排序方式: 共有55条查询结果,搜索用时 31 毫秒
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JT Lowe MD Lee LB Akella E Davoine EJ Donckele L Durak JR Duvall B Gerard EB Holson A Joliton S Kesavan BC Lemercier H Liu JC Marié CA Mulrooney G Muncipinto M Welzel-O'Shea LM Panko A Rowley BC Suh M Thomas FF Wagner J Wei MA Foley LA Marcaurelle 《The Journal of organic chemistry》2012,77(17):7187-7211
The synthesis and diversification of a densely functionalized azetidine ring system to gain access to a wide variety of fused, bridged, and spirocyclic ring systems is described. The in vitro physicochemical and pharmacokinetic properties of representative library members are measured in order to evaluate the use of these scaffolds for the generation of lead-like molecules to be used in targeting the central nervous system. The solid-phase synthesis of a 1976-membered library of spirocyclic azetidines is also described. 相似文献
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R Beniazza V Desvergnes E Girard B Kauffmann M Berlande Y Landais 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(38):11976-11986
7-Silyl- and 7-silylmethylcycloheptatrienes were shown to react with acylnitroso reagents at room temperature, through their norcaradiene forms, to generate the corresponding cycloadducts 5?a-b and 6?a-b as single diastereomers. The course of the reaction was dramatically modified by changing the reaction conditions. Using a polar medium, functionalized cyclohexa-1,3-dienes 7?a-b and bicyclic compounds 13?a-b were instead generated, incorporating one or two amino groups. Similar behavior was observed by using other dienophiles, including triazolinedione, but also activated aldehydes and ketones. A tentative mechanism has been proposed to rationalize the formation of both classes of products that relies on a domino process involving four consecutive elementary steps, in this order: 1)?electrocyclic process, 2)?hetero-Diels-Alder reaction, 3)?cyclopropane ring opening, and 4)?hetero-Diels-Alder reaction. Trapping of the cationic intermediate and isolation of the primary cycloadduct provide support for this hypothesis. An enantioselective version of the cascade using cycloheptatriene 4?b and aldehydes and ketones, under copper(II) catalysis was also carried out, leading to cyclohexa-1,3-dienes 21, 28, and 30 with enantioselectivities up to 93?% ee. Finally, elaboration of the intermediates above has been carried out, opening a straightforward access to sugar mimics 42-43 and complex polycyclic systems 36 and 39. 相似文献
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Effect of bio‐based monomers on the scratch resistance of acrylate photopolymerizable coatings
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Emeline Prandato Sébastien Livi Michel Melas Justine Auclair Vincent Verney Etienne Fleury Françoise Méchin 《Journal of Polymer Science.Polymer Physics》2015,53(5):379-388
Photopolymerizable clear coatings based on bio‐sourced acrylates, dedicated to the protection of polycarbonate substrates, were studied. The bio‐sourced compounds were not based on triglycerides but were smaller, industrially available molecules similar to classical petro‐based monomers. Their polymerization kinetics was studied by photo‐DSC and was shown to allow high acrylate conversions even at 25 °C. Closely related coatings enriched in alkyl segments, or in monoacrylates to decrease the crosslinking density, were compared. The material composition affects its nanomorphology deduced from X‐ray diffraction. Although these changes in composition can slightly shift the mechanical relaxation, it remains wide, and the elastic modulus remains high (>108 Pa) for all the tested materials. Microscratch experiments highlighted the efficiency of all the new coatings in terms of protection against scratches. Incorporating a monoacrylate, particularly isobornyl acrylate, can improve the scratch resistance especially in terms of critical load (up to 175% increase compared with a classical petro‐based coating). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 379–388 相似文献
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Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta0.33V0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV2. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase. 相似文献
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Daniela Saviello Emeline Pouyet Lucia Toniolo Marine Cotte Austin Nevin 《Analytica chimica acta》2014
Synchrotron-based Fourier transform infrared micro-spectroscopy (SR-μFTIR) was used to map photo-oxidative degradation of acrylonitrile–butadiene–styrene (ABS) and to investigate the presence and the migration of additives in historical samples from important Italian design objects. High resolution (3 × 3 μm2) molecular maps were obtained by FTIR microspectroscopy in transmission mode, using a new method for the preparation of polymer thin sections. The depth of photo-oxidation in samples was evaluated and accompanied by the formation of ketones, aldehydes, esters, and unsaturated carbonyl compounds. This study demonstrates selective surface oxidation and a probable passivation of material against further degradation. In polymer fragments from design objects made of ABS from the 1960s, UV-stabilizers were detected and mapped, and microscopic inclusions of proteinaceous material were identified and mapped for the first time. 相似文献
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Emeline Bessard Olivier De Almeida Gérard Bernhart 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1669-1678
A differential generalized Avrami’s law is used to model crystallization kinetic of PEEK in considering that PEEK crystallization results from the contribution of two distinct mechanisms. The form of this equation allows to predict with good accuracy both isothermal and non-isothermal crystallization kinetics. Nevertheless, isothermal model parameters are not entirely satisfactory for predicting non-isothermal crystallization and the identification of kinetic parameters is needed for both isothermal and non-isothermal cases. The results show that the Avrami exponents and Arrhenius activation energies remain constant for both conditions and therefore suggest that these parameters are only material dependent. On the other hand, the other kinetic parameters depend on the crystallization condition and vary with temperature and/or cooling rate. 相似文献
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Emeline AV Zhang X Jin M Murakami T Fujishima A 《The journal of physical chemistry. B》2006,110(14):7409-7413
We report for the first time an experimental application of the concept of a "black body" like reactor to measure quantum yields (Phi) of photochemical reactions in liquid-solid heterogeneous systems. A major advantage of this new method is its simplicity since the fractions of reflected and transmitted light are negligible due to reactor geometry and high optical density of the heterogeneous systems. The average quantum yield of a test reaction (phenol photodegradation) over TiO(2) (Degussa P25) as determined by this method was 0.14, identical to the quantum yield measured earlier for this same reaction under similar conditions by Salinaro and Serpone. We also report the quantum yield of phenol photodegradation over N-doped TiO(2) during photoexcitation at the fundamental absorption band (lambda = 365 nm; Phi = 0.12) and at the N-doping induced extrinsic absorption band (lambda = 436 nm; Phi = 0.08) of the photocatalyst. 相似文献