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891.
Fei Wang Jacques Roovers 《Journal of polymer science. Part A, Polymer chemistry》1994,32(13):2413-2424
Bromomethyl poly (aryl ether ether ketone) has been prepared from methyl poly (aryl ether ether ketone) (MePEEK) and has been used as the precursor to many forms of functionalized PEEK. MePEEK was brominated directly with bromine. Bromination takes place exclusively at the methyl group. The reaction conditions for bromination have been studied. The bromination level can be controlled by the amount of bromine used, up to 90% of the methyl groups can be brominated to mono-bromo and di-bromo methyl PEEK. Modification reactions have been carried out on the brominated methyl PEEK. The bromomethyl group has been converted to different functional groups, such as ? CH2OH, ? CH2OCH3, ? COOCH3, ? CH2CN, ? CH2COOH ? CH2OCOCH3, ? CH2N+H (CH2CH3)2Br?, ? CH2N (CH2CH3)2, ? CH2N+ (CH2CH3)3 Br?. Published 1994 John Wiley & Sons, Inc. 相似文献
892.
Xavier Colin Emmanuel Richaud Jacques Verdu Carole Monchy-Leroy 《Radiation Physics and Chemistry》2010,79(3):365-370
A non-empirical kinetic model has been built for describing the general trends of radiooxidation kinetics of ethylene–propylene copolymers (EPR) at low γ dose rate and low temperature. It is derived from a radical chain oxidation mechanism composed of 30 elementary reactions: 19 relative to oxidation of methylene and methyne units plus 11 relative to their eventual cooxidation. The validity of this model has been already checked successfully elsewhere for one homopolymer: polyethylene (PE) (Khelidj et al., 2006a, Khelidj et al., 2006b; Colin et al., 2007). In the present study, it is now checked for polypropylene (PP) and a series of three EPR differing essentially by their mole fraction of ethylene (37%, 73% and 86%) and their crystallinity degree (0%, 5% and 26%). Predicted values of radiation-chemical yields are in good agreement with experimental ones published in the last half past century. 相似文献
893.
894.
Sylvain Keav Agnès Martin Jacques Barbier Jr Daniel Duprez 《Comptes Rendus Chimie》2010,13(5):508-514
The formation of a carbonaceous deposit was shown to occur during catalytic wet air oxidation of phenol over ceria and doped-ceria supported platinum and ruthenium monometallic catalysts. This deposit came in the form of a layer of organic species adsorbed on the catalytic surface. Polycyclic aromatic compounds of the chromenone, xanthenone and fluorenone families could be extracted and identified via chromatographic techniques coupled with mass spectroscopy. These species result from the condensation of phenol with products of its partial oxidation. 相似文献
895.
896.
Dolors Edmont Christophe Marot Jacques Chenault 《Journal of heterocyclic chemistry》2002,39(6):1161-1165
A versatile methodology to build the 1H‐[1,2,4]triazino[1,6‐a]quinoline‐2,4,6(3H)‐trione structure from methyl 6‐fluoro4‐oxo‐1,4‐dihydro‐2‐quinolinecarboxylate was developed. The method involves an N‐ami‐nation followed by condensation of an aroyl isocyanate to form an alpha semicarbazidocarboxylate that readily cyclizes to the fused [1,2,4]triazino ring under ammonia/ethanol condition. Also, the reactivity of the [1,2,4]triazino ring thus obtained was studied. 相似文献
897.
Zanardi J Lamazure D Minière S Reboul V Metzner P 《The Journal of organic chemistry》2002,67(25):9083-9086
Asymmetric allylidenation of aldehydes with sulfur ylides is possible with proper substitution of the initial sulfide, to avoid the [2,3] sigmatropic rearrangement of the unsaturated ylides. One-pot reaction of (2R,5R)-dimethylthiolane with allyl halides, aldehydes, and sodium hydroxide in tert-butyl alcohol affords vinyl oxiranes in good yields. Enantiomeric excesses up to 90% and trans selectivities have been achieved with methallyl-type halides. 相似文献
898.
