Furfural is anorganic compound with the formula C4H3OCHO. It is a colorless liquid, although commercial samples are often brown. It has analdehyde group attached to the 2-position offuran. It is a product of thedehydration of sugars, as occurs in a variety ofagricultural byproducts, includingcorncobs,oat,wheatbran, andsawdust. The namefurfural comes from theLatin wordfurfur, meaningbran, referring to its usual source. Furfural is derived only from dried biomass. In addition toethanol,acetic acid, andsugar, furfural is one of the oldest known organic chemicals available readily purified from natural precursors.[6]
Furfural was first isolated in 1821 (published in 1832) by the German chemistJohann Wolfgang Döbereiner, who produced a small sample as a byproduct offormic acid synthesis.[7] In 1840, the Scottish chemistJohn Stenhouse found that the same chemical could be produced by distilling a wide variety of crop materials, including corn, oats, bran, and sawdust, with aqueoussulfuric acid; he also determined furfural'sempirical formula (C5H4O2).[8]George Fownes named this oil "furfurol" in 1845 (fromfurfur (bran), andoleum (oil)).[9] In 1848, the French chemistAuguste Cahours determined that furfural was analdehyde.[10] Determining the structure of furfural required some time: the furfural molecule contains a cyclicether (furan), which tends to break open when it's treated with harsh reagents. In 1870, German chemistAdolf von Baeyer speculated about the structure of the chemically similar compounds furan and2-furoic acid.[11] Additional research by German chemistHeinrich Limpricht supported this idea.[12] From work published in 1877, Baeyer had confirmed his previous belief on the structure of furfural.[13] By 1886, furfurol was being called "furfural" (short for "furfuraldehyde") and the correct chemical structure for furfural was being proposed.[14] By 1887, the German chemistWilly Marckwald had inferred that some derivatives of furfural contained a furan nucleus.[15] In 1901, the German chemistCarl Harries determined furan's structure through work withsuccindialdehyde and2-methylfuran, thereby also confirming furfural's proposed structure.[16][17]
Furfural remained relatively obscure until 1922,[6] when theQuaker Oats Company began mass-producing it from oat hulls.[18] Today, furfural is still produced from agricultural byproducts likesugarcane bagasse and corn cobs. The main countries producing furfural today are the Dominican Republic, South Africa and China.
Furfural dissolves readily in most polar organic solvents, but it is only slightly soluble in either water oralkanes.
Furfural participates in the same kinds of reactions as other aldehydes and other aromatic compounds. It exhibits less aromatic character thanbenzene, as can be seen from the fact that furfural is readilyhydrogenated totetrahydrofurfuryl alcohol. When heated in the presence of acids, furfural irreversibly polymerizes, acting as athermosetting polymer.
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 areIllovo Sugar in South Africa and Central Romana in the Dominican Republic.[20]
In the laboratory, furfural can be synthesized from plant material by heating withsulfuric 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.
Furfural is an important renewable, non-petroleum based, chemicalfeedstock which can be converted into solvents, polymers, fuels and other useful chemicals by a range ofcatalyticreduction.[28]
^abPeters, Fredus N. (1936). "The Furans: Fifteen Years of Progress".Industrial & Engineering Chemistry.28 (7):755–759.doi:10.1021/ie50319a002.ISSN0019-7866.
^J. W. Döbereiner (1832)."Ueber die medicinische und chemische Anwendung und die vortheilhafte Darstellung der Ameisensäure" [On the medical and chemical application and the profitable preparation of formic acid].Annalen der Pharmacie (in German).3 (2):141–146.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 … )
^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.)
^Limpricht, H. (1870)."Ueber das Tetraphenol C4H4O" [On tetraphenol C4H4O].Berichte der Deutschen Chemischen Gesellschaft (in German).3:90–91.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.
^In 1877, Baeyer published a series of papers on furfural, as he tried to determine its structure.
^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.
^Brownlee, Harold J.; Miner, Carl S. (1948). "Industrial Development of Furfural".Industrial & Engineering Chemistry.40 (2):201–204.doi:10.1021/ie50458a005.ISSN0019-7866.
^Cai, Charles M.; Zhang, Taiying; Kumar, Rajeev; Wyman, Charles E. (2014). "Integrated furfural production as a renewable fuel and chemical platform from lignocellulosic biomass".Journal of Chemical Technology & Biotechnology.89 (1):2–10.Bibcode:2014JCTB...89....2C.doi:10.1002/jctb.4168.
^Bonomi, Antonio; Cavalett, Otavio; Cunha, Marcelo Pereira da; Lima, Marco A. P., eds. (2015-12-09).Virtual biorefinery: an optimization strategy for renewable carbon valorization. Cham: Springer.ISBN978-3-319-26045-7.OCLC932064033.
