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  • 1
    Electronic Resource
    Electronic Resource
    Olefin metathesis reaction (1972)
    s.l. : American Chemical Society
    Accounts of chemical research 5 (1972), S. 127-132 
    Details
    ISSN: 1520-4898
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ar50052a002
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  • 2
    Electronic Resource
    Electronic Resource
    Olefin metathesis. I. Acyclic vinylenic hydrocarbons (1968)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 90 (1968), S. 4133-4140 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01017a039
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on the low pressure polymerization of propylene using catalysts containing alkali metal alkyls (1959)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 40 (1959), S. 149-158 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The low pressure polymerization of propylene was investigated using catalysts prepared from alkali metal alkyls and titanium tetrachloride. In all cases the efficiency of the catalysts depended on the molecular ratio of the metal alkyl to the titanium tetrachloride. In general the polymerization conditions were similar to those for ethylene although the propylene polymerized much more slowly. With n-butyllithium-titanium tetrachloride, optimum molecular ratios were found between 1.8-2.5, with sharp drops on both sides. With amylsodium-titanium tetrachloride the optimum extended over a wide range (5.7-15), the activity decreasing sharply with lower molecular ratios. The catalysts prepared from sodium alkyls were more active than those prepared from lithium alkyls. Increasing yield was obtained on lowering the concentration of the catalyst. Up to a pressure of about 3 atmospheres, increase in the rate of polymerization was observed with increase in pressure; above this no influence of the pressure was observed. Isotactic polymers were isolated from the polymerization products by successive fractionation of the crude polymers in acetone, ether, and isooctane which dissolved the atactic polymers. With butyllithium-titanium tetrachloride catalysts, at and above optimum ratios, the isotactic fractions were about 60%. At lower ratios there was a great increase in atactic polymers. With amylsodium-titanium tetrachloride catalysts the isotactic fractions were about 70%. Phenylsodium-titanium tetrachloride catalysts were found to be very weak in the polymerization of propylene.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1959.1204013611
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  • 4
    Electronic Resource
    Electronic Resource
    Studies on the low pressure polymerization of ethylene using catalysts containing sodium alkyls (1958)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 33 (1958), S. 141-152 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The low pressure polymerization of ethylene with the use of catalysts prepared from various sodium alkyls and titanium tetrachloride was studied. Catalysts prepared from amylsodium were very active over a wide range of molar ratios of amylsodium to titanium tetrachloride (2-50); the activity decreased sharply with lower molar ratios. Rate of polymerization was found to decrease sharply, probably as a result of fusing of polyethylene particles to the catalyst surface during polymerization. Up to a pressure of about three atmospheres, the polymerization gave better yields with increase in pressure, but no increase in rate was observed on using higher pressures. Yields increased also with lowering of temperature; 0°C. gave the best yields. Molecular weight determinations showed that the polyethylenes produced had high molecular weights which did not vary over a wide range. With butylsodium, catalysts similar to those with amylsodium were formed; they showed a smaller optimum range (5-9) of molar ratios of alkyl sodium to titanium tetrachloride. Catalysts prepared from phenylsodium were much weaker, and the optimum molar ratio of phenylsodium to titanium tetrachloride, contrary to the other sodium alkyls, was found to lie at much lower molar ratios of alkyl sodium to titanium tetrachloride. Polymerizations were, in the case of phenylsodium, accompanied by an induction effect. Preliminary studies on the preparation of catalysts for the low pressure polymerization of ethylene in the presence of cyclopentadienylsodium and titanium tetrachloride were as yet not successful.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1958.1203312614
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  • 5
    Electronic Resource
    Electronic Resource
    Equilibrium ring-opening polymerization of mono- and multicyclic unsaturated monomersMain Lecture, Symposium M-14, IUPAC, Boston, July 1971XXIII IUPAC Symposium on Macromolecular Chemistry, Boston, 1971, (Abstracts of Papers, p. 222). (1972)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 154 (1972), S. 21-34 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Theorie der ringöffnenden Gleichgewichtspolymerisation wurde auf die Polymerisation von Cycloolefinen ausgedehnt. In früheren Arbeiten wurde die reversible Natur der Olefin-Metathese aufgezeigt, der Grundprozeß, nach dem Cycloolefine einer Ringöffnung unterliegen. Die vorliegende Arbeit bestätigt den reversiblen Charakter der Cycloolefin-polymerisation für Cyclopenten und Bicyclo-[4.3.0]-nona-3.7-dien. Die Daten des Reaktionsgleichgewichts der Polymerisation von Cyclopenten lassen eine Abschätzung der Enthalpie der Polymerisation (-4,4 kcal/Mol) und der Polymerisationsentropie (-14,9 cal/Mol·Grad) zu. Außerdem werden einige Faktoren diskutiert, die die Polymerisierbarkeit von mono- und multicyclischen Monomeren beeinflussen.