Garcia Y Moscovici J Michalowicz A Ksenofontov V Levchenko G Bravic G Chasseau D Gütlich P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(21):4992-5000
[Fe(hyptrz)3](4-chloro-3-nitrophenylsulfonate)22 H2O (1; hyptrz=4-(3-hydroxypropyl)-1,2,4-triazole) has been synthesized and its physical properties have been investigated by several physical techniques including magnetic susceptibility measurements, calorimetry, and M?ssbauer, optical, and EXAFS spectroscopy. Compound 1 exhibits a spin transition below room temperature, together with a very wide thermal hysteresis of about 50 K. This represents the widest hysteresis loop ever observed for an FeII-1,2,4-triazole spin transition material. The cooperativity is discussed on the basis of temperature-dependent EXAFS studies and of the structural features of a CuII analogue. The EXAFS structural model of (1) in both spin states is compared to that obtained for a related material whose spin transition occurs above room temperature. EXAFS spectroscopy suggests that 1,2,4-triazole chain compounds retain a linear character whatever the spin state of the iron(II). 相似文献
899.
Lamkadem M Aziz M Schwob I Rabier J Mimouni J Fontonge R Melhaoui A 《Natural product research》2004,18(4):311-318
R-irniine is a natural 2-alkylpyrrolidine alkaloid extracted from Arisarum vulgare Targ., a species belonging to the Araceae family known in Morocco for its toxicity. Cytotoxic and electrophysiological studies of this compound on human MRC-5 fibroblasts were carried out. Cytotoxic potential of R-irniine was detected on MRC-5 fibroblasts at 40 microg/mL. We carried out the electrophysiological study of this compound on MRC-5 cells by using the technique of patch-clamp in "Whole cell" configuration. R-irniine showed no effect on the outward potassium current of the MRC-5 fibroblasts. 相似文献
900.
Appelqvist LA Addis P Björkhem I Bosset JO Caboni MF Dutta P Grandgirard A Guardiola F Hau LB Nielsen JH Hugget A Hwang LS Kumpulainen J McCluskey S Ohshima T Przbylski R Sevanian A Yan P 《Journal of AOAC International》2004,87(2):511-519
A compilation of literature data on the content of cholesterol oxidation products (COP) in various food products and in blood demonstrates a large variation in content in products or tissues of very similar nature when analyzed in different laboratories according to a large number of methods. The lack of validated, internationally recognized methodology with published accuracy and precision has so far hindered such assessments. Hence an interlaboratory comparision of methodologies of COP analysis was undertaken on egg yolk powders (EYP), whole milk powders (WMP), skim milk powders (SMP), and lard (L). Each product type had one fresh sample (low) and one aged (high) in COP contents. A total of 17 sets of results on WMP, 15 on SMP and EYP, and 13 on L were compared. Overall results (mg/kg sample) varied extensively: Fresh EYP 0.72-265, aged EYP 2.51-361; fresh WMP 0.02-18.1, aged WMP 0.02-26.9; fresh SMP 0.02-6.51, aged SMP <0.01-6.51; fresh L 0.18-97, aged L 4.15-452. Some results were questioned, viz., those from laboratories not indicating substantial differences between samples "low" and "high" in total COP. Others were excluded because of lack of verification of identity of gas chromatographic peaks by mass spectrometry. Then a more narrow range of core results (mg/kg sample) was observed: Fresh EYP 5.69-29.5 sample, aged EYP 11.8-79.0; fresh WMP 0.12-1.76, aged WMP 1.17-13.7; fresh SMP <0.30-<1.21, aged SMP 0.30-2.26; fresh L 0.18-5.07, aged L 94.4-231. At a workshop discussing the results, numerous recommendations were made toward more reliable methodology for determination of COP in foods. 相似文献