排序方式: 共有17条查询结果,搜索用时 15 毫秒
1.
M. A. Zuenko M. P. Nemtseva O. V. Lefedova E. V. Gladkova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(2):164-168
The scheme of chemical transformations of 2-nitroazobenzene derivatives during catalytic hydrogenation on Raney nickel was found to be common to compounds containing electron donor and electron acceptor substituents. A qualitative correlation between solvation interaction parameters and the solubility of substituted 2-nitroazobenzenes was observed. The selectivity of the reaction with respect to intermediate products was determined by the composition of the solvent and weakly depended on the nature of the substituent. The introduction of sodium hydroxide and acetic acid into solvents ensured high selectivity of the hydrogenation of substituted 2-nitroazobenzene derivatives with respect to the corresponding N-oxides and nitrohydrazo derivatives, respectively. 相似文献
2.
Sulfonated and sulfoacylated poly(styrene-divinylbenzene) copolymers as packing materials for cation chromatography 总被引:1,自引:0,他引:1
Pirogov AV Chernova MV Nemtseva DS Shpigun OA 《Analytical and bioanalytical chemistry》2003,376(5):745-752
Three different types of cation exchangers were produced from four basic poly(styrene-divinylbenzene) substrates with different properties. Porous PS-DVB resin beads were functionalized by sulfonation and sulfoacylation under various conditions to produce sulfonated resins with exchange capacities of 0.03-1.80 mM g(-1). The matrix with 50% of cross-linking is most suitable for updating by the proposed technique. Sulfuric and chlorosulfonic acids were used as the reagents for sulfonation. The sulfonating conditions, capacities, and the technique of the synthesis are given. The effects of parameters of the sulfonation reaction and the composition of the reactionary mixture on ion-exchange capacity of the sorbents were investigated. Selectivity and efficiency of the separation of some inorganic cations and derivatives of amines and hydrazines on the resins obtained are compared by ion chromatography with conductometric detection. As a result, the sulfoacylated resin was proved more efficient for the separation of these analytes. The resolution of the analytes strongly depends on the degree of functionalization. The best performance about 19,000 plates m(-1) was obtained using the sulfopropionylated beads with an ion-exchange capacity of 0.3 mM g(-1). The prepared sulfoacylated cation exchanger was compared with the commercially available Dionex CS-12 packing material. It was found that the separation of alkaline ions and 1,1-dimethylhydrazine (UDMH) were much better that those for the commercial material. 相似文献
3.
Lefedova O. V. An’ Khoang Belova A. V. Nemtseva M. P. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(4):720-724
Russian Journal of Physical Chemistry A - An analysis is made of the kinetic characteristics of the hydrogenation of 4-nitro- and 2-nitro-2'-hydroxy-5'-methylazobenzenes, 4-nitroaniline and... 相似文献
4.
5.
Dmitry Gromov Alexey Sherchenkov Egor Lebedev Alexey Babich Svetlana Nemtseva Yury Shaman Tomasz Maniecki Waldemar Maniukiewicz Pawel Mierczynski Radoslaw Ciesielski Sergey Gavrilov 《Journal of Thermal Analysis and Calorimetry》2018,134(1):35-44
The paper deals with the effect of the compression conditions on the propagation front velocity of exothermal reaction and the specific heat release in Al–Ni powder reactive materials with mean particle sizes of 70–110 nm. It was shown that the velocity increases from 2.7 to 8 cm s?1 and comes to saturation with the lowering of the porosity (η) from 0.91 to 0.34, while the dependence of the specific heat release has its maximum for η?=?0.5. The results of the X-ray diffraction analysis obtained in situ during the sample heating suggest that the sequence of phase transformations in the system does not depend on the porosity. In all cases, first in the temperature range of ~?500–540 °C the NiAl compound is formed. With the further heating up to ~?640 °C, the Ni3Al, Ni2Al3 and NiAl3 compounds are additionally formed. The calculation of kinetic parameters was performed using the obtained curves of the differential scanning calorimetry: activation energy, pre-exponential factor and reaction model. The comparison of the calculated results and the scanning electron microscopy data has shown that such behavior of the Al–Ni system with the porosity lowering occurs due to the growth of the transformation degree and is associated with the presence in the final powder mixture of mutually non-contacting Al and Ni agglomerates with the dimensions of over 10 μm. 相似文献
6.
O. V. Lefedova I. V. Smirnova M. P. Nemtseva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(10):1727-1730
The influence of the nature of substituents on the rate of liquid-phase hydrogenation of nitrobenzenes on Raney nickel was
studied in an aqueous solution of 2-propanol. Interrelation between the rate of the reaction on the equiaccessible surface
of the catalyst and solvation parameters, reactivity indices, and adsorption values of hydrogenated compounds containing electron
acceptor (4-nitrobenzoic acid) and electron donor (4-nitroaniline) substituents was considered. 相似文献
7.
Hoang Anh M. P. Nemtseva O. V. Lefedova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(4):669-673
The kinetics of hydrogenation of 4-nitro-2′-hydroxy-5′-methylazobenzene in aqueous 2-propanol solution over the skeletal nickel is investigated at different initial concentrations. It is established that the hydrogenation of 4-nitro-2′-hydroxy-5′-methylazobenzene over a skeletal nickel in azeotropic aqueous 2-propanol solution proceeds via two parallel pathways at both low and high initial concentrations. It is shown that increasing the initial concentration of the hydrogenated compound above its level of solubility raises the rate of azo group transformation in 4-nitro-2′-hydroxy-5′-methylazobenzene, while the content of 4-amino-2′- hydroxy-5′-methylazobenzene does not change in the hydrogenate and is not accumulated in the bulk of solution. 相似文献
8.
Subham Majumdar EV Sampathkumaran St Berger M Della Mea H Michor E Bauer M Brando J Hemberger A Loidl 《Pramana》2002,58(5-6):777-782
Recently, the solid solution Ce2Au1−
x
Co
xSi3 has been shown to exhibit many magnetic anomalies associated with the competition between magnetic ordering and the Kondo
effect. Here we report high pressure electrical resistivity of Ce2AuSi3, ac susceptibility (X) and magnetoresistance of various alloys of this solid solution in order to gain better knowledge of the magnetism of these
alloys. High pressure resistivity behavior is consistent with the proposal that Ce2AuSi3 lies at the left-hand side of the maximum in Doniach’s magnetic phase diagram. The ac X data reveal that there are in fact two magnetic transitions, one at 2 K and the other at 3 K for this compound, both of which
are spin-glass-like. However, as the Co concentration is increased, antiferromagnetism is stabilized for intermediate compositions
before attaining non-magnetism for the Co end member. 相似文献
9.
Thermodynamic and kinetic characteristics of liquid phase hydrogenation of substituted nitrobenzenes
Yu. V. Minenkov O. V. Lefedova I. V. Smirnova M. P. Nemtseva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(6):908-912
Quantum-chemical calculations of the thermodynamic characteristics of hydrogenation of nitrobenzoic acid isomers and nitrophenol
in the gas phase and also in aqueous and alcoholic media were performed. Correlation dependences between the calculated Δr
G
298○ values and rate constants for the reaction in various media were obtained. 相似文献
10.
Nebykov D. N. Popov Yu. V. Mokhov V. M. Latyshova S. E. Shcherbakova K. V. Nemtseva N. V. Shishkin E. V. 《Russian Journal of General Chemistry》2019,89(10):1985-1989
Russian Journal of General Chemistry - The processes of unsaturated cyclic hydrocarbons hydrogenation in a three-phase gas-liquid-solid catalyst system in the presence of nanostructured nickel,... 相似文献