The formation of a series of barium tungsten bronzes

The phases occurring in samples of gross composition Ba_xWO₃ (0.01 < x < 0.33) heated at temperatures between 1073 and 1373°K have been determined using X-ray diffraction and electron microscopy. At all temperatures a tetragonal tungsten bronze phase with a narrow homogeneity range of x = 0.20?0.21 was observed to form. In addition, at temperatures up to 1273°K, a series of orthorhombic intergrowth bronzes forms within a restricted composition range around x = 0.04. The latter phases are unstable at higher temperatures and were not found in preparations made at 1323°K. Similarly a new type of bronze phase forms at x = 0.14?0.16 at temperatures up to 1323°K, but not at 1373°K. The structure of this phase is unknown. Aspects of the crystal chemistry of the barium bronzes and the relationships to other bronze phases are discussed.     

Determination of traces of impurities in high-purity sodium chloride by differential pulse polarography and flame spectrometry

Summary Detection limits for the determination of a number of elements in solid sodium chloride by differential pulse polarography, flame absorption and emission spectrometry were established. These methods were used for a quantitative investigation on the distribution of ppm quantities of Cu, Pb, Cd, Zn, Mn, Mg, Sr and Ba between the crystallizate and the mother solution obtained in a partial crystallization of sodium chloride from its saturated solution. Recoveries of the crystallization process, calculated from the results of the analysis, vary from 86% for Pb to 115% for Sr.

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Bestimmung von Spurenverunreinigungen in reinstem Natriumchlorid durch Differential-Pulspolarographie und Flammenspektrometrie

Zusammenfassung Die Nachweisgrenzen für die Bestimmung einer Zahl von Elementen im festen Natriumchlorid wurden mit Differential-Pulspolarographie, Absorptions- und Emissions-Flammenspektrometrie bestimmt. Diese Methoden wurden benutzt zur quantitativen Untersuchung der Verteilung von ppm-Mengen Cu, Pb, Cd, Zn, Mn, Mg, Sr und Ba zwischen kristallisiertem Salz und Mutterlösung bei teilweiser Kristallisation vom Natriumchlorid aus seiner gesättigten Lösung. Die Ausbeuten des Kristallisationsprozesses, berechnet aus den Analysenergebnissen, schwanken von 86% für Pb bis 115% für Sr.

Lecture presented at Euroanalysis I Conference, 28. 8.–1. 9. 1972 in Heidelberg, Germany.     

温度及pH值敏感水凝胶的合成和应用

直接将丙烯酸单体与N-异丙基丙烯酸胺共聚交联合成了温度及pH值敏感的水凝胶。包埋于水凝胶中的药物的释放随温度升高和pH值增大而加快，药物的释放兼有温度和pH值敏感性，对pH值的响应更加显著。     

Multidimensional separation of isomeric species of chlorinated hydrocarbons such as PCB,PCDD, and PCDF

A multidimensional GC-system containing two capillary columns of different polarities, operated within a double oven instrument, was used for the optimized separation of complex isomeric mixtures of various types of chlorinated aromatic compounds such as PCB, PCDD, or PCDF. Electron capture was applied parallel to flame ionization detection to obtain sensitive signals of the PCB or PCDD and the n-alkane standards required for identification by Kovats indices, respectively. Electron capture detection within a valvelessly operated MDGC system forced changes in the usual instrumental set-up, the live-switching coupling piece being located within the second oven of the double oven instrument. This oven is operated isothermally to ensure optimal and interference-free detection, for stable flow conditions within the coupling piece and for the determination of the isothermal retention indices (Kovats), which are much more suitable for identification by retention than the so-called “linear” indices.     

Application of kinetic investigations for interpretation ofn-hexane and benzene adsorption on active carbon

Differencies between the mechanism ofn-hexane and benzene adsorption on active carbon were investigated on the ground of kinetic measurements. As it has been stated, the kinetic measurements show fundamental differencies between the mechanism of adsorption in spite of analogy existing in the state of adsorption equilibrium. Within the range investigated, only the adsorption ofn-hexane follows the model of volume filling of micropores. Existence of those differencies is also confirmed by measurements of effective diffusion coefficient values as well as changes of activation energy of the diffusion—adsorption process.

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Anwendung kinetischer Untersuchungen zur Interpretation des Adsorptionsverhaltens vonn-Hexan und Benzol an Aktivkohle

Zusammenfassung Mittels kinetischer Messungen untersuchte man die Unterschiede im Mechanismus des Adsorptionsverlaufes vonn-Hexan und Benzol an Aktivkohle. Man stellte fest, daß trotz der Analogie im Adsorptionsgleichgewichtszustand die kinetischen Messungen auf prinzipielle Unterschiede im Adsorptionsmechanismus hinweisen. Im untersuchten Bereich verläuft nur die Adsorption vonn-Hexane nach dem Modell der Mikroporenvolumenausfüllung. Die auftretenden Unterschiede wurden auch durch die Berechnungen der Werte der effektiven Diffusionskoeffizienten sowie Änderungen der Aktivierungsenergie des Diffusions-Adsorptionsprozesses bestätigt.

