+2 aromatic system (see Hückel's rule) similar to benzene. Because of the aromaticity, the molecule is flat and lacks discrete double bonds. The other lone pair of electrons of the oxygen atom extends in the plane of the flat ring system. The sp2 hybridization is to allow one of the lone pairs of oxygen to reside in a p orbital and thus allow it to interact within the pi-system.

The name furan comes from the Latin furfur, which means bran.[1] The first furan derivative to be described was 2-furoic acid, by Carl Wilhelm Scheele in 1780. Another important derivative, furfural, was reported by Johann Wolfgang Döbereiner in 1831 and characterised nine years later by John Stenhouse. Furan itself was first prepared by Heinrich Limpricht in 1870, although he called it tetraphenol.[2][3]


Synthesis and isolation


Due to its aromaticity, furan's behavior is quite dissimilar to that of the more typical heterocyclic ethers such as tetrahydrofuran. It is considerably more reactive than benzene in electrophilic substitution reactions. Furan serves as a diene in Diels-Alder reactions with electron-deficient dienophiles such as ethyl (E)-3-nitroacrylate.[5] The reaction product is a mixture of isomers with preference for the endo isomer:

Hydrogenation of furans affords sequentially dihydrofurans and tetrahydrofurans.

See also


  1. ^ Alexander Senning. Elsevier's Dictionary of Chemoetymology. Elsevier, 2006. ISBN 0444522395.
  2. ^ H. Limpricht (1870). "Ueber das Tetraphenol C4H4O". Berichte der deutschen chemischen Gesellschaft 3 (1): 90-91. doi:10.1002/cber.18700030129.
  3. ^ Ernest Harry Rodd. Chemistry of Carbon Compounds: A Modern Comprehensive Treatise. Elsevier, 1971.
  4. ^ Wilson, W. C. "Furan" Organic Syntheses, Collected Volume 1, p.274 (1941).
  5. ^ Masesane I, Batsanov A, Howard J, Modal R, Steel P (2006). "The oxanorbornene approach to 3-hydroxy, 3,4-dihydroxy and 3,4,5-trihydroxy derivatives of 2-aminocyclohexanecarboxylic acid". Beilstein Journal of Organic Chemistry 2 (9). doi:10.1186/1860-5397-2-9.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Furan". A list of authors is available in Wikipedia.
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