ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1970-1974  (54)
Collection
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 94 (1972), S. 3633-3635 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 92 (1970), S. 6548-6553 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    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 protonenentkoppelten 13C-Kernresonanzspektren (natürliche Isotopenhäufigkeit) des äquibinären (cis-1,4 - 1,2)-Polybutadiens wurden gemessen. Alle Resonanzen im aliphatischen Bereich wurden zugeordnet; hierbei wurden geschätzte Korrekturterme für die chemischen Verschiebungen im vorliegenden System zusammen mit den GRANTschen Parametern verwendet. Für jeden Peak wurde außerdem angegeben, ob er zu einer Diade oder Triade von cis-1,4- und 1,2-Einheiten gehört. Die gemessenen relativen Intensitäten der Peaks stimmten mit den berechneten Intensitäten überein; der Rechnung wurde eine regellose Verteilung der cis-1,4- und der 1,2-Einheiten zugrunde gelegt. Die gaschromatographische Analyse der Ozonolyseprodukte der Polymere zeigte ebenfalls eine regellose Verteilung der beiden Einheiten an.
    Notes: The proton decoupled natural abundant 13C-NMR spectra of equibinary (cis-1,4 - 1,2)-polybutadiene were measured. Assignments of spectra were made for all peaks of the aliphatic range using chemical shift corrective terms estimated for the present system together with GRANT's parameters. Each peak was interpreted in terms of the diad or triad of cis-1,4 and 1,2 units. The relative intensities of the peaks were in good agreement with the calculated ones from the random assumption with respect to the distribution of cis-1,4 and 1,2 units. The gas-chromatographic analysis of the ozonolysis product of the polymers also showed that the sequence distribution of cis-1,4 and 1,2 units was random.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    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: Das Verhalten von Hydridonickel-Koordinationsverbindungen als Katalysatoren der Oligomerisation und Polymerisation von Butadien in verschiedenen Lösungsmitteln wurde untersucht. In Gegenwart von Alkohol katalysiert Bis(tricyclohexylphosphin)chlorhydridonickel (4, X = Cl) (HNiCl[P(C6H11)3]2) die lineare Dimerisation. Mit Hydridotetrakis(phosphit)-nickel(1+) (2) ([HNi{P(OR)3}4]+), das durch Reaktion von Tetrakis(phosphit)nickel (1) (Ni[P(OR)3]4) mit Trifluoressigsäure dargestellt wird, erfolgt in sec-Alkohol Dimerisation, nicht dagegen in tert-Alkohol. Das Hauptprodukt ist 2-Methlenvinylcyclopentan (8). Weitere Produkte sind 4-Vinylcyclohexen (10), 1,5-Cyclooctadien (5), 1,3,7-Octatrien (7) und 1,3,6-Octatrien (9). Die mit anorganischen Säuren dargestellte Hydridonickel-Koordinations-verbindung ergibt keine Dimeren, sondern das 1,4-trans-Polymere.
    Notes: The behavior of hydridonickel coordination compounds as catalysts for the oligomerization and polymerization of butadiene in various solvents was studied. In the presence of alcohol bis(tricyclohexylphosphine)chlorohydridonickel (4, X = Cl) (HNiCl[P(C6H11)3]2) catalyzes the linear dimerization. With hydridotetrakis(phosphite)nickel(1+) (2) ([HNi{P(OR)3}4]+), which is prepared from tetrakis(phosphite)nickel (1) (Ni[P(OR)3]4) and trifluoroacetic acid, dimerization occurs in sec-alcohol but there is no reaction in tert-alcohol. The main product is 2-methylenevinylcyclopentane (8). The other products are 4-vinylcyclohexene (10), 1,5-cyclooctadiene (5), 1,3,7-octatriene (7) and 1,3,6-octatriene (9). The hydridonickel coordination compound, prepared with inorganic acids, does not afford the dimers but the 1,4-trans polymer.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 170 (1973), S. 247-249 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 155 (1972), S. 185-196 
    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: Nitro-Verbindungen erwiesen sich in Verbindung mit Dialkylzink- oder Trialkylaluminium-Katalysatoren als wirksame Cokatalysatoren für die Polymerisation von Alkylenoxiden wie Äthylenoxid, Propylenoxid, Styroloxid, Allylglycidyläther und Phenylglycidyläther. Das System Dialkylzink/Nitromethan zeigt eine hohe katalytische Aktivität und liefert ein Polymeres mit außerordentlich hoher Viskositätszahl, die z. B. bei Polyäthylenoxid 32 dl/g beträgt. Zur Aktivierung dieses Systems ist eine Wärmebehandlung bei 100°C erforderlich, der entstehende Katalysator ist jedoch temperaturstabil. Während der Wärmebehandlung reagiert Nitromethan mit Diäthylzink unter Entwicklung gasförmigen äthans, Ausbildung einer Zink-Sauerstoff-Bindung und Entstehung von Zinkmethazonat. Gasanalyse, IR- und NMR-spektroskopische Untersuchungen zeigen, daß der Katalysator zusätzlich zu der für die katalytische Aktivität verantwortlichen äthyl-Zink-Bindung eine Zink-Sauerstoff-Bindung besitzt. Der Katalysator ähnelt dem System Diäthylzink/Wasser, besitzt jedoch größere Temperaturstabilität und auf Grund des Fehlens eines beweglichen Wasserstoffs im Cokatalysator eine längere Lebensdauer während der Polymerisation.
