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  • Polymer and Materials Science  (26)
  • Inorganic Chemistry  (5)
  • Animals  (3)
  • 1985-1989  (34)
  • 1970-1974
  • 1987  (34)
  • 1
    Electronic Resource
    Electronic Resource
    Conformational characteristics of aromatic polyesters: Comparative study of the polarity of poly(propyleneglycol terephthalate) and poly(ethyleneglycol terephthalate) (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 2403-2407 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090251115
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  • 2
    Electronic Resource
    Electronic Resource
    Alkylation of Position C-5 of Triacetic Acid Lactone by [2,3] Sigmatropic Rearrangement of Sulphonium Ylides (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1413-1419 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkylierung der 5-Stellung von Triessigsäurelacton durch [2,3]-sigmatrope Umlagerung von Sulfonium-YlidenDie Reaktionen von 4-Methoxy-6-(phenylthiomethyl)-2H-pyran-2-onen 4 mit drei verschiedenen Diazoverbindungen unter Kupfer- oder Rhodium-Katalyse liefern entsprechende Sulfonium-Ylide, die durch [2,3]-sigmatrope Umlagerung und nachfolgende Prototropie die Pyrone 6, die an der schwer zugänglichen 5-Stellung funktionalisiert sind, ergeben. Entschwefelung von 6 mit desaktiviertem Raney-Nickel ergibt die Pyrone 17-19. Der Einfluß der experimentellen Bedingungen auf die Konkurrenz von [2,3]-sigmatroper und Stevens-Umlagerung wurde bei der Reaktion von 4-Methoxy-6-(phenylthiomethyl)-2H-pyran-2-on (4a) mit Diazomalonsäure-dimethylester studiert. Zusammen mit den aus [2,3]-sigmatroper und Stevens-Umlagerungen abgeleiteten Verbindungen 6d und 8 wurden noch andere Produkte (9, 10 und 11), die über Sulfonium-Ylid-Gleichgewichtseinstellung und Radikalverknüpfung entstehen, isoliert.
    Notes: Reactions of the 4-methoxy-6-(phenylthiomethyl)-2H-pyran-2-ones 4 with three different diazo compounds under copper or rhodium catalysis give the corresponding sulphonium ylides, which through [2,3] sigmatropic rearrangement and further prototropy afford the pyrones 6, functionalized at the difficutly accessible position C-5. Desulphurations of products 6 with deactivated Raney nickel give the pyrones 17-19. The influence of the experimental conditions on the competition between [2,3] sigmatropic and Stevens rearrangement has been studied for the reaction of 4-methoxy-6-(phenylthiomethyl)-2H-pyran-2-one (4a) and dimethyl diazomalonate. Several products (9, 10, and 11) arising from sulphonium ylides equilibration and radical recombination have been found in addition to the [2,3] sigmatropic and the Stevens rearrangement products 6d and 8.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200819
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  • 3
    Electronic Resource
    Electronic Resource
    Neue [2.2]Paracyclophan-1,9-diene aus 1,9(10)-Dibrom-[2.2]paracyclophan-1,9-dien (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1667-1674 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New [2.2]Paracyclophane-1,9-dienes from 1,9(10)-Dibromo-[2.2]paracyclophane-1,9-dieneThe mixture of 1,1,9,9- and 1,1,10,10-tetrabromo[2.2]paracyclophane (4), obtained by photobromination of [2,2]paracyclophane (1) upon treatment with potassium tert-butoxide in tert-butyl-methyl ether, gave the 1,9(10)-dibromo[2,2]paracyclophane-1,9 dienes (5). One-step reactions led to [2,2]paracyclophane-1,9-dienes (2) and 1,9(10)-bis(trimethylsilyl)[2.2]paracyclophane-1,9-dienes (12). Palladium(0)-catalyzed coupling reactions of 5 with several vinyl-Z substrates (Z = H, SiMe3, CHO, CO2Me, and phenyl) yielded new bridge-substituted divinyl derivatives 14 of [2.2]paracyclophane-1.9-diene, which upon Diels-Alder addition of appropriate dienophiles can be transformed into bridge-annelated systems such as 18 and 23.
