Quantenchemische Untersuchung der Reaktionsfähigkeit von π-Elektronen-Systemen in angeregtem Singulett- und Triplettzustand

Zusammenfassung Anhand der Methode der Konfigurationenwechselwirkung wurde die Ladungsdichteverteilung in einer Reihe von aromatischen Aminen und N-haltigen Heteroaromaten im angeregten Singulett- und Triplettzustand untersucht. Durch die Untersuchungen wurde die Formulierung der folgenden Regel ermöglicht: im angeregten Singulett- und Triplettzustand ist die Basizität bei den Aminen wesentlich vermindert; die N-haltigen Heteroaromaten weisen im angeregten Singulettzustand eine erhöhte Basizität auf, und im Triplettzustand tritt eine Verminderung der Basizität ein.

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The electron density distribution in excited singlet and triplet states of a number of aromatic amines and heterocyclic compounds containing nitrogen atoms is studied using the CI-method. The investigation allows the formulation of the following rule: in excited singlet and triplet states the amines possess significantly reduced basicity; the nitrogen heterocyclic compounds in excited singlet states increase their basicity, whereas in excited triplet states their basicity is decreased.

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Résumé Au moyen de la méthode d'interaction de configuration, on a étudié la répartition de la densité électronique dans un certain nombre d'aminés aromatiques et de composés hétérocycliques azotés dans l'état excité singulet et triplet.Les études effectuées ont permis d'établir la règle suivante: à l'état excité singulet ou triplet la basicité des aminés est sensiblement réduite; la basicité des composés N-hétérocycliques augmente dans l'état excité singulet et diminue dans le triplet.

     

Chloridionenübergänge in Phenylphosphoroxychlorid, 3. Mitt.: Konduktometrische Untersuchungen

Zusammenfassung Leitfähigkeitsmessungen an Et₄NCl-Lösungen zeigen die Gültigkeit derBjerrumschen Theorie in PhPOCl₂; die Dissoziationskonstante beträgt 1,5·10^–2. FeCl₃ verhält sich nicht wie eine Ionenverbindung, doch ähnlich wie in POCl₃. Zur Verfolgung von Ionenreaktionen wurden konduktometrische Titrationen ausgeführt. ZnCl₂ und AlCl₃ geben 2 Chloridionen, BCl₃, TiCl₄, SnCl₄ und PCl₅ je 1 Chloridion an die Akzeptoren FeCl₃ oder SbCl₅, ab. In Gegenwart von polaren Chloriden nehmen BCl₃, AlCl₃, FeCl₃, PCl₅ und SbCl₅ je 1 Chloridion, ZnCl₂, TiCl₄ und SnCl₄ je nach Angebot 1 oder 2 Chloridionen auf. Sowohl die Chlorometallate, als auch die Chloroniumverbindungen sind im gleichen Ausmaß wie Et₄NCl ionisiert.Mit 4 Abbildungen2. Mitt.:M. Baaz, V. Gutmann, M. Y. A. Talaat undT. S. West, Mh. Chem.92, 150 (1961).Herrn Prof. Dr.L. F. Audrieth zum 60. Geburtstag gewidmet.     

Cycloaddition of carbonyl compounds on Si(100): new mechanisms and approaches to selectivity for surface cycloaddition reactions

Density functional theory has been used to explore cycloaddition reactions of organic molecules containing carbonyl functional groups on the Si(100) surface. As with other pi bonds, carbonyl groups can add to the surface by a [2+2] cycloaddition with negligible activation barrier, as previously shown through experiment. However, the present calculations indicate that 1,2-dicarbonyls, such as glyoxal, may also react by means of a [4+2] addition to form a hetero-Diels-Alder product in which the organic ring stands normal to the surface. Calculations of [2+2] and [4+2] pathways indicate that both reactions proceed without significant barriers. This reactivity is analogous to that of conjugated dienes, in which evidence for both reactions has been observed. In contrast to unsaturated alkyl systems, which must react through the pi electron system, the reactions of carbonyls may proceed through a very different mechanism, in which the initial surface interaction is through the oxygen lone pair. The presence of lone pairs affects the geometry of the [4+2] adduct, and may alter the competition between [2+2] and [4+2] addition. Some potential rearrangement reactions of the initial binding products are described. Recent experimental studies of a 1,2-dicarbonyl on Si(100) are reinterpreted in light of these calculations, and found to be consistent with the presence of the [4+2] adduct. Finally, some molecules are suggested as cycloaddition reagents for experimental tests of the conclusions presented here.     

