• Journal of the Korean Chemical Society
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• v.40 no.9
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• pp.635-639
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• 1996

New bis-crown ether containing siloxane chain was synthesized. 1,3-Bis(trimethylsiloxy)-1,3-dimethyl-1,3-di(4'-ethylbenzo-18-crown-6) disiloxane (1) was synthesized by reaction of 4'-vinylbenzo-18-crown-6 with 1,3-bis(trimethylsiloxy)-1,3-dimethyl-1,3-disiloxane in the presence of Pt catalyst. 4'-Vinylbenzo-18-crown-6 was prepared through five-step reaction which started from the reaction of catechol and acetic anhydride.

• Journal of the Korean Chemical Society
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• v.39 no.2
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• pp.114-117
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• 1995

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.416-421
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• 1998

In the reversed-phase ion-pair high performance liquid chromatographic (RPIP-HPLC) elution behavior of noble metal-thiacrown ether complexes, the effects of the concentration of ion-pairing reagent and kind of ligands were studied. It was found that the less the number of atoms in the ring of the thiacrown ether molecule was, the larger the selectivity was, and the elution mechanism of the complexes was explained due to the formation of ion-pair when the concentration of sodium dodecyl sulfate (SDS) in mobile phase was lower than 10 mM and due to the formation of micelle when the SDS concentration was higher than 10 mM. As a conclusion, separations of the noble metal-thiacrown ether complexes in an optimum separation condition were accomplished successfully and the method was proved to be an useful one for the separation and determination of Ag (Ⅰ) ion in a black-white photographic fixing solution.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.154-161
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• 1993

Four kinds of new phosphinate derivatives with a pendant monoazacrown ether were synthesized and their biological activities were tested. These biologically active phosphinates were synthesized in relatively good yields (61∼72%) by one step reactions of phenylphosphinate with aldehyde and monoazacrown ether. Toxicity of these compounds was tested by intraperitoneal injection of the compounds to male mouse and revealed $LD_{50}$ value of 65∼90 mg/kg, which showed enhanced toxicity by attachment of a pendant azacrown ether to a simple phenylphosphinate structure. Although the ring size effect of the pendant crown ethers, (monoaza-15-crown-5 and monoazo-18-crown-6), beening negligible, the identity of the ester functional group in the phosphinate structure exerted sizable influence on toxicity. Thus, phosphinate derivative with octyl or propyl ester group showed somewhat higher toxicity than that with ethyl ester group.

• Journal of the Korean Chemical Society
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• v.38 no.5
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• pp.377-381
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• 1994

New bis-crown ethers containing siloxane chain were synthesized. 1,3-Bis(trimethylsiloxy)-1,3-dimethyl-1,3-dipentaoxacyclohexadecamethyl disiloxane (1) was synthesized by reaction of 3-methylene-16-crown-5 (8) with 1,3-bis(trimethylsiloxy)-1,3-dimethyl disiloxane (10) in the presence of Pt catalyst. 1,1,3,3,5,5-Hexamethyl-1,5-dipentaoxacyclohexadecamethyl trisiloxane (2) was synthesized by the reaction of crown ether (8) with 1,1,3,3,5,5-hexamethyl trisiloxane (11) in the presence of Pt catalyst. 3-Methylene-13-crown-4 (7), 3-methylene-16-crown-5 (8), and 3-methylene-19-crown-6 (9) were synthesized by the reaction of triethylene glycol (3), tetraethylene glycol (4), and pentaethylene glycol (5) respectively with 3-chloro-2-chloro-methyl-1-propene (6) in the presence of NaH.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.266-272
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• 1992

Azacrownoalkyl phenylphosphinic acids were synthesized and their competitive solvent extraction characteristics from water to chloroform layer were investigated. Phosphinic acids were synthesized in good yields by one step reaction of phenylphosphinate, aldehyde, and monoazacrown ether and then basic hydrolysis of the resulting phosphinate dsters. These complexing agents revealed a wide effective pH range in extraction of alkali metal ions from water to the organic phase and total metal ion loading at pH 11 was about 75%. The selectivity of the cation extraction was determined mainly by the cavity size of the azacrown ethers, showing $Na^+$ >> $K^+$ > $Rb^+$ > $Li^+$ > $Cs^+$ for the alkyl phenylphosphinic acid ${\underline{2}}$, containing monoaza-15-crown-5 and $K^+$ >> $Rb^+$ > $Na^+$ > $Cs^+$ > $Li^+$ for the alkyl phenylphosphinic acid, ${\underline{3}}$, containing monoaza-18-crown-6 moiety. Applicable pH range of these azacrown ether phosphinic acids in solvent extraction of alkali metal cations was wider than a crownether carboxylic acid with similar selectivity, showing considerable amount of metal ion loading in slightly acidic or neutral media.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.593-602
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• 1988

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 $(k_{obsd})$ 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 $mol^{-1}, 20~55eu. respectively, and the free energy of activation was ~30kcal mol^{-1}$.

• Journal of the Korean Chemical Society
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• v.38 no.7
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• pp.529-532
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• 1994

• Journal of the Korean Chemical Society
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• v.53 no.5
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• pp.521-529
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• 2009

Molecular structures of the various conformers for the 1,3-dimethoxy-p-tert-butylthiacalix[4] crown-5-ether (3) were optimized by using DFT B3LYP/6 - 31 + G(d,p) and mPW1PW91/6 - 31 + G(d,p) (hybrid HF-DF) calculation methods. We have analyzed the energy differences and structures of eight in/out orientations (cone_oo, cone_oi, pc_oo, pc_io, pc_oi, pc_ii, 13a_oo, 13a_io) of two methoxy groups in three major conformations (cone, partial-cone and 1,3-alternate). The 13a_oo (out-out orientation of the 1,3-alternate conformer) is calculated to be the most stable among eight different conformations of 3, and in accord with the experimental result. The ordering of relative stability resulted from the mPW1PW91/6 - 31 + G(d,p) calculation method is following: 13a_oo > 13a_io$\sim$pc_io$\sim$cone_oo > cone_oi$\sim$pc_oo$\sim$pc_oi > pc_ii.

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.37-45
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• 1989

Voltammetric behavior of alkylammonium ion was studied in the absence and in the presence of crown ether in propylene carbonate as solvent. The peak potentials and the peak currents, their dependency on the concentrations, the reversibility of the electrode reactions are described. In the presence of crown ether chemical reaction might be preceeded before the electron-transfer process, the peak potential for the reduction shifts at the negative direction as the concentration of crown ether to the electrolyte solution increases. The addition of crown ether(20mM 18CR6)to the electrolyte solution made it possible to determine voltammetrically the dialkylammonium ions($Me_2NH^{+}_{2};O.6{\sim}0.8mM$) in the presence of the monoalkylammonium ions ($EtNH^{+}_{3} ;1.6mM$) and the monoalkylammonium ions ($EtNH^{+}_{3} ; 0.5{\sim}2.5mM$) in the presence of the dialkylammonium ions($Me_2NH^{+}_{2};0.5mM$)