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901.
Procedures for separating products of the synthesis of ethylene oxide by two-column gas chromatography using both conventional capillary PLOT columns and packed capillary columns of a new type bearing microparticulated adsorbents are proposed. A combination of packed capillary columns with a microthermostat reduces both separation time and the size of the chromatographic system, which becomes compatible with microreactors. The short time of analysis enables the control over the work of a series of microreactors in a cyclic mode using one chromatographic system. 相似文献
902.
Quantum dynamics of H2 formation on a graphite surface through the Langmuir Hinshelwood mechanism 总被引:1,自引:0,他引:1
We have studied the formation of the H2 molecule on a graphite surface, when both H atoms are initially physisorbed. The graphite surface is assumed to be planar, and a model potential is obtained in a semiempirical way to reproduce the experimental properties of H physisorption on graphite. The reaction probability has been computed in the case when the angular momentum of the relative H-H motion lies parallel to the surface plane. Three-dimensional wave packet calculations have been performed for collision energies ranging from 2 to 50 meV. It is shown that the reaction occurs with a significant probability and produces the H2 molecule with a considerable amount of vibrationnal energy. A simple mechanical model is presented, where desorption of the nascent H2 molecule results from two successive binary elastic collisions. 相似文献
903.
Yu. A. Yuzhelevskii E. G. Kagan V. N. Frolov A. L. Klebanskii 《Chemistry of Heterocyclic Compounds》1970,4(1):24-28
The influence of the number of 3, 3, 3-trifluoropropyl(methyl)siloxane links (/) in the cyclotetrasiloxanes mD4-m, where D represents the dimethylsiloxane link and m=0–4, on the rearrangement of these compounds in acetone solution under the action of sodium siloxanolate has been studied. The rearrangement takes place with the formation of a linear polysiloxane the degradation of which yields, in addition to the initial ring, cyclosiloxanes with a different structure. The rate of rearrangement of mD4-m and of the formation of a linear polysiloxane rises with an increase in m from 0 to 3. The equilibrium concentration of the linear polysiloxane formed from mD4-m is inversely proportional to m. Results have been obtained on the kinetics of the formation of the cyclosiloxanes mDn, where m=0–5, n=0–5, and m+n=3–6, in the rearrangement of the rings D3, 2D2, 3D, and 4. The reactivity of the siloxane links rises in the sequence (CH3)2Si-O-Si(CH3)2 < (CF3CH2CH2)-(CH3) Si-O-Si(CH3)2 <(CF3CH2CH2) (CH3)Si-O-Si(CH3) (CH2CH2CF3) . Because of the negative inductive effect transferred through the siloxane links, the 3, 3, 3-trifluoropropyl groups strongly activate the siloxane ring with respect to nucleophiiic reagents.For part I, see [3]. 相似文献
904.
E. Bujdosó 《Journal of Radioanalytical and Nuclear Chemistry》1993,174(1):187-198
905.
N. S. Prostakov N. M. Mikhailova Yu. M. Talanov 《Chemistry of Heterocyclic Compounds》1970,6(10):1266-1268
The position of the pyridine ring is arylated by reaction of 2,5-dimethyl-4-phenylpyridine with phenyllithium and p-tolyllithium. Destructive oxidation of the diaryl-substituted pyridines primarily affects the pyridine ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1359–1361, October, 1970. 相似文献
906.
M. G. Voronkov N. N. Vlasova S. A. Bolshakova S. V. Kirpichenko 《Journal of organometallic chemistry》1980,190(4):335-341
The hydrosilylation of mono- and di-alkenyl sulphides of the type RS(CH2)nCH=CH2 (R = C2H5, CH2=CH, CH2=CHCH2, C3H7, n = 0, 1 and 4) by triethyl- and triethoxy-silane, catalyzed by H2PtCl6·6 H2O, (Ph3P)3RhCl and (PhCN)2PdCl2·Ph3P, has been studied. The addition of hydrosilane to the double bond of alkenyl sulphide leads to a mixture of two isomeric monoadducts. The hydrosilane can cleave the C---S bond of the initial sulphides giving the corresponding derivatives of thiosilanes, X3SiS(CH2)nCH=CH2 (X = C2H5, C2H5O). Hydrosilylation of alkenyl sulphides is accompanied by some side reactions such as dehydrocondensation, reduction and polymerization. The effect of the catalyst nature, the structure of hydrosilane and alkenyl sulphide on the reaction route has been investigated. 相似文献
907.
Heptakis(2,6-di-O-methyl)-β-cyclodextrin interacts with 5,15-diphenylporphine to produce a 2:1 complex in dimethyl sulfoxide. This complex possesses a hydrophobic groove that circumscribes the metal binding site of the porphyrin moiety. 相似文献
908.
Institute of the Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh
Soedinenii, No. 6, pp. 899–900, November–December, 1993. 相似文献
909.
A. M. Zhizhaev E. N. Merkulova I. V. Bragin 《Russian Journal of Applied Chemistry》2007,80(10):1632-1635
Mechanism of interaction of copper sulfate with natural calcium carbonates, responsible for low residual copper concentrations in solutions and for the behavior of open and closed systems in storage is considered. 相似文献
910.
Ya. S. Yakhyaev S. N. Khadzhiev T. M. Gairbekov S. E. Spiridonov 《Reaction Kinetics and Catalysis Letters》1986,30(2):263-268
The effect of hydrothermal treatment of decationized superhigh-silica zeolite on the mechanism of n-hexane conversion has been studied. It has been established that thermosteam modification sharply decreases the cracking activity and increases the selectivity to aromatization reactions. Zeolite acidity markedly decreases, but its crystal structure does not become amorphous.
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