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  • 1
    Electronic Resource
    Electronic Resource
    Ion-exchange rate limitation on a polymer-supported phase transfer catalytic reaction (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1393-1399 
    Details
    ISSN: 0887-624X
    Keywords: ion-exchange ; triphase catalysis ; phosphazene substitution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ion-exchange rate limitation on the kinetics of the series substitution reactions between hexachlorocyclotriphosphazene (NPCl2)3 and 2,2,2-trifluoroethanol (HOCH2CF3) by polystyrene-bound tri-n-butylammonium ion in an organic solvent/alkaline solution was studied. It was found that the diffusional limitation involves both ion diffusion and organic reactant diffusion within the catalyst pellet. The displacement reaction rate of (NPCl2)3 in the organic phase was limited by the particle diffusion and the intrinsic reactivity together. The film diffusion in the bulk solution limited the rate of ion exchange. The mass transport of the ion-exchange step in the aqueous phase was not improved by increasing the concentration of NaOCH2CF3. Drastic kinetic rate improvement was achieved with proper adjustment of the volume of the aqueous solution which was a low concentration of salt in the aqueous phase.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300718
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of the polymer-support on the synthesis of 2,4-dibromophenyl allyl ether in a triphase catalysis (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 1171-1177 
    Details
    ISSN: 0887-624X
    Keywords: triphase catalysis ; macroporous polymer particle ; 2,4-dibromophenyl allyl ether, synthesis of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 2,4-dibromophenyl allyl ether by reacting allyl bromide with 2,4-dibromophenol in an organic solvent/alkali solution by triphase catalysis was studied. A macroporous polymer pellet which served as the support of the catalyst was prepared by reacting styrene monomer with chloromethyl styrene and divinylbenzene through suspension polymerization. Tri-n-butylamine was immobilized on the surface of the polymer pellet to form the triphase catalysts. Immobilization of the catalyst on the polymer support carried out in a mechanical agitator was suggested to obtain a high catalyst reactivity. In the three-phase reaction, the effects of agitation speed, and the characteristics of the catalyst pellet which affect the conversion of allyl bromide in the three-phase catalytic reaction were examined in detail. Based on the experimental data, the optimum operating parameters for preparing the triphase catalyst to get a high yield of 2,4-dibromophenyl allyl ether were: using a low degree of polymer crosslinking (2%), and small particle size. The yield of the product obtained from the present study is higher than that which was obtained in a two-phase reaction. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310512
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of some structural features of the polymer support on synthesizing 2,4,6-tribromophenyl benzyl ether in a triphase catalysis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 34 (1994), S. 187-195 
    Details
    ISSN: 0959-8103
    Keywords: Triphase catalysis ; synthesis of 2,4,6-tribromophenyl benzyl ether ; structural features of polymer support ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The substitution reaction of benzyl bromide and 2,4,6-tribromophenol in an organic solvent/alkaline aqueous solution of KOH by triphase catalysis in which tributylamine was immobilized on a polymer support was investigated. Our main purpose was to evaluate the effect of some structural features of the polymer-supported pellet on the conversion of the organic-phase reactant (benzyl bromide). The polymer-supported pellet was obtained from copolymerization of styrene and chloromethylstyrene monomers. The reaction was identified as occurring both on the surface and within the particles of the polymer support when using a highly polar solvent. The effects of the structural features of the polymer support, which are related to the degree of cross-linking, ring substitution, lipophilicity of the polymer pellet, the chloride density and the solvents, on the conversion of benzyl bromide were investigated in detail. The experimental results indicate that 2% of cross-linking with 10% ring substitution of the macroporous polymer support provides a rapid reaction and high conversion of benzyl bromide reactant.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210340210
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