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  • Wiley-Blackwell  (920)
  • 1965-1969  (484)
  • 1960-1964  (298)
  • 1950-1954  (64)
  • 1935-1939  (74)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 76 (1964), S. 794-795 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 80 (1968), S. 620-620 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 52 (1961), S. 317-323 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To elucidate some details of the mechanism of isoprene polymerization by means of the complex catalyst TiCl4 + Al(i-C4H9)3 an analysis has been made of the data on the molecular weight distribution of the polymers. A relation has been established between the heterogeneous character of the polymerization process and the degree of dispersity of the polymer. In particular, it has been shown that for very small catalyst particles polymerization proceeds slowly and is a nonstationary process. The molecular weight distribution of the polymers changes with time. On increasing the catalyst particle size above certain, critical dimensions required for carrying out heterogeneous catalysis, a stationary molecular weight distribution of the polymers sets in, remaining unchanged up to the end of the process. An investigation of the molecular weight distribution of the polymers obtained at various catalyst component ratios and various methods of addition to the monomer permitted a number of details of the chain termination mechanism in catalytic polymerization to be elucidated. Chain breaking has been shown to be not the result of reversible interaction of growing chains with the active centers on the surface.
    Additional Material: 3 Ill.
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  • 4
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal degradation of epoxy resins was studied in a static system over the temperature range 300-450°C. The reaction proceeds without an induction period, the initial rate being maximum. The rate W increases with temperature according to the law W = Ae-E/RT. The effective activation energy was 35 kcal./mole. The reaction products consist of gases, a resinous liquid, and a solid residue. The liquid has practically the same spectral characteristics in the infrared as the initial epoxy compound. In the infrared spectrum of the residue the bands characteristic of the epoxy group are absent. Water and formaldehyde were found among the liquid products. Methane and carbon monoxide were found in large amounts by means of a chromatographic method. In the thermal degradation of the unhardened epoxy resin the low molecular fraction volatilizes, and the high molecular fraction degrades liberating the radical which isomerizes and decomposes to CO and ĊH3. The methyl radical abstracts a hydrogen atom from the polymer and is converted to methane. The RO—ĊH2 radical formed on liberation of the epoxy group yields formaldehyde. Among the gaseous products formed in the thermal degradation of the epoxy resin hardened by polyethylene polyamine (PEPA) were found H2, CO, CH4, C2H6, C2H4, C3H6, and C3H8. Ethane, ethylene, propylene, and propane are possibly produced by decomposition of the PEPA radical. The thermooxidative degradation of epoxy resins was investigated in a static system. The reaction was shown to be of the degenerate branching chain type. The dependence of the induction period on the oxygen pressure and on the temperature was determined.
    Additional Material: 5 Ill.
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  • 5
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polycarbonates, in particular poly-4,4′-bis(hydroxyphenyl)-2,2-propane carbonate, are distinguished by their thermal stability and may be processed at temperatures about 300°. The present report deals with some chemical conversions of this polymer, taking place in solution and in the molten state. In the fractional precipitation of the polymer from chloroform solutions by methyl alcohol an enhanced yield in the low molecular fraction is observed, the latter continually forming even on repeated precipitation. If a small amount of methanol, insufficient to precipitate the polymer, is added to the chloroform solution, a gradual fall in viscosity (which does not occur in absence of the alcohol) is observed. The reaction is accelerated in the presence of hydrogen chloride. Such precipitants as acetone and petroleum ether do not cause this effect. Alcoholysis is a characteristic reaction of the polycarbonates, taking place at a relatively high rate. An alcoholic solution of alkali will decompose the polycarbonate at room temperature and especially rapidly (within a few minutes) on boiling. In this way one may obtain with high yield bisphenol used for the synthesis of the polymer. The melting of polydisperse polycarbonates (ca. 300°) in the absence of atmospheric oxygen leads to a very rapid (10-60 min.) levelling of the molecular chain lengths and hence to decrease in polydispersity (according to fractional precipitation data), causing a corresponding fall in the viscometrically determined molecular weights. Such levelling annuls the harmful effect of the low molecular fractions on the properties of the material. At higher temperatures (350°) decarboxylation (evolution of CO2) is quite marked, and the formation of a certain amount of three-dimensional polymer may be observed. Polycarbonates prepared by the heterophase polycondensation of phosgene with phenolates, for instance, 4,4′-bis(hydroxyphenyl)-2,3-propane and containing hydroxyl and acyl chloride endgroups are capable of undergoing further polycondensation on heating to 270-300°C. for 30-60 min. or more. Hydrogen chloride is evolved. As a result the mean viscometric molecular weight may increase three- to fourfold in comparison with the initial compound. Additional polycondensation in the melt may also proceed by another pathway, without hydrogen chloride evolution but as the result of the elimination of a certain amount of 4,4′-bis(oxyphenyl)-2,2-propane on endgroup interaction. This reaction is catalyzed by small quantities of titanium alcoholates. The high lability of the ester links in polycarbonates may also be illustrated on the example of the interaction between these polymers and other esters, in particular with polybis(phenyl)-2,2-propane terephthalate [—OC6H4—C(CH3)2C6H4—O—CO—C6H4—CO—O]. The reaction taking place without catalyst at temperatures above 300° results in a mixed polyster carbonate with composite properties.
