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21.
Mélanie Gardette Anthony Perthue Jean-Luc Gardette Tünde Janecska Enikő Földes Béla Pukánszky Sandrine Therias 《Polymer Degradation and Stability》2013
The behaviour of polyethylene with different contents in vinyl and t-vinylene groups have been studied by photooxidation with λ ≥ 300 nm light or by thermooxidation at a temperature of 100 °C. The oxidation was studied by infrared spectroscopy and it was shown that the same oxidation products were obtained, but with different relative concentrations depending on the conditions of ageing, i.e. photochemical or thermal conditions. The mechanisms by which the oxidation products are formed were recalled. The differences between photo- and thermo-oxidation were evidenced on the basis of the stability of ketones that do not accumulate in photochemical conditions, as a result of Norrish reactions. The influence of the initial amount of unsaturated groups on the rates of oxidation was characterized. It was shown that the concentration of unsaturations had no effect on the rate of photooxidation but dramatically influenced the stability in thermooxidative conditions. 相似文献
22.
Laurence Muhr Steve Pontvianne Katalin Selmeczi Cdric Paris Sandrine Boschi‐Muller Laetitia Canabady‐Rochelle 《Journal of separation science》2020,43(11):2031-2041
Some metal‐chelating peptides have antioxidant properties, with potential nutrition, health, and cosmetics applications. This study aimed to simulate their separation on immobilized metal ion affinity chromatography from their affinity constant for immobilized metal ion determined in surface plasmon resonance, both technics are based on peptide‐metal ion interactions. In our approach, first, the affinity constant of synthetic peptides was determined by surface plasmon resonance and used as input data to numerically simulate the chromatographic separation with a transport‐dispersive model based on Langmuir adsorption isotherm. Then, chromatographic separation was applied on the same peptides to determine their retention time and compare this experimental tR with the simulated tR obtained from simulation from surface plasmon resonance data. For the investigated peptides, the relative values of tR were comparable. Hence, our study demonstrated the pertinence of such numerical simulation correlating immobilized metal ion affinity chromatography and surface plasmon resonance. 相似文献
23.
Using a double Suzuki cross-coupling reaction ortho- or para-bromobenzyl bromides are easily transformed into unsymmetrical diaryl (or heteroaryl) methanes 相似文献
24.
Sandrine PerocheHélène Parrot-Lopez 《Tetrahedron letters》2003,44(2):241-245
A new series of fluorinated amphiphilic β-cyclodextrin derivatives has been synthesized. The strategy is based on the modification of the C-6 position of the mono-6-deoxy-6A-para-tolylsulfonyl, di-6A, 6D-deoxy-6A, 6D-(para-tolylsulfonyl) and heptakis-(6-deoxy-6-iodo)-β-cyclodextrin precursors. The synthesis lead to mono-perfluoroalkylthio-, di-perfluoroalkylthio- and heptakis-perfluoroalkylthio-β-cyclodextrin in excellent yields (90-99%). 相似文献
25.
Sandrine LangleFranck David-Quillot Mohamed AbarbriAlain Duchêne 《Tetrahedron letters》2003,44(8):1647-1649
Using double Stille cross-coupling reaction bromo (or chloro)benzylbromide is easily transformed into substituted styrene monomers bearing a wide range of substituents in para position 相似文献
26.
An expeditious synthesis of 1-epitrehazolamine is presented from readily available 2,3,4,6-tetra-O-benzyl-D-glucose. The key step involves a samarium diiodide-promoted reductive cyclization of a masked keto-nitrone to form a five-membered ring aminocyclitol. The excellent cis selectivity observed in this nitrone-ketone reductive coupling contrasts surprisingly with the trans selectivity of ketone-oxime reductive couplings. 相似文献
27.
A new three-component domino reaction catalyzed by palladium was devised, producing polysubstituted bicyclic molecules in good yields from readily available substrates. The reaction conditions and the scope of the process were examined, and a possible mechanism is proposed. [reaction: see text] 相似文献
28.
Guillaume Lafitte Audrey Beillard Sandrine Chambon Catherine Soulet Laurence Dumais Grégoire Mouis Jean-François Fournier Laurence Clary Claire Bouix-Peter Loic Tomas Craig S. Harris 《Tetrahedron letters》2018,59(3):256-259
During our search for novel CGRP antagonists, we had great difficulty in accessing one of our key motifs. Herein, we communicate how we solved the problem by an unprecedented Mitsunobu alkylation using unprotected amino alcohols. 相似文献
29.
The purpose of this paper is to establish universality of the fluctuations of the largest eigenvalue for some non-necessarily
Gaussian complex Deformed Wigner Ensembles. The real model is also considered. Our approach is close to the one used by A.
Soshnikov (cf. [11]) in the investigations of classical real or complex Wigner Ensembles. It is based on the computation of
moments of traces of high powers of the random matrices under consideration. 相似文献
30.
Rapid stereoselective separations of amphetamine derivatives with highly sulfated gamma-cyclodextrin
The highly sulfated gamma-CD (HS-gamma-CD) is a chiral selector widely used in CE for the enantioseparation of pharmaceutical compounds. This paper investigated different approaches to reduce the stereoselective analysis time of amphetamine (AT) derivatives according to the chiral selector concentration in the BGE. With high HS-gamma-CD concentration, tested analytes were separated in 3.5 min as anionic complexes with short-end injection technique in reversed polarity mode. However, this procedure presented some limitations in terms of efficiency and resolution, excessive Joule heating and poor compatibility with MS detection. With low HS-gamma-CD concentration, compounds were separated as cations. Conventional approaches to reduce CE analysis time demonstrated critical resolution between some analytes. Therefore, the use of the partial-filling technique compatible with MS detection was carried out. Under optimized conditions, the analysis time for the chiral separation of seven AT like compounds was reduced to 6 min. Moreover, sensitivity of CE-MS was sufficient for the determination of ATs in plasma following a simple liquid-liquid extraction. 相似文献