Assessment of the retention properties of poly(vinyl alcohol) stationary phase for lipid class profiling in liquid chromatography

Potentialities of polymerized vinyl alcohol on silica gel were assessed for class separation of simple lipids, sphingolipids, glyceroglycolipids and phospholipids by high-performance liquid chromatography. A screening of pure solvents in binary gradient elution and a chemometric approach was used to define a rugged two segment linear gradient formed from four solvents for total lipid class separation. Triethylamine and formic acid were added in all mobile phase components for acidic phospholipid separation and evaporative light scattering response enhancement. Simple analytical procedures are described for the analysis of complex lipid materials.     

New Synthetic Approaches to Functionally Substituted 4,5-Dihydro-1,2,3-oxadiazole 2-Oxides

A practical procedure has been proposed for the synthesis of functionally substituted 4,5-dihydro-1,2,3-oxadiazole 2-oxides on the basis ofsulfamic acid derivatives.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 121–123.Original Russian Text Copyright © 2005 by Tartakovskii, Ermakov, Strelenko, Vinogradov, Petrov.     

Synthesis of N-substituted 2-benzoxalones

3-Acetylaminomethyl-2-benzoxazolones are obtained by Beckmann rearrangement of the anti-oximes of 3-acetonyl-2-benzoxazolones. The isomeric 3-(N-methylcarbamoylmethyl)-2-benzoxazolones are synthesized by alkylation of 2-benzoxazolone with chloroacetic acid, followed by reaction of the 3-carboxymethyl-2-benzoxazolones obtained with thionyl chloride and methylamine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1185–1188, September, 1985.     

Copolymers of the C9 hydrocarbon fraction of liquid pyrolysis products with maleic anhydride and their esterification products as additives to paper pulp

The influence exerted by copolymers of the C₉ fraction of liquid pyrolysis products of petroleum raw materials with maleic anhydride and by their esterification products, added to paper pulp, on the main paper properties was examined.     

MONOFUNCTIONAL3,4-and4',5'-PHOTOCYCLOADDUCTS BETWEEN 4,5'-DIMETHYLANGELICIN and THYMINE

By irradiating (365 nm) an aqueous liquid solution of 4,5'-dimethylangelicin. a monofunctional photosensitizing furocoumarin, in the presence of an excess of thymine, two new compounds, I and II, have been obtained; they do not show fluorescence when observed with Wood's light. The nuclear magnetic resonance data, the marked similarity of UV absorption and fluorescence spectra of these compounds with those of synthetic 3.4-dihydro-4,5'-dimethylangelicin and their capacity to undergo photodissociation (254 nm) yielding the starting thymine and 4,5'-dimethylangelicin in equimolecular amounts, are consistent with C₄-cycloadducts between the 3,4-double bond of the furocoumarin and 5,6-double bond of thymine. Nuclear magnetic resonance data indicate for I and II a head-to-head and a head-to-tail structure, respectively. When irradiation is carried out in the frozen state, two adducts. III and IV, fluorescent at Wood's light, have been obtained other than the two above-mentioned compounds I and II. Compounds III and IV have been identified as 4'.5'-fluorescent adducts between the 4',5'-double bond of the furocoumarin and the 5.6-double bond of thymine; one of them (III) is identical to that formed in the photoreaction between DNA and 4,5'-dimethylangelicin; for this last compound a cis head-to-head structure has been suggested.     

Temperature-programmed reduction and oxidation of bimetallic Pd?Ni/Al2O3 catalysts

Temperature-programmed reduction and oxidation of bimetallic catalysts Pd–Ni/Al₂O₃ seem to indicate phase segregation of palladium and nickel oxides and alloying of palladium and nickel in the process of reduction of oxidized catalysts.

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- Pd–Ni/Al₂O₃ , .

     

Tandem purification of mouse IgM monoclonal antibodies produced in vitro using anion-exchange and gel fast protein liquid chromatography

A tandem chromatographic procedure was used to isolate rapidly mouse IgM monoclonal antibodies produced by cultivation of hybridomas in vitro. Hybridoma culture supernatants containing mouse IgM monoclonal antibodies were first chromatographed on an anion-exchange Mono Q column connected to a fast protein liquid chromatography system. This anion-exchange step offers the advantage of obtaining IgM antibodies in a concentrated form. The IgM-rich fractions from the Mono Q column were then injected on a gel filtration Superose 6 column equilibrated with a low-ionic strength buffer and eluted with a high-ionic strength buffer. Assessment of the purity of isolated IgM monoclonal antibodies was performed by sodium dodecyl sulphate polyacrylamide gel electrophoresis together with a Coomassie Brillant Blue R 250 staining technique. Assessment of the immunoreactivity of isolated IgM monoclonal antibodies was performed by an enzyme linked immunosorbent assay using a solid phase adsorbed antigen against which IgM monoclonal antibodies were directed. The chromatographic procedures described allows the rapid isolation of mouse IgM monoclonal antibodies produced in vitro at a high degree of purity and in an immunoreactive state.