    Notes: Nitro-compounds were found to be suitable as cocatalysts for the polymerization of alkylene oxides, such as ethylene oxide, propylene oxide, styrene oxide, allylglycidyl ether, and phenylglycidyl ether when they were used with dialkylzinc or trialkylaluminum catalysts. The nitromethane/diethylzine system exhibits a high catalytic activity to give a polymer of extraordinary high intrinsic viscosity as high as 32 dl/g for ethylene oxide. The system requires heat-treatment at 100°C for activation, but the resulting catalyst is heat-stable. During heat-treatment nitromethane reacts with dialkylzine evolving ethane gas to give a zinc-oxygen linkage together with zinc methazonate. Gas analysis, IR, and NMR studies confirm that the catalyst contains a zinc-oxygen linkage in addition to the ethyl-zinc bond responsible for catalyst activity. The catalyst resembles the diethylzinc/water system, but the catalyst is more heat-stable and has a longer life-time in the polymerization due to the lack of mobile hydrogen in the cocatalyst.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 155 (1972), S. 197-210 
    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: Verschiedene, gut definierte Alkylmonoalkoxide tertiärer Carbinole wie äthylzinktriphenylmethoxid (EtZnTPC), Äthylzinkdiphenylmethylmethoxid (EtZnDPC), äthylzinkdimethylphenylmethoxid (EtZnMPC), (+)-2-Methylbutylzinktriphenylmethoxid (AmZnTPC), (+)-2-Methylbutyldiphenylmethylmethoxid (AmZnDPC) und (+)-2-Methylbutylzinkdimethylphenylmethoxid (AmZnMPC) wurden dargestellt; sie erwiesen sich als aktive Katalysatoren für die Polymerisation von Propylenoxid.Die katalytische Aktivität der äthylzink-tert-alkoxide wird stark durch die Polarität der entsprechenden tert-Alkylgruppe beeinflußt; sie nimmt in der Reihenfolge EtZnMPC 〈 EtZnDPC 〈 EtZnTPC zu und geht somit Hand in Hand mit der nach der HAMMETT schen Indikatormethode abgeschätzten Säurestärke, die in derselben Richtung zunimmt. In ähnlicher Weise bestehen Zusammenhänge sowohl zwisclien der LEWIS-Acidität und der Abnahme des Aggregationsgrades, die ihrerseits in einer liearen Beziehung zu der polaren σ*-Substitucnten-Konstante der tert-Alkylgruppe stehen, als auch der chemisclien Ver-schiebung der Protonenresonana der α-Methylengruppc des an das Zinkatoni gebundenen Athylrests des betreffenden Monoalkoxids.Mit Hilfe von Alkylzinkalkoxiden mit asyrnmetrisrhem Alkylzinkrest ist eine asym-metrisch-selektive Polymerisation des einen Enantiomeren aus einern DL-Propylenöxid moglich, bei der optisch aktives Polypropylenoxid entsteht und das andere Enantiomere zuriiekbleibt. Die Selektivität dieser Ibtalysatoren steigt parallel zu der Zunahme der σ*-Konstanten in der Richtung AmZnMPC 〈 AmZnDPC 〈 AmZnTPC. Daraus läßt sich scliließen, daß die Zink-Nkyl-Rindung an der asymmetrischen Polymerisation beteiligt ist.
