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  • 11
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Halosilane Adducts. XIV. Neutral Ligand Complexes of Silicon Containing Six N-Donor Atoms[Si · 3 bipy]4+ is obtained in high yield by the oxidation of Si · 3 bipy with the halogens. [Si · 3 bipy]I4 may also be prepared by directly reacting SiI4 and bipy in the melt. Phen and SiI4 yield [Si · 3 phen]I4 under the same conditions. Mimi and vimi and dimi react with SiI4 in CHCl3 to give [Si · 6 L]I4 (L = mimi, vimi) and [Si · 3 dimi]I4. Thiazole and pyridine and 4-dimethylaminopyridine, on the other hand, yield 1:4 complexes, isoxazole does not react at all. The complex stoichiometry is dependant on the basicity and the structure of the ligands. The 1:4 complexes are easily hydrolysed whereas the N-hexacoordinated complexes are very resistant against solvolysis. They are soluble in water without decomposition. Spectroscopic investigations (i.r., u.v., 1H-nmr) prove the presence of octahedral complex cations of the charge +4 according to the given formulae for the solid and dissolved compounds. Complete anion-exchange is possible. Using ion-exchangers the complexes [Si · 6(3)L](ClO4)4 are obtained.
    Notes: [Si · 3 bipy]4+ wird in hoher Ausbeute durch Oxydation von Si · 3 bipy mit Halogen erhalten. Die Darstellung von [Si · 3 bipy]I4 gelingt auch durch direkte Reaktion von SiI4 und bipy in der Schmelze. Mit phen wird unter gleichen Bedingungen [Si · 3 phen]I4 gebildet. 1-Methyl(Vinyl)-imidazol (mimi, vimi) und 1,1′-Dimethyl-2,2′-diimidazol (dimi) reagieren mit SiI4 in CHCl3 zu [Si · 6 L]I4 (L = mimi, vimi) und [Si · 3 dimi]I4. Mit Thiazol, Pyridin und 4-Dimethyl-aminopyridin werden 1:4 Komplexe, mit Isoxazol keine Reaktion erhalten. Die Komplexstöchiometrie hängt von Basizität und Struktur der Liganden ab. Die 1:4 Komplexe sind hydrolyseempfindlich, die N-hexakoordinierten Komplexe sehr solvolysebeständig. Sie sind unzersetzt in Wasser löslich. Spektroskopische Untersuchungen (IR, UV, 1H-NMR) weisen für die festen und gelösten Titelverbindungen oktaedrische Komplexkationen der Ladung 4+ entsprechend den gegebenen Formeln nach. Über Ionenaustauscher ist vollständiger Anionenaustausch möglich. Mit dieser Methode werden die Komplexe [Si · 6(3)L](ClO4)4 dargestellt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 64 (1992), S. 870-871 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 2 (1947), S. 21-35 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A polyvinyl acetate polymer of medium viscosity was fractionated into sixteen fractions (first series) and three of the larger of these further separated into twenty subfractions (second series). The intrinsic viscosities and the osmotic pressure molecular weights were determined at 25°C. and the relation between them was found to be expressed by the equations: first series: [η] = (1.88 × 10-4) M0.69; second series: [η] = (1.76 × 10-4) M0.68. The data indicate that little, if any, increase in homogeneity is to be expected by further successive fractionations and that the equations applicable to the second fractionation series are representative of essentially homogeneous polyvinyl acetates in acetone. An equation applicable to fractionated and unfractionated vinyl acetate polymers is described that is useful in obtaining the intrinsic viscosity from a single viscosity measurement. Several unfractionated materials from different sources were also studied and the calculated ratios of the viscosity-average to the number-average molecular weight indicate that the degree of heterogeneity of chain-length distribution increases with increasing average molecular weight.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 542-542 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton-NMR. spectra of amino- and hydroxypyrimidines including biologically important bases have been measured in four solvents: CF3COOH, CF3COOH—SO2, FSO3H and FSO3H—SbF5-SO2 at 27° and -55°C. In CF3COOH mono-cations are formed, whereas in FSO3H and FSO3H—SbF5-SO2 double protonation occurs. In each case the structures of the protonated species are derived from the chemical shifts of CH, NH and OH protons and proton-proton spin coupling constants. A combination of the measurements described leads to a complete assignment of all proton resonances of the protonated pyrimidines. This approach is also recommended for the structural determination of heterocyclic compounds.
    Additional Material: 7 Ill.
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  • 16
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton NMR. spectra of purine, adenine, guanine and methylsubstituted guanines have been measured in CF3COOH, FSO3H and FSO3H—SbF5—SO2 at 27° and low temperatures. These conditions permit to study multiple protonation of purines, using chemical shifts of CH, NH and OH protons. The spectra of mono-, di- and tri-cations are described and fully assigned.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 64 (1848), S. 293-293 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 18
    ISSN: 0268-2605
    Keywords: siloxanes ; carbohydrate modified ; surfactants ; saccharide ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New siloxanyl-modified carbohydrate surfactants of the amide and glycoside type have been synthesized by coupling between defined as well as higher-molecular-weight siloxanes and carbohydrate structures via spacers of different lengths and hydrophilic power. Linear and branched monohydrogen di-, tri-, tetra- and penta-siloxanes and polyhydrogen siloxanes as well as mono- and di-saccharide lactone structures have been found to be good starting materials for the synthesis of amides, often in quantitative yield, whereas glycosides had to be prepared in low-yield multistep sequences including protection/deprotection steps. Selected strategies were applied to polysiloxanes yielding quantitatively a broad variety of carbohydrate-modified comb-like structures. The new substances were characterized by means of 13C NMR spectroscopy, GC, capillary GC, GC-MS coupling and elemental analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 437-450 
    ISSN: 0268-2605
    Keywords: siloxanes ; surfactant ; carbohydrate ; amino ; regioselective ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Branched siloxanyl-modified carbohydrate surfactants have been synthesized by coupling mono-, di- and poly-functional siloxanes to carbohydrate units either via a branched spacer or by attaching a separate modifying element to a straight-chained structure. Hydrophilic as well as extremely hydrophobic elements have been incorporated successfully. Siloxanyl-modified carbohydrates bearing a secondary amino function were alkylated in regioselective reactions by different epoxides ranging from glycidol- to siloxanyl-modified allyl glycidyl ether derivatives. Alternatively, carbohydrate-modified piperazinyl structures yielded cyclic subunits after alkylation. Structures bearing two identical hydrophilic groups are accessible by alkylation of carbohydrate-modified bisamides. The derivatives synthesized were characterized by means of GC, NMR and elemental analysis.
    Additional Material: 6 Ill.
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  • 20
    ISSN: 0268-2605
    Keywords: surfactants ; carbohydrate ; carbosilane ; silane ; wetting ; surface tension ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of carbohydrate surfactants bearing carbosilane, silane, polysilane and non-permethylated siloxane moieties is described. These surfactants consist of three structural elements: (1) a silicon-containing moiety, (2) a spacer and (3) a carbohydrate unit. Additionally two different types of mixed structures have been synthesized: (a) single-chained carbosilane-siloxane surfactants and (b) double-chained combinations of carbo- silanes, silanes and siloxanes. The wetting behaviour of the key intermediates, the allyl glycidyl derivatives, has been investigated by static surface tension (γlv, σ) and wetting tension (γsv-γsl, α) measurements on a non-polar perfluorinated surface (FEP® plate). The contact angles obtained for these pure liquids are not a linear function of the surface tension but depend on the polarity of the substructures. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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