    Additional Material: 7 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 358 (1968), S. 90-96 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The ternary compounds with the structure of the NaZn13 type were found in the course of the X-ray investigation of the systems lanthanum-nickel-silicon (∼ LaNi10.5Si2.5, a = 11.27-11.35 Å) and lanthanum-iron-silicon (∼ LeFe11.5Si1.5, a = 10.51-10.52 Å); one can regard these compounds as the members of two isoelectronic series, one beginning with LaZn13 and other with LaCo13. The ternary phases of the NaZn13 type in the systems lanthanum-cobalt-silicon and lanthanum-cobalt-aluminium are solid solutions based on LaCo13. Compounds of the NaZn13 type are formed also in the systems cerium-cobaltsilicon (Ce(Co, Si)13, a = 11.36 Å), praseodymium-cobalt-silicon (∼ PrCo10.5Si2.5, a = 11.28 Å) and neodymium-cobalt-silicon (∼ NdCo10.5Si2.5, a = 11.24 Å).
    Notes: Die ternären Verbindungen vom NaZn13-Typ wurden bei der röntgenographischen Strukturuntersuchung der Systeme Lanthan-Nickel-Silicium (∼ LaNi10,5Si2,5, a = 11,27 bis 11,35 Å) und Lanthan-Eisen-Silicium (∼ LaFe11,5Si1,5, a = 10,51-10,52 Å) gefunden; diese Verbindungen kann man als Glieder der isoelektronischen Reihen, die mit LaZn13 bzw. LaCo13 beginnen, ansehen. Die ternären Phasen von demselben Typ in den Systemen Lanthan-Kobalt-Silicium und Lanthan-Kobalt-Aluminium sind LaCo13-Mischkristalle. Die Verbindungen vom NaZn13-Typ bilden sich auch in den Systemen Cer-Kobalt-Silicium (Ce(Co, Si)13, a = 11,36 Å), Praseodym-Kobalt-Silicium (∼ PrCo10,5Si2,5, a = 11,28 Å) und Neodym-Kobalt-Silicium (∼ NdCo10,5Si2,5, a = 11,24 Å).
    Additional Material: 4 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 344 (1966), S. 95-101 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The existence of the ternary compounds R3Ni6Si2 (R = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tu, Yb, Lu) with the superstructure of the Ca3Ag8 type has been established by means of X-ray diffraction analysis. The lattice constants are given. The atoms in the Ce3Ni6Si2 structure have the following positions (space group Im3m—Oh9): 12 (e) x 0 0 with x = 0.280, 24 Ni in 24 (h) 0 x x with x = 0.670, 8 Si in 8 (c) 1/4 1/4 1/4.
    Notes: Die Existenz der ternären Verbindungen R3Ni6Si2 (R = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tu, Yb, Lu) mit der Überstruktur des Ca3Ag8-Typs wurde röntgenographisch festgestellt. Die Gitterkonstanten sind in Tab. 2 zusammengefaßt. Die Atome in der Ce3Ni5Si2-Struktur besetzen folgende Lagen (Raumgruppe Im3m—Oh9): 12 Ce in 12 (e) x 0 0 mit x = 0,280, 24 Ni in 24 (h) 0 x x mit x = 0,670, 8 Si in 8 (c) 1/4 1/4 1/4.
    Additional Material: 3 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 7 (1968), S. 618-618 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 1203-1221 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper deals with some new methods for synthesis of the polymeric semiconductors by conjugated reactions and also with electrophysical properties of the polymers. Elimination of hydrogen halides from α,β-dihalo derivatives by bases (calcium oxide or tertiary amines) yields polymers with conjugated bonds. The reaction proceeds at 200-300°C. under atmospheric or elevated pressures, acetylenes being the intermediates. α,β-Dihalo compounds with calcium carbide above 150°C. produce polyacetylenic copolymers by elimination of two moles of hydrogen halide, also by generating acetylene from calcium carbide. The identical reaction (elimination of water) was observed between carbonyl compounds and calcium carbide. Elimination of water from monoand bifunctional phenols in the presence of zinc chloride under pressure above 200°C. yields polyphenylenes and polyhydroxyphenylenes, dehydrobenzene (benzyne) and hydroxybenzyne being intermediates. The polyhydroxyphenylenes prepared have a degree of polymerization from 4-5 to several thousand and are of interest as intermediates for thermostable resins, inhibitors etc. Linear polycyanamide and polycyanic acid were first prepared by polycondensation of urea with ammonium bicarbonate in the presence of zinc chloride. Analogous polymers were obtained from the ring-opening polymerization of melamine and cyanuric acid. The polymers show good semiconductor and ion-exchange properties. Polycondensation of ketones with ammonium bicarbonate also gave conjugated polymers. Thus, organometallic polymers were prepared from acetyl- and diacetyl ferrocene. We have also studied electrophysical, magnetic, and catalytic properties of the conjugated polymers prepared by the new methods. The electrical conductivity of the best specimens ranged from 10-3 to 10-6 ohm-1 cm.-1; the number of electrons unpaired was 1018-1019 spins/g.
    Additional Material: 1 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 2972-2976 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Am Stickstoff nicht substituierte Ketimine reagieren mit Phosgen zu N-Chlorcarbonyl ketiminen (1), die mit α-Chlor-alkylisocyanaten im Gleichgewicht stehen. Die Umsetzung von 1 mit Alkoholen und primären Aminen führt zu den Verbindungen 3-6, Derivaten der zwei tautomeren Formen. N-Fluorcarbonyl-ketimine liegen nach IR-und 19F-NMR-Spektren vollständig in der Struktur 2 vor, reagieren aber mit primären Aminen zu Derivaten beider Tautomeren.
    Additional Material: 2 Tab.
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