Ionenaustausch- und Extraktionsmethoden zur Abtrennung von Uran

Zusammenfassung Im vorliegenden Übersichtsartikel wird auf die wichtigsten Ionenaustausch- und Extraktionsmethoden zur Abtrennung des Urans eingegangen. Unter den Anionenaustauschprozessen, die am häufigsten zur Uranabtrennung verwendet werden, sind jene von größter Bedeutung, bei denen das Uran entweder als anionischer Sulfato- oder Chlorokomplex auf stark basischen Harzen, wie z. B. Dowex 1, adsorbiert wird. Dabei sind jene Methoden für analytische Zwecke besonders geeignet, die auf der Trennung des Urans in salzsauren, gemischt wäßrig-organischen Systemen beruhen. Auch bei den Kationenaustauschmethoden wird eine hohe Selektivität der Trennungen in gemischt wäßrig-organischen Medien, insbesondere in einer salpetersauren Tetrahydrofuranlösung, erreicht. Bei der Besprechung der Extraktionsmethoden wird auf die Extraktion des Urans aus salpetersauren Lösungen mit phosphororganischen Verbindungen näher eingegangen.

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Summary The most important ion exchange and extraction methods for the separation of uranium are discussed in this review article. Among the anion exchange methods, most frequently employed for the separation of uranium, the ones of most importance are those in which the uranium is absorbed either as anionic sulfato- or chloro complex on strongly basic resins, such as Dowex 1. The methods particularly suited for analytical purposes are those based on the separation of the uranium in hydrochloric acid-mixed water-organic systems. Likewise, in the cation exchange methods, a high selectivity of the separations is attained in mixed water-organic media, especially in a nitric acid-tetrahydrofuran solution. The extraction of the uranium from nitric acid solutions by means of phosphorus organic compounds is discussed in more detail in the discussion of the extraction methods.

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Résumé Dans l'article d'ensemble qui est présenté, on s'intéresse aux méthodes les plus importantes d'échange ionique et d'extraction pour la séparation de l'uranium. Parmi les processes d'échange anionique utilisés le plus couramment pour la séparation de l'uranium, les plus importants sont ceux oú l'uranium est absorbé sous forme de complexe anionique chloro ou sulfato sur résines fortement basiques comme par exemple Dowex 1. Dans ce cas, les méthodes répondant à des buts analytiques et reposant sur la séparation de l'uranium dans les systèmes chlorhydriques, aquo-organiques, conviennent particulièrement bien. Pour les méthodes avec échange cationique, on obtient aussi une sélectivité élevée des séparations dans les milieux organiques aqueux en mélanges, en particulier dans une solution nitrique de tétrahydrofurane. Pour décrire les méthodes d'extraction, on considère d'une manière plus approfondie l'extraction de l'uranium en solution nitrique par des composés phosphoro-organiques.

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Herrn Prof. Dr.F. Wessely anläßlich seines 70. Geburtstages am 3. August 1967 herzlichst gewidmet.     

The mass spectra of 2-alkyl N-methyl pyrrolidines

The mass spectra of a series of 2-alkyl N-methyl pyrrolidines have been examined and fragments which may be pyrrole type structures are apparent. These ions are most prominent in the spectra of the long chain alkyl derivatives.     

Flow-injection determination of nonylphenol in liquid media using a piezoelectric immunosensor

A piezoelectric flow immunosensor for the rapid determination of nonylphenol in aqueous solutions was developed. An aminophenol-protein conjugate (4-AP-GA-BSA) immobilized on the presilanized surface of a silver electrode was used as a bioreceptor coating of the sensor. The effects of the nature and concentration of monoclonal and polyclonal antibodies on the analytical signal of the sensors were studied; the activity of immunoreagents was evaluated based on the binding constants K _b. The cross reactions of various phenols with antibodies were studied and the cross reaction percentages were found. A procedure for the flow-injection determination of nonylphenol in liquid media was developed using a piezoelectric immunosensor as a detector. The calibration graph was linear over the concentration range 1–20 ng/mL; the detection limit for nonylphenol was 0.8 ng/mL.     

Chemoselective cross-metathesis reaction. Application to the synthesis of the C1-C14 fragment of amphidinol 3

[reaction: see text] An efficient synthesis of the C1-C14 fragment of amphidinol 3 is described. The synthesis is based on chemoselective cross-metathesis reactions and enantioselective allyltitanations.     

