- A short and efficient synthesis of 2-methyltetrahydrofuran-3-one
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2-Methyltetrahydrofuran-3-one (3), a volatile constituent of the aroma complex of roasted coffee, is efficiently prepared in satisfactory yield (55,2%) by oxidative hydroxylation of the 2-acetylbutyrolactone (4).
- Ragoussis, Valentine,Lagouvardos, Dimitrios J.,Ragoussis, Nikitas
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- Effect of pH on the maillard reaction of [C]xylose, cystein, and thiamin
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The influence of different pH values, ranging from 4.0 to 7.0, on the formation of sulfur volatiles in the Maillard reaction was studied using a model system with [13C5]xylose, cysteine, and thiamin. The use of 13C-labeled xylose allowed, by analysis of the mass spectra, volatiles that incorporated xylose carbons in the molecule from other carbon sources to be discerned. For 2-furaldehyde and 2-furfurylthiol, which were favored at low pH, the labeling experiments clearly indicated that xylose was the exclusive carbon source. On the other hand, xylose was virtually not involved in the formation of 3-mercapto-2-butanone, 4,5-dihydro-2-methyl-3- furanthiol, and 5-(2-hydroxyethyl)-4-methylthiazole, which apparently stemmed from thiamin degradation. Both xylose and thiamin seemed to significantly contribute to the formation of 2-methyl-3-furanthiol, 3-mercapto-2-pentanone, and 2-mercapto-3-pentanone, and therefore different formation pathways must exist for each of these molecules. In general, the pH determined strongly which volatiles were formed, and to what extent. However, the relative contribution of xylose to the C-skeleton of a particular compound changed only slightly within the investigated pH range, when both xylose and thiamin were involved in the formation.
- Cerny, Christoph,Briffod, Matthieu
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scheme or table
p. 1552 - 1556
(2009/10/01)
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- Thermal decomposition of ascorbic acid
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Thermal degradation of L-ascorbic acid at 300 °C in the absence of a solvent yielded mostly furan derivatives and α,β-unsaturated cyclic ketones with a five-membered ring. Some of the furan derivatives are the same as those obtained in the Maillard reaction, with the reductones undergoing retroaldol reaction, decarboxylation, oxidation, and hydrolysis. In propylene glycol, under milder conditions (180 °C), the carbonyl and dicarbonyl derivatives resulting from the decomposition react with the solvent and give cyclic acetals and ketals (1,3-dioxolanes). The products were identified by GC-MS using the SPECMA data bank.
- Vernin, Gaston,Chakib, Soundouss,Rogacheva, Sonia M.,Obretenov, Tzvetan D.,Parkanyi, Cyril
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- On the Role of 2,3-Dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one in the Maillard Reaction
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To investigate the thermal degradation pathways of 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one (1) in the Maillard reaction, the 13C-labeled and unlabeled 1 were synthesized and heated in model systems of food processing. The extent and position of the labeling of the reaction products were interpreted by the mass spectroscopy data. The volatiles identified were, among others, 2,4-dihydroxy-2,5-dimethyl-3(2H)-furanone (2), 2,5-dimethyl-4-hydroxy-3(2H)-furanone, cyclotene, maltol, 5-hydroxymaltol, and some acyclic carbonyls. Under roasting conditions, 2 was formed as a major product. It was concluded that 1 might be transferred to highly reactive open-chain intermediates like the enolic forms of 1-deoxyosone. The further reaction pathways varied with the reaction conditions. Possible degradation pathways of 1 that resulted from the labeling experiments as well as the formation of the described products are discussed.
- Kim, Myong-Ock,Baltes, Werner
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p. 282 - 289
(2007/10/03)
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- A CONDENSED SYNTHESIS OF DIHYDRO-3(2H)-FURANONE
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A straight forward synthesis of dihydro-3(2H)-furanone is described.An attempted preparation of the oxetan-3-one precursor 10 by this method gave, instead, the ring enlargement product 11.
- Tarnchompoo, Bonkoch,Thebtaranonth, Yodhathai
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p. 5567 - 5570
(2007/10/02)
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