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921.
Sol-gel Cu//MgOSiO2 catalysts were prepared gelling tetraethoxysilane (TEOS), magnesium ethoxide and copper acetylacetonate at pH 3 and pH 9. The catalysts shown specific surface areas ca. 500 m2/g and 140 m2/g for pH 9 and pH 3 preparations respectively. Si(OH) and Si(OH)2 hydroxy groups were observed by MAS-RMN spectroscopy in both preparations. CO2-TPD and NH3-TPD desorption thermograms showed that acid and basic sites were formed on the catalysts surface. It has been found that the catalysts having the highest density of basic sites were the catalysts showing the highest activity for the CO oxidation. It is proposed that the catalytic activity depends of the relative Cu=1/Cu=2 stability given by the support acidity. 相似文献
922.
A new approach to calculating the equilibrium characteristics of the adsorption of noble gases on the amorphous surfaces of
adsorbents was developed and applied to the Ar−TiO2(rutile) system. Intermolecular adsorbate-adsorbate interactions are taken into account for the nearest neighbors in the quasi-chemical
approximation. The lattice energy parameters of all interactions of the model are determined from the Lennard-Jones potential
(12-6). The formation of amorphous TiO2(rutile) surface includes completion of the surface layers and partial removal of the surface oxygen ions. The quality of
the amorphization procedure was confirmed by the experimentally measured heats and isotherms of adsorption of the system under
study.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1109–1118, June, 1997. 相似文献
923.
Analysis of changes in 35Cl NQR frequency of complexes MCl4.L and MCl4.2L for M = Si, Ge, Sn and Ti was performed. The population of the atomic orbitals was calculated by the quantum chemistry methods PM3 and INDO. The results provided an explanation of the changes in 35Cl NQR frequency and the asymmetry parameter upon complex formation. In the complexes of non-transition elements, a decrease in 35Cl NQR frequency is first of all related to increasing population of pz orbitals on Cl atoms. In the complexes of Ti, the increase in 35Cl NQR frequency depends on a decrease in the pπ to dπ electron density transfer. 相似文献
924.
N-[2(3)-Hydroxyalkylj-4-thiazolidinones have been synthesized by the reaction of 2(3)-vinyloxyalkylamines with mercaptoacetic acid in 24–69 % yield. The structure of the compounds obtained was supported by (R and1H NMR spectroscopic data.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 677–679, March, 1996. 相似文献
925.
Hiromu Hayashi 《Catalysis Surveys from Japan》1999,3(1):43-52
Additive telluromolybdates, MoO3·2TeO2 and MIIO·TeO2·MoO3 (MIITeMoO6; MII = Co, Mn, Zn), converted ethyl lactate selectively to pyruvate in a vaporphase fixedbed flow system at 250–300 °C. A synergy in activity was observed for binary TeO2–MoO3, and crystalline Te2MoO7 was suggested as the active species. The Rietveld analysis of powder XRD patterns of ternary CoTeMoO6 revealed the layer structure quite different from that of the reference Te2MoO7, but tellurium was again located adjacent to molybdenum linked through lattice oxygen. 相似文献
926.
Yu Yang Maya Belghazi Arnaud Lagadec David J. Miller Steven B. Hawthorne 《Journal of chromatography. A》1998,810(1-2):149-159
The intermolecular interactions between organic solutes and sorbent matrices under subcritical water conditions have been investigated at a pressure of 50 bar and temperatures ranging from 50 to 250°C. Both polar and nonpolar organics (chlorophenols, amines, n-alkanes, and polycyclic aromatic hydrocarbons) and five different sorbent matrices (glass beads, alumina, Florisil, silica-bonded C18, and polymeric XAD-4 resins) were used. From the same matrix, the polar solutes always eluted at lower temperatures, while the moderately polar and nonpolar solutes only eluted at higher temperatures. Similar to matrix effects previously observed using supercritical carbon dioxide, the sorbent type greatly influenced the elution efficiency under subcritical water conditions. Lower temperatures are sufficient to elute a particular solute from glass beads, alumina, and Florisil, but higher temperatures (less polar water) are needed to elute the same solute from silica-bonded C18. The highest temperatures were required to elute aromatic organics from XAD-4. These matrix effects demonstrate that, while low temperature water can break inert or dipole interactions between solutes and glass beads, alumina, and Florisil, higher temperature water is required to interrupt the van der Waals attractions between solutes and silica-bonded C18, and even higher temperatures needed to overcome the π-electron interactions between aromatic solutes and XAD-4. 相似文献
927.
