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951.
Michał Rachwalski Stanisław Leśniak Piotr Kiełbasiński 《Tetrahedron: Asymmetry》2010,21(21-22):2687-2689
Diastereomerically pure tridentate heteroorganic ligands containing hydroxyl, sulfinyl and aziridine moieties as nucleophilic centers, capable of binding to various organometallic reagents, have been proven to be highly efficient catalysts in the enantioselective addition of phenylethynylzinc to aldehydes to give the desired products in very high yields (up to 95%) and with ee’s up to 90%. The influence of the stereogenic centers located on the sulfinyl sulfur atom and in the aziridine moiety on the stereochemical course of the reaction is also discussed. 相似文献
952.
Mateusz Drach Jolanta Narkiewicz-Micha?ek Marta Szymula 《Applied Surface Science》2010,256(17):5444-5448
Propyl gallate (PG) adsolubilisation in the cationic, anionic and nonionic surfactant micelles formed in the bulk solution and at the silica/solution interface has been investigated. It was found that in the absence of surfactant, propyl gallate does not adsorb on the silica surface from aqueous solution. However, in the presence of hexyltrimethylammonium bromide (CTAB), its uptake by silica significantly increases. Alumina is quite an effective adsorbent for SDS and propyl gallate and does not adsorb nonionic TX-100. The addition of PG promotes adsorption of SDS and TX-100. 相似文献
953.
Mihaela Gulea Małgorzata Kwiatkowska Piotr Łyżwa Remi Legay Annie-Claude Gaumont Piotr Kiełbasiński 《Tetrahedron: Asymmetry》2009,20(3):293-297
The Michael addition of selected sulfur and nitrogen nucleophiles to a chiral non-racemic 2-phosphono-2,3-didehydrothiolane S-oxide is fully diastereoselective. The enantiomeric excesses of the adducts obtained could be determined by 31P NMR spectroscopy using (R)-(+)-tert-butyl(phenyl)phosphinothioic acid as a chiral solvating agent. The addition of thiophenol was monitored by 31P NMR spectroscopy which made it possible to observe the formation and evolution of the kinetic and thermodynamic adducts in the reaction mixture. The structures of both enantiomeric thiophenol adducts have been determined by X-ray analysis. 相似文献
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JPC – Journal of Planar Chromatography – Modern TLC - A new, simple, accurate, and rapid high-performance thin-layer chromatographic method has been developed for the determination of... 相似文献
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It is shown that the empirical pseudo-second order kinetic equation is a very efficient formula to correlate the kinetic data
generated by applying theoretical expressions developed from the fundamental SRT (Statistical Rate Theory) approach to the
interfacial transport. This is especially true when the most popular linear representation is used in which time/adsorbed
amount is plotted vs. time. However, the commonly observed goodness of such linear plots does not necessarily speak for the
applicability of the pseudo-second order kinetic equation. A reliable estimation, for instance, of the equilibrium adsorbed
amount is possible only when a substantial part of a kinetic isotherms corresponds to the conditions close to equilibrium.
Energetic surface heterogeneity increases the goodness of these linear regressions. Then, experimental errors have only little
effect on the pseudo-second linear plots.
This article is dedicated to Professor Mietek Jaroniec on the occasion of his 60th birthday. 相似文献
960.
Bogusław Buszewski Agnieszka Ulanowska Tomasz Ligor Natalia Denderz Anton Amann 《Biomedical chromatography : BMC》2009,23(5):551-556
In this study, 38 samples of expired air were collected and analyzed from 20 non‐smoking volunteers, four passive smokers and 14 smokers (21 women and 17 men). Measurements were carried out using solid‐phase microextraction (SPME) as an isolation and preconcentration technique. The determination and identification were accomplished by gas chromatography coupled with mass spectrometry (GC/MS). Our data showed that ca 32% of all identified compounds in the breath of healthy non‐smokers were saturated hydrocarbons. In the breath of smoking and passive smoking volunteers hydrocarbons were predominant, but also present were more exogenous analytes such as furan, acetonitrile and benzene than in the breath of non‐smokers. Acetonitrile, furan, 3‐methylfuran, 2,5‐dimethylfuran, 2‐butanone, octane and decane were identified in breath of smoking and passive smoking persons. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献