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51.
K. Južnič 《Journal of Radioanalytical and Nuclear Chemistry》1977,40(1-2):217-220
The equilibria between the solution of TOA in toluene and mixtures of sulphuric and hydrochloric acid been studied. They were
characterized by ratios of stability constants of amine salts formed in the organic phase. 相似文献
52.
Zusammenfassung Die Reaktion von 2-Nitroso-1-naphthol mit Resorcin bzw. Orcin in Äther bei Anwesenheit von HNO3 liefert Benzo[c]phenoxazon-(9) (I), Benzo[c]phenoxazon-(9)-12-oxid (II), Methyl-benzo[c]phenoxazon-(9) (III) sowie 11-Methyl-benzo[c]phenoxazon-(9)-12-oxid (IV). Die Struktur der isolierten Substanzen wurde durch Reduktion mittels TiCl3 sowie durch die UV- und IR-Spektren gestützt.
Mit 1 Abbildung 相似文献
The reaction of 2-nitroso-1-naphthol with resorcinol and orcinol in ether solution in the presence of nitric acid has been studied. From the reaction mixture the benzophenoxazones I–IV have been isolated. Structures were assigned on the grounds of UV and IR spectra and partly by using TiCl3 as a reducing agent.
Mit 1 Abbildung 相似文献
53.
P. M. Nikolić Lj. Milković P. Mihajlović B. Lavrenčić 《Czechoslovak Journal of Physics》1978,28(4):456-459
Zone center optical phonons in SnSe were investigated using Raman scattering data obtained here and previously reported far infrared reflectivity measurements. The values of the ratio of the pairs of interlayer force constants were calculated te be between 3·3 and 4·5. Thus it can be concluded that SnS is a layer like semiconductor but less layer like than GeS, GeSe or SnS. 相似文献
54.
Zusammenfassung Eine Halbmikromethode zur Bestimmung der an Kohlenstoff oder Sauerstoff gebundenen Nitro- und Nitrosogruppen in organischen Verbindungen wurde ausgearbeitet. Die Methode beruht auf dem oxydativen Aufschluß der Substanz mit einem Chromsäure—Schwefelsäure-Gemisch, wobei die Nitro- und Nitrosogruppen quantitativ in Salpetersäure übergehen. Diese wird mit Devarda-Legierung in alkalischem Medium zu Ammoniak reduziert, das dann im Stickstoffstrom abdestilliert und acidimetrisch titriert wird.
Summary A semimicro method for determining nitro- and nitroso groups attached to carbon or oxygen in organic compounds has been worked out. The method is based on the oxidative decomposition of the sample with a chromic acid-sulfuric acid mixture, the nitro and the nitroso groups being quantitatively transformed into nitric acid. The latter is reduced to ammonia by means of Devarda alloy in alkaline medium, and is then distilled off in a stream of nitrogen and titrated with a standard acid solution.
Résumé On a mis au point une méthode à l'échelle semimicro pour le dosage dans les substances organiques de groupes nitro et nitroso liés au carbone ou à l'oxygène. La méthode repose sur l'attaque oxydante de la substance par un mélange acide chromique-acide sulfurique, ce qui transforme quantitativement les groupes nitro et nitroso en acide nitrique. Au moyen de l'alliage de Devarda en milieu alcalin, on réduit celui-ci en ammoniac que l'on chasse par distillation dans un courant d'azote et que l'on titre par acidimétrie.相似文献
55.
The principles of the method of NMR line narrowing by measurement with spinning of the sample about the magic axis (MAR-NMR) are introduced, with particular emphasis on the effects of internal motion upon the possibilities and limitations of the method. The applications of the method in 1H-NMR studies of polymer structure and dynamics are then reviewed. Due to both theoretical and experimental limitations, narrowing of dipolar broadened NMR lines by MAR can be observed in 1H NMR spectra only in those cases where internal motion is anisotropic, or in heterogeneous systems where line width is limited by differences of magnetic susceptibility. In polymers, both solid and liquid, the method makes possible differentiation between isotropic and anisotropic internal motion. In systems with anisotropic internal motion, MAR-NMR makes possible a characterization of motional codes which normally are obscured by residual dipolar interactions, as well as of geometrical restrictions upon these motions. 相似文献
56.
