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  • 1
    Electronic Resource
    Electronic Resource
    Modification des condensats phénoliques par des groupes phtalimides. Résines dérivées des phtalimidométhylphénols. Synthèse et caractérisation (1982)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 1113-1122 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By reacting N-hydroxymethylphthalimide (5a) or N-chloromethylphthalimide (5b) with an excess of phenol, a mixture of 2-phthalimidomethylphenol (6) and 4-phthalimidomethylphenol (7) was obtained. The ratio 6/7 was found to be 2:3 for the reaction with 5a and 3:2 with 5b, as determined by 1H NMR at 250 MHz. The condensation of 6 with hexamethyleneteraamine (3) at the mole ratio 6/3 equal to 2 and 7,5 was performed at 190°C. The resulting resins (H—PP) were compared to those prepared from o-cresol and 3 (H—OC), and GPC of the resulting products was made. A higher thermal stability of the resins H—PP was evidenced by thermogravimetric analysis. This improvement of the thermal stability was also observed for the condensation products of the ortho and para isomers 6 and 7 with phenol and formaldehyde, leading to modified novolacs F—PP, although the amount of incorporated 6 and 7 was found to be less than the original amount in the reaction mixture.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1982.021830505
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Polymérisation anionique des diènes. III. Etude thermodynamique de la propagation du butadiène et de i'isoprène par les organo-alcalins (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 1855-1867 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present work is concerned with the influence of the polymerization temperature on the propagation mechanisms of polyisoprenyl- and polybutadienyl-alkali metals. The thermodynamic parameters of the contact ion pairs and free ions propagations have been calculated. With Li+ in dioxane solvent, the vinyl propagation is stereospecific (for isoprene, the propagation is mainly 4-3). In comparison with benzene, the vinyl propagation of the polydienyl-Li contact ions pairs should be due to complexation of Li+ by dioxane, an electron donor having a weak dielectric constant. In general, the stereospecificity of the propagation of contact ion pairs decreases with increasing counterion size; little difference has been observed with K+ and Cs+ ion pairs in dioxane and benzene media. For isoprene, the methyl substituant should have chiefly a steric effect in the propagation of free ions, whereas it should confer a polar character to the isoprene molecule in the presence of ions pairs.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.170130810
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  • 3
    Electronic Resource
    Electronic Resource
    Polymérisation anionique des diènes. IV. Contribution aux etudes des mécanismes de propagation stéréospécifique des isoprène et butadiène par les organo-alcalins (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 1869-1877 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By taking into account different possible interactions between the living end, the counterion and the nature of the solvent used on the one hand, and the influence of the temperature on the kinetics and the microstructures of polydienes on the other hand, it has been possible to suggest some new explanations concerning the mechanisms of the anionic propagation of butadiene and isoprene. In hydrocarbon media, the stereospecificity of the 1,4 propagation initiated by lithium should be considered as the consequence of the coordination of the counterion by both of the two bonds of the diene molécule. The stereospecificity of the vinyl propagation by the same counterion in dioxane solvent should be the consequence of the competition between the (Li+, dioxane) and (Li+, diene) coordination complexations. In this case, the Li+ counterion should only be coordinated by only one of the two double bonds of the diene molecule. With isoprene, the π-electron donation should originate mainly from the C3=C4 double bond. The decrease of the stereospecificity is due to the increasing size of the alkali counterion and the separation or the dissociation of the growing ion-pairs.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.170130811
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Polymérisation anionique de l'isoprène: Nature de la paire d'ions et stéréospécificité. II. Influence de la nature du solvant (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 1847-1853 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present work reports some new results on the dependence between the stereospecificity of the anionic propagation of isoprene and the nature of the active centers. The stereospecificity of the propagation of macroheterobicylce separated ion pairs does not depend on the nature of the alkali counterions, and the microstructure of the polyisoprenes obtained does not differ from that of those produced by free ions. Variations in the microstructure were observed in the propagation of contact ion pairs, depending on the nature of the cation and the solvent used. These variations are likely to be related to the degree of intimacy of the contact ion pairs. There are two main factors which affect the stereospecificity of the propagations in different ways: the size of the cation and the donating power of the solvent. Finally, the external solvation of the propagation ions pairs was confirmed by the microstructure of polyisoprenes synthesized in mixed (inert + donor) solvents.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.170130809
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  • 5
    Electronic Resource
    Electronic Resource
    Polymérisation anionique des diènes. V. Configurations des oligopolyisoprènyl-lithium en milieu benzènique et en présence de dioxanne. Étude par résonance magnétique protonique: Haute résolution (RMP-HR) (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 1199-1210 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By PMR, three dioxane-Li+ complexes have been detected for the oligopolyisoprenyl-lithium-dioxane mixtures in benzene solution. The (4-1) living end isomerizes into the cis configuration when the sample temperature or the dioxane concentration is increased, but the isomerization phenomenon is reversible only if dioxane/Li+ ratios are smaller than unity. The specificity of the vinyl addition (86%), mainly (4-3) (70%), due to the stronger negative charge at the Cγ carbon atom is effective only at low temperature (+15°C). At higher temperature, because of the steric hindrance of the methyl group, this stereospecificity decreases.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.170150517
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  • 6
    Electronic Resource
    Electronic Resource
    Polymérisation anionique des diènes. VI. Microstructure des polybutadiène et polyisoprène par résonance magnétique protonique à 250 MHz et mécanismes de propagation (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 1799-1810 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis by 250-MHz proton magnetic resonance (PMR) allows more precise examination of the microstructure of anionic polyisoprenes and polybutadienes obtained in the presence of organo-alkali metals. Besides vinyl addition, the propagation of contact ion pairs in dioxane solvent gives a mixture of cis and trans products with isoprene, whereas only trans product is obtained with butadiene. The presence of 1,4-trans-polyisoprene appears to be inconsistent with the cis configuration of the polyisoprenyllithium living end in dioxane or tetrahydrofurane media. In taking into account the existence of complexation phenomena, it was suggested that propagation mechanisms should involve a transition state which should begin with the trans configuration before isomerization into the more stable cis configuration. For the free ions, the living end of the carbanion should be entirely trans.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.170150802
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