    Notes: Das durch Photobromierung von [2.2]Paracyclophan (1) erhältliche Gemische aus 1,1,9,9- und 1,1,10,10-Tetrabrom[2.2]paracyclophane (4) lieferte mit Kalium-tert-butylat in tert-Butylmethylether die 1,9(10)-Dibrom[2.2]paracyclophan-1,9-diene (5). Hieraus ließen sich in jeweils einem Schritt [2.2]Paracyclophan-1,9-dien (2) und 1,9(10)-Bis(trimethylsilyl)[2.2]paracyclophan-1,9-dien (12) gewinnen. Palladium (0)-katalysierte Kupplungen von 5 mit Vinyl-Z-Substraten (Z = H, SiMe3, CHO, CO2Me und Phenyl) ergaben neue brückensubstituierte Divinyl-Derivate 14 des [2.2]Paracyclophan-1,9-diens, die durch Diels-Alder-Addition geeigneter Dienophile in brückenanellierte Systeme wie 18 und 23 übergeführt werden können.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871201010
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  • 4
    Electronic Resource
    Electronic Resource
    Halogen(halogenvinyl)carbene durch α-Eliminierung aus Oligohalogenpropenen und ihr intermolekularer Abfang: Ein neuer Weg zu (Halogenvinyl)cyclopropanen (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 395-400 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkyl- and alkoxy-substituted 1-fluoro-1-(trichlorovinyl)cyclo-propanes 6 were prepared by α-dehydrohalogenation of 1,1,2-trichloro-3,3-difluoro-1-propene (4) with lithium 2,2,6,6-tetramethylpiperidide (LiTMP) in the presence of olefins. 1,1,3,3-Tetrachloro-1-propene (7) reacts with lithium hexamethyldisilazide (LiHMDS) and olefins to give 1-chloro-1-(2,2-dichlorovinyl)cyclopropanes 8 with modest to good yields. The ethoxy-substituted vinylcyclopropane 8g is obtained by this method in 20-g amounts. The treatment of (E/Z)-1,2,3,3-tetrachloro-1-propene (10) with LiHMDS in 2,3-dimethyl-2-butene gives 1-chloro-1-[(Z)-1,2-dichlorovinyl]cyclopropane 11, and (dichloroethenylidene)cyclopropane 9 as a by-product.
    Notes: Durch α-Dehydrohalogenierung von 1,1,2-Trichlor-3,3-difluor-1-propen (4) mit Lithium-2,2,6,6-tetramethylpiperidid (LiTMP) in Gegenwart von Olefinen wurden mit Ausbeuten von 2-20% alkyl- und alkoxysubstituierte 1-Fluor-1-(trichlorvinyl)cyclopropane 6 dargestellt. 1,1,3,3-Tetrachlor-1-propen (7) reagiert mit Lithium-hexamethyldisilazid (LiHMDS) und Olefinen in mäßigen bis guten Ausbeuten zu 1-Chlor-1-(2,2-dichlorvinyl)cyclopropanen des Typs 8. Das ethoxysubstituierte Vinylcyclopropan 8g ist auf diese Weise im 20-g-Maßstab zugänglich. Die Behandlung von (E/Z)-1,2,3,3-Tetrachlor-1-propen (10) mit LiHMDS in 2,3-Dimethyl-2-buten liefert 1-Chlor-1-[(Z)-1,2-dichlorvinyl]cyclopropan 11 und (Dichlorethenyliden)cyclopropan 9 als Nebenprodukt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200323
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  • 5
    Electronic Resource
    Electronic Resource
    Cycloaddition Behavior of 2-Substituted Norbornadienes towards 4-Phenyl-4H-1,2,4-triazole-3,5-dione (PTAD): Homo Diels-Alder Reactivity versus Insertion, Rearrangement, and [2 + 2] Cycloaddition (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 531-535 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Reaktion von PTAD mit den 2-Trimethylsilyl-, 2-Chlor-, 2-Cyan- oder 2-Methoxycarbonylnorbornadienen 1a-d wurde untersucht. In allen Fällen wurden Homo-Diels-Alder-Addukte erhalten, von 1a das unerwartete Regioisomere 1-Trimethylsilderivat 2a und von 1b-d die gewöhnlichen cyclopropansubstituierten Produkte 2b-d. Zusätzlich führte das Trimethylsilylsystem 1a zu den Dicarboximiden 4a bzw. 4′a (Umlagerungsurazole). Die Norbornadiene 1b-d bildeten die Insertionsprodukte 5b-d. Mit steigendem Elektronenzug der 2-Substituenten werden die Einschiebungsprodukte 5b-d auf Kosten der Homo-Diels-Alder-Addukte 2b-d in steigendem Maß gebildet. Diese Ergebnisse erklären wir unter der Annahme eines mehrstufigen Cycloadditionsmechanismus über 1,5-dipolare Zwischenstufen. Im Fall von 2-Chlornorbornadien (1b) wurde neben dem Homo-Diels-Alder-Addukt 2b, dem Umlagerungsurazol 4b und dem Einschiebungsprodukt 5b auch das [2 + 2]-Cycloaddukt 3b erhalten.
