Cleavage of different ether bonds in butyl glycidyl ether and allyl glycidyl ether by K, K(15-crown-5)2

The kind of substituent in alkyl glycidyl ethers affects the course of their reaction with K⁻, K⁺(15-crown-5)₂. The cyclic oxirane ring is exclusively cleaved in the case of butyl glycidyl ether whereas the presence of the unsaturated allyl group in the glycidyl ether molecule unexpectedly prefers the scission of the linear ether bond. In both the systems organometallic intermediates are formed. They react with crown ether causing its ring opening. Allylpotassium formed from allyl glycidyl ether reacts also with another glycidyl ether molecule; the oxirane ring is opened in this case.     

Synthesis of γ-tetrazole analogues of l-glutamic acid and its derivatives

The γ-(5-tetrazolyl)-α-amino-l-butyric acid, an analogue of l-glutamic acid, was synthesized from methyl γ-cyano-α-benzyloxycarbonylamino-l-butyrate by transformation of the nitrile group into tetrazole nucleus by using tri-n-butyl-tin azide and removal of protecting groups. The synthesis of peptide derivatives containing γ-(5-tetrazolyl)-α-amino-l-butyryl residue is also described.     

Vibrational frequencies and force constants of N2O4 in complexes with molecules of different solvents determined by Raman spectra andAb initio calculation

The Raman spectra of N₂O₄ solutions in organic solvents have been recorded. The frequencies ofv ₁,v ₂, andv ₃ bands of N₂O₄ increase with increasing solvent electron-donor properties. Especially large changes ofv ₃ N-N stretching band have been observed (254.5 cm^–1 in n-hexane, 276.5 cm^–1 in 1,4-dioxane). The ab initio calculations have shown that the interaction between N₂O₄ and electron-donor molecules causes an increase of N-N and N-O stretching and O-N-O bending force constants of N₂O₄ in agreement with the results of Raman study.     

Development of solvent-free acrylic pressure-sensitive adhesives

The present publication describes a problem to develop solvent-free acrylic pressure-sensitive adhesives (PSA). Solvent-free PSA are established materials for the manufacturing of various self-adhesive products. Only by means of these acrylic PSA was it possible to succeed in drafting the present surprisingly efficient generation of double-sided pressure-sensitive adhesive tapes, medical products, protective masking films, films for the graphics market, and various specialty products. New applications and technical specifications stimulate the continuous development of new methods of polymerization of solvent-free acrylates. New syntheses of solvent-free acrylic PSA include polymerization in the reactor with removal of the solvent and polymerization on the carrier. The polymerization process is connected with UV-crosslinking.     

The moment problem in the spaceC 0(S)

The goal of this paper is to study the problem of finding a regular nonnegative Borel measure ? on a locally compact Hausdorff spaceS satisfying the conditions $$\int\limits_S {p_i d\varphi = \mu _i } for all i \in T \cup \{ 0\} , \mu _0 = 1, \varphi (S)< B$$ wherep ⁱ εC ₀(S),T is an arbitrary set andBε(0, ∞]. We provide a number of equivalent conditions for the existence of a solution ? which generalize some known conditions for denumerableT and linearly independentp _i . As an application we prove a negative result on Schauer's bases inC(S).     

Surface clusters of colloid particles produced by deposition on sites

The possibility of producing surface clusters of well-defined structure formed by colloid particles was analyzed theoretically and experimentally. Theoretical results were derived by performing Monte Carlo-type simulations according to the generalized random sequential adsorption (RSA) mechanism. In these simulations, the jamming coverage of particles adsorbing irreversibly on spherical sites was determined as a function of the particle-to-site size ratio lambda. It was revealed that, by properly choosing lambda, a targeted site coordination can be achieved; for example, there can be one, two, three, and so forth particles attached to one site. The structure of the heterogeneous clusters produced in this way was described in terms of the pair correlation function. It was predicted that the extent of ordering within surface clusters was diminished as the concentration of sites increased. These theoretical predictions were checked by performing deposition experiments of negatively charged polystyrene latex particles (average diameter 0.9 mum) under the diffusion-controlled transport regime. Mica sheets precovered by positively charged polystyrene latex (average diameters 0.45 and 0.95 microm) were used as the substrate surface in these experiments. Positive latex (site) deposition was also carried out under diffusion-controlled transport conditions. The concentration of the sites and the adsorbed particles was determined by direct particle counting using optical microscopy. It was found, in quantitative agreement with theoretical simulations, that the structure of surface clusters produced in this way exhibits a significant degree of short-range ordering. It also was proven experimentally that clusters containing a targeted number of colloid particles (e.g., 2 and 4) could be produced by the deposition procedure.     