    Notes: Equilibrium ring-opening polymerization theory has been extended to cycloolefin polymerizations. Previous work had established the reversible nature of the olefin metathesis reaction, the basic process whereby cycloolefins undergo ring-opening. The present work confirms the reversible character of cycloolefin polymerization for the cases of cyclopentene and bicyclo[4.3.0]nona-3.7-diene polymerization. Equilibrium conversion data for cyclopentene polymerizations have provided estimates of the enthalpy (-4.4 kcal/mole) and entropy (-14.9 cal/mole·deg) of polymerization. In addition, some factors governing the polymerizability of mono- and multicyclic monomers are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1972.021540102
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  • 6
    Electronic Resource
    Electronic Resource
    Melting temperature of trans-polyoctenamer (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1283-1292 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of microstructure on crystallizability of polyoctenamers prepared by R3Al-WCl6 catalyst was studied. The results indicate that polyoctenamers with a broad range of trans-vinylene content do crystallize. The measured melting points are dependent on the trans-vinylene content. From the dependence of melting temperature on copolymer composition, a value of 73 ± 2°C. for the melting point and a molar heat of fusion ΔHu of 3520 cal./mole are calculated for 100% trans-polyoctenamer. From the melting point depression in the presence of diluent, a value for ΔHu of 4800 cal./mole is obtained.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.160050622
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanistische Aspekte der Olefin-Metathese (1976)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 88 (1976), S. 433-442 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In diesem Aufsatz werden Anschauungen über die Art des Übergangszustands bei der Olefin-Metathese diskutiert. Die früher angenommene paarweise Umordnung ist kürzlich angezweifelt worden. Metathese-Studien sowohl an acyclischen als auch an cyclischen Olefinen legen einen Kettenmechanismus nahe, bei dem die Umwandlung eines Carbens in einen Metallocyclus für die Umalkylidenierung verantwortlich sein könnte. Einige Katalysator-Systeme, die bei terminalen Olefinen nur eine niedrige Metathese-Aktivität zeigen, führen in Mischungen von terminalen Olefinen und Olefinen mit innenständiger Doppelbindung dagegen selektiv zu gekreuzten Produkten. Kritische Experimente zeigen, daß terminale Olefine bevorzugt einer schnellen regenerativen Metathese unterliegen. Einige Ergebnisse deuten darauf hin, daß die strengsten sterischen Anforderungen an das β-C-Atom gestellt werden; einleuchtende Gründe für diese sterische Forderung gibt es jedoch nicht.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19760881303
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  • 8
    Electronic Resource
    Electronic Resource
    Determination of the molecular weight distribution of polyisoprenes from the sol dependence on crosslinkingPresented, in part, at the American Chemical Society national meeting, New York, September 1963. (1965)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 3 (1965), S. 551-567 
    Details
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A polyisoprene with a narrow molecular weight distribution was prepared with a polyisoprenyl lithium catalyst by the “seeding” technique. Dicumyl peroxide was shown to be a quantitative crosslinking agent for this polyisoprene. The dependence of the sol fraction on the amount of crosslinking introduced by dicumyl peroxide vulcanization was determined and found to give excellent agreement with gel network formation theory. Two procedures for estimating the breadth of the molecular weight distribution from the sol dependence on crosslinking yield the value of 1.05 ± 0.05 for the ratio of the weight-average to number-average molecular weight for this polyisoprene. These results demonstrate that it is possible to determine the molecular weight and molecular weight distribution of polyisoprenes, containing cis-1,4, trans-1,4, or moderate amounts of 3,4 addition structures, from the sol dependence on the amount of dicumyl peroxide used in crosslinking. Temporary or permanent molecular chain scission that might accompany the crosslinking by dicumyl peroxide was negligible, as there was no evidence of broadening of the molecular weight distribution due to scission. For the most likely set of recombination reactions that might occur it is estimated that less than 0.3% of the dicumyl peroxide is used in reactions leading to temporary molecular chain scission.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1965.100030212
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  • 9
    Electronic Resource
    Electronic Resource
    Ring-opening polymerization of unsaturated alicyclic compounds (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 2209-2217 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ring-opening polymerizations of cyclooctene, cyclododecene, 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, 3-methylcyclooctene, and 3-phenylcyclooctene have been carried out by using a two-component catalyst system composed of ethylaluminum dichloride and tungsten hexachloride. NMR and infrared analyses of the respective polymers indicate structures which are consistent with a ring-cleavage mode of propagation. No evidence for double-bond shifts or transannular reactions during the polymerizations of 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, 3-methylcyclooctene, and 3-phenylcyclooctene was found. The polymerizability of substituted, unsaturated, mediumsized alicyclic monomers suggests a convenient method for synthesis of certain perfectly alternating terpolymers. Since polymerizations occurred rapidly with little evolution of heat, it was concluded that entropy is a substantial contributor to the free energy of the ring-opening polymerization of medium-sized, unsaturated alicyclic monomers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050901
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  • 10
    Electronic Resource
    Electronic Resource
    Polymerization of propylene oxide with a dialkylzinc-hydrazine catalyst (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 917-919 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050417
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