• Bulletin of the Korean Chemical Society
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• v.19 no.2
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• pp.183-188
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• 1998

Incorporation of metalloporphyrins into polypyrrole (PPy) film was achieved either by electropolymerization of pyrrole in the presence of metal-tetra(sulfonatophenyl)porphyrin anion (MTSPP, M=Co, Fe) or by metalizing hydrogenated tetra(4-sulfonatophenyl)porphyrin anion (H2TSPP) doped into PPy through ion-exchange. Electrochemical reduction of oxygen on the PPy doped with metallo porphyrin (PPy-MTSPP) was studied in acidic and basic solutions. Oxygen reduction on PPy-MTSPP electrodes appeared to proceed through a 4-electron pathway as well as a 2-electron path. In acidic solutions, the overpotential for O2 reduction on PPy-CoTSPP electrode was smaller than that on gold by about 0.2 V. In basic solutions the overpotential of the PPy-CoTSPP electrode in the activation range was close to those of Au and Pt. The limiting current was close to that of Au. However, polypyrrole doped with cobalt-tetra(sulfonatophenyl)porphyrin anion (PPy-CoTSPP) or with iron-tetra(sulfonatophenyl)porphyrin anion (PPy-FeTSPP) was found to have limited potential windows at high temperatures (above 50 ℃), and hence the electrode could not be held at the oxygen reduction potentials in basic solutions (pH 13) without degradation of the polymer.

• Bulletin of the Korean Chemical Society
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• v.16 no.4
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• pp.344-348
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• 1995

As an effort to elucidate the chiral recognition mechanisms exerted by the (S)-naproxen-derived CSP bearing both π-acidic and π-basic sites, a homologues series of π-basic N-acyl-α-(1-naphthyl)alkylamines and π-acidic N-(3,5-dinitrobenzoyl)-α-amino esters were prepared and resolved. Based on the chromatographic resolution trends of the homologues series of analytes on the (S)-naproxen-derived chiral stationary phase, we proposed chiral recognition mechanisms which demonstrate that the intercalation of the substituent in the analyte molecule between the strands of bonded phase does significantly influence the enantioselectivity for resolving N-acyl-α-(1-naphthyl)alkylamines but the intercalation process is not involved in resolving N-(3,5-dinitrobenzoyl)-α-amino esters.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 2000.06a
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• pp.215-232
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• 2000

The Valence(Z) of positively and negatively charged alumina particles in the dilute suspensions was analyzed with the electrical conductivity of the suspensions. The mobility of negative particles was lower than that of positive particles at a similar Z value because of the stronger effect of chemical bonding over the hydrated particle surfaces. The apparent viscosity of acidic suspensions of 1-40 vol % solid was lower than that of basic suspensions. This result was discussed based on the three important effects of the valence, concentration and nature of hydrated surface of alumina particles. The density of alumina compacts consolidated by filtration through gypsum molds became lower for the basic suspensions than for the acidic suspensions. This result was correlated to the properties of the colloidal alumina suspensions.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1844-1850
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• 2006

Two types of catalyst samples were prepared, one sulfated zirconia and the other silica doped sulfated zirconia. The acidity tests indicate that sulfated zirconia doped with silica has higher concentration and strength of acidic catalyst sites than undoped sulfated zirconia. The acidic surface sites have been characterized using FTIR, NMR, pyridine adsorption, TPD, XRD and nitrogen adsorption. Doping with silica increased the concentration of surface Lewis and Brfnsted acid sites and resulted in generation of proximate acid sites.The activity test indicates that doping sulfated zirconia with silica increases both the acidity and catalytic activity for liquid phase dehydration of methanol at 413-453 K. Methanol is sequentially dehydrated to dimethyl ether and ethylene over both catalysts. Significant amounts of propylene are also formed over the silica-doped catalyst, but not over the undoped catalyst.

• Journal of the Korean Chemical Society
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• v.66 no.6
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• pp.521-525
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• 2022

• Bulletin of the Korean Chemical Society
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• v.10 no.2
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• pp.208-210
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• 1989

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.253-254
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• 1991

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2677-2682
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• 2011

Direct nitrolysis of 3,7-dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane (DPT) is a feasible way to synthesize HMX, and it has multiple practical applications. In this paper, a new nitrolysis process involving the use of an $N_2O_5-HNO_3$ system catalyzed by acidic ionic liquids (AILs) was developed. The results show that [$Et_3NH$]TsO was the best catalyst among the 28 AILs used and that HMX was formed at a higher yield of 61%, compared to 45% without any AIL. Moreover, with the addition of $N_2O_5$, the yield was further increased to a maximum value of 69%. The AILs were also efficiently recovered by simple extractions without any apparent loss of catalytic activity, even after five runs.

• Archives of Pharmacal Research
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• v.13 no.4
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• pp.330-337
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• 1990

The crude polysaccharide from Panax ginseng prepared by hot water extration and precipiation with ethanol was further fractionated into neutral and acidic fractions by DEAE- cellulose ion exchange chromatography. The chemical compositions were 85.0% carbohydrorate and 15.0% protein for the neutral fraction, and 28.4% carbohydrate, 10.0% protein and 29.0% uronic acid for the acidic fraction. The acidic fraction was more effective in increasing of the ratio of spleen to body weight, the number of antibody secreting cells to SRBC and phagocytic activity of reticuloendothelial system, as well as antitumor activity against the solid form of sarcoma 180 in ICR mice than the neutral fraction. All polysaccharide fractions were mitogenic to cultured spleen cells of C57BL/6 mice. However, FA was different from FN in the co-mitogenicities with lectin mitogens. Both crude and acidic fractions potentiated remarkably the mitogenic activity of PHA-P or LPS in dose-dependent manner but neutral fraction enhanced only that of LPS. Three polysaccharide fractions had no effect on that of Con A. These results suggest that the acidic fraction may stimulate B and Td cells as well as macrophages while the neutral fraction may simulate only B cells and macropages.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.685-690
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• 2011

Novel acidic ionic liquids, 1-(${\omega}$-sulfonicacid)propyl-3-methylimidazolium bromide ([$HSO_3$pmim]Br)and 1-(${\omega}$-sulfonicacid)butyl-3-methylimidazolium bromide ([$HSO_3$bmim]Br), were prepared and used as brominating agents, catalysts and solvents in the synthesis of 1,7-dibromoheptane, respectively. 1,7-dibromoheptan with a yield of 95% was obtained at $100^{\circ}C$ for 2 h by simple phase separation. The acidic ionic liquid [$HSO_3$pmim]Br was recycled for 5 times and the yield of 1,7-dibromoheptane did not decrease remarkably, which indicates that catalysts still maintain good selectivity and activity after recycling. The structure of the acidic ionic liquid [$HSO_3$pmim]Br was characterized with IR, and it was found that [$HSO_3$pmim]Br had stronger acidity than other ionic liquid.