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981.
N. S. Kozlov A. F. Yanchuk L. Ya. Mostovaya 《Reaction Kinetics and Catalysis Letters》1982,19(3-4):337-339
Sorption studies of Pt(II) and Pt(IV) complexes on -Al2O3 indicate that in catalyst preparation support and active components interact.
Pt(II) Pt(IV) -Al2O3 , .相似文献
982.
L.S. Khaikin A.V. Belyakov L.V. Vilkov E.T. Bogoradovskii V.S. Zavgorodnii 《Journal of Molecular Structure》1980
The geometrical parameters of tetraethynyltin and triethynyltin iodide have been determined by gas-phase electron diffraction. Triethynyltin iodide was present as an admixture in both the tetraethynyltin samples studied. Because the samples differed significantly in percentage of the iodide (17.4 ± 4.0 and 47.1 ± 3.5 mol %, in samples A and B, respectively), it was possible to determine the structures of both molecules to a sufficient degree of accuracy.The rα, structures were solved by the least-squares treatment of the molecular intensities, using mean amplitudes and shrinkage corrections calculated from the force fields of a number of tin derivatives.The Td-symmetry model of Sn(CCH)4 was refined to give the following parameters: Sn-C, 2.068(5); CC, 1.228(8); CH, 1.079(51). The structural parameters for ISn(CCH)3 (on the basis of the C3v model with linear Sn-CC-H fragments) are as follows: Sn-I, 2.646(4); Sn-C, 2.062(17); CC, 1.226(6); ∠ISnC 108.0(2.8). (The thermal average bond distances, rg, are given in Å, and the valence angle, rα, in degrees; the values in paren- theses are three times the standard deviations, 3σ.)The Sn-C bonds in Sn(CCH)4, and ISn(CCH)3 are shorter than the corresponding bonds in the monoethynyltin derivatives, Me3SnCCH and Me3SnCCSnMe3. The SnI bond in ISn(CCH)3 is noticeably shorter than those in stannane iodide and trimethylstannane iodide. 相似文献
983.
High-speed liquid chromatography in the system silica gel/dry n-hexane and ultraviolet spectrometry have been used to study the composition of various types of commercially available mixtures of chlorinated biphenyls. Special attention has been paid to the analysis of highly chlorinated products. In addition to data previously published, retention times are recorded for 11 individual polychlorinated biphenyls. The results of high-speed liquid chromatography are compared with those obtained in several normal and reversed-phase thin-layer chromatographic systems. 相似文献
984.
Using CD data (solution, solid state, various temperatures), X-ray data and MO calculations for a number of substituted mandelic acids (phenylglycolic acids) an attempt was made to explain the different results for the relation between sign of the 1Lb CD band and substitution pattern as described in the literature for various types of aromatic compounds. Moreover the reported sector rule has been reconsidered taking into account the sign and magnitude of the spectroscopic moments. It has been found that in any explanation of the signs of the 1Lb CD bands of substituted aromatic compounds both the conformational behaviour and the spectroscopic moments should be taken into account. 相似文献
985.
The potentiometric determination of zinc in chloride solutions with a coated wire electrode is described. The electroactive membrane contains the chlorozincate(II) salt of Aliquat 336S in poly (vinyl chloride). The electrode shows a useful response over the range 10-5 M–10-1 M zinc(II) in 3 M total chloride solutions in the pH range 1.5–6. The electrode is more responsive to the divalent tetrachlorozincate(II) than to the monovalent trichlorozincate(II) species. Applications in compleximetric titrations, and to the analysis of zinc oxide and zinc concentrates are reported. 相似文献
986.
The stereochemistry of substituted cyclopent-2-en-1-ones was studied by NMR. The existence of non-planar rings is indicated and conformational analysis, based principally upon examination of the coupling constants enables the conformational population to be estimated; trans dihalogeno derivatives, for example, occur predominantly in the diaxial form. 相似文献
987.
