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Hansgeorg Schmarr - One of the best experts on this subject based on the ideXlab platform.
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Quantitative determination of α-ionone, β-ionone, and β-damascenone and enantiodifferentiation of α-ionone in wine for authenticity control using multidimensional gas chromatography with tandem mass spectrometric detection
Analytical and Bioanalytical Chemistry, 2016Co-Authors: Johannes Langen, Pascal Wegmann-herr, Hansgeorg SchmarrAbstract:Native concentRations of α-ionone, β-ionone, and β-damascenone were studied in various authentic and commercial wines. In addition, the Enantiomeric distribution of α-ionone was determined and its merits as a potential marker for aroma adulteRation in wine were discussed. For extraction of volatiles, headspace solid-phase microextraction (HS-SPME) was applied, followed by heart-cut multidimensional gas chromatography coupled to tandem mass spectrometric detection for trace-level analysis. The enantioselective analysis of α-ionone was achieved with octakis(2,3-di- O -pentyl-6- O -methyl)-γ-cyclodextrin as the chiral selector in the sepaRation column for gas chromatography (GC). In all the authentic wines studied, α-ionone showed a high Enantiomeric Ratio in favor of the ( R )-enantiomer. Since an illegal addition of α-ionone in a racemic form changes the Enantiomeric Ratio, this Ratio may serve as an adulteRation marker. ConcentRations varied between
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quantitative determination of α ionone β ionone and β damascenone and enantiodifferentiation of α ionone in wine for authenticity control using multidimensional gas chromatography with tandem mass spectrometric detection
Analytical and Bioanalytical Chemistry, 2016Co-Authors: Johannes Langen, Pascal Wegmannherr, Hansgeorg SchmarrAbstract:Native concentRations of α-ionone, β-ionone, and β-damascenone were studied in various authentic and commercial wines. In addition, the Enantiomeric distribution of α-ionone was determined and its merits as a potential marker for aroma adulteRation in wine were discussed. For extraction of volatiles, headspace solid-phase microextraction (HS-SPME) was applied, followed by heart-cut multidimensional gas chromatography coupled to tandem mass spectrometric detection for trace-level analysis. The enantioselective analysis of α-ionone was achieved with octakis(2,3-di-O-pentyl-6-O-methyl)-γ-cyclodextrin as the chiral selector in the sepaRation column for gas chromatography (GC). In all the authentic wines studied, α-ionone showed a high Enantiomeric Ratio in favor of the (R)-enantiomer. Since an illegal addition of α-ionone in a racemic form changes the Enantiomeric Ratio, this Ratio may serve as an adulteRation marker. ConcentRations varied between
Rations up to 4.6 μg/L for α-ionone, 3.6 μg/L for β-ionone, and 4.3 μg/L for β-damascenone. Elevated α- and β-ionone concentRations serve as additional indicators for a potential adulteRation. In order to classify the concentRations of the analytes in the context of their odor activity in wine, odor thresholds were determined.
J Sivaguru - One of the best experts on this subject based on the ideXlab platform.
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Enantiospecific 6π-photocyclization of atropisomeric α-substituted acrylanilides in the solid-state: role of crystalline confinement on enantiospecificity
Photochemical & Photobiological Sciences, 2011Co-Authors: Anoklase Jeanluc Ayitou, Nandini Vallavoju, Angel Ugrinov, J SivaguruAbstract:Direct irradiation of optically-pure axially-chiral α-substituted acrylanilides in the crystalline state leads to 3,4-dihydro-2-quinolin-2-one photoproduct with an Enantiomeric Ratio of 85: 15 while a racemic mixture of photoproduct is observed in solution.
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reactive spin state dependent enantiospecific photocyclization of axially chiral α substituted acrylanilides
Chemical Communications, 2011Co-Authors: Anoklase Jeanluc Ayitou, J SivaguruAbstract:The Enantiomeric Ratio (e.r.) in the 3,4-dihydroquinolin-2-one photoproduct during 6π-photocyclization of α-substituted axially chiral ortho-tert-butyl-acrylanilides depends on the nature of the reactive spin state (singlet or triplet), where the singlet-spin state reactivity gives a racemic mixture and the triplet reactivity gives an e.r. value >95 ∶ 5.