     

High resolution field desorption mass spectrometry III

Summary For the examples shown in this study in all cases FD-MS allowed the determination of the molecular weight and the elemental composition. Some of the characteristic features of sulphonic acids and sulphonates in field desorption are described. The method is obviously very well suited for the analysis of non-volatile technical products (e.g. dyestuffs, detergents, drugs). Information about the molecular weight, the structure, organic and inorganic by-products and impurities is obtained and thus the applicability of FD-MS to the analysis of actual analytical problems is clearly demonstrated.

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Hochauflösungs-Felddesorptions-MassenspektrometrieIII. Sulfonsäuren und Sulfonate

Zusammenfassung Für die untersuchten Verbindungen ergab FD-MS in allen Fällen das Molekulargewicht und die Bruttoformel. Einige der charakteristischen Merkmale von Sulfonsäuren und Sulfonaten bei der Felddesorption werden beschrieben. Die Methode ist für die Analyse nichtflüchtiger, technischer Produkte (z. B. Farbstoffe, Detergentien, Pharmazeutica) sehr gut geeignet. Sie liefert Informationen über das Molekulargewicht, die Struktur, organische und anorganische Nebenprodukte und Verunreinigungen.

Part II.: Schulten, H.-R., Games, D. E.: Glycosides. Biomed. Mass Spectrom. 1, 120 (1974).     

Analysis of polynuclear aromatic hydrocarbons by glass capillary gas chromatography using simultaneous flame ionization and electron capture detection

The possibility of simultaneous application of an electron capture (ECD) and a flame ionization detector (FID) connected to a glass capillary column for analyzing polynuclear aromatic hydrocarbons (PNA) has been investigated. The ECD/FID ratio is determined for 46 PNA compounds. The ratios vary from 0.02 to 117 with relative standard deviations better than 20 percent determined from 10 replicate analyses. The results suggest that the method may be used for obtaining additional evidence in identifying PNA in environmental samples. Impurities and transformation products in the standard were identified by computerized glass capillary gas chromatography/mass spectrometry. Quinones and diones are responsible for the high EC-response determined in some trace components in the standard. An application of the method is shown for PNA from particulates in urban atmospheres.     

Reactions of Polycyclic Ketones with Dimethoxycarbene; a Convenient Route for a ‘One‐Pot’ Preparation of Some α‐Hydroxycarboxylic Acid Esters

Polycyclic ‘cage’ ketones, such as pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecan‐8‐one ( 10 ), pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane‐8,11‐dione ( 11 ), and adamantan‐2‐one ( 16 ) were treated with the nucleophilic dimethoxycarbene (DMC; 1 ), which was generated thermally from 2,5‐dihydro‐2,2‐dimethoxy‐5,5‐dimethyl‐1,3,4‐oxadiazole ( 4a ) in boiling toluene. In this ‘one‐pot’ procedure, the α‐hydroxycarboxylic acid ester 12 or a corresponding derivative 15 or 17 was obtained (Schemes 4–7). Additionally, ‘cage’ thione 21 was treated with DMC under the same conditions yielding dimethoxythiirane 22 (Scheme 8). Subsequent hydrolysis or desulfurization (followed by hydrolysis on silica gel) of 22 gave α‐mercaptocarboxylate 25 and the corresponding desulfurized ester 24 , respectively. In all cases, the addition of DMC occurred stereoselectively, and the addition from the exo‐face is postulated to explain the structures of the isolated products.     

Further Daphniphyllum Alkaloids from the Leaves of Daphniphyllum macropodum Miq.

Five new polycyclic Daphniphyllum alkaloids, macropodumines F ( 1 ) and G ( 2 ), 17‐oxoyuzurimine ( 3 ), and macropodumines H ( 4 ) and I ( 5 ), were isolated from the leaves of D. macropodum Miq ., collected in Sichuan Province, China. The structures and relative configurations of the new compounds – as well as of four known, related alkaloids – were elucidated on the basis of in‐depth spectroscopic and mass‐spectrometric analyses, by chemical derivatization, and by comparison of spectroscopic data with those of known compounds.     

α-Oxohydrazones as imine component in the synthesis of 4-functionalized azetidinones by the Staudinger reaction

1-(Methyl-p-tolyl-amino)-3-phenoxy-2-azetidinones 4-COX and 4-R substituted (COX: X=Me, Et, Ph, NMe₂, NEt₂, OBu^t; R=Me, Et, Ph) were smoothly prepared from the corresponding α-(methyl-p-tolyl)hydrazonylated ketones, amides and esters via [2+2] cycloaddition with phenoxyketene. The reaction was generally high-yielding and diastereoselective, leading to β-lactams with a cis relationship between the PhO and the COX moieties, except for R=Ph, where an opposite stereoselectivity was instead observed. The azetidinones represent interesting intermediates which couple protection at N(1) and functionalization at position 4 of the ring. Deprotection of N(1) can be easily attained by oxidative N-N cleavage with magnesium monoperoxyphthalate.