- Structure-odor correlations in homologous series of alkanethiols and attempts to predict odor thresholds by 3d-qsar studies
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Homologous series of alkane-1-thiols, alkane-2-thiols, alkane-3-thiols, 2-methylalkane-1-thiols, 2-methylalkane-3-thiols, 2-methylalkane-2-thiols, and alkane-1,??-dithiols were synthesized to study the influence of structural changes on odor qualities and odor thresholds. In particular, the odor thresholds were strongly influenced by steric effects: In all homologous series a minimum was observed for thiols with five to seven carbon atoms, whereas increasing the chain length led to an exponential increase in the odor threshold. Tertiary alkanethiols revealed clearly lower odor thresholds than found for primary or secondary thiols, whereas neither a second mercapto group in the molecule nor an additional methyl substitution lowered the threshold. To investigate the impact of the SH group, odor thresholds and odor qualities of thiols were compared to those of the corresponding alcohols and (methylthio)alkanes. Replacement of the SH group by an OH group as well as S-methylation of the thiols significantly increased the odor thresholds. By using comparative molecular field analysis, a 3D quantitative structure-activity relationship model was created, which was able to simulate the odor thresholds of alkanethiols in good agreement with the experimental results. NMR and mass spectrometric data for 46 sulfur-containing compounds are additionally supplied.
- Polster, Johannes,Schieberle, Peter
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p. 1419 - 1432
(2015/03/05)
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- Nuclear Heptylation of Benzene and Naphthalene and Cyclopentylation of Toluene
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Thermal decomposition of 1-, 2-, 3- and 4-heptyltoluene-p-sulphonates in the presence of aromatic substrates like benzene or naphthalene at 130-35 deg, affords differently substituted α- and β-isomers in the case of naphthalene.Skeletal isomerisation of the alkyl group is observed where different isomeric 1-, 2-, 3- and 4-heptyl-aromatics are obtained.Also thermal decomposition of cyclopentylmethane sulphonate in the presence of toluene at 130-35 deg, furnishes the corresponding o-, m- and p-substituted toluenes.The isomers have been identified and estimated quantitatively by GLC.
- Badr, M. Z. A.,El-Naggar, G. M.,Aly, M. M.,Fahmy, A. M.
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p. 961 - 964
(2007/10/02)
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