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251.
O. V. Krylov 《Kinetics and Catalysis》2002,43(2):284-289
This paper presents an overview of the plenary lectures and some of the oral and poster presentations at the 4th International Congress on Oxidation Catalysis in Potsdam (Germany). The main topics were the partial oxidation of alkanes and the oxidation of olefins by H2O2. Considerable attention is given to the use of modern physical methods in the mechanistic studies of oxidation catalysis and in the studies of catalyst structures. 相似文献
252.
A number of ruthenium triphenylphosphine complexes catalyse the reduction of ketones to their corresponding alcohols in the presence of water. The most convenient catalyst precursors are carbonyl containing complexes which do not promote decarbonylation of the substrate. The hydrogenation of acetone with hydridochlorocarbonyltris(triphenylphosphine)ruthenium is first order with respect to the substrate concentration, the catalyst concentration, the hydrogen pressure and the water concentration. Turnover numbers up to 15,000 have been achieved with this catalyst. Other ketones are also reduced by RuHCl(CO)(PPh3)3 and the rate of the reaction is dependent on the nature of the substrate. 相似文献
253.
A. N. Vasil’ev A. N. Lyshchikov O. E. Nasakin Ya. S. Kayukov V. A. Tafeenko 《Russian Journal of Organic Chemistry》2005,41(2):279-282
Reduction of alkyl-2-amino-5,6-dialkyl-3-cyanopyridine-4-carboxylates with sodium borohydride in protic solvents gave rise to 4-amino-3-imino-6,7-dialkyl-1,3-dihydrofuro[3,4-c]pyridines that at hydrolysis in acid medium afforded the corresponding lactones.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 288–291.Original Russian Text Copyright © 2005 by Vasil’ev, Lyshchikov, Nasakin, Kayukov, Tafeenko. 相似文献
254.
Weak interactions of nonaromatic amino acids with - and -cyclodextrins in aqueous solutions at 298.15 K were studied calorimetrically. The structure and solvation of these compounds noticeably affect the thermodynamic characteristics of interparticle interactions. 相似文献
255.
O. B. Mokhodoeva G. V. Myasoedova I. V. Kubrakova 《Journal of Analytical Chemistry》2007,62(7):607-622
Combined methods for the determination of noble metals with the use of sorption preconcentration with complexing, anion-exchange, and other sorbents are reviewed. Characteristics of sorbents, techniques of sorption preconcentration, and techniques for the preparation of a concentrate for determination are considered. Features of instrumental methods for the determination of noble metals in the analysis of different materials are discussed. Examples of the use of sorption preconcentration in combined methods for the determination of noble metals are given from publications between 1996–2005. 相似文献
256.
L. V. Baikalova V. I. Sokol I. A. Zyryanova I. V. Fedyanin V. N. Khrustalev E. A. Zel’bst O. A. Tarasova V. S. Sergienko B. A. Trofimov 《Russian Journal of General Chemistry》2006,76(5):791-797
The crystal and molecular structures of bis(1-isopropenylimidazole)dichlorocobalt (C12H16Cl2·N4Co) [R 0.036 (R W 0.089) for 3229 unique reflections with I > 2σ(I)] and tetra(1-vinylimidazole)dichlorocobalt (C20H24Cl2N8Co) [R 0.031 (R W 0.072) for 1863 unique reflections with I > 2σ(I)] were determined. In these molecular complexes, the monodentate terminal 1-alkenylimidazole ligands coordinate to the metal via a “pyridine” nitrogen atom. In C12H16Cl2N4Co, the Co atom has a distorted tetrahedral 2N,2Cl coordination. The coordination polyhedron of cobalt in C20H24Cl2N8Co is a strongly elongated 4N,2Cl octahedron. The Co-N and Co-Cl bonds [Co-N 2.015(2) and 2.032(4) Å; Co-Cl 2.229(2) Å] in the tetrahedral complex C12H16Cl2N4Co are shorter than those in the octahedral complex C20H24Cl2N8Co [Co-N 2.134(2) and 2.157(2) Å; Co-Cl 2.518(1) Å]. In the structures of both complexes there are short contacts involving the Cl atoms. 相似文献
257.
Aromatic bisorthoesters were found to be good polymer intermediates and could be condensed with aromatic tetramines under mild conditions, in DMSO at 100°C in a relatively short reaction time to give polybenzimidazoles. The hexapropyl orthoesters of terephthalic and isophthalic acid were the preferred aromatic orthoesters because they were relatively easily purified by vacuum distillation to polymer grade intermediates, since they are liquids. Higher orthoesters distill even under good vacuum near or above the decomposition temperature of the orthoester group. Hexaethyl orthooxalate was also used and is a very useful and stable derivative of oxalic acid, which can be used for condensation reactions. These three orthoesters were used for condensations with 3,3′,4,4′-tetraaminobiphenyl, 1,2,3,4-tetraaminobenzene, 3,3′,4,4′-tetraaminobiphenyl ether, and 3,3′,4,4′-tetraaminobenzophenone. All polybenzimidazoles were obtained in high to quantitative yields and with varying molecular weights (ηinh = 0.1?0.8 dl/g), which in some cases were in the fiber forming range. 相似文献
258.
Conditions for the formation of rare earth element (Y, La–Lu) 3-methylglutarates were studied and their quantitative composition
and solubilities in water at 293 K were determined (10–2 mol dm–3). The IR spectra of the prepared complexes with general formula Ln2(C6H8O4)3
nH2O (n=3–8) were recorded and their thermal decomposition in the air were investigated. During heating the hydrated 3-methylglutarates
are dehydrated in one step and next anhydrous complexes decompose to oxides Ln2O3 with intermediate formation Ln2O2CO3 (Y, La, Nd–Gd) or directly to the oxides, Ln2O3, CeO2, Pr6O11 and Tb4O7 (Ce, Pr, Tb–Lu).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
259.
The coulometric electrolytic principle is utilized for the measurement of moisture sorbed on sintered thorium dioxide. Moisture is removed from the sample by heating and is swept by dry argon gas through a hygrometer. The resulting hygrometer output is converted into frequency pulses and counted cumulatively. The instrument is calibrated by use of standard hydrated chemicals. The number of counts/mu;g of water obtained from standards compares favourably with the theoretical number of counts/mu;g calculated from performance specifications of the components employed. The error is <5% for 1-350mu;g of water. A high sensitivity and low operating blank recommends application of this method to materials other than thorium dioxide, having very low moisture contents. 相似文献
260.