A preparative one-step method for the synthesis of 1,1,1,5,5,5-hexafluoro-4-trifluoromethylpentane-2,3-dione dihydrazone from perfluoro-4-methylpent-2-ene and hydrazine hydrate has been developed. Oxidation of this dihydrazone with bromine in water gives 3-diazo-1,1,1,5,5,5-hexafluoro-4-trifluoromethylpentane-2-one. The same product is obtained from 3-hydrazono-1,1,1,5,5,5-hexafluoro-4-trifluoromethylpentane-2-one under similar conditions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2039–2041, November, 1994.This work was supported by the Russian Foundation for Basic Research (the project code 94-03-08548). 相似文献
928.
A. S. Balueva E. I. Ayupova G. N. Nikonov Yu. T. Struchkov A. P. Pisarevskii 《Russian Chemical Bulletin》1994,43(9):1561-1567
Fused 1,3,2-dioxaborinanes, derivatives of 4-diphenylphosphino- and 4-diphenylphosphoryl-4H-1, 3-dioxa-2-boraphenanthrenes, and their complexes with amines have been synthesized. According to X-ray diffraction data, the complex of 2-phenyl-4-diphenylphosphoryl-4H-1, 3-dioxa-2-boraphenanthrene with butylamine exists as a dimer due to the formation of intermolecular hydrogen bonds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1649–1655, September, 1994.The present work was financially supported by the International Science Foundation (grant No. RHBOOO). 相似文献
929.
M. A. Pudovik S. A. Terent'eva I. A. Litvinov O. N. Kataeva V. A. Naumov A. N. Pudovik 《Russian Chemical Bulletin》1993,42(10):1706-1709
The reaction of 2-diethylamino-3-diethylaminomethyl-1,3,2-benzoxazaphospholine with functionally substituted alcohols and
phenols occurs with the cleavage of exocyclic P-N bond followed by N→P migration of the diethylaminomethyl group and formation
of imidophosphonate dimers. A similar reaction with polyhydroxy compounds (diethylene glycol, glycerol) results in symmetrical
and asymmetrical spirophosphoranes.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1781–1784, October, 1993. 相似文献
930.
Gertraud Chiste Helmut Egg Klemens Kraus Elisabeth Pipitz Elisabeth Spanyar 《Monatshefte für Chemie / Chemical Monthly》1991,122(6-7):537-544
Summary A new method for the synthesis of 1,2-diaryl-1,2-dihydro-5-methyl-3H-pyrazol-3-ones3 and 4-acetyl-1,2-diaryl-1,2-dihydro-5-methyl-3H-pyrazol-3-ones5 is presented. The reaction of 4,4-disubstituted 1,2-diarylhydrazines1 with acetic anhydride in the presence of an equimolar amount of 4-(dimethylamino)pyridine leads to mixtures of the corresponding acetyl derivatives2 and3. Under the same conditions, 2,2-disubstituted 1,2-diarylhydrazines yield mixtures of3 and5.
4-(Dimethylamino)pyridin-katalysierte Reaktion von 1,2-Diarylhydrazinen mit Essigsäureanhydrid
Zusammenfassung Eine neue Methode zur Synthese von 1,2-Diaryl-1,2-dihydro-5-methyl-3H-pyrazol-3-onen3 und 4-Acetyl-1,2-diaryl-1,2-dihydro-5-methyl-3H-pyrazol-3-onen5 wird beschrieben. Die Reaktion von 4,4-disubstituierten 1,2-Diaryl-hydrazinen1 mit Essigsäureanhydrid führt in Gegenwart eines Äquivalentes 4-(Dimethylamino)pyridin zu Gemischen der entsprechenden Acetylderivate2 und3. Unter den gleichen Bedingungen werden aus 2,2-disubstituierten 1,2-Diarylhydrazinen Gemische aus3 und5 erhalten.相似文献