- 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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- Organic preparations with molar amounts of volatile malodorous thiols
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Thiols are indispensable for the preparation of many organic sulfur compounds. Their strong smell and use for gas leakage perception render it almost impossible to work with them without arousing public attention. Molar amounts of the very odoriferous thiol 2-methyl-2-propanethiol (t-butylthiol) are needed, for example, for the large-scale synthesis of two useful synthetic building blocks, 1,2,4,5-tetrakis(t-butylthio)benzene and tetramethylbenzo-2,2, 6,6-[1,2-d;4,5-d']bis[1,3]dithiol. We investigated an array of alternatives to circumvent the problem: (1) alternative thiols (primary, long-chain, tertiary thiols of larger molar mass); (2) exhaust cleaning methods (adsorption, oxidation, conversion to a salt); and (3) thermal exhaust treatment. Only combustion of the fumehood exhaust with domestic gas at 900 °C in a regenerative thermal oxidation unit was able to completely prevent the thiol smell from escaping. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- Mueller, Diana,Adelsberger, Klaus,Imming, Peter
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supporting information
p. 1447 - 1454
(2013/05/22)
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