Bestimmung von Mikromengen Schwefel in Kupfer-,Silber-, Gold-, Zink-, Cadmium- und Quecksilbersulfiden mit Hilfe einer induzierten Reaktion von Natriumazid mit Jod

Zusammenfassung Feindisperser Schwefel induziert im Gegensatz zu praktisch unwirksamem, kristallinem Schwefel die Reaktion von Natriumazid mit Jod. Diese Tatsache wurde zum Zwecke der Bestimmung von Mikromengen Schwefel in Sulfiden der Metalle der Nebengruppen der I. und II. Gruppe des Periodensystems ausgenutzt. Zu diesem Zweck sind fünf Losungsmittel für Schwefel brauchbar. Die Methode ist genau, einfach in ihrer Durchführung und sensitiv.

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Determination of microamounts of sulfur in copper, silver, gold, zinc, cadmium and mercury sulfides with the aid of an induced reaction of sodium azide with iodine

Summary In contrast to practically ineffective, crystalline sulfur, finely dispersed sulfur induces the reaction of sodium azide with iodine. This fact was exploited for the purpose of determining microamounts of sulfur in sulfides of the metals of the side groups of the first and second group (I and II) of the periodic system. Five solvents for sulfur can be used for this purpose. The method is accurate, simple to perform and sensitive.

     

Dünnschichtcliromatographie der Glyceride

Zusammenfassung Die Trennung von Glyceriden auf Papier und auf Kieselgurplatten wurde verglichen. Dabei ergab sich die Überlegenheit der Dünnschichtchromatographie. Die präparative Trennung der Glyceride auf Dünnschichten wurde beschrieben.

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Summary The separation of glycerides on paper and on kieselguhr sheets was compared. The superiority of thin layer chromatography became apparent. The preparative separation of glycerides on thin layers is described.

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Résumé On a comparé la séparation des glycérides sur papier et sur couche de kieselguhr. On a mis ainsi en évidence la supériorité de la Chromatographie en couche mince. On a décrit la technique de séparation des glycérides sur couches minces.

     

Photometrische Bestimmung von Perchlorat mit Ferroin

Zusammenfassung Ein Verfahren zur photometrischen Bestimmung des Perchlorations wurde ausgearbeitet. Die Untersuchungslösung wird mit überschüssigem Ferroin und mit Chloroform versetzt. Der Niederschlag wird, abfiltriert und der Ferroinüberschuß im Filtrat photometrisch bestimmt. Für die Bestimmung kleiner Perchloratmengen zwischen 0,2 und 1 mg extrahiert man den gefärbten Ferroinperchloratkomplex mit n-Amylalkohol und photometriert die alkoholische Phase. Der Einfluß von Fremdionen auf die Analysenergebnisse wurde untersucht.

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Summary A method was worked out for the photometric determination of perchlorate ion. The test solution is treated with excess ferroin and chloroform. The precipitate is filtered off and the excess ferroin in the filtrate is determined photometrically. When slight amounts of perchlorate are to be determined, say between 0.2 and 1 mg, the colored ferroin-perchlorate complex is extracted withn-amyl alcohol and the alcoholic phase is photometerized. The effect of foreign ions on the analytical findings was studied.

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Résumé On a mis au point un procédé pour le dosage photométrique de l'ion perchlorate. On additionne la solution à l'étude de ferroine et de chloroforme. en excès. Le précipité est séparé par filtration et l'excès de ferroine dosé photométriquement sur le filtrat. Pour le dosage de petites quantités de perchlorate, entre 0,2 et 1 mg, on extrait le complexe coloré perchlorate de ferroine par l'alcooln-amylique et l'on effectue la photométrie sur la phase alcoolique. On a étudié l'influence des ions étrangers sur les résultats d'analyse.