CAS number 110-00-9 YesY
PubChem 8029
ChemSpider 7738 YesY
KEGG C14275 YesY
ChEBI CHEBI:35559 YesY
Jmol-3D images Image 1
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

31.3 °C

Flash point -69 °C
Related compounds
Related heterocycles Pyrrole
Related compounds Tetrahydrofuran (THF)
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen. The class of compounds containing such rings are also referred to as furans.

Furan is a colorless, flammable, highly volatile liquid with a boiling point close to room temperature. It is toxic and may be carcinogenic. Furan is used as a starting point to other specialty chemicals.[2]



The name furan comes from the Latin furfur, which means bran.[3] 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.[4][5]


Industrially, furan is manufactured by the palladium-catalyzed decarbonylation of furfural, or by the copper-catalyzed oxidation of 1,3-butadiene:[2]

Manufacture of furan.png

In the laboratory, furan can be obtained from furfural by oxidation to furan-2-carboxylic acid, followed by decarboxylation.[6]. It can also be prepared directly by thermal decomposition of pentose-containing materials, cellulosic solids especially pine-wood.

Synthesis of furans

The Feist-Benary synthesis is a classic way to synthesize furans, although many syntheses have been developed.[7] One of the simplest synthesis methods for furans is the reaction of 1,4-diketones with phosphorus pentoxide (P2O5) in the Paal-Knorr Synthesis. The thiophene formation reaction of 1,4-diketones with Lawesson's reagent also forms furans as side products. 2,4-Disubstituted furans can be synthesized by sulfone-mediated cyclization of 1,3-diketones[8]


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.

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, due to the electron-donating effects of the oxygen heteroatom. Examination of the resonance contributors shows the increased electron density of the ring, leading to increased rates of electrophilic substitution.[9]

Resonance contributors of furan

  • Furan serves as a diene in Diels-Alder reactions with electron-deficient dienophiles such as ethyl (E)-3-nitroacrylate.[10] The reaction product is a mixture of isomers with preference for the endo isomer:
Furan Diels-Alder reaction with ethyl (E)-3-nitroacrylate

See also

  • Simple aromatic rings
  • Furanose
  • bs4994 Furan resin as thermoset FRP for chemical process plant equipments
  • Furantetracarboxylic acid
  • Furanoflavonoid


  1. ^ Webster's Online Dictionary
  2. ^ a b H. E. Hoydonckx, W. M. Van Rhijn, W. Van Rhijn, D. E. De Vos, P. A. Jacobs (2005), "Furfural and Derivatives", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a12_119.pub2 
  3. ^ Alexander Senning. Elsevier's Dictionary of Chemoetymology. Elsevier, 2006. ISBN 0444522395.
  4. ^ Limpricht, H. (1870). "Ueber das Tetraphenol C4H4O". Berichte der deutschen chemischen Gesellschaft 3 (1): pp. 90–91. doi:10.1002/cber.18700030129. 
  5. ^ Rodd, Ernest Harry (1971). Chemistry of Carbon Compounds: A Modern Comprehensive Treatise. Elsevier. 
  6. ^ Wilson, W.C. (1941), "Furan", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1p0274 ; Coll. Vol. 1: 274 
  7. ^ Hou XL, Cheung HY, Hon TY, Kwan PL, Lo TH, Tong SY, Wong HNC (1998). ""Regioselective syntheses of substituted furans"". Tetrahedron 54 (10): 1955–2020. doi:10.1016/S0040-4020(97)10303-9. 
  8. ^ Haines, N. R.; VanZanten, A. N.; Cuneo, A. A.; Miller, J. R.; Andrews, W. J.; Carlson, D. A.; Harrington, R. M.; Kiefer, A. M.; Mason, J. D.; Pigza, J. A.; Murphree, S. S. [1] Journal of Organic Chemistry, Volume 76, p. 8131 (2011).
  9. ^ Bruice, Paula Y. (2007). Organic Chemistry (Fifth ed.). Upper Saddle River, NJ: Pearson Prentice Hall. ISBN 0-13-196316-3. 
  10. ^ 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): 9. doi:10.1186/1860-5397-2-9. PMC 1524792. PMID 16674802. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1524792. 

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Look at other dictionaries:

  • furan — FURÁN s.m. Combinaţie chimică organică lichidă, obţinută la distilarea răşinilor de conifere şi folosită ca important intermediar în sintezele de mase plastice şi de medicamente. – Din fr. furanne. Trimis de LauraGellner, 15.05.2004. Sursa: DEX… …   Dicționar Român

  • Furān — Furān, s. Furfuran …   Meyers Großes Konversations-Lexikon

  • fùrān — m 〈G furána〉 kem. bezbojna tekućina aromatskih spojeva; furfuran …   Veliki rječnik hrvatskoga jezika

  • furan — fùrān m <G furána> DEFINICIJA kem. bezbojna tekućina aromatskih spojeva; furfuran ETIMOLOGIJA nlat. furanum …   Hrvatski jezični portal

  • furan — [fyo͞o′ran΄, fyo͞o ran′; fyoor′an΄] n. [contr. < FURFURAN] a colorless, liquid heterocyclic compound, C4H4O, prepared from wood tar or furfural, and used in organic synthesis …   English World dictionary

  • Furan — 45°31′29″N 4°14′59″E / 45.52472, 4.24972 …   Wikipédia en Français

  • Furan — Strukturformel Allgemeines Name Furan Andere Namen Furfuran Divinylenox …   Deutsch Wikipedia

  • furan — /fyoor an, fyoo ran /, n. a colorless, liquid, unsaturated, five membered heterocyclic compound, C4H4O, obtained from furfural: used chiefly in organic synthesis. Also called furfuran. [1890 95; aph. form of FURFURAN] * * * ▪ chemical compound… …   Universalium

  • Furan — Fu|ran 〈n. 11; unz.; Chem.〉 organ. chem. Verbindung mit heterozyklisch gebundenem Sauerstoffatom u. chloroformartigem Geruch, durch Oxidation des Furfurols gewonnen, lässt sich zu Tetrahydrofuran, einem wichtigen Lösungsmittel, hydrieren [zu lat …   Universal-Lexikon

  • furan — also furane noun Etymology: International Scientific Vocabulary, from furfural Date: 1894 a cyclic flammable liquid compound C4H4O that is obtained from wood oils of pines or made synthetically and is used especially in organic synthesis; also… …   New Collegiate Dictionary

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