Coffee furanone
{{Chembox
| ImageFile = Coffee furanone.svg
| ImageSize = 120px
| PIN = 2-Methyloxolan-3-one
| OtherNames = 2-Methyltetrahydrofuran-3-one; 2-Methyl-3-oxotetrahydrofuran; 2-Methyltetrahydro-3-furanone; Dihydro-2-methyl-3-furanone; 2-Methyldihydrofuran-3(2H)-one
|Section1={{Chembox Identifiers
| CASNo = 3188-00-9
| CASNo_Ref = {{cascite|correct|}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = I3703CL967
| PubChem = 18522
| ChemSpiderID = 17494
| SMILES = O=C1C(OCC1)C
| InChI = 1/C5H8O2/c1-4-5(6)2-3-7-4/h4H,2-3H2,1H3
| InChIKey = FCWYQRVIQDNGBI-UHFFFAOYAD
| StdInChI = 1S/C5H8O2/c1-4-5(6)2-3-7-4/h4H,2-3H2,1H3
| StdInChIKey = FCWYQRVIQDNGBI-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
| C=5 | H=8 | O=2
| Appearance =
| Density = 1.040 g/cm3 (20 °C)
| MeltingPt =
| BoilingPtC = 139
| Solubility =
}}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
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Coffee furanone (2-methyltetrahydrofuran-3-one) is a pleasant smelling liquid furan derivative which is a volatile constituent of the aroma complex of roasted coffee.{{cite journal | author = M. A. Gianturco | title = Volatile constituents of coffee. III. Structures of two heterocyclic compounds and the synthesis of tetrahydrofuranones | journal = Tetrahedron | volume = 20 | pages = 1763–1772| year = 1964 |last2 = Friedel | first2 = P. | last3 = Giammarino | first3 = A. S. | issue = 7 | doi=10.1016/s0040-4020(01)99177-x}} Coffee furanone is less odorous than furfuryl mercaptan, which with an odor threshold of 0.005 ppb was the first high impact aroma chemical, but has a very pleasant sweet caramel character, with some nuttiness.{{Cite book |url=https://onlinelibrary.wiley.com/doi/book/10.1002/9781118352434 |title=Handbook of Meat, Poultry and Seafood Quality |date=2012-07-20 |publisher=Wiley |isbn=978-0-470-95832-2 |editor-last=Nollet |editor-first=Leo M. L. |edition=1 |pages=137-138 |language=en |doi=10.1002/9781118352434}}
Synthesis
Coffee furanone was synthesized in 1963 by Wynberg via acid-catalyzed ring closure of β-alkoxy diazoketones.{{cite journal | author = H. Wynberg| title = Tetrahydrofuran-3-one, spirans, and dithienyls| journal = Angewandte Chemie| volume = 75 | issue = 10| pages =453| year = 1963| doi=10.1002/ange.19630751014}} Coffee furanone has also been prepared via the condensation of ethyl lactate and methyl acrylate in DMSO solution{{cite journal | author = M. A. Gianturco | title = Volatile constituents of coffee. III. Structures of two heterocyclic compounds and the synthesis of tetrahydrofuranones | journal = Tetrahedron | volume = 20 | pages = 1763–1772| year = 1964 |last2 = Friedel | first2 = P. | last3 = Giammarino | first3 = A. S. | issue = 7 | doi=10.1016/s0040-4020(01)99177-x}} and (under phase transfer conditions) in ionic liquids.{{cite journal | author = Xiaogeng Liu | title = Synthesis of 2-methyltetrafuran-3-one from ethyl lactate and methyl acrylate. | journal = Shipin Kexue (Beijing, China) | volume = 26 | pages = 165–167| year = 2005 |last2 = Chen | first2 = Yousheng | issue = 5}} A related lactic acid synthesis was described as having the advantages of a simple process, high conversion rate, low pollution, and low cost.Cunzhao Cheng "Synthesis method of natural flavoring 2-methyltetrahydrofuran-3-one", Zhuanli Shenging Gonkai Shuomingshu, CN Patent 2009:1544311 (2009) This compound has also been prepared in acceptable yield via oxidative hydroxylation of the 2-acetylbutyrolactone.{{cite journal | author = Valentine Ragoussis | title = A short and efficient synthesis of 2-methyltetrahydrofuran-3-one | journal = Synthetic Communications | volume = 28 | pages = 4273–4278 | year = 1998 |last2 = Lagouvardos | first2 = Dimitrios J. | last3 = Ragoussis | first3 = Nikitas | issue = 22 | doi=10.1080/00397919809458708}} Further approaches to the synthesis of coffee furanone involved the hydrolysis of the corresponding dithioketals{{cite journal | author = Bonkoch Tarnchompoo | title = A condensed synthesis of dihydro-3(2H)-furanone | journal = Tetrahedron Letters | volume = 25 | pages = 5567–70 | year = 1984 |last2 = Thebtaranonth | first2 = Yodhathai | issue = 48 | doi=10.1016/s0040-4039(01)81628-2}} and the oxidation of 2-methyltetrahydrofuran employing lithium hypochlorite in the presence of ruthenium catalysts.{{cite journal | author = Mario Bressan | title = Selective oxygenation of aliphatic ethers catalyzed by ruthenium(II) complexes | journal = Inorganic Chemistry | volume = 29 | pages = 2976–2979 | year = 1990 |last2 = Morvillo | first2 = Antonino | last3 = Romanello | first3 = Giorgio | issue = 16 | doi=10.1021/ic00341a024}}
Applications
The synthetic version of this natural flavorant and odorant is used in a variety of food and beverage applications, including coffee, nuts, cocoa, brandy, meat sauces and as a general food flavorant at a typical dosage (about 5-20 ppm), similar to the natural concentration (30 ppm) of coffee furanone in roasted coffee.{{cite journal | author = M. A. Gianturco | title = Volatile constituents of coffee. III. Structures of two heterocyclic compounds and the synthesis of tetrahydrofuranones | journal = Tetrahedron | volume = 20 | pages = 1763–1772| year = 1964 |last2 = Friedel | first2 = P. | last3 = Giammarino | first3 = A. S. | issue = 7 | doi=10.1016/s0040-4020(01)99177-x}}{{cite journal | author = R. Silwar | title = Gas chromatographic-mass spectrometric study of roasted coffee aroma - quantitative determination of steam-volatile aroma constituents | journal = Chemie, Mikrobiologie, Technologie der Lebensmittel | volume = 10 | pages = 176–187| year = 1987 |last2 = Kamperschroer | first2 = H. | last3 = Tressl | first3 = R. | issue = 5-6}}