Periodic solutions of some infinite-dimensional Hamiltonian systems associated with non-linear partial difference equations. II

This is our second paper devoted to the study of some non-linear Schrödinger equations with random potential. We study the non-linear eigenvalue problems corresponding to these equations. We exhibit a countable family of eigenfunctions corresponding to simple eigenvalues densely embedded in the band tails. Contrary to our results in the first paper, the results established in the present paper hold for an arbitrary strength of the non-linear (cubic) term in the non-linear Schrödinger equation.     

4-Amino-imidazole durchThorpe-Cyclisierung

The alkylation of arylaminomethylenecyanamides1 or cyano-imidothiocarbamates2 with -halogen carbonyl compounds followed by base catalysed cyclization yields substituted 4-amino-imidazoles4. Imidazo[4,5-d]pyrimidones5, 6 and imidazo[4,5-b]pyridines7 can be obtained from4.     

The electrocapillarity of polyacrylates

Summary The electrocapillary properties of polyacrylic acid have been studied by two methods. Exploratory measurements have been made of the effect of the polymer on the differential capacity of a mercury drop in 0.1 m sodium perchlorate. They showed that the polymer was strongly adsorbed over a wide range of potentials but that it did not appear to form a monolayer. The surface excess of polymer obtained from drop weight data showed a maximum at very low concentrations and then a decline at higher concentrations. The bulk of the work was carried out by making surface tension measurements, using a sessile mercury drop, in solutions of a fraction of polyacrylic acid (mol. wt. 7.02×10⁴) in potassium chloride at 0.01, 0.1, 0.2, and 0.5 m at 25°C.The data have been used to evaluate the surface excesses of the polymer and of the inorganic ions. The distribution of K⁺ and Cl^– in the electrical double layer and the contact adsorption of Cl^– on the mercury were very little affected by the presence of the polymer. The surface excess of polymer was always found to be greatest at low concentrations, to decrease steeply at first as the concentration was increased and then to decrease more slowly at higher concentrations.Possible explanations of this behaviour are discussed and it is concluded that the rapid decrease is a consequence of molecular weight dispersion and the stronger adsorption of high molecular weight polymer. The slow decrease in surface excess at higher concentrations may be a result of configurational changes of the polymer molecules.Surface pressure data show that, despite this decrease in the surface excess, the surface coverage reaches a high level at very low polymer concentrations and then continues to increase slowly as the concentration of polymer is increased. This apparent contradiction is due to changes in configuration of the adsorbed polymer molecules. At higher bulk concentrations the chain configurations are more compact and each adsorbed molecule makes more contacts with and so occupies a greater area of the mercury surface than at low concentrations.The conclusion is reached that the surface excess of polymer is mostly contained in a layer probably more than 1000 Å thick. It consists of a concentrated and entangled mass of polymer chains. Relatively few of these chains are in contact with the mercury at any istant. The concentration in this surface layer decreases steadily with increasing distance from the mercury surface and it merges without discontinuity into the bulk solution.With 10 figures in 22 details     

Stereochemie von Metallocenen, 40. Mitt.

Starting from optically active methylferrocene-- and--carboxylic acids (1 a and1 b) of known absolute configuration and enantiomeric purity about 15 chiral ferrocenes (of each isomeric series— and ) were obtained by suitable ligand transformations. Thereby (almost) all possible chiral combinations of the ligands CH₃, COOH (COO^–), COOCH₃, CN and NH₂ (NH₃ ⁺) were accessible which are necessary for a potential test of approximations of chirality functions for compounds with basic symmetry C_5v. The chiroptical properties of these disubstituted ferrocenes are recorded.Preliminary tests using a shortened Ansatz revealed large discrepancies between calculated () and found [M]_D-values. Possible reasons for this failure are discussed.

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61. Mitt. über Ferrocenderivate

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39. Mitt.:A. Meyer, H. Neudeck undK. Schlögl, Chem. Ber.110, 1403 (1977).

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60. Mitt.:V. Rapi, K. Schlögl undB. Steinitz, J. Organometal. Chem.94, 87 (1975).     

Buchbesprechungen

Ohne Zusammenfassung     

Neue Wege der Analytik durch Kombination der direkten quantitativen Dünnschicht-Chromatographie mit elektronischer Datenverarbeitung

A computer program for direct evaluation of thin-layer chromatograms, which already was described earlier [3] has been tested with a laboratory and some technical formulations of a pesticide. Results have been compared with those obtained by two conventional methods. Mean relative standard deviation calculated from results compiled by electronic data processing (method A) is about 6%, compared to 10% received by graphic method (method C) which is employed by most investigators. In addition, overall time of analysis is 34% higher if graphic method is used. Method A saves time and expense especially in routine analysis because working of the process is easier and may be performed even by assistent personal. The proposed method is suitable for the determination of different active ingredients and impurities even in difficult technical products.     

Anionenaustauschtrennungen der mit Tributylphosphat extrahierbaren Elemente. VII

Zusammenfassung Eine Methode zur Abtrennung des Urans wird beschrieben, bei der das Uran aus einer 6-m salzsauren Lösung mit reinem, unverdünntem TBP extrahiert und aus einer Mischung von 30 Vol.% TBP, 60 Vol.% Methylglykol und 10 Vol.% 12-m Salzsäure am stark basischen Anionenaustauscher Dowex 1-X8 (Chloridform) adsorbiert wird. Da der TBP-Extrakt zur Bereitung dieser Mischung verwendet wird, lassen sich Extraktion und Ionenaustausch kombinieren, wodurch nicht nur die Selektivität der Abtrennung des Urans wesentlich erhöht wird, sondern auch eine so weitgehende Anreicherung des Urans auf dem Harz erfolgt, daß auch ppm-Mengen leicht zu bestimmen sind. Das Harz wird zu diesem Zweck zunächst zur Entfernung des TBP mit einer Mischung von 90 Vol.% Methylglykol und 10 Vol.% 12-m Salzsäure, dann zur Entfernung von mitadsorbierten Elementen mit 6-m Salzsäure behandelt; anschließend wird das Uran mit 1-m Salzsäure eluiert und fluorimetrisch bestimmt. Zu Vergleichszwecken wurden 16 geologische Proben nach dieser Methode und auch unter Anwendung einer anderen Anionenaustauschmethode analysiert. Die Ergebnisse zeigen, daß das hier beschriebene Trennverfahren eine quantitative Abtrennung des Urans ermöglicht und zu gut reproduzierbaren Resultaten führt.

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Anionic exchange separations of the elements that are extractable with tributyl phosphate. VII

Summary A method is described for the separation of uranium in which the latter is extracted from a 6M hydrochloric acid solution by means of pure undiluted TBP and adsorbed from a mixture of 30 volume % TBP, 60 volume % methylglycol and 10 volume % of 12M hydrochloric acid on the strongly basic anionexchanger Dowex 1-X8 (chloride form). Since the TBP-extract is used for the preparation of this mixture, the extraction and the ion-exchange may be combined, whereby not only the selectivity of the separation of the uranium is significantly raised but also there follows such a rar-reaching enrichment of the uranium on the resin that even ppm quantities are readily determined. For this latter purpose, the resin is first treated with a mixture of 90 volume % methylglycol and 10 volume % 12M hydrochloric acid to remove the TBP, and then with 6M hydrochloric acid to remove the co-adsorbed elements; and then the uranium is eluted by means of 1M hydrochloric acid and determined fluorimetrically. For comparison purposes, 16 geologic specimens were analyzed in accord with this procedure and also employing another anion exchange method. The results show that the separation method described here makes possible a quantitative separation of the uranium and leads to good reproducible results.