• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.92-93
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• 1996

PVA membrane was widely used in the dehydration pervaporation process. PVA membrane showed remakable selectivity towed water and an excellent film-forming polymer, with a good resistance to orgamic solvents but it has poor stability in aqueous mixtures. Generally the PVA is manufactured by the hydrolysis reaction from poly vinyl acetate(PVAc) and so the degree of PVA hydrolysis is a major parameter for properties of PVA membrane such as the crystallinity and polarity.

• Archives of Pharmacal Research
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• v.17 no.1
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• pp.17-20
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• 1994

Friedel-Crafts reaction of fluorene with methyl ${\alpha}$-chloro-${\alpha}$-(methylthio)acetate 1 gave methyl $\alpha$-methylthio-2-fluoreneacetate 2. Cicloprofen 8, a potent antiinflammatory agent, was prepared by methylation of 2 followed by reductive desulfurization of methyl 2(2-fluorenyl)-2-(methylthio)propionate 6 and hydrolysis of methyl 2-(2-fluorenyl)propionate 7.

• Journal of Microbiology and Biotechnology
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• v.9 no.4
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• pp.509-513
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• 1999

The molecular size reduction and the formation of bitterness during a tryptic hydrolysis of soybean 11S glycinin were determined by using quantitative analysis and organoleptic evaluation. The 11S glycinin of 90% purity was prepared by cryoprecipitation and Con A Sepharose 4B affinity chromatography, and hydrolyzed with trypsin in a pH-stat reactor for 4 h. Bitterness was formed within 1 h of hydrolysis, and then slowly increased up to $3.5\times10^{-5}$ M quinine-HCl equivalent. The extent of hydrolysis (DH) was 7% at 1 h and increased up to 12% by the end of the reaction. The -amino nitrogen content increased from an initial 0.7 mM to 7 mM at the end of the period. The SDS-PAGE analysis showed that the acidic subunit of 11S glycinin was mostly hydrolyzed. The GP-HPLC analysis indicated that the bitterness was mainly contributed by the peptide fractions of molecular weights of 360-2,100 Da.

• Journal of the Korean Chemical Society
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• v.44 no.5
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• pp.429-434
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• 2000

The rate constants for the hydrolysis of styryldiphossphine oxide(SDPO) were deter-mined by ultraviolet visible spectrophotometric method and rate equation which can be applied over wide pH ranges was obtained. On the basis of pH-rate profile, hydrolysis product analysis, general base catalysis and substituent effect, a plausible hydrolysis mechanism is proposed : Below pH 4.5, the hydrolysis reaction is pro-ceeded by the attack of water to carbocation after protonaticentration of hydroxide ion.

• Journal of the Korean Chemical Society
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• v.68 no.3
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• pp.139-145
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• 2024

This study aims to elucidate the mechanism involved in the hydrolysis of the hexacyanoferrate(III) complex ion (Fe(CN)₆^3-) and the mechanism leading to the formation of Prussian blue (Fe^III₄[Fe_II(CN)₆]₃·xH₂O, PB) in acidic aqueous solutions at moderately elevated temperatures. Hydrolysis constitutes a crucial step in generating PB through the widely used single-source or precursor method. Recent PB syntheses predominantly rely on the single-source method, where hexacyanoferrate(II/III) is the exclusive reactant, as opposed to the co-precipitation method employing bare metal ions and hexacyanometalate ions. Despite the widespread adoption of the single-source method, mechanistic exploration remains largely unexplored and speculative. Utilizing UV-vis spectrophotometry, negative-ion mode liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and a devised reaction, this study identifies crucial intermediates, including aqueous Fe^2+/3+ ions and hydrocyanic acid (HCN) in the solution. These two intermediates eventually combine to form thermodynamically stable PB. The findings presented in this research significantly contribute to understanding the fundamental mechanism underlying the acid-catalyzed hydrolysis of the hexacyanoferrate(III) complex ion and the subsequent formation of PB, as proposed in the sequential mechanism introduced herein. This finding might contribute to the cost-effective synthesis of PB by incorporating diverse metal ions and potassium cyanide.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.74-76
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• 2008

The hydrolyses of ten VS dyes were examined at 40$^{\circ}C$, 50$^{\circ}C$, and 60$^{\circ}C$ and the kinetic parameters were estimated. The values of free energy, enthalpy and entropy of hydrolysis and reaction with cellulose for VS dyes were calculated. The linear relationship exist between the enthalpy and entropy. The structure and entropy of VS dyes gave a effect on the dimerization for VS reactive dyes. The VS dyes have small value of entropy were formed dimer. It was confirmed that no dimer form for m-substituted VS dyes. There were similarities among various reactions including homo- and mixed dimerization.

• Journal of the Korean Applied Science and Technology
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• v.15 no.3
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• pp.39-45
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• 1998

In recent years, there has been considerable interest in the development of new functional surfactant including new type of anionic surfactants. Anionic surfactants, ${\alpha}-sulfo$ fatty acids that straight long chain alkyl group having from 12 to 18 carbon atoms, were synthesized with sulfur trioxide-dioxane complex to good yield. Xylitol ${\alpha}-sulfo$ fatty acid esters were obtained by reaction that the acetification and esterification of xylitol, by addition reaction with sodium chloride and hydrolysis respectively. These compounds were a new group of destructible surfactants which readily hydrolyzed and oxidized in natural water reservoirs. Physical properties of these new compounds involved surface tension, critical micelle concentration(cmc), foaming power, emulsion power, and hydrolysis properties, were measured. The cmc values of the compounds by ring method were assumed to $7.0{\times}10^{-3}{\sim}3.0{\times}10^{-2}mol/{\ell}$ range and surface tensions at cmc were $25{\sim}31dyne/cm$ respectively.

• KSBB Journal
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• v.13 no.3
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• pp.312-319
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• 1998

The dilute-acid pretreatment/hydrolysis of hemicellulose in oak wood using a percolation reactor was investigated. The experimental conditions ranged 160∼180$^{\circ}C$ and 0.05∼0.2 wt.% sulfuric acid. XMG(xylan+mannan+galactan) recovery was higher when sulfuric acid was used as leaching solvent than water. Also it was important for high XMG recovery to keep leaching temperature higher after reaction. XMG recovery was decreased as the size of wood chips was increased. At an optimum condition (reaction condition= 170$^{\circ}C$, 0.1% sulfuric acid, 1ml/min, 10min, leaching condition=0.1% sulfuric acid, 2mL/min, 20 min), the product yield and the sugar concentration were about 92% and 2.7%, respectively.

• Journal of the Korean Ceramic Society
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• v.24 no.5
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• pp.500-506
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• 1987

In order to synthesize monodispersed spherical silica fine particles, we investigated the reaction of hydrolysis of 0.05∼4.0 mole Si(OC2H5)4-0.01∼7.60mole NH3 -0.24∼38.40 mole H2O-2.62∼16.88mole C2H5OH systems. The range of the composition of solution which spherical silica particles were formed was enlarged according to an increase in concentration of Si(OC2H5)4. Larger particles were obtained at higher molar ratios of Si(OC2H5)4/C2H5OH, NH3/H2O and H2O/Si(OC2H5)4 and at a lower reaction temperature.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.593-596
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• 2000

Chiral epoxides are useful chiral synthons in organic synthesis and various biological methods have been investigated for the production of chiral epoxides. In this work, enantioselective resolution of