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991.
Sequential leaching methods have been used for the speciation of Be, Ni, and V in five soil samples from Csepel Island on the Danube river located near an oil-fired power plant. The concentrations of the elements of the extracts were determined by inductively coupled plasma mass spectrometry. The total efficiency (the sum of the extracted metals divided by metal fraction which is soluble in aqua regia) of the five-step method was always higher. The difference for Ni was considerable, because of the high abundance of Ni found in the moderately reducible fraction, which is absent from the three-step method. The sum of the mobile species (exchangeable, carbonatic, and easily reducible) determined by both methods, were in reasonable agreement; this was not so for the individual fractions. There were greater differences between the non-mobile fractions (moderately reducible and oxidizable), because of the presence or absence of the moderately reducible fraction. For both methods there was good correlation between the oxidizable fraction and the organic matter content of the soils.  相似文献   
992.
[graph: see text] A new probe, 1,4-bis(1-pyrenyl)-2,3-diaza-1,3-butadiene, selectively senses Hg2+ and Cu2+ through two different channels: the yellow-deep-pink color change and the enhancement of the fluorescence with the red shift of the excimer emission, which can visually be discernible by a green fluorescence in the presence of Hg2+ and an orange fluorescence in the presence of Cu2+.  相似文献   
993.
The X-ray and spectroscopic results clearly indicate that the (+)-2-thiono-17-oxosparteine (1) and (+)-2,17-ditihionosparteine (2) are conformationally rigid. In order to analyze deviations of lactam/thiolactam groups from planarity induced by ring constraints, the Dunitz-Winkler approach has been used. The lactam and thiolactam groups are close to planarity, only the lactam group in one of the two independent molecules of 1 is markedly non-planar. The bond angles in the thiolactam and lactam groups are highly diverse. Rings A and C adopt a distorted sofa conformation in both compounds. The distortions in the molecules of 2 as compared with those in the related monothiolactams correspond to the unusual chemical shifts of H5(eq), H5(ax) and H11, as well as to the extremely low J5ax-6 and extremely large J5eq-6 coupling constants. Also chemical shifts show a similar regularity being extremely high and low for C2 and C17, respectively.  相似文献   
994.
Domino metathesis of N-alkylated derivatives of (1S)-2-azanorborn-5-en-3-one allowed for the enantioselective synthesis of pyrrolizidine, quinolizidine, pyrrolidinoazepine, and pyrrolidinoazocine derivatives in a straightforward process.  相似文献   
995.
Zusammenfassung Im Rahmen der Suche nach neuen neurotropen und psychotropen Substanzen, besonders nach antidepressiv wirkenden Psychopharmaka, wurde eine systematische präparative Arbeit in den Gruppen der 10-substituierten Derivate des 10,11-Dihydrodibenzo[a,d]cycloheptens (I) und des 10,11-Dihydrodibenzo[b,f]-thiepins (II) unternommen. Im ersten Fall war die Ausgangssubstanz das Keton XIV, das mit üblichen Methoden zum basischen Äther XVI, zu Aminen und Derivaten XVIII–XXII und schließlich in dieMannich-Base XXVI übergeführt wurde. DieBeckmannsche Umlagerung des Oxims XVII eröffnete den Weg zu Derivaten eines neuen Systems, des 5,6,7,12-Tetrahydrodibenz[b,e]azocins (Verbindungen XXVIII, XXX und XXXI). Auch im zweiten Fall bildete das entsprechende Keton (XXXVIII) die Schlüsselsubstanz, die einerseits zu Aminen mit der Aminogruppe in der Seitenkette (XXXIX, XL, XLII, LV, LVI), anderseits zu Aminen mit der direkt am Skelett haftenden Aminogruppe (XLIV–LIII) umgesetzt wurde. Außer den angeführten Aminen wurde in allen drei Gruppen eine Reihe von neutralen Verbindungen hergestellt (Zwischenprodukte und Nebenprodukte), deren Struktur meistens mit Hilfe der Spektren geklärt wurde. Die vorläufigen Ergebnisse der pharmakologischen Prüfung einiger Produkte deuten interessante Wirksamkeit an, besonders vom Standpunkt der erwarteten neurotropen und psychotropen Eigenschaften aus.
In the effort to find new neurotropic and psychotropic substances a systematic chemical study was undertaken in the groups of the 10-substituted derivatives of 10,11-dihydrodibenzo[a,d]-cycloheptene (I) and 10,11-dihydrodibenzo[b,f]thiepine (II). In the first case the ketone XIV was transformed by usual methods into the basic ether XVI, to the amines and derivatives XVIII–XXII, and to theMannich base XXVI. TheBeckmann rearrangement of the oxime XVII opened the way to derivatives of a new system — 5,6,7,12-tetrahydrodibenz[b,e]azocine (compounds XXVIII, XXX and XXXI). In the second case (derivatives of II) the syntheses started from the ketone XXXVIII and two series of amines were prepared: with the amino group in the side chain (XXXIX, XL, XLII, LV, LVI) and with the amino group attached directly to the skeleton (XLIV–LIII). In addition to the amines several neutral compounds in either group were synthesized (intermediates and byproducts), the structure of which was elucidated mainly by means of the spectra. Preliminary results of the pharmacological testing show a rather important degree of activity of some substances, especially in the line of the expected neurotropic and psychotropic properties.