Andreas Goeke - One of the best experts on this subject based on the ideXlab platform.
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Sequential Diels-Alder reaction/rearrangement sequence: synthesis of functionalized bicyclo[2.2.1]heptane derivatives and revision of their relative configuRation.
The Journal of organic chemistry, 2014Co-Authors: Demin Liang, Yue Zou, Quanrui Wang, Andreas GoekeAbstract:A sequential Diels–Alder reaction/rearrangement sequence was developed for the synthesis of diverse functionalized bicyclo[2.2.1]heptanes as novel floral and woody odorants. The outcome of the rearrangement depended on the substitution pattern of the dienes. 2D NMR analysis has established the correct relative configuRation of the bicyclo[2.2.1]heptanone, which was originally misassigned. Furthermore, when the initiating DA reaction was catalyzed by a chiral Lewis acid, the bicyclo[2.2.1]heptane derivatives including (+)-herbanone can be obtained in an Enantiomeric Ratio (er) up to 96.5:3.5.
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sequential diels alder reaction rearrangement sequence synthesis of functionalized bicyclo 2 2 1 heptane derivatives and revision of their relative configuRation
Journal of Organic Chemistry, 2014Co-Authors: Demin Liang, Quanrui Wang, Andreas GoekeAbstract:A sequential Diels–Alder reaction/rearrangement sequence was developed for the synthesis of diverse functionalized bicyclo[2.2.1]heptanes as novel floral and woody odorants. The outcome of the rearrangement depended on the substitution pattern of the dienes. 2D NMR analysis has established the correct relative configuRation of the bicyclo[2.2.1]heptanone, which was originally misassigned. Furthermore, when the initiating DA reaction was catalyzed by a chiral Lewis acid, the bicyclo[2.2.1]heptane derivatives including (+)-herbanone can be obtained in an Enantiomeric Ratio (er) up to 96.5:3.5.
Thorleif Anthonsen - One of the best experts on this subject based on the ideXlab platform.
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influence of substituents on Enantiomeric Ratio in transesterification of racemic c 3 synthons using lipase b from candida antarctica
Journal of Molecular Catalysis B-enzymatic, 2000Co-Authors: Bard Helge Hoff, Liv Ljones, Anja Ronstad, Thorleif AnthonsenAbstract:Abstract The fluorides, chlorides and bromides of 3-halo-1-phenoxy-2-propanol, 3-halo-1-phenylmethoxy-2-propanol and 3-halo-1-(2-phenylethoxy)-2-propanol have been resolved by transesterification with various butanoates as acyl donors in hexane and lipase B from Candida antarctica (Novozyme 435) as catalyst. The Enantiomeric Ratio E depended on the hydroxy protecting groups in 1-position and the halogens in 3-position. For some substrates, the Enantiomeric Ratio was dependent on the acylating agent.
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lipase catalyzed resolution of esters of 4 chloro 3 hydroxybutanoic acid effects of the alkoxy group and solvent on the Enantiomeric Ratio
ChemInform, 1999Co-Authors: Bard Helge Hoff, Thorleif AnthonsenAbstract:Abstract Various lipases have been investigated for their potential use as catalysts for the resolution of esters of 4-chloro-3-hydroxybutanoic acid via transesterification in organic solvents. Rhizomucor miehei lipase was found to be the most efficient lipase, with the Enantiomeric Ratio ( E ) being dependent upon of the nature of the alkoxy group of the ester and the resolution medium. Higher E -values were obtained when transesterification was performed in benzene or carbon tetrachloride than was the case in hexane. In mixtures of benzene and hexane the trend in E -values followed a linear relationship.