V. Kontrimavičiūtė H. Breton F. Barnay J. C. Mathieu-Daudé F. M. M. Bressolle 《Chromatographia》2006,63(11-12):533-541
A specific and sensitive liquid chromatography-electrospray ionization mass spectrometry method was developed for the determination of ibogaine and noribogaine in human urine. The work-up procedure involved a solid phase extraction of the compounds and the internal standard (fluorescein) using Oasis HLB columns. The system used a Zorbax eclipse XDB C8 analytical column packed with 5µm diameter particles as the stationary phase. The mobile phase consisted of a 20-min gradient (mobile phase A: 0.02% (v/v) trimethylamine in acetonitrile, mobile phase B: 2 mM ammonium formate buffer (pH 3)). Mass spectrometric data were acquired in single ion monitoring mode at m/z 311.1, 297.2 and 333 for ibogaine, noribogaine and fluorescein, respectively. The drug/internal standard peak area ratios were linked via a quadratic relationship to concentrations (1.78?358 μg L?1 for ibogaine; 2?400 μg L?1 for noribogaine). Precision ranged from 5.8 to 14.8% and accuracy was between 93.2 and 112.9%. Mean extraction recoveries of ibogaine, noribogaine and fluorescein were 70.0, 81.7 and 94.8%, respectively. The extraction efficiency was independent of concentration over the range studied. The lower limits of quantitation were 1.78 μg L?1 for ibogaine and 2 μg L?1 for noribogaine. In this paper, extensive stability testing was undertaken using a wide range of storage conditions. This method was found suitable for urine analysis of a poisoning involving ingestion of drink made from powdered root of shrub Tabernanthe iboga. 相似文献
57.
J. Rybníček 《Czechoslovak Journal of Physics》1980,30(12):1307-1314
The variations in time of mass spectra of ions, extracted from the hollow-cathode discharge in the regime of the intensive sputtering of the cathode material were measured. The mass spectrum changes in time conspicuously. From the results of measurements a distinct anisotropy of ion beam is inferred. The discharge turns into a metal-ions regime.The helpful discussions with Dr. J. Musil are gratefully acknowledged. 相似文献
58.
J. Hladký S. NĚmeček M. Novák A. Prokeš J. Votruba K. -F. Albrecht A. Meyer M. Sachwitz B. N. Guskov V. G. Krivokhizhin M. F. Likhachev I. A. Savin G. Vesztergombi 《Czechoslovak Journal of Physics》1977,27(11):1210-1218
Results of the first elastic K
S
o
regeneration experiment on carbon, using magnetic spark chamber spectrometer, are presented in the beam momentum interval 10p50 GeV/c. The d ifferentia cross section d/dt is reconstructed in the range 0·0025–t0·02 (GeV/c)2 and its slopeB is found to be momentum independent with an average valueB=(65±11) (GeV/c)–2. The results are in agreement with the calculations using the coherent production model. 相似文献
59.
Zusammenfassung Eine Reihe sauerstoffhaltiger Modellsubstanzen, die Methylgruppen am primären, sekundären oder doppelt gebundenen Kohlenstoffatom enthalten, wurden mit einem Gemisch von 2 T. 5-n Chromsäure und 1 T. konz. Schwefelsäure 45 Minuten bei 130° C oxydiert. Die entstandene Essigsäure wurde mit Wasserdampf abdestilliert und alkalimetrisch titriert. Die angeführten Reaktionsbedingungen können als optimal angesehen werden, da sie die größte oxydative Wirkung haben, bei der jedoch Essigsäure nicht weiter oxydiert wird. Der Abbau des Kohlenstoffskeletts verläuft schneller und vollständiger als bei der Methode vonKuhn undRoth. Die Essigsäureausbeute lag zwischen 0,70 und 0,95 Mol Essigsäure je C-Methylgruppe und wurde in Abhängigkeit von der Struktur der untersuchten Stoffe diskutiert.
In dieser Mitteilung ist der erste Teil der Dissertationsarbeit von Frau Dipl.-Ing.B. Voláková inbegriffen. 相似文献
Determination of C-methyl groups in organic oxygen compounds through oxidation with chromic acid under optimal conditions
Summary A number of oxygen-containing model substances, which contained methyl groups on primary, secondary or doubly bound carbon atoms, were oxidized with a mixture of 2 parts of 5N chromic acid and 1 part of conc. sulfuric acid for 45 minutes ar 130° C. The resulting acetic acid was distilled off with steam and titrated alkametrically. The cited reaction conditions may be regarded as optimal, because they exert the greatest oxidative action, which however the acetic acid is not further oxidized. The degradation of the carbon skeleton proceeds faster and more completely than in the method ofKuhn andRoth. The yield of acetic acid lay between 0.70 and 0.95 mol acetic acid per C-methyl group and was discussed with respect to the structure of the investigated material.
In dieser Mitteilung ist der erste Teil der Dissertationsarbeit von Frau Dipl.-Ing.B. Voláková inbegriffen. 相似文献
60.
V. Jedináková L. Kuča M. Vojtíšková 《Journal of Radioanalytical and Nuclear Chemistry》1980,59(1):125-132
We have investigated the effect of coextraction of lanthanides and yttrium on the distribution coefficients DAm in the extraction of americium by benzyldimethyldodecylammonium nitrate (BDMLNNO3) from nitrate solutions. In the coextraction of lanthanides, the extraction of Am(NO3)3 is suppressed, which is markedly manifested in the extraction of light lanthanides (La, Ce, Pr); of the series of lanthanides their extraction is the highest. The effect of nitric acid and the possibility of separation of lanthanides and americium by the application of three-stage multiple extraction is discussed. 相似文献