Фурфурал: история, свойства и применение

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|Verifiedfields = changed
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|verifiedrevid = 477167491
|ImageFileL1 = Furfural. svg
|ImageFileR1 = Furfural from xtal 3D bs 17. png
|PIN = Furan 2 carbaldehyde
|OtherNames = Furfural, furan 2 carboxaldehyde, fural, furfuraldehyde, 2 furaldehyde, pyromucic aldehyde
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|LCLo = ubl
| 370ppm (mouse, 6hr)
| 260ppm (rat)

Furfural was first isolated in 1821 (published in 1832) by the German chemist Johann Wolfgang Döbereiner, who produced a small sample as a byproduct of formic acid synthesis. In 1840, the Scottish chemist John Stenhouse found that the same chemical could be produced by distilling a wide variety of crop materials, including corn, oats, bran, and sawdust, with aqueous sulfuric acid; he also determined furfural's empirical formula (C5H4O2). George Fownes named this oil "furfurol" in 1845 (from furfur (bran), and oleum (oil)). In 1848, the French chemist Auguste Cahours determined that furfural was an aldehyde. Determining the structure of furfural required some time: the furfural molecule contains a cyclic ether (furan), which tends to break open when it's treated with harsh reagents. In 1870, German chemist Adolf von Baeyer speculated about the structure of the chemically similar compounds furan and 2 furoic acid. Additional research by German chemist Heinrich Limpricht supported this idea. From work published in 1877, Baeyer had confirmed his previous belief on the structure of furfural. By 1886, furfurol was being called "furfural" (short for "furfuraldehyde") and the correct chemical structure for furfural was being proposed. By 1887, the German chemist Willy Marckwald had inferred that some derivatives of furfural contained a furan nucleus. In 1901, the German chemist Carl Harries determined furan's structure through work with succindialdehyde and 2 methylfuran, thereby also confirming furfural's proposed structure. Furfural remained relatively obscure until 1922, 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.

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.

It is commonly found in many cooked or heated foods such as coffee (55–255 mg/kg) and whole grain bread (26 mg/kg). Hydrogenation of furfural provides furfuryl alcohol (FA), which is used to produce furan resins, which are exploited in thermoset polymer matrix composites, cements, adhesives, casting resins and coatings. Further hydrogenation of furfuryl alcohol leads to tetrahydrofurfuryl alcohol (THFA), which is used as a solvent in agricultural formulations and as an adjuvant to help herbicides penetrate the leaf structure. In another application as a feedstock, palladium catalyzed decarbonylation on furfural manufactures industrially furan. Another important solvent made from furfural is methyltetrahydrofuran. Furfural is used to make other furan derivatives, such as furoic acid, via oxidation, and furan itself via palladium catalyzed vapor phase decarbonylation. The median lethal dose is high, 650–900 mg/kg (oral, dogs), consistent with its pervasiveness in foods. The Occupational Safety and Health Administration has set a permissible exposure limit for furfural at 5ppm over an eight hour time weighted average (TWA), and also designates furfural as a risk for skin absorption.