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21.
The vibrational spectra of compounds Ln2WO6 and Ln2MoO6 (Ln = lanthanide, including Y and Bi) are reported. Neglecting details it is possible to assign the internal vibrations of the molybdate and tungstate group. The results are in agreement with the structural data known up till now and suggest further that tungsten in the unknown Y2WO6 structure is in six-coordination, that Bi2MoO6 shows still another modification than koechlinite and that vibrational spectroscopy may yield additional structural information for compounds like those under consideration. 相似文献
22.
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
23.
C. Samara I. Papadoyannis Th. Kouimtzis S. Spyroudis A. Varvoglis 《Microchemical Journal》1984,29(2):232-236
A new oxidimetric titrant, bis(trifluoroacetoxy)iodobenzene is proposed for potentiometric titrations in acetonitrile and water-acetonitrile media. The general analytical conditions for using this titrant and the results for the potentiometric titrations of various inorganic and organic reductants are described. 相似文献
24.
The aim of the paper is the simplification of calibration procedures in the investigation of multi-element-systems by calculating
calibration curves. This requires, as well as taking into account the measuring geometry and the detector properties, above
all the calculation of the number of the characteristic X-rays emitted by the sample per incident particle. For the calculation
of the thick target yield a computer programme has been developed which makes possible a simple exchange of subroutines describing
the stopping power of the sample, the cross-section of K-shell ionization, the fluorescence yield and the matrix absorption
for the resulting K-X-rays of the elements contained in the sample. The agreement between experiment and calculation is discussed,
when various approximations for the functions mentioned are used, as well as the possible influence of the grain size and
surface roughness of the samples on the measurements, on which the calculations are based.
相似文献
25.
Th. Kartnig 《Mikrochimica acta》1963,51(1):88-92
Zusammenfassung Eine Bestimmung von HCH und DDT aus Pulvergemischen und Streupudern wird beschrieben. Die beiden Insektizide werden über einer Säule, die mit Aluminiumoxyd neutral beschickt ist, mit Äther oder n-Hexan eluiert und das Eluat im Vakuum vorsichtig getrocknet. Aus der Schmelze des Rückstandes wird mit Hilfe der Glaspulvermethode die prozentuelle Zusammensetzung an Hand von Eichkurven ermittelt.
Summary A method is described for determining HCH and DDT obtained from mixed powders and dusting powders. The two insecticides are passed through a column packed with neutral aluminium oxide, and then eluted with ether or n-hexane, and the eluate then carefully dried in vacuo. The percentage composition is found by means of standard curves when the glass powder method is applied to the melt of the residue.
Résumé On décrit un dosade de HCH et de DDT sur le mélange des poudres et sur des poudres d'épandage. On réalise l'élution des deux insecticides avec l'éther ou le n-hexane, sur une colonne remplie d'oxyde d'aluminium neutre et l'on sèche avec prudence l'éluat dans le vide. On obtient la composition en pour-cent sur la partie fondue du résidu, au moyen de la méthode à la poudre de verre et en se servant de courbes d'étalonnage.相似文献
26.
Zusammenfassung Der Lösungsmitteleinfluß bei der Alkylierung von 4-Hydroxy-carbostyrilen (1–3) mit Äthyl- bzw. Methyljodid und Allylbromid wird untersucht. Während inDMF und Äthanol fast ausschließlich O-Alkylierung zu den 4-Alkoxy-carbostyrilen (4–7) eintritt, beobachtet man in wäßr. Alkalien auch die Bildung von C,C-dialkylierten Verbindungen (8–10). 3-Äthyl-4-hydroxy-carbostyril (2) reagiert leichter mit C2H5J zum 3,3-Diäthyl-2,4-dioxo-tetrahydrochinolin (8) als das unsubstit. 4-Hydroxy-carbostyril (1). Einige in der Literatur als 3,3-disubstit. 2,4-Dioxo-tetrahydrochinoline formulierte Verbindungen werden als Carbostyril-4-äther erkannt.