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organic co solvents restore the inherently high Enantiomeric Ratio of lipase b from candida antarctica in hydrolytic resolution by relieving the enantiospecific inhibition of product alcohol
Tetrahedron-asymmetry, 1998Co-Authors: Kamilla Lundhaug, P.l.antoine Overbeeke, Jaap A. Jongejan, Thorleif AnthonsenAbstract:Abstract The Enantiomeric Ratio in the hydrolysis of racemic 3-chloro-1-phenylmethoxy-2-propyl butanoate with lipase B from Candida antarctica , CALB, is raised from E =50 to E =180 upon addition of acetone to the aqueous medium. This co-solvent effect is now explained as an enantiospecific inhibition of the lipase by the liberated alcohol. In the range from 0 to 30% acetone, the effect correlates with the increased solubility of the alcohol in the reaction medium. Free and immobilized CALB show similar behaviour.
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resolution of derivatives of 1 2 propanediol with lipase b from candida antarctica effect of substrate structure medium water activity and acyl donor on Enantiomeric Ratio
Chemistry and Physics of Lipids, 1998Co-Authors: Thorleif Anthonsen, Bard Helge HoffAbstract:Abstract The glycerol-related racemic derivatives 1a–15a and 1b–15b have been resolved by hydrolysis and transesterifications using lipase B from Candida antarctica. Influence of substrate structure for the Enantiomeric Ratio E has been explained on the basis of previous molecular modelling. E values and equilibrium constants Keq have been calculated on the basis of ees and eep measured throughout the reaction, and ping-pong bi-bi mechanism using the computer program EK however, the latter gave irreversible conditions.
Johannes Langen - One of the best experts on this subject based on the ideXlab platform.
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Quantitative determination of α-ionone, β-ionone, and β-damascenone and enantiodifferentiation of α-ionone in wine for authenticity control using multidimensional gas chromatography with tandem mass spectrometric detection
Analytical and Bioanalytical Chemistry, 2016Co-Authors: Johannes Langen, Pascal Wegmann-herr, Hansgeorg SchmarrAbstract:Native concentRations of α-ionone, β-ionone, and β-damascenone were studied in various authentic and commercial wines. In addition, the Enantiomeric distribution of α-ionone was determined and its merits as a potential marker for aroma adulteRation in wine were discussed. For extraction of volatiles, headspace solid-phase microextraction (HS-SPME) was applied, followed by heart-cut multidimensional gas chromatography coupled to tandem mass spectrometric detection for trace-level analysis. The enantioselective analysis of α-ionone was achieved with octakis(2,3-di- O -pentyl-6- O -methyl)-γ-cyclodextrin as the chiral selector in the sepaRation column for gas chromatography (GC). In all the authentic wines studied, α-ionone showed a high Enantiomeric Ratio in favor of the ( R )-enantiomer. Since an illegal addition of α-ionone in a racemic form changes the Enantiomeric Ratio, this Ratio may serve as an adulteRation marker. ConcentRations varied between
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quantitative determination of α ionone β ionone and β damascenone and enantiodifferentiation of α ionone in wine for authenticity control using multidimensional gas chromatography with tandem mass spectrometric detection
Analytical and Bioanalytical Chemistry, 2016Co-Authors: Johannes Langen, Pascal Wegmannherr, Hansgeorg SchmarrAbstract:Native concentRations of α-ionone, β-ionone, and β-damascenone were studied in various authentic and commercial wines. In addition, the Enantiomeric distribution of α-ionone was determined and its merits as a potential marker for aroma adulteRation in wine were discussed. For extraction of volatiles, headspace solid-phase microextraction (HS-SPME) was applied, followed by heart-cut multidimensional gas chromatography coupled to tandem mass spectrometric detection for trace-level analysis. The enantioselective analysis of α-ionone was achieved with octakis(2,3-di-O-pentyl-6-O-methyl)-γ-cyclodextrin as the chiral selector in the sepaRation column for gas chromatography (GC). In all the authentic wines studied, α-ionone showed a high Enantiomeric Ratio in favor of the (R)-enantiomer. Since an illegal addition of α-ionone in a racemic form changes the Enantiomeric Ratio, this Ratio may serve as an adulteRation marker. ConcentRations varied between
Rations up to 4.6 μg/L for α-ionone, 3.6 μg/L for β-ionone, and 4.3 μg/L for β-damascenone. Elevated α- and β-ionone concentRations serve as additional indicators for a potential adulteRation. In order to classify the concentRations of the analytes in the context of their odor activity in wine, odor thresholds were determined.