Furfural

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Furfural
Names
Preferred IUPAC name
Furan-2-carbaldehyde
Other names
Furfural, furan-2-carboxaldehyde, fural, furfuraldehyde, 2-furaldehyde, pyromucic aldehyde
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.002.389 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C5H4O2/c6-4-5-2-1-3-7-5/h1-4H checkY
    Key: HYBBIBNJHNGZAN-UHFFFAOYSA-N checkY
  • InChI=1/C5H4O2/c6-4-5-2-1-3-7-5/h1-4H
    Key: HYBBIBNJHNGZAN-UHFFFAOYAD
  • c1cc(oc1)C=O
Properties
C5H4O2
Molar mass 96.085 g·mol−1
Appearance Colorless oil
Odor Almond-like[1]
Density 1.1601 g/mL (20 °C)[2][3]
Melting point −37 °C (−35 °F; 236 K)[2]
Boiling point 162 °C (324 °F; 435 K)[2]
83 g/L[2]
Vapor pressure 2 mmHg (20 °C)[1]
−47.1×10−6 cm3/mol
Hazards
Flash point 62 °C (144 °F; 335 K)
Explosive limits
 2.1–19.3%[1]
Lethal dose or concentration (LD, LC):
300–500 mg/kg (oral, mice)[4]
  • 370 ppm (dog, 6 hr)
  • 175 ppm (rat, 6 hr)
  • 1037 ppm (rat, 1 hr)[5]
  • 370 ppm (mouse, 6 hr)
  • 260 ppm (rat)[5]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 5 ppm (20 mg/m3) [skin][1]
REL (Recommended)
 No established REL[1]
IDLH
(Immediate danger)
 100 ppm[1]
Related compounds
Related Furan-2-carbaldehydes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Furfural is an organic compound with the formula C4H3OCHO. It is a colorless liquid, although commercial samples are often brown. It has an aldehyde group attached to the 2-position of furan. It is a product of the dehydration of sugars, as occurs in a variety of agricultural byproducts, including corncobs, oat, wheat bran, and sawdust. The name furfural comes from the Latin word furfur, meaning bran, referring to its usual source. Furfural is only derived from dryed biomass. In addition to ethanol, acetic acid, and sugar, furfural is one of the oldest organic chemicals available readily purified from natural precursors.[6]

History

Furfural was first isolated in 1821 (published in 1832) by the German chemist

2-methylfuran, thereby also confirming furfural's proposed structure.[16][17]

Furfural remained relatively obscure until 1922,[6] when the Quaker Oats Company began mass-producing it from oat hulls.[18] Today, furfural is still produced from agricultural byproducts like sugarcane bagasse and corn cobs. The main countries producing furfural today are the Dominican Republic, South Africa and China.

Properties

Furfural dissolves readily in most polar organic solvents, but it is only slightly soluble in either water or alkanes.

Furfural participates in the same kinds of reactions as other aldehydes and other aromatic compounds. It exhibits less aromatic character than benzene, as can be seen from the fact that furfural is readily hydrogenated to tetrahydrofurfuryl alcohol. When heated in the presence of acids, furfural irreversibly polymerizes, acting as a thermosetting polymer.

Production

Furfural may be obtained by the acid catalyzed dehydration of 5-carbon sugars (pentoses), particularly xylose.[19]

C
5H
10O
5 → C
5H
4O
2 + 3 H
2O

These sugars may be obtained from pentosans obtained from hemicellulose present in lignocellulosic biomass.

Between 3% and 10% of the mass of crop residue feedstocks can be recovered as furfural, depending on the type of feedstock. Furfural and water evaporate together from the reaction mixture, and separate upon condensation. The global production capacity is about 800,000 tons as of 2012. China is the biggest supplier of furfural, and accounts for the greater part of global capacity. The other two major commercial producers are Illovo Sugar in South Africa and Central Romana in the Dominican Republic.[20]

In the laboratory, furfural can be synthesized from plant material by heating with sulfuric acid[21] or other acids.[22][20] With the purpose to avoid toxic effluents, an effort to substitute sulfuric acid with easily separable and reusable solid acid catalysts has been studied around the world.[23] The formation and extraction of xylose and subsequently furfural can be favored over the extraction of other sugars with varied conditions, such as acid concentration, temperature, and time.

In industrial production, some lignocellulosic residue remains after the removal of the furfural.[24] This residue is dried and burned to provide steam for the operation of the furfural plant. Newer and more energy efficient plants have excess residue, which is or can be used for co-generation of electricity,[25][26] cattle feed, activated carbon, mulch/fertiliser, etc.

