- Identification of Character Impact Odorants of Different White Wine Varieties
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Application of gas chromatography/olfactometry (GC/O) to the analysis of extracts of Scheurebe and Gewuerztraminer wines yielded 36 and 40 odor-active compounds, respectively. Ethyl 2-methylbutyrate, ethyl isobutyrate, 2-phenylethanol, 3-methylbutanol, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 3-ethylphenol, and an unknown compound named wine lactone showed high flavor dilution factors in both varieties. Wine lactone was identified as 3a,4,5,7a-tetrahydro-3,6-dimethylbenzofuran-2(3H)-one and was detected for the first time among the volatiles of wine or a food. The compound exhibited an intense coconut, woody, and sweet odor. 4-Mercapto-4-methylpentan-2-one belongs to the most potent odorants only in the variety Scheurebe, whereas cis-rose oxide was a key substance for the overall flavor of Gewuerztraminer wine. GC/O of static headspace samples of both wine varieties revealed butane-2,3-dione, dimethyl sulfide, and dimethyl trisulfide as further potent odorants.
- Guth
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- Quantitative determination of sulfur containing wine odorants at sub-ppb levels. 1. Synthesis of the deuterated analogues
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[2H10]-4-Sulfanyl-4-methylpentan-2-one (d10-SMP), [2H2]-3-sulfanylhexan-1-ol (d2-3SH), and [2H5]-3-sulfanylhexyl acetate (d5-3SHAc), the labeled analogues of impact odorants of wines and other foods, were synthesized to be used for the quantitative determination of the natural compounds in white and red wines by stable isotope dilution assay. The sulfidation was achieved by Michael addition, on mesityl oxide or ethyl hex-2-enoate, respectively, of the sulfhydryl anion generated in situ from triphenylsilanethiol and potassium fluoride under phase transfer conditions. The labeling of4-sulfanyl-4-methylpentan-2-one(SMP) was obtained from the commercial starting material, [2H6]-acetone, so that this method could be used to synthesize 13C-labeled SMP from 13C-labeled acetone. The labeling of 3-sulfanylhexan-1-ol (3SH) and 3-sulfanylhexyl acetate (3SHAc) was obtained from reduction with lithium aluminum deuteride of the Michael adduct ethyl 3-sulfanylhexanoate and [2H3]-acetylation. During the synthesis, 3SH and 3SHAc were partially oxidized to their disulfide, which were reduced back to the thiols by an additional reduction step; the tertiary thiol SMP was less sensitive to this oxidation.
- Kotseridis, Yorgos,Ray, Jean-Loic,Augier, Christian,Baumes, Raymond
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- Cassis and Green Tea: Spontaneous Release of Natural Aroma Compounds from β-Alkylthioalkanones
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In depth headspace analysis of the slow degradation of β-alkylthioalkanones in ambient air led to the discovery of a novel δ-cleavage pathway, by which β-mercaptoketones are released. Since β-mercaptoketones are potent natural aroma compounds occurring in many fruits, herbs and flowers, the discovery of an enzyme-independent molecular precursor for this class of high-impact molecules is of practical importance. Moreover, the formation of β-diketones and aldehydes by concomitant oxidation at the α-sulfur-position enhances the versatility of this class of aroma precursors. A mechanistic model is proposed which suggests that the oxidative degradation occurs through a novel Pummerer-type rearrangement of initially formed persulfoxides.
- B?ttig, Sarah,Egger, Timothy,Gey, Olga,Bochet, Christian G.,Flachsmann, Felix
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- Studies on the low-temp oxidation of coal containing organic sulfur and the corresponding model compounds
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This paper selects two typical compounds containing organic sulfur as model compounds. Then, by analyzing the chromatograms of gaseous low-temp oxidation products and GC/MS of the extractable matter of the oxidation residue, we summarizing the mechanism of low-temp sulfur model compound oxidation. The results show that between 30 °C to 80 °C, the interaction between diphenyl sulfide and oxygen is mainly one of physical adsorption. After 80 °C, chemical adsorption and chemical reactions begin. The main reaction mechanism in the low-temp oxidation of the model compound diphenyl sulfide is diphenyl sulfide generates diphenyl sulfoxide, and then this sulfoxide is further oxidized to diphenyl sulphone. A small amount of free radicals is generated in the process. The model compound cysteine behaves differently from diphenyl sulfide. The main reaction low-temp oxidation mechanism involves the thiol being oxidized into a disulphide and finally evolving to sulfonic acid, along with SO2 being released at 130 °C and also a small amount of free radicals. We also conducted an experiment on coal from Xingcheng using X-ray photoelectron spectroscopy (XPS). The results show that the major forms of organic sulfur in the original coal sample are thiophene and sulfone. Therefore, it can be inferred that there is none or little mercaptan and thiophenol in the original coal. After low-temp oxidation, the form of organic sulfur changes. The sulfide sulfur is oxidized to the sulfoxide, and then the sulfoxide is further oxidized to a sulfone, and these steps can be easily carried out under experimental conditions. What's more, the results illustrate that oxidation promotes sulfur element enrichment on the surface of coal.
- Zhang, Lanjun,Li, Zenghua,Li, Jinhu,Zhou, Yinbo,Yang, Yongliang,Tang, Yibo,McPhee, Derek J.
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p. 22241 - 22256
(2016/01/25)
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- A centrosymmetrical di-thiolato-bridged dinuclear nickel(II) compound; Bis-μ-S-(7-amino-2,4-dimethyl-5-azahept-4-ene-2-thiolato)dinickel(II) perchlorate
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The title compound, formed by reaction of 4-mercapto-4-methylpentan-2-one with bis(ethane-1,2-diamine)nickel(II) perchlorate, has a centrosymmetrical dinuclear cation. Each singlet ground-state nickel(II) ion is in tetrahedrally twisted square-planar coordination by the primary amine and imine nitrogen atoms and the thiolato sulfur atom of one molecule of 7-amino-2,4-dimethyl-5-azahept-4-ene-2-thiolate (adet-), and the sulfur atom of another molecule, with the sulfur atoms of two ligands forming a planar Ni2S2 bridging group {[Ni2-μ-(adet)2] (ClO4)2, C16H34Cl2N4Ni2O 8S2, Mr 662 · 9, monoclinic, P 21/cr a 8·267(1), b 9·952(1), c 16·234(2) A, β 103·010(2)°, RI, 0·033 for 2531 reflections}.
- Curtis, Neil F.,Gladhikh, Olga P.,Heath, Sarah L.,Morgan, Keith R.
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- Reaction of thiodiacetone alcohol with chlorides of trivalent phosphorus acids
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1. Thiodiacetone alcohol reacts with the monochlorides of trivalent phosphorus acids in the presence of a base to give tricoordinated phosphorus derivatives. 2-Ethoxy-2-thio-3,5,5-trimethyl-1,2-thia-3-phos-pholanol is formed in the case of ethyl dichlorophosphite. 2. The reaction of thiodiacetone alcohol with phenyldichlorophosphine in the absence of a base gives 2-phenyl-2-thio-1,2-oxa-3,3,5-trimethyl-4-phospholene.
- Rizpolozhenskii,Stepashkina,Eliseenkova
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p. 2039 - 2041
(2007/10/05)
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