2-Furoic acid

2-Furoic Acid
Names
	Preferred IUPAC name Furan-2-carboxylic acid[1]
	Systematic IUPAC name 1-Oxacyclopenta-2,4-diene-2-carboxylic acid
	Other names 2-Furoic acid; pyromucic acid; 2-furancarboxylic acid; α-furancarboxylic acid; α-furoic acid; 2-carboxyfuran
Identifiers
CAS Number	88-14-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:30845 ;
ChemSpider	10251740 ;
ECHA InfoCard	100.001.639
KEGG	C01546;
PubChem CID	6919;
UNII	P577F6494A ;
CompTox Dashboard (EPA)	DTXSID6041420 ;
	InChI InChI=1S/C5H4O3/c6-5(7)4-2-1-3-8-4/h1-3H,(H,6,7) Key: SMNDYUVBFMFKNZ-UHFFFAOYSA-N ; InChI=1/C4H9.Li/c1-3-4-2;/h1,3-4H2,2H3;/rC4H9Li/c1-2-3-4-5/h2-4H2,1H3 Key: MZRVEZGGRBJDDB-NESCHKHYAE;
	SMILES OC(=O)C1=CC=CO1;
Properties
Chemical formula	C5H4O3
Molar mass	112.084 g·mol−1
Appearance	White/ Off-White (Beige) Crystalline Powder
Density	0.55 g/cm3
Melting point	128 to 132 °C (262 to 270 °F; 401 to 405 K)
Boiling point	230 to 232 °C (446 to 450 °F; 503 to 505 K)
Solubility in water	Easily soluble in cold and hot water, 27.1 g/L
Acidity (pKa)	3.12 at 25 °C
Hazards
Main hazards	Irritating to eyes, respiratory system and skin.
NFPA 704 (fire diamond)	1 2 0
Related compounds
Related compounds	2-Thiophenecarboxylic acid, ; 3-Furoic acid, Furfuryl alcohol, ; 2,5-Furandicarboxylic acid, ; Furfurylamine
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

2-Furoic acid is a heterocyclic carboxylic acid, consisting of a five-membered aromatic ring and a carboxylic acid group. Its name is derived from the Latin word furfur, meaning bran.[2] The salts and esters of furoic acids are known as furoates.

2-Furoic acid is an organic compound most widely found in food products as a preservative and a flavoring agent. Other uses for 2-furoic acid include nylon preparation and optic technologies.

History

The molecule first described by Carl Wilhelm Scheele in 1780 and was the first known derivative of the heterocycle known as furan. Since then, the compound's reactivity with different substances and organisms was tested. It was discovered that 2-furoic acid can be the sole source of carbon and energy for the organism Pseudomonas putida. The organism aerobically degrades the compound. [3] [4]

Preparation and synthesis

Biotransformation of furfuryl alcohol (R = CH₂OH) or furfural (R = CHO) to 2-furoic acid by Nocardia corallina

2-Furoic acid can be synthesized by the oxidation of either furfuryl alcohol or furfural. This can be achieved either chemically or biocatalytically. Currently the industrial route involves the Cannizaro reaction of furfural in an aqueous NaOH solution; this route produces both 2-furoic acid and furfuryl alcohol.[5] The bio-catalytic route involves the microorganism Nocardia corallina. Experiments involving this microbial conversion resulted in high yields: 98% from 2-furfuryl alcohol and 88% from 2-furanaldehyde. Oxidation with N. corallina is unique because most other microorganisms produce two products from the oxidation, the acid and the alcohol. Furthermore, aromatic ring destruction does not occur.[6]

Applications and occurrences

In industrial use, 2-furoic acid is a preservative, acting as a bactericide and fungicide. It is also considered an acceptable flavoring ingredient and achieved a generally recognized as safe (GRAS) status in 1995 by the Flavor and Extract Manufacturers Association (FEMA). 2-Furoic acid is characterized as a white to off-white crystalline solid and has a distinct odor described in the Encyclopedia of Food and Color Additives as sweet, oily, herbaceous, and earthy.[7] 2-Furoic acid is often used as a starting material for the production of furoate esters. It and its derivatives also aid in the production of nylons, and are often used in biomedical research.

Reactions

For the most part 2-furoic acid is relatively stable. However, 2-furoic acid is reactive with oxidizing materials. It is not reactive with reducing agents, combustible materials, organic materials, metals, acids, or alkalis.

Importance in optic technology

2-furoic acid may have an important role in the field of optic technology. Studies concerning the preparation of 2-furoic acid crystals have shown indication of several favorable properties of non-linear optical materials (NLOs). These 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 spectrums.[8] In optical and dielectric studies, 2-furoic acid crystals have been shown to have decreasing dielectric constants with increasing frequencies. This could mean that the crystals may act as paraelectrics in the temperature range before 318 K and ferroelectrics in temperature ranges after 318 K.[9] These qualities indicate that 2-furoic acid crystals will have enhanced optical quality with less defects, which is important in the application of optical devices. Depending on the process of crystal formation, the surface of the grown crystals is generally smooth, with occasional microcrystals on the surface.[8]

2-Furoic acid in foods

2-furoic acid helps sterilize and pasteurize many foods. The main mechanism that produces the 2-furoic acid for food sterilization is known as the Cannizzaro reaction of 2-furfural.[10] 2-furoic acid is also formed during coffee roasting, with up to 205 mg/kg.[11]

Hazards

Research on the effects of 2-furoic acid in rats showed an increase in bile salts and acute toxicity suggesting potential toxic effects.[12] 2-Furoic acid may also cause mutagenic effects in bacteria and yeasts, leading to damage and irritation to the gastrointestinal tract, respiratory tract, skin, and eyes.

References

"Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 746. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
Senning, Alexander (2006). Elsevier's Dictionary of Chemoetymology. Elsevier. ISBN 0-444-52239-5.
Limpricht, H. (1870). "Ueber das Tetraphenol C₄H₄O" [On tetraphenol C₄H₄O]. Berichte der Deutschen Chemischen Gesellschaft. 3 (1): 90–91. doi:10.1002/cber.18700030129.
KOENIG, KERSTIN (1988). "Molybdenum Involvement in Aerobic Degradation of 2-Furoic Acid by Pseudomonas putida Ful". Applied and Environmental Microbiology. 55 (7): 1829–34. PMC 202958. PMID 16347977.
Mariscal, R.; Maireles-Torres, P.; Ojeda, M.; Sádaba, I.; López Granados, M. (2016). "Furfural: a renewable and versatile platform molecule for the synthesis of chemicals and fuels" (PDF). Energy Environ. Sci. 9 (4): 1144–1189. doi:10.1039/C5EE02666K. ISSN 1754-5692.
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).
Burdock, George (1996). "P–Z indexes". Encyclopedia of Food and Color Additives. 3. Bob Stern. p. 2359. ISBN 0-8493-9414-7.
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: International Journal for Light and Electron Optics. 124 (17): 2754–2757. Bibcode:2013Optik.124.2754U. doi:10.1016/j.ijleo.2012.08.075.
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: 128165. doi:10.1016/j.foodchem.2020.128165.
Hall, Iris; Wong, Oi; Reynolds, David; Chang, J. J. (2006). "Hypolipidemic Effects of 2-Furoic Acid in Sprague-Dawley Rats". Archiv der Pharmazie. 3 (1): 15–23. doi:10.1002/ardp.19933260105.