    Notes: The reaction of PTAD with 2-trimethylsilyl-, 2-chloro-, 2-cyano-, and 2-methoxycarbonylnorbornadienes 1a-d, respectively, was investigated. In all cases homo Diels-Alder adducts were obtained, for 1a the unexpected regioisomer, the 1-trimethylsilyl derivative 2a, and for other norbornadienes 1b-d the usual cyclopropane-substituted products 2b-d. Except for the trimethylisilyl system 1a, for which also the dicarboximides 4a and 4′a, respectively, (rearrangement urazoles) were obtained, the other norbornadienes 1b-d afforded the insertion products 5b-d. With increasing electron-withdrawal by the 2-substituents the insertion products 5b-d increased at the expense of the homo Diels-Alder adducts 2b-d. These results are mechanistically rationalized in terms of stepwise cycloaddition via 1,5-dipolar intermediates. In the case of 2-chloronorbornadiene (1b), besides the homo Diels-Alder 2b, the rearrangement urazole 4b and the insertion product 5b, also the [2 + 2] cycloadduct 3b was formed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200412
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  • 6
    Electronic Resource
    Electronic Resource
    Strained Hydrocarbon Skeletons: Pentacyclo[6.4.0.02,4.03,10.07,9]dodecanes by [2+2+2]Cycloadditions to Substituted Dihydrobullvalenes (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 2083-2085 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of some pentacyclo[6.4.0.02,4.03,10.07,9]dodecane derivatives 2 by [2+2+2] cycloaddition of tetracyanoethylene (TCNE) to dihydrobullvalene derivatives 6 is described. Upon pyrolysis of the acetate 2d and the xanthate 2e a [2+2+2] cycloreversion is observed instead of an elimination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871201221
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of termination and transfer on molecular weight distribution of polymers, 7Part 6: Cf.4.. Impurity transfer (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 333-339 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A mathematical procedure is developed to deal with the kinetics of ionic polymerization with impurity transfer and instantaneous initiation. Besides the technique of variable transformation, the integration of an implicit function is applied. The expressions of the molecular size distribution function and other molecular parameters are derived regorously, and several examples for numerical computations are given.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880210
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  • 8
    Electronic Resource
    Electronic Resource
    Cationic graft copolymerization of tetrahydrofuran with partially α-brominated polystyrene (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1005-1015 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Partially α-brominated polystyrene was first prepared from commercial polystyrene and N-bromosuccinimide by the Wohl-Ziegler reaction. It was treated with silver perchlorate to initiate cationic graft copolymerization with tetrahydrofuran leading to polystyrene-graft-polytetrahydrofuran. The influence of reaction time, reaction temperature, initial concentrations of silver perchlorate and partially α-brominated polystyrene, etc., on the graft polymerization was studied. It partially α-brominated polystyrene with a bromination degree of 5-15% was used, a leather-like graft copolymer was obtained with a high grafting efficiency at or below 0°C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880506
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  • 9
    Electronic Resource
    Electronic Resource
    Equilibrium polymerization initiated by polymer chains with active sites (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1885-1896 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: According to the theory of multifunctional equilibrium polymerization, the two-dimensional molecular weight distribution function for the equilibrated copolymers generated from polymer chains with active sites is derived. On this basis the average molecular weights, grafting ratio, grafting efficiency, grafting success, branching distribution, and frequency of grafts, etc. can be predicted from polymerization conditions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880812
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  • 10
    Electronic Resource
    Electronic Resource
    Influence of termination and transfer on molecular weight distribution of polymers, 8Part 7: Cf.:2.. Spontaneous transfer (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 341-348 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of cationic polymerization with instantaneous initiations and spontaneous transfer is treated theoretically. By means of a non-steady state analysis, rigorous expressions for the molecular weight distribution and other molecular parameters are derived from the set of differential equations without introducing any approximations. The influence of spontaneous transfer on the molecular weight distribution is discussed in detail based on several numerical examples.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880211
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