    Notes: Several well defined alkylzine monoalkoxide of tertiary carbinols, viz. ethylzine triphenylmethoxide (EtZnTPC), ethylzinc diphenylmethylmethoxide (EtZnDPC), ethylzinc dimethylphenylmethoxide (EtZnMPC), (+)-2-methylbutylzine triphenylmethoxide (AmZnTPC), (+)-2-methylbutylzinc diphenylmethylmethoxide (AmZnDPC), and (+)-2-methylbutylzinc dimethylphenylmethoxide (AmZnMPC) were prepared and were found to be active in the polymerization of propylene oxide.The catalytic activity of these ethylzinc monoalkoxides was strongly influenced by the polar nature of the corresponding tertiary alkyl group. The order of catalytic activity is EtZnMPC 〈 EtZnDPC 〈 EtZnTPC, which runs parallel to the increasing order of acid strength estimated by HAMMETT indicator method. This also holds in the relation among LEWIS acidity and decreasing order of aggregation degree which in turn are linearly correlated with the polar substituent constant, σ*-constant, of tertiary alkyl group as well as the H1-chemical shift of the α-methylene group of the ethyl group bonded to zinc of the respective ethylzinc monoalkoxide.The alkylzinc monoalkoxides with asymmetric alkyl groups induced an asymmetric-selection polymerization of DL-propylene oxide and were found to transform one of the enantiomers into an optical active poly(propylene oxide) leaving behind the antipode monomer. It was also found that the increasing order of asymmetric-selection efficiency of these catalysts is AmZnMPC 〈 AmZnDPC 〈 AmZnTPC and this order runs parallel to the increasing order of σ*-constant. Consequently, the bond between the optically active alkyl group and the zinc atom is believed to participate in the asymmetric polymerization.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 23 (1972), S. 189-204 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein alternierend aufgebautes Copolymerisat aus Propylen und Butadien wurde mit Vanadiuni- oder Titan-Alkylaluminium-Verbindungen als Initiator hergestellt. Der Katalysator wurde bei -70°C zubereitet, für seine Aktivität sind Halogenatome wesentlich. Carbonylverbindungen, Ketone, Säuren, Ester, Säureanhydride und Säureperoxyde erwiesen sich als wirksame Zusätze zur Erhöhung des Molekulargewichts des Polymeren. Auf Grund von potentiometrischen Titrationen und ESR-Untersuchungen wird vermutet, daß eine zweiwertige Vanadium-Verbindung sich über Chlorbrücken zu einem Vorläufer der aktiven Spezies dimerisiert. Es wird ein anionischer Mechanismus für die die alternierende Copolymerisation vorgeschlagen.Das Copolymerisat enthält, unabhängig von der Zusammensetzung des Ausgangsmonomerengemischs, die Grundbausteine immer im Verhaltnis 1 : 1; die alternierende Struktur aus Propylen- und trans-1,4-Butadien-Einheiten wird aus IR- und NMR-Daten geschlossen. Das Copolymere scheint ein neuer brauchbarer Synthesegummi mit ausgezeichneten Eigenschaften bei niedriger Temperatur, hoher Rückstellfähigkeit, guter Verträglichkeit mit anderen Gummis und hoher Alterungsbeständigkeit zu sein.
    Notes: An alternating copolymer of propylene and butadiene is prepared with vanadium or titanium compounds and alkylaluminum compounds as the polymerization catalyst. The catalyst should be prepared at extremely low temperature as-70°C and halogen atom is essential to the catalyst activity. Carbonyl compounds such as ketone, acid, ester, acid anhydride, and acid peroxide are very effective additives to the catalyst for enhancement of the molecular weight of the polymer. The potentiometric titration and the ESR study suggest that a divalent vanadium compound associated to form the dimer through chlorine bridge is a precursor of the active species. An anionic copolymerization mechanism involving the alternating coordination of monomers is proposed.The copolymer is always of a 1 : 1 composition irrespective of the composition of monomer feed and the alternating structure of polypropylene and trans-1,4-polybutadiene is estimated from IR and NMR data. The copolymer seems to be a new versatile synthetic rubber having excellent low temperature properties, high rebound, good compatibility with conventional rubbers and high resistance toward aging.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 1091-1109 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Three different polyolefins, a linear polyethylene, an isotactic polypropylene, and an isotactic polybutene-1, were melt-spun into filaments. The degree of orientation of the filaments was measured by polarized-light microscopy, x-ray diffraction, and a retraction technique, and the results were then related to the melt-draw ratio. The increase in the elastic deformation ratio of polymer chains by spin-stretching, estimated by thermal retraction at a temperature above Tm, was monotonic with respect to the melt-draw ratio. On the other hand, as-spun filaments of polyethylene and polypropylene were characterized by a plateau in birefringence over the range of melt-draw ratios from 8 to 80. The change in orientation functions for crystals in these filaments was similar to the change of birefringence. On the other hand, the birefringence and the crystalline orientation functions for polybutene-1 increased smoothly with increasing melt-draw ratio. The most highly melt-drawn filaments of these polymers had a strongly oriented structure, corresponding to that in highly cold-drawn specimens.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 1799-1807 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C NMR spectra of acrylic monomers complexed with a Lewis acid were measured and their electronic structures discussed in relation to their alternating copolymerizability. The β-carbon of acrylonitrile and methacrylonitrile showed a downfield shift due to the complex formation with the Lewis acid, while the α-carbon showed an upfield shift and the nitrile carbon showed no significant shift. The degree of shift of olefinic carbons decreased in the following order: AlCl3 〉 EtAlCl2 〉 Et1.5AlCl1.5 〉 Et2AlCl 〉 SnCl4, EtOAlCl2 〉 Et(EtO)AlCl, which seems to run parallel to the Lewis acidity and acid strength. On the other hand, the chemical shift of olefinic carbons of methyl acrylate, methyl methacrylate, and olefinic diesters was influenced little by complex formation with Lewis acids, whereas the carbonyl and alkoxyl carbons were deshielded significantly by the complex formation. These results are discussed in terms of electron distribution on the carbons and an alternating polymerization mechanism.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...