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.[2] 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.[3]
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.[4][5]
Despite this, it was furfural which came to set naming conventions for later furans.
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).[6] 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,[7] but has yet to be commercialised.
Applications and occurrences
In terms of commercial uses, 2-furoic acid is often used in the production of furoate esters, some of which are drugs and pesticides.[10]
2-Furoic acid helps sterilize and
pasteurize many foods. It forms in situ from 2-furfural.[11] 2-Furoic acid is also formed during coffee roasting, with up to 205 mg/kg.[12]
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.[13] 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.[14]
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.
[15][16]
^Senning, Alexander (2006). Elsevier's Dictionary of Chemoetymology. Elsevier.
ISBN0-444-52239-5.
^
abBurdock, George (1996). "P–Z indexes". Encyclopedia of Food and Color Additives. Vol. 3. Bob Stern. p. 2359.
ISBN0-8493-9414-7.
^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 … )
^Pérez, Herminia (2009). "Microbial biocatalytic preparation of 2-furoic acid by oxidation of 2-furfuryl alcohol and 2-furanaldehyde with Nocardia corallina". African Journal of Biotechnology. 8 (10).
^Farthing, Michael JG (August 2006). "Treatment options for the eradication of intestinal protozoa". Nature Clinical Practice Gastroenterology & Hepatology. 3 (8): 436–445.
doi:
10.1038/ncpgasthep0557.
PMID16883348.
S2CID19657328.
^World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization.
hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
^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.
doi:
10.1016/j.foodchem.2010.12.017.
^Macheiner, Lukas; Schmidt, Anatol; Karpf, Franz; Mayer, Helmut K. (2021). "A novel UHPLC method for determining the degree of coffee roasting by analysis of furans". Food Chemistry. 341 (Pt 1): 128165.
doi:
10.1016/j.foodchem.2020.128165.
PMID33038777.
S2CID222280614.
^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.
Bibcode:
2011PhyB..406.2834U.
doi:
10.1016/j.physb.2011.04.038.
^Uma, B.; Murugesan, K. Sakthi; Krishnan, S.; Das, S. Jerome; Boaz, B. Milton (2013). "Optical and dielectric studies on organic nonlinear optical 2-furoic acid single crystals". Optik. 124 (17): 2754–2757.
Bibcode:
2013Optik.124.2754U.
doi:
10.1016/j.ijleo.2012.08.075.