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991.
R. G. Aflyatunova N. A. Aliev Ch. Sh. Kadyrov M. R. Yagudaev 《Chemistry of Natural Compounds》1984,19(4):478-482
The reactions of benzoxazolinone and benzoxazolinethione with alkyl -chlorovinyl ketones have been studied. The reaction products are N-(-acylvinyl)benzoxazolinones and N-(-acylvinyl)benzoxazolinethiones. The reaction of alkali-metal salts of benzoxazolinone with alkyl -chlorovinyl ketones leads to the opening of the oxazolinone ring. The structures of the compounds synthesized have been studied by IR, mass, and PMR spectroscopy.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 507–511, July–August, 1983. 相似文献
992.
Summary On the basis of IR, PMR, and mass spectra and chemical transformations, the alkaloid kesselringine isolated from the epigeal parts ofColchicum kesselringii Rgl. has been shown to have the structure of 2,11-dihydroxy-12-methoxyhexahydro-1,12-epoxyhomoproaporphine with the R absolute configuration at the C6a atom.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 350–354, May–June, 1976. 相似文献
993.
Summary Two new analytical techniques are described. The so-called injection technique operates on evaluating a dynamic concentration signal as a result of following the concentration change in a certain part of a flow-through channel after injecting a sample or reagent at a small volume into the current of an appropriate solution flowing at a constant rate.The second technique, the programmed coulometric titration technique, also uses the flow-through channel principle; that means this novel technique allows the more precise titrimetric way of analysis in flowing solutions. In the case of both techniques potentiometric and voltammetric detectors were involved. Several examples proved the multifold advantages of these techniques for environmental analysis.
Neue elektroanalytische Verfahren für die Umweltanalyse
Zusammenfassung Zwei neue Methoden werden beschrieben. Die sog. Injektionstechnik wertet ein dynamisches Konzentrationssignal aus, das sich aus der Änderung in einem Durchflußkanal ergibt, wenn Probe oder Reagens in kleinen Volumina in einen konstant fließenden Flüssigstrom injiziert werden. Das zweite Verfahren, die programmierte coulometrische Titration, erlaubt die Anwendung der genaueren titrimetrischen Technik auf fließende Lösungen. Bei beiden Methoden werden potentiometrische und voltammetrische Detektoren verwendet. Mehrere Beispiele zeigen die vielfachen Vorteile dieser Verfahren bei der Anwendung auf die Analyse von Umweltmaterial.
Presented at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria 相似文献
994.
The exchange reaction of D2 with OH groups of HY zeolites was followed both in the solid and gas phase by IR and MS. The rates of D2–OH and D2–H2 exchange increase considerably with dehydroxylation of the sample. The active centers are probably vacancies formed by removal of oxygen from the lattice, they catalyze the dissociation of D2. Dehydroxylation of the sample is accompanied by the formation of 3 740 cm–1 hydroxyls, whose exchange with D2 is slower than that with other OH groups and which affect the kinetics in the gas phase.
D2 OH HY - O2–OH O2–H2 . , , , O2. OH, 3740 –1, , OH .相似文献
995.
Heterogeneous-homogeneous decomposition of HNO3 总被引:1,自引:0,他引:1
A. P. Ballod T. A. Titarchuk G. S. Ticker A. Ya. Rozovskii 《Reaction Kinetics and Catalysis Letters》1989,40(1):95-100
In contrast to ZSM zeolites impregnated with V5+ salts, catalysts prepared by adding V3+ salts during zeolite synthesis exhibited (even when transformed into cristobalite by oxidative activation) higher selectivity to furane in the oxidation of butadiene. Non-oxidative activation preserved the zeolitic structure and increased both the total activity and the selectivity to furane.
ZSM, V5+, V3+ ( ) . , , .相似文献
996.
Xin Sheng Li Yao Jun Zhang Qin Xin Chun Xin Ji Yan Fen Miao Li Wang 《Reaction Kinetics and Catalysis Letters》1996,57(1):177-182
Volumetric H2-uptake measurements on an Mo2N (79 m2g–1) sample reduced at 673 K have been carried out and the uptake isotherms in the temperature range of 308–623 K have been determined. Both the total and reversible hydrogen uptake increased with the uptake temperature. The irreversible hydrogen uptake increased abruptly when the uptake temperature was raised up to 423 K. The maximum of irreversible hydrogen uptake was measured at 473 K. The HIR/Mo ratio calculated from the uptakes obtained in the temperature range of 308–623 K varies in the range of 0.0010–0.0202. One possible mechanism for hydrogen adsorption is proposed to be heterolytic dissociation on Mo-N paris, in which the molybdenum atoms are in unsaturated coordination. 相似文献
997.
The layered perovskites Sr2TiO4 and Sr2SnO4 are more active and selective for the oxidative coupling of methane at 1073 K than the corresponding perovskites SrTiO3 and SrSnO3. The role of the surface oxygen species for this reaction is discussed. 相似文献
998.
The search for pharmacologically active compounds among substituted 2-benzyl-1,2,3,4-tetrahydroisoquinolines has been continued, and compounds possessing bile-stimulating activity have been found.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX (3712) 62 73 48. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 403–406, May–June, 1994. 相似文献
999.
Di-lithiated octamethylcyclotetrasilazane (OMCTS, 1) reacts with halosilanes in different ways. Ring contraction with formation of the isomeric cyclodisilazanes 2, 3 occurs in the reaction with chloro- and fluorotrimethylsilanes. Substitution (6) and ring contraction with formation of the isomeric six-membered ring 7 occurs with chlorodimethylsilane. 2, 3, 6 and 7 are excellent precursors of silyl-bridged, SiH-functional, four-membered ring systems (4, 5, 9–11). The mechanism of the isomerization reactions are discussed. 相似文献
1000.
三溴偶氮胂催化光度法测定痕量铁 总被引:19,自引:2,他引:19
本文研究了硫酸介质中痕量 Fe(Ⅲ)催化加速抗坏血酸、溴酸钾和三溴偶氮胂之间的褪色反应及动力学条件,建立了动力学光度法测定痕量Fe(Ⅲ)的新方法.方法灵敏度为1.82×10~(-12)g·ml~(-1).测定范围为Fe(Ⅲ)0~30ng/25ml.已用于人发和食品中痕量铁的测定.结果满意. 相似文献