mit technischer Hilfe von

Herrn Professor Dr.Hermann Bretschneider zum 60. Geburtstag gewidmet

4. Mitt.:J. O. Jílek, K. Pelz, D. Pavlíková undM. Protiva, Coll. Czechoslov. Chem. Commun.30, im Druck (1965).  相似文献   
996.
Alkaloids such as cinchonidine, quinine and N-methylephedrine have been N-alkylated using polymeric benzyl halides or co-polymerized and then N-alkylated, thus affording a series of polymer-supported chiral ammonium salts which have been employed as phase-transfer catalysts in the asymmetric benzylation of an N-(diphenylmethylene)glycine ester. These new polymeric catalysts can be easily recovered by simple filtration after the reaction and reused. The best ee's were achieved when Merrifield resin-anchored cinchonidinium ammonium salts were employed.  相似文献   
997.
The inclusion complexes of β-cyclodextrin (β-CD) with naphthalene and some of its derivatives in the solid state have been studied by infrared spectroscopy. Digital subtraction, deconvolution and curve fitting have been used to investigate the interactions between the naphthalene derivatives andβ-CD. Several preparation methods for the solid dispersions have been tested, using FTIR as an effective tool to evaluate the interactions at the molecular level. The effects of temperature and humidity on the spectra have been also analyzed. A carbonyl moiety in the guest molecule can increase the stability of the complex by establishing specific interactions with the hydroxyl groups of the CD cavity rims. The stability of the complexes is higher for 2-naphthylacetate than that for 1-naphthyl acetate, andso is the degree of association of its carbonyl groups. On the other hand, 2-acetylnaphthaleneforms very stable inclusioncomplexes although its carbonyl groups appear to be significantly less associated.  相似文献   
998.
'Non-covalent synthesis' of novel chiral hosts (calix[6]arene-chiral amine complexes) and its application to enantiomeric discrimination was investigated by (1)H NMR spectroscopy. The topology of a ternary complex was proposed for the calix[6]arene-amine-sulfoxide to rationalize the chiral recognition.  相似文献   
999.
[reaction: see text] A highly versatile approach to the enantioselective synthesis of securinega alkaloids is presented. Crucial steps are a palladium-catalyzed enantioselective imide alkylation, a vinylogous Mannich reaction, and a ring-closing metathesis process. Through this strategy, the synthesis of (-)-norsecurinine has been accomplished in nine steps and 11% overall yield.  相似文献   
1000.
Summary Radiochemical neutron activation procedures using liquid-liquid extraction with tetraphenylarsonium chloride in chloroform from 1M HCl and solid extraction with ALIQUAT 336 incorporated in a polyacrylonitrile binding matrix from 0.1M HCl were developed for accurate determination of rhenium in biological and environmental samples at the sub-ng . g-1 level. Concentrations of Re in the range of 0.1 to 2.4 ng . g-1 were determined in several botanical reference materials (RM), while in a RM of road dust a value of ~10 ng . g-1 was found. Significantly elevated values of Re, up to 90 ng . g-1 were found in seaweed (brown algae). Results for Re in the brown algae Fucus vesiculosus in which elevated 99Tc values had previously been determined suggested possible competition between Re and Tc in the accumulation process.  相似文献   
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