• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2737-2742
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• 2011

Ring-opening metathesis polymerization (ROMP) of an ethyl-substituted tetracyclododecene (8-ethyltetracyclo[$4.4.0.1^{2,5}.1^{7,10}$] dodec-3-ene, Et-TCD) was carried out in the presence of a ternary catalyst system consisting of $WCl_6$, triisobutyl aluminium (iso$Bu_3Al$), and ethanol. The optimal molar ratio of Et-TCD/$WCl_3$/iso-$Bu_3Al$/ethanol was found as 500/1/3/2 at which the yield of ring-opened polymer was 100%. 1-Hexene was shown to be an effective molecular weight controlling agent for ROMP reaction of Et-TCD. The hydrogenation of the ring opened polymer (p-Et-TCD) was conducted successfully using Pd(5 wt %)/${\gamma}$-$Al_2O_3$ at $80^{\circ}C$ for 1 h. Chemical structures of p-Et-TCD and its hydrogenated product($H_2$-p-Et-TCD) were characterized using 2D NMR techniques ($^1H-^1H$ COSY and $^1H-^{13}C$ HSQC). The changes of physical properties such as thermal stability, glass transition temperature and light transmittance after the hydrogenation were also investigated using TGA, DSC, and UV.

• Applied Chemistry for Engineering
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• v.2 no.1
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• pp.64-69
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• 1991

A lipid containing a 1, 2-dithiolane group was synthesized, and polymerized vesicle was prepared from the vesicle of this lipid by ring-opening polymerization. Reaction rate of the polymerization was monitored by UV absorption, and the results showed that it followed the first order kinetics and the rate constant $3.84{\times}10^{-2}min^{-1}$. Permeation rate of sucrose through the polymerized vesicle was $4.7{\times}10^{-8}cm\;hr^{-1}$, which is 1.5 times lower than that of monomeric analog.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.199-199
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• 2006

Microwave-irradiation has become a common heat source in organic chemistry in the last decade. In recent years, polymer chemists also discovered the advances of microwave heating that include fast and efficient heating as well as the homogeneous heat profile and the easy access to pressurized reaction conditions. In this contribution, we report our investigations on the cationic ring-opening polymerization of 2-oxazolines that lead to a tremendous acceleration from several days to several minutes polymerization time. In addition, the optimized microwave-assisted polymerization procedure was applied for the preparation of libraries of diblock and triblock copolymers that were used for the determination of structure-property relationships in poly(2-oxazoline)s.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2989-2992
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• 2009

An efficient synthetic route of novel 2′(${\alpha}$)-C-fluoro-2′(${\beta}$)-C-methyl carbocyclic nucleoside analogues is described. The key fluorinated intermediate 7 was prepared from the epoxide intermediate 5 via selective ring-opening of epoxide. Coupling of 7 with nucleosidic bases under the Mitsunobu reactions followed by deprotection afforded the target carbocyclic nucleoside analogues. The synthesized compounds were evaluated as inhibitors of the hepatitis C virus (HCV) in Huh-7 cell line in vitro.

• YAKHAK HOEJI
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• v.34 no.5
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• pp.348-364
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• 1990

The activities of twenty-one flavonoids and their related compounds on the hypersensitivity reaction against various antigens were studied in vitro and in vivo. 1. Generally flavonoids inhibited significantly the homologous passive cutaneous anaphylaxis (PCA) induced by reaginic antibody as compared as anaphylaxis by compound 48/80-induced mast cell degranulation, and so more strongly active in the IgE-mediated anaphylaxis than non-IgE-mediated anaphylaxis. 2. Flavonids inhibited remarkably Arths reaction, hemolysin titer, delayed hypersensitivity, haemagglutinin titer, rosette forming cells and plague forming cells against sheep red blood cells, and so it exhibited that flavonoids inhibited type 2, 3 and 4 hypersensitivity. 3. Quercetin, kaempferol, hesperetin, disodium cromoglycate, malvin and baicalein were active dose-dependently in the all types of hypersensitivity. Fisetin, daidzein, morin, narigin, flavone, catechin, rutin, hesperidin, neophsperidin, apigenin and chrysin were significantly active in the various types of hypersensitivity, but apigenin, rutin and catechin were less active in the delayed hypersensitivity. Taxifolin was significantly active in PCA and histamine-induced anaphylaxis except other types of hypersensitivity. Rotenone and cyanin also inhibited all types of hypersensitivity, but they are toxic. 4. Based on these results from hypersensitivity, the following flavonoid structure-activity relationships became apparent. 1) Flavonoids with $C_{2-3}$ double bond in C-ring were more active than that of $C_{2-3}$ saturation. 2) Flavonoids with $C_4$ ketone group in C-ring were more active than abscence of them except catechin and malvin. 3) Flavonoids with benzene ring at positions 2 or 3 in C-ring exhibited same activities. 4) Flavonoids with opening of the C-ring does not abolish their activities. 5) The glycosylated flavonoids in position 3 or 7 was less active than their aglycone. 6) Flavonoids with the more hydroxy group in A and B-ring were more active. 7) Flavonoids with or without $C_3-OH$ did not change their activities.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.2
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• pp.228-235
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• 2009