Uses and occurrence

It is commonly found in many cooked or heated foods such as coffee (55–255 mg/kg) and whole grain bread (26 mg/kg).[4]

Furfural is an important renewable, non-petroleum based, chemical

catalytic reduction.[27]

herbicides
penetrate the leaf structure.

In another application as a feedstock, palladium-catalyzed decarbonylation on furfural manufactures industrially furan.[4]

Another important solvent made from furfural is

furoic acid, via oxidation,[29] and furan itself via palladium catalyzed vapor phase decarbonylation.[4]

Furfural is also a specialized chemical solvent.[20]

There is a good market for value added chemicals that can be obtained from furfural.[20]

Safety

Furfural is

hepatotoxic.[30][31][32][33]

The median lethal dose is high, 650–900 mg/kg (oral, dogs), consistent with its pervasiveness in foods.[4]

The Occupational Safety and Health Administration has set a permissible exposure limit for furfural at 5 ppm over an eight-hour time-weighted average (TWA), and also designates furfural as a risk for skin absorption.[1]

See also

References

  1. ^ a b c d e f g NIOSH Pocket Guide to Chemical Hazards. "#0297". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b c d Record of CAS RN 98-01-1 in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  3. doi:10.1007/s10765-019-2570-9
    .
  4. ^
    ISBN 978-3527306732
    .
  5. ^ a b "Furfural". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  6. ^
    ISSN 0019-7866
    .
  7. doi:10.1002/jlac.18320030206
    . From p. 141: "Ich verbinde mit diese Bitte noch die Bemerkung, … Bittermandelöl riechende Materie enthält, … " (I join to this request also the observation that the formic acid which is formed by the simultaneous reaction of sulfuric acid and manganese peroxide with sugar and which contains a volatile material that appears oily in an isolated condition and that smells like a mixture of cassia and bitter almond oil … )
  8. JSTOR 111080
    .
  9. JSTOR 108270
    .
  10. ^ Cahours, Auguste (1848). "Note sur le furfurol" [Note on furfurol]. Annales de Chimie et de Physique. 3rd series (in French). 24: 277–285. (English translation: Cahours, A. (1848). "Observations on furfurol". The Chemical Gazette. 6: 457–460.)
  11. doi:10.1002/cber.187000301169
    .
  12. doi:10.1002/cber.18700030129
    . From p. 90: "Die Ansicht, dass die Pyroschleimsäure eine der Salicylsäure ähnliche Constitution besitzt, macht das Auftreten des Tetraphenols bei der Destillation der pyroschleimsauren Salze wahrscheinlich." (The belief that 2-furoic acid has a structure similar to salicylic acid makes probable the presence of tetraphenol [furan] during the distillation of salts of 2-furoic acid.) That is, just as heating salts of salicylic acid produces phenol, so heating salts of 2-furoic acid should produce an analog of phenol containing 4 carbon atoms.
  13. ^ In 1877, Baeyer published a series of papers on furfural, as he tried to determine its structure.
  14. ^ Tilden, William A., ed. (1886). Watts' Manual of Chemistry: Theoretical and Practical. Vol. II: Chemistry of Carbon-Compounds or, Organic Chemistry (2nd ed.). Philadelphia, Pennsylvania, USA: P. Blakiston, Son, & Co. pp. 379–380.
  15. doi:10.1002/cber.188702002140
    .
  16. doi:10.1002/cber.19010340225
    .
  17. doi:10.1002/cber.18980310109
    .
  18. ISSN 0019-7866
    .
  19. doi:10.1002/jctb.4168
    .
  20. ^
    doi:10.1016/j.biombioe.2018.04.005
    .
  21. doi:10.15227/orgsyn.001.0049
    .
  22. OCLC 162130560
    .
  23. S2CID 106216043
    .
  24. doi:10.1007/s13399-020-00702-4
    .
  25. OCLC 967224456
    .
  26. OCLC 932064033
    .
  27. PMID 30362725
    .
  28. ISBN 978-0-7506-4132-6
    .
  29. doi:10.15227/orgsyn.036.0036
    .
  30. ^ "Furfural (CAS 98-01-1)". Carcinogenic Potency Project. Archived from the original on 24 November 2018. Retrieved 24 November 2018.
  31. PMID 9097102
    . Retrieved 24 November 2018.
  32. ^ "Furfural(Group 3)". IARC. Retrieved 24 November 2018.
  33. ^ Richard Irwin, Ph.D. (1990). NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF FURFURAL (CAS NO. 98-01-1) IN F344/N RATS AND B6C3F1 MICE (GAVAGE STUDIES) (PDF) (Report). U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES. Retrieved 24 November 2018.

External links

  • Furfural in the Pesticide Properties DataBase (PPDB)
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