Furan

Source: Wikipedia, the free encyclopedia.
This article is about the industrial chemical compound. For other uses, see Furan (disambiguation).
Furan
Full structural formula of furan
Full structural formula of furan
Skeletal formula showing numbering convention
Skeletal formula showing numbering convention
Ball-and-stick model
Ball-and-stick model
Space-filling model
Space-filling model
Names
Preferred IUPAC name
Furan[1]
Systematic IUPAC name
1,4-Epoxybuta-1,3-diene
1-Oxacyclopenta-2,4-diene
Other names
Oxole
Oxa[5]annulene
1,4-Epoxy-1,3-butadiene
5-Oxacyclopenta-1,3-diene
5-Oxacyclo-1,3-pentadiene
Furfuran
Divinylene oxide
Identifiers
3D model (
JSmol
)
103221
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.003.390 Edit this at Wikidata
EC Number
  • 203-727-3
25716
KEGG
RTECS number
  • LT8524000
UNII
UN number 2389
  • InChI=1S/C4H4O/c1-2-4-5-3-1/h1-4H checkY
    Key: YLQBMQCUIZJEEH-UHFFFAOYSA-N checkY
  • InChI=1/C4H4O/c1-2-4-5-3-1/h1-4H
    Key: YLQBMQCUIZJEEH-UHFFFAOYAC
  • c1ccoc1
Properties
C4H4O
Molar mass 68.075 g·mol−1
Appearance Colorless, volatile liquid
Density 0.936 g/mL
Melting point −85.6 °C (−122.1 °F; 187.6 K)
Boiling point 31.3 °C (88.3 °F; 304.4 K)
-43.09·10−6 cm3/mol
Hazards
GHS labelling:
GHS02: FlammableGHS07: Exclamation markGHS08: Health hazard
Danger
H224, H302, H315, H332, H341, H350, H373, H412
P201, P202, P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P273, P280, P281, P301+P312, P302+P352, P303+P361+P353, P304+P312, P304+P340, P308+P313, P312, P314, P321, P330, P332+P313, P362, P370+P378, P403+P235, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
3
4
1
Flash point −36 °C (−33 °F; 237 K)
390 °C (734 °F; 663 K)
Explosive limits
 Lower: 2.3%
Upper: 14.3% at 20 °C
Lethal dose or concentration (LD, LC):
> 2 g/kg (rat)
Safety data sheet (SDS) Pennakem
Related compounds
Related
heterocycles
 Pyrrole
Thiophene
Related compounds
 Tetrahydrofuran (THF)
2,5-Dimethylfuran
Benzofuran
Dibenzofuran
Structure
C2v
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Furan is a

aromatic ring with four carbon atoms and one oxygen
atom. Chemical compounds containing such rings are also referred to as furans.

Furan is a colorless,

carcinogenic in humans. Furan is used as a starting point for other speciality chemicals.[4]

History

The name "furan" comes from the

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" (as if it were a four-carbon analog to phenol, C6H5OH).[6][7]

Production

Industrially, furan is manufactured by the

1,3-butadiene:[4]

In the laboratory, furan can be obtained from furfural by oxidation to 2-furoic acid, followed by decarboxylation.[8] It can also be prepared directly by thermal decomposition of pentose-containing materials, and cellulosic solids, especially pine wood.

Synthesis of furans

The

diketones with α-bromoketones followed by dehydration of an intermediate hydroxydihydrofuran.[9] The other traditional route involve the reaction of 1,4-diketones with phosphorus pentoxide (P2O5) in the Paal–Knorr synthesis.[10]

Many routes exist for the synthesis of substituted furans.[11][12]


Structure and bonding

Furan has

resonance energies of benzene, pyrrole, thiophene, and furan are, respectively, 152, 88, 121, and 67 kJ/mol (36, 21, 29, and 16 kcal/mol). Thus, these heterocycles, especially furan, are far less aromatic than benzene, as is manifested in the lability of these rings.[13] The molecule is flat but the C=C groups attached to oxygen retain significant double bond
character. The other lone pair of electrons of the oxygen atom extends in the plane of the flat ring system.

Examination of the resonance contributors shows the increased electron density of the ring, leading to increased rates of electrophilic substitution.[14]

Resonance contributors of furan

Reactivity

Because of its partial aromatic character, furan's behavior is intermediate between that of an enol ether and an aromatic ring. It is dissimilar vs ethers such as tetrahydrofuran.

Like enol ethers, 2,5-disubstituted furans are susceptible to hydrolysis to reversibly give 1,4-diketones.

Furan serves as a

endo isomer
:

Furan Diels–Alder reaction with ethyl (E)-3-nitroacrylate

Diels-Alder reaction of furan with arynes provides corresponding derivatives of dihydronaphthalenes, which are useful intermediates in synthesis of other polycyclic aromatic compounds.[16]

Reaction of furan with a benzyne
  • It is considerably more reactive than benzene in electrophilic substitution reactions, due to the electron-donating effects of the oxygen heteroatom. It reacts with bromine at 0 °C to give 2-bromofuran.

Safety

Furan is found in heat-treated commercial foods and is produced through

thermal degradation of natural food constituents.[18][19] It can be found in roasted coffee, instant coffee, and processed baby foods.[19][20][21] Research has indicated that coffee made in espresso makers and coffee made from capsules contain more furan than that made in traditional drip coffee makers, although the levels are still within safe health limits.[22]

Exposure to furan at doses about 2,000 times the projected level of human exposure from foods increases the risk of hepatocellular tumors in rats and mice and bile duct tumors in rats.[23] Furan is therefore listed as a possible human carcinogen.[23]

See also

References

  1. ISBN 978-0-85404-182-4
    .
  2. ISBN 0-89925-457-8
    .
  3. ^ DHHS (NIOSH) Publication No. 2016–171, p. 2, Accessed Nov 2019
  4. ^
    ISBN 978-3527306732
    .
  5. ISBN 0-444-52239-5
    .
  6. doi:10.1002/cber.18700030129
    .
  7. ^ Rodd, Ernest Harry (1971). Chemistry of Carbon Compounds: A Modern Comprehensive Treatise. Elsevier.
  8. ^ Wilson, W. C. (1941). "Furan". Organic Syntheses; Collected Volumes, vol. 1, p. 274.
  9. doi:10.1016/S0040-4020(97)10303-9
    .
  10. ^ a b Gilchrist, Thomas L. (1997). Heterocyclic Chemistry (3rd ed.). Liverpool: Longman. p. 209-212.
  11. doi:10.15227/orgsyn.084.0199.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  12. doi:10.15227/orgsyn.076.0263
    .
  13. ISBN 978-0-471-72091-1
  14. ISBN 978-0-13-196316-0
    .
  15. PMID 16674802
    .
  16. PMID 23205621. Archived from the original
    (PDF) on 2020-02-19.
  17. ISBN 978-3527306732
    .
  18. PMID 23627283. Archived from the original
    (PDF) on 2017-08-08.
  19. ^
    S2CID 12446132
    .
  20. doi:10.2903/j.efsa.2011.2347. Open access icon
  21. S2CID 29027966
    .
  22. Science Daily
    . April 14, 2011.
  23. ^
    S2CID 19389984
    .

External links

Wikimedia Commons has media related to Furan.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Furan&oldid=1191680443"
This page is based on the copyrighted Wikipedia article: Furan. Articles is available under the CC BY-SA 3.0 license; additional terms may apply.Privacy Policy