The influence of the solvent in the alkylation reaction of 4-hydroxyquinol-2-ones (1–3) with various alkyl halogenides has been studied.DMF and ethanol favor high yields of O-alkylated products (4–7), in aqueous alkali, however, carbon alkylation successfully competes with O-alkylation, affording a substantial amount of 3.3-disubstituted 2.4-dioxo-tetrahydro-quinolines (8–10). The reexamination of a patent showed that some compounds previously described as 2.4-dioxo-tetrahydro-quinolines actually are carbostyril-4-ethers.相似文献
27.
Thérèse Dupuis 《Mikrochimica acta》1967,55(3):452-460
Résumé Par chauffage à 1000° de mélanges d'oxyde stannique et d'oxyde de cadmium en proportions diverses, comme par déshydratation de précipités mixtes des hydroxydes correspondants, il se forme une série de solutions solides de l'oxyde de cadmium dans l'oxyde d'étain. Elles sont solubles dans l'acide chlorhydrique et présentent un spectre d'absorption infrarouge caractéristique que l'on a comparé avec celui des 2 métastannates de cadmium CdSnO3, l'un de type ilménite, l'autre de type perovskite.
Summary By heating various mixture of stannic oxide and cadmium oxide to 1000° C, a series of solid solutions of cadmium oxide in stannic oxide results as is the case when mixed precipitates of the corresponding hydroxides are dehydrated. They are soluble in hydrochloric acid and yield a characteristic infrared absorption spectrum that was compared with that of the two cadmium métastannates CdSnO3, one of the ilmenite type, the other of the perovskite type.
Zusammenfassung Erhitzt man verschieden zusammengesetzte Gemische von Zinnoxid und Cadmiumoxid auf 1000° C oder werden Mischfällungen der entsprechenden Hydroxide dehydratisiert, so entsteht eine Reihe fester Lösungen von Cadmiumoxid in Zinnoxid. Sie sind in Salzsäure löslich und zeigen ein charakteristisches Absorptionsspektrum im IR. Dieses wurde mit dem Spektrum zweier Cadmium-Metastannate (CdSnO3) vom Typus des Ilmenits bzw. Perovskits verglichen.相似文献
28.
Zusammenfassung Bei der Reaktion vonSchiffschen Basen mit Cyanacetylchlorid entstehen über labile Addukte -Cyanzimtsäure-anilide, die in Gegenwart von AlCl3 zu Derivaten des 3-Cyan-4-phenyl-3,4-dihydrocarbostyrils reagieren. Aus diesen kann durch Verseifung die Cyangruppe eliminiert werden.
Herrn KollegenO. Hromatka, Wien, mit den besten Wünschen zum 60. Geburtstag. 相似文献
The reaction of azomethines with cyanoacetyl chloride leads via instable adducts to -cyanocinnamic anilides, which with AlCl3 undergo cyclisation to derivatives of 3-cyano-4-phenyl-3,4-dihydrocarbostyrils. The cyano group in these compounds can be removed by hydrolysis and decarboxylation.
Herrn KollegenO. Hromatka, Wien, mit den besten Wünschen zum 60. Geburtstag. 相似文献
29.
G. J. De Jong U. A. Th. Brinkman W. Th. Kok 《Journal of Radioanalytical and Nuclear Chemistry》1977,35(2):245-252
An investigation has been made on the system liquid anion-exchanger-Cd(II)-NCS−. The influence of the acidity and thiocyanate concentration of the aqueous phase on the extraction has been studied. Using
various methods of analysis, it has been shown that the complex anion present in the organic extracts is Cd(NCS)
4
2−
. Details are given concerning the removal of traces of Zn(II) from Cd(II)-containing solutions, and the quantitative separation
of Cd(II) from Cr(III). 相似文献
30.
Fluorocarbons containing higher halogens have the potency of breaking certain hydrogen bonds in solutions. The relative strength of this potency varies in the series F < Cl < Br < I and the presence of hydrogen atoms in the fluorocarbon increases it. There is a striking parallelism between the hydrogen bond breaking and the anaesthetic potency of these molecules. It is suggested that the breaking of hydrogen bonds is an important step in the mechanism of anaesthesia. 相似文献