Dynamics of photodissociation of 3,3,3-d(3)-propene at 157 nm: site effect and hydrogen migration

In a preceding paper [Lee et al., J. Chem. Phys. 119, 827 (2003)], we measured the kinetic-energy distributions P(E(t)) and branching ratios of products from photolysis of propene at 157 nm using time-of-flight spectroscopy combined with photoionization. In the present work, hydrogen migration before fragmentation and a site effect on P(E(t)) and branching ratios were revealed from the photodissociation of CD(3)CHCH(2). Labeling of the methyl group with deuterium enabled us to differentiate between elimination of atomic and molecular hydrogen from the vinyl moiety and from the methyl moiety; the P(E(t)) and relative yields for the formation of H, D, H(2), HD, and D(2) were measured. Deuterium labeling allowed us to also differentiate the fragmentation after hydrogen transfer from that before hydrogen migration. The observation of isotopic variants of CD(3) and C(2)H(3) radicals in the C-C bond cleavage provides evidence for hydrogen transfer of propene because of site specificity. The fraction of fragmentation after hydrogen transfer is estimated to be 25%. The isotope-specific branching ratios for five dissociation pathways of CD(3)CHCH(2) were evaluated.     

Direct analysis of selected N-acyl-L-homoserine lactones by gas chromatography/mass spectrometry

A rapid, simple and selective method involving direct separation by gas chromatography (GC) with electron ionization mass spectrometry (EI-MS) was employed to determine some N-acylhomoserine lactones (AHLs). Using GC/EI-MS, simultaneous separation and characterization of AHLs were possible without prior derivatization. Informative fragmentation patterns were obtained to identify the structures of N-acyl chains of AHLs. Electron ionization resulted in a common fragmentation pattern with the most abundant ion at m/z 143 and other minor peaks at m/z 71, 57, and 43. The presence of AHLs in extracts of Burkholderia cepacia strains was achieved in selected ion monitoring mode by using the prominent fragment at m/z 143.     

Direct observation of eta 2-imine formation through beta-H abstraction between amide ligands. Neutron and X-ray diffraction structure of a dihydride imine ditantalum complex

Reactions of Ta(NMe2)5 with D2SiR'Ph (R' = Me, Ph) were found to give a dideuteride eta 2-imine complex (Me2N)3Ta(mu-D)2(mu-N-eta 2-N,C-CH2NMe)Ta(NMe2)3(1-d2) through C-H activation of an amide ligand via beta-H abstraction, and the structure of 1 was confirmed by single crystal neutron and X-ray diffraction.     

Neurotrope und psychotrope Substanzen, 5. Mitt.: Synthese neuer Aminoderivate von 10,11-Dihydrodibenzo-[a,d]cyclohepten und 10,11-Dihydrodibenzo[b,f]thiepin

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.

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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.

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mit technischer Hilfe von

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Herrn Professor Dr.Hermann Bretschneider zum 60. Geburtstag gewidmet

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4. Mitt.:J. O. Jílek, K. Pelz, D. Pavlíková undM. Protiva, Coll. Czechoslov. Chem. Commun.30, im Druck (1965).     

Polaron-exciton model of resonance energy transfer

It is shown that F?rster's expression for the electronic energy transfer rate can be recast in a form predicted for exciton motion that interacts strongly with molecular vibrations. Using a simple model based on the Kennard-Stepanov theory, F?rster's expression for the spectral overlap is shown to be of a thermally activated form, as obtained previously by multiphonon theory. In contrast, the high-frequency internal vibrations contribute a factor which results from tunneling through a potential barrier between potential curves in the configuration coordinate diagram. We thus show that resonance energy transfer is equivalent to phonon-assisted hopping of a trapped excitonic polaron.     

Isotope effects in tritium exchange between liquid pyrrole, pyrrolidine and gaseous hydrogen

The overall tritium separation factor between molecular hydrogen and liquid pyrrole and pyrrolidine has been measured between 280 and 325 K. The data are comparable with values of α measured for similar exchange reactions involving ammonia and methylamine. There is a visible correlation of the isotope effect with the energy of hydrogen bond formed by NH groups of liquid ammonia, methylamine, pyrrole and pyrrolidine.