We synthesized glycidyl azide monomer(GAM) as a monomer for polymerization of glycidy azide polymer(GAP) which is a promising energetic prepolymer for a plastic-bonded explosive. Using quantitative real-tim in-situ infrared(in-situ IR) spectroscopy, kinetic study on the cationic ring opening polymerization of GAM was carried out. The reaction rate was obtained from monitoring the change of ether C-O stretching band($1050cm^{-1}$) in series IR spectra. The reaction was in accordance with the first-order reaction law for each of reaction temperature at 100/1 mole ratio of [GAM]/[$BF_3*etherate$]. In the ring opening polymerization of GAM, with ratio of [GAM]/[$BF_3*etherate$] to equal 100/1 at various temperature, the activation parameters obtained from the evaluation of kinetic data were ${\Delta}H^*$=14.34kcal/mol, ${\Delta}S^*=-12.31cal/mol{\cdot}K$ and $E_a$=14.89kcal/mol.

• Clean Technology
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• v.17 no.4
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• pp.325-328
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• 2011

Atom-efficient preparation of 9, 9'-bis[4-(2'-hydroxy-3'-acryloyloxypropoxy) phenyl]fluorene (3), the extensively used building block for fluorene-containing acrylic epoxy polymers has been described. The epoxide ring opening esterification of 9, 9-bis[4-(glycidyloxy)phenyl]fluorene (1) with acrylic acid was catalyzed by some onium salts such as quaternary ammonium and phosphonium salts. While the coupling reactions depend greatly on the kind of the onium salts, the reaction of 9, 9-bis[4-(glycidyloxy)phenyl]fluorene (1) with acrylic acid proceed most efficiently in the presence of a catalytic amount of tetrabutylphosphonium bromide at $110^{\circ}C$ with 90% yield. This reaction is a cleaner reaction that minimizes the use of reactants and the production of chemical wastes.

• Archives of Pharmacal Research
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• v.23 no.4
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• pp.329-331
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• 2000

4-(p-Chlorophenyl)tetralone (6) and 7-chloro-5-(p-chlorophenyl)tetralone (9) are key intermediates for the development of benzazepinone derivative haftens. These compounds could be synthesized from 4-phenyltetralone derivatives by triflic acid catalyzed Friedel-Crafts reaction. The reaction mechanism of Friedel-Crafts alkylation/acylation with lactones in triflic acid is presented. According to our tentative research, ring opening of protonated lactone (2) occurs in alkyl cleavage and the rate of the reaction is not dependent on concentration of triflic acid. So, alkylation of lactone in Friedel-Crafts reaction is presumed to be $A_{AL}$ 1. In second step, intramolecular acylation of the intermediates 4 to 6, 4 can be transformed to a triflic acid-carboxylic anhydride and then the cyclization is undergone after leaving of the triflate anion.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.562-567
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• 2007

The stereoselective synthesis of chiral terminal epoxide is of immense academic and industrial interest due to their use as versatile starting materials as well as chiral intermediates. In this study, new polymeric chiral Co(salen) complexes bearing tallium (III)chloride and iron (III)chloride (ferric chloride) have been synthesized and characterized. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides using water and phenol derivatives as nucleophiles. The easily prepared polymeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ and phenol nucleophiles, providing enantiomerically enriched terminal epoxides (> 98% ee). The system described in this work is very efficient for the synthesis of chiral epoxide, 1,2-diol and ${\alpha}$-aryloxy alcohol intermediates.

• Macromolecular Research
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• v.16 no.5
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• pp.441-445
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• 2008

A series of aluminum complexes supported by $\beta$-ketoamino, ligand-bearing, 3-position substituents $LAlEt_2$ ($L=CH_3C(O)C(Cl)=C(CH_3)NAr\;(L_1)$, $L=CH_3C(O)C(H)=C(CH_3)NAr\;(L_2)$, $L=CH_3C(O)C(Ph)=C(CH_3)NAr\;(L_3)$, and $L=CH_3C(O)C(Me)=C(CH_3)NAr\;(L_4)$, $Ar=2,6-^iPr_2C6H_3$) were synthesized in situ and employed in the ring-opening polymerization (ROP) of $\varepsilon$-caprolactone ($\varepsilon$-CL) and cyclohexene oxide (CHO). The 3-position substituents on the $\beta$-ketoamino ligand backbone of the aluminum complexes influenced the catalyst activity remarkably for both ROP of $\varepsilon$-CL and CHO. Aluminum $\beta$-ketoamino complexes displayed different catalytic behavior in ROP of $\varepsilon$-CL and CHO. The order of the catalytic activity of $LAlEt_2$ was $L_1AlEt_2$>$L_2AlEt_2$>$L_3AlEt_2$>$L_4AlEt_2$ for ROP of $\varepsilon$-CL, being opposite to the electron-donating ability of the 3-position substituents on the $\beta$-ketoamino ligand, while the order of the catalytic activity for ROP of CHO was $L_1AlEt_2$>$L_3AlEt_2$>$L_4AlEt_2$>$L_2AlEt_2$. The effects of reaction temperature and time on the ROP were also investigated for both $\varepsilon$-CL and CHO.