2-Furoic acid explained

2-Furoic acid is an organic compound, consisting of a furan ring and a carboxylic acid side-group. Along with other furans, its name is derived from the Latin word furfur, meaning bran, from which these compounds were first produced.[1] The salts and esters of furoic acids are known as furoates. 2-Furoic acid is most widely encountered in food products as a preservative and a flavouring agent, where it imparts a sweet, earthy flavour.

History

The compound was first described by Carl Wilhelm Scheele in 1780, who obtained it by the dry distillation of mucic acid. For this reason it was initially known as pyromucic acid. This was the first known synthesis of a furan compound, the second being furfural in 1821.[2] [3] Despite this, it was furfural which came to set naming conventions for later furans.

Preparation and synthesis

2-Furoic acid can be synthesized by the oxidation of either furfuryl alcohol or furfural. This can be achieved either chemically or biocatalytically.

The current industrial route involves the Cannizaro reaction of furfural in an aqueous NaOH solution. This is a disproportionation reaction and produces a 1:1 ratio of 2-furoic acid and furfuryl alcohol (a 50% yield of each).[4] It remains economical because both products have commercial value. The bio-catalytic route involves the microorganism Nocardia corallina. This produces 2-furoic acid in higher yields: 98% from 2-furfuryl alcohol and 88% from 2-furfural,[5] but has yet to be commercialised.

Applications and occurrences

thumb|left|Diloxanide, an amebicide derived from 2-feroic acid,[6] is on the World Health Organization's List of Essential Medicines.[7] In terms of commercial uses, 2-furoic acid is often used in the production of furoate esters, some of which are drugs and pesticides.[8]

In foods

It is a flavoring ingredient and achieved a generally recognized as safe (GRAS) status in 1995 by the Flavor and Extract Manufacturers Association (FEMA). 2-Furoic acid has a distinct odor described as sweet, oily, herbaceous, and earthy.[9]

2-Furoic acid helps sterilize and pasteurize many foods. It forms in situ from 2-furfural.[10] 2-Furoic acid is also formed during coffee roasting, with up to 205 mg/kg.[11]

Optic properties

2-Furoic acid crystals are highly transparent in the 200–2000 nm wavelength region, are stable up to 130 °C, and generally have low absorption in the UV, visible, and IR ranges.[12] In optical and dielectric studies, 2-furoic acid crystals may act as paraelectrics in the temperature range < 318 K and ferroelectrics in temperature ranges > 318 K.[13]

Microbial metabolism

2-Furoic acid can be the sole source of carbon and energy for the organism Pseudomonas putida. The organism aerobically degrades the compound.[14] [15]

Hazards

The LD50 is 100 mg/kg (oral, rats).

Further reading

Notes and References

  1. Book: Senning, Alexander. Elsevier's Dictionary of Chemoetymology. Elsevier. 2006. 0-444-52239-5.
  2. 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. 141–146. J. W. Döbereiner. 3. 2. 1832. Annalen der Pharmacie. 10.1002/jlac.18320030206. de . 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 …)
  3. On the Oils Produced by the Action of Sulphuric Acid upon Various Classes of Vegetables. [Abstract]]. 939–941. John Stenhouse. 5. 1843. Abstracts of the Papers Communicated to the Royal Society of London. 111080. 10.1098/rspl.1843.0234. free.
    • See also: Stenhouse . John . On the oils produced by the action of sulphuric acid upon various classes of vegetables . Philosophical Transactions of the Royal Society of London . 1850 . 140 . 467–480 . 10.1098/rstl.1850.0024 . 186214485 . free .
  4. Mariscal. R.. Maireles-Torres. P.. Ojeda. M.. Sádaba. I.. López Granados. M.. Furfural: a renewable and versatile platform molecule for the synthesis of chemicals and fuels. Energy Environ. Sci.. 9. 4. 2016. 1144–1189. 1754-5692. 10.1039/C5EE02666K. 10261/184700. 101343477 . free.
  5. Microbial biocatalytic preparation of 2-furoic acid by oxidation of 2-furfuryl alcohol and 2-furanaldehyde with Nocardia corallina . Herminia . Pérez . 8 . 10 . 2009 . African Journal of Biotechnology.
  6. Farthing. Michael JG. Treatment options for the eradication of intestinal protozoa. Nature Clinical Practice Gastroenterology & Hepatology. August 2006. 3. 8. 436–445. 10.1038/ncpgasthep0557. 16883348. 19657328.
  7. Book: ((World Health Organization)) . World Health Organization model list of essential medicines: 21st list 2019 . 2019 . 10665/325771 . World Health Organization . World Health Organization . Geneva . WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO . free .
  8. Zitt . Myron . Kosoglou . Teddy . Hubbell . James . Mometasone Furoate Nasal Spray: A Review of Safety and Systemic Effects . Drug Safety . 2007 . 30 . 4 . 317–326 . 10.2165/00002018-200730040-00004. 17408308 . 42398133 .
  9. Encyclopedia: Burdock . Encyclopedia of Food and Color Additives . 0-8493-9414-7 . George . Bob Stern . P–Z indexes . 3 . 2359 . 1996 .
  10. Hucker . B. . Varelis . P. . 2011 . Thermal decarboxylation of 2-furoic acid and its implication for the formation of furan in foods . Food Chemistry . 126 . 3. 1512–1513 . 10.1016/j.foodchem.2010.12.017 .
  11. A novel UHPLC method for determining the degree of coffee roasting by analysis of furans. Food Chemistry . 341. 128165 . 10.1016/j.foodchem.2020.128165. 2021. Macheiner . Lukas . Schmidt . Anatol . Karpf . Franz . Mayer . Helmut K. . Pt 1 . 33038777 . 222280614 .
  12. Uma . B. . Das . S. Jerome . Krishnan . S. . Boaz . B. Milton . 2011 . Growth, optical and thermal studies on organic nonlinear optical crystal: 2-Furoic acid . Physica B: Condensed Matter . 406 . 14. 2834–2839 . 10.1016/j.physb.2011.04.038 . 2011PhyB..406.2834U .
  13. B.. Uma. K. Sakthi. Murugesan. S.. Krishnan. S. Jerome. Das. B. Milton. Boaz. Optical and dielectric studies on organic nonlinear optical 2-furoic acid single crystals. Optik. 124. 17. 2754–2757. 10.1016/j.ijleo.2012.08.075. 2013. 2013Optik.124.2754U.
  14. Ueber das Tetraphenol C4H4O . On tetraphenol C4H4O . 90–91 . H. . Limpricht . 3 . 1 . 1870 . Berichte der Deutschen Chemischen Gesellschaft . 10.1002/cber.18700030129.
  15. Molybdenum Involvement in Aerobic Degradation of 2-Furoic Acid by Pseudomonas putida Ful. . KERSTIN . KOENIG . 55 . 7 . 1988 . Applied and Environmental Microbiology . 202958 . 16347977 . 1829–34. 10.1128/aem.55.7.1829-1834.1989 .

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