A.Kh. Khusid G.V. Kryshtal V.A. Dombrovsky V.F. Kucherov L.A. Yanovskaya V.I. Kadentsev O.S. Chizhov 《Tetrahedron》1977,33(1):77-84
α,β-Unsaturated aldehyde acetals add :CCl2 (obtained in accordance with Makosza procedure) to form gem-dichlorocyclopropanecarboxaldehyde acetals (1) in high yields when the ratio of reactants is no less than 1:4. The addition of :CCl2 to polyunsaturated aldehyde acetals in the above conditions proceeds regioselectively at double bonds enriched by electrons. Compounds 1 are reduced by sodium in liquid ammonia to give cyclopropanecarboxaldehyde acetals (2). Both 1 and 2 are hydrolized by dilute H3P04 to the corresponding aldehydes and are added to vinyl ethers in the presence of BF3·Et2O to produce only 1:1 adducts which are hydrolyzed by a mixture of AcOH-AcONa-H2O to give β-formylcyclopropanes which were previously unknown. 相似文献
988.
L. P. Blanchard K. T. Dinh J. Moinard F. Tahiani 《Journal of polymer science. Part A, Polymer chemistry》1972,10(5):1353-1362
Anionic polymerizations of 1,2-butylene oxide were carried out in vacuum-sealed dilatometers in the range of 30–60°C. Potassium terbutoxide and dimsyl sodium were used as initiators; dimethyl sulfoxide (DMSO) and mixtures of DMSO with tetrahydrofuran were solvents. The polymer products were analyzed by gel permeation chromatography and infrared spectroscopy. The object of the investigation was to obtain information on the mechanism of the reaction and to elucidate some of its kinetic aspects. It has been shown that the polymerizations occur by two different processes, depending on the choice of experimental conditions. One of the processes involves free ions and ion-pairs, the other, ion-pairs alone. In the first case, where dimethyl sulfoxide is used as solvent, the order of the reaction with respect to the initiator concentration far exceeds unity (~1.8), while in the second case, involving mixed solvents, the order of the reaction, for all practical purposes, is one. 相似文献
989.
Zusammenfassung Die derivatographische Methode wurde weiterentwickelt. Mit Hilfe einer neuen Einrichtung kann man die Temperatur, die Gewichtsänderung und die Dilatation der Probe sowie auch die Geschwindigkeit der Enthalpie- und Gewichtsänderungen und die Geschwindigkeit der Dilatation messen. Die Vorteile der Einrichtung wurden an einigen praktischen Beispielen erläutert.
Bei der Ausführung der Versuche waren uns FrauM. Csonka und FrauE. Borsay behilflich, wofür wir ihnen auch an dieser Stelle danken. 相似文献
Summary The derivatographic method was further developed. With the aid of a new apparatus it is possible to measure the temperature, the change in weight and the dilatation of the sample, as well as the velocity of the changes; in enthalpy and weight and the velocity of the dilatation. The advantages of the apparatus were demonstrated by means of several practical examples.
Résumé On a élargi le domaine des méthodes dérivatographiques. A l'aide d'un nouveau dispositif, on peut mesurer la température, la variation de poids et la dilatation de l'échantillon, ainsi que la vitesse des changements d'enthalpie et de poids, et aussi la vitesse de la dilatation. On a montré les avantages de ce dispositif sur un certain nombre d'exemples pratiques.
Bei der Ausführung der Versuche waren uns FrauM. Csonka und FrauE. Borsay behilflich, wofür wir ihnen auch an dieser Stelle danken. 相似文献
990.
Summary The chelating agent, 2-thenoyltrifluoroacetone has been employed for rapid extraction and colorimetric determination of milligram amounts of copper(II) in one operation. At pH 2.4–6.0 copper(II) is extracted quantitatively from an aqueous solution by TTA-benzene in a single extraction. The green-coloured copper(II)-TTA chelate solution in benzene obeysBeer's law at 430 m over the range of 16–180g copper per millilitre. The coloured system is stable for 143 hours. It can tolerate silver, mercury(II), bismuth (<5 mg) and small amounts (<100 mg) of citrate and tartrate, whereas cobalt(II), nickel(II), iron(III), aluminium(III), cerium(IV), thorium and zirconium seriously interfere. The proposed method is reproducible to within ±1.4%. 相似文献