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KMID : 1059519880320060593
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Journal of the Korean Chemical Society
1988 Volume.32 No. 6 p.593 ~ p.602
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Polymer-Supported Crown Ethers (II). Efficiency for Phase Transfer Catalyst
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Shim Jae-Hu
Chung Kwang-Bo
Chang Seung-Hyun
Song Dae-Kyung
Sung Yong-Kiel
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Abstract
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Polymer-supported crown ethers (Ps-CE) which can be used for phase-transfer catalyst (PTC) were synthesized for the purpose of allowing reusable function to ordinary crown ethers, and the kinetics of the liquid-solid-liquid triphase-catalyzed nucleophilic displacement reaction of iodide (aqueous phase) on 1-bromooctane (organic phase) using synthesized Ps-CE (solid) were studied. Ps-CE were obtained by grafting of hydroxymethyl crown ethers to 1~2% cross-linked chloromethylated polystyrene. All reactions followed a pseudo-first order dependency on the 1-bromooctane concentration and the observed rate constants (kobsd) were linearly related to the molar equivalents of Ps-CE, and were subjected to the influence of cross-linking density of polymer backbone, solvent and the reaction temperature. The catalytic activity of Ps-CE was also compared with that of structurally similar soluble crown ethers, and used Ps-CE were easily recovered after the reaction by simple filtration and could be reused without loss of catalytic activity in the same anionic displacement reaction. Enthalpies and entropies of activation associated with the displacement were 10~20kcal mol-1, 20~55eu. respectively, and the free energy of activation was ~30kcal mol-1.
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KEYWORD
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