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991.
[reaction: see text] A new route to oxcarbazepine (Trileptal), the most widely prescribed antiepileptic drug, starting from commercially available 2'-aminoacetophenone and 1,2-dibromobenzene, is reported. The sequentially accomplished key steps are palladium-catalyzed intermolecular alpha-arylation of ketone enolates and intramolecular N-arylation reactions. After several experiments to establish the best conditions for both arylation processes, the target oxcarbazepine is obtained in a satisfactory overall yield, minimizing the number of steps and employing scalable catalytic procedures developed in partially aqueous media. 相似文献
992.
Ruiz-Medina A Ortega-Barrales P Fernández-de Córdova ML Molina-Díaz A 《Journal of AOAC International》2002,85(2):369-374
A simple, rapid, inexpensive, and automated flow-through solid-phase spectroscopic sensing device is proposed for the sequential determination of 2 vitamins: thiamine and ascorbic acid. The vitamins are concentrated on ion-exchange gels, thiamine on Sephadex SP C-25, and ascorbic acid on Sephadex QAE A-25; both solid supports are packed in 2 different flow cells. The absorbance is monitored directly on the solid phase with a double-beam spectrophotometer at 250 nm, without derivatization or additional elution. With the use of 2 carrier/self-eluting solutions (0.1 5M sodium acetate/acetic acid and 0.18M citric acid/K2HPO4) and a sample volume of 1000 microL, the sensor responds linearly in the range of 0.5-15 and 3-50 microg/mL with detection limits of 0.14 and 0.36 microg/mL for thiamine and ascorbic acid, respectively. When the method was applied to synthetic samples and pharmaceutical preparations, precise and accurate values were obtained. 相似文献
993.
Fátima Nunes Serralha José Madeira Lopes Francisco Lemos Duarte Prazeres Maria Aires-Barros Joo Rocha Joaquim Cabral Fernando Ramôa Ribeiro 《Reaction Kinetics and Catalysis Letters》2000,69(2):217-222
Novel [CrIII(amp)(bipy)(Cl)] (1) (H2amp = N-(hydroxyphenyl)salicyldimine; bipy = 2,2-bipyridyl) and [CrIII(app)(bipy)(Cl)]+ (2) (H2app = N-(hydroxyphenyl)pyridine-2-carboxaldimine; bipy = 2,2-bipyridyl) complexes have been synthesized and characterized by physico-chemical methods. Complexes 1 and 2 have been employed as catalysts in the oxidation of both saturated and unsaturated hydrocarbons using tert-butylhydroperoxide (t-BuOOH). The significance of the results with respect to oxo-functionalization of C-H bonds both in unsaturated and saturated hydrocarbons is noted. 相似文献
994.
Gy. Marosi R. Lágner Gy. Bertalan P. Anna A. Tohl 《Journal of Thermal Analysis and Calorimetry》1996,47(4):1155-1161
Nucleating and transcrystallization behaviour of additives in engineering PP composites and the effect of modified interfacial structure is the subject of this series of papers. The first part concentrates on polypropylene/liquid crystalline polyester blends. Increased crystallisation temperature and degree of crystallinity of polypropylene is characteristic to the blends containing different amount of LCP additive. Transcrystallization process governs the formation of crystalline structure in these systems in course of isothermal crystallisation at 132C. The nucleating effect of LCP gives rise to more uniform crystalline structure in the polypropylene phase.The financial support of the OTKA 014194 is acknowledged with gratitude. 相似文献
995.
A. Bumbálová A. Pikulíková M. Komová A. Muchová 《Journal of Radioanalytical and Nuclear Chemistry》1992,164(6):357-364
Determination of Cr, Fe, Cu, Zn and Pb in drinking water preconcentrated on a chelating ion exchanger of Czechoslovak production is described. The analytical system consisted of a radionuclide source238Pu, a Si/Li semiconductor detector and a multichannel analyzer. Results are compared with trehshold limit values recommended for drinking water. 相似文献
996.
Barluenga J Diéguez A Rodríguez F Flórez J Fañanás FJ 《Journal of the American Chemical Society》2002,124(31):9056-9057
Eight-membered carbocycles with up to five new stereogenic centers are enantioselectively obtained following a one-pot procedure that involves the coupling of three components: an alkenyl Fischer carbene complex, a ketone enolate, and allyl lithium. 相似文献
997.
I. Labádi E. Pál R. Tudose O. Costisor 《Journal of Thermal Analysis and Calorimetry》2006,83(3):681-686
The
thermal behaviour of the mixed-ligand complexes of cobalt(II) and copper(I)
ions with antipyrine derivatives of 1,2-ethanediamine or piperazine (BAMP
and TAMEN), with water and with 2-mercapto-benzothiazole (Hmbt) was investigated.
The complexes contain 2-mercaptobenzothiazole (Hmbt, in the case of cobalt(II)
ion) or dimercaptobenzothiazine (mbt–mbt, in the case of copper(I) ion)
molecules as ligands and perchlorate (ClO4–) or
thiocyanate (SCN – ) ion as counterion. By heating, water and ligands
release the solid phase at lower temperature. At higher temperatures process
of different organic reactions of ligands (e.g. polymerization, polycondensation)
could be suggested to interpret the relative high final mass values. 相似文献
998.
Jaime González Velasco 《Central European Journal of Chemistry》2005,3(3):470-481
The analytical treatment of a model considering the electrooxidation of p-porous silicon layers under galvanostatic conditions
is able to give account of experimental facts such as the shape and location of the electroluminescence peak as well as of
the spectral shift of the electroluminescence peak produced by oxidation. The proposed model considers electroluminescence
to be the result of electron injection into the conduction band by an adsorbed intermediate produced by electrooxidation of
the surface coverage with hydrogen or siloxene of the silicon nanocrystallites. The access of holes to the surface is made
possible by low accumulation layer conditions and is the rate determining step in the electroluminescence mechanism. In this
way it is possible to give a satisfactory explanation to the shift towards the blue experimented by the electroluminiscence
emission maximum as a consequence of electrooxidation. 相似文献
999.
Based on the method of SAMSAHL a programmed, semi-automated processing system has been developed and tested for the neutron
activation analysis of the following elements: As, Se, Sb, Br, Sn and Te. The main characteristics of the procedure are the
following: wet ashing of the sample (by means of digestion in a mixture of concentrated sulphuric acid and hydrogen peroxide),
bromination, and chlorination. The procedure is controlled via the appropriate dosage of the reagents and a carefully managed
thermal balance. The chemical yield and its reproducibility were determined by tracer techniques using exactly the same parameters
as for the active runs. According to the results the method can be used for the routine determination of the given elements
except antimony.
Presented at the 4th Symposium on the Recent Developments in Neutron Activation Analysis, 1975, Cambridge. 相似文献
1000.
Katarína Györyová Ján Skoršepa Jozef Chomič 《Monatshefte für Chemie / Chemical Monthly》1983,114(10):1137-1139
Two cyano complexes of the type [R 3S]2 [Pd(CN)4] (R 3S+=Me 3S+,Ph 3S+ cations) were prepared. The identity of the obtained samples was verified by chemical analysis and investigated by IR-spectroscopy. Thev CN stretching frequencies of the complexes were compared with similar frequencies of the corresponding alkaline cyano complex. The thermal decomposition of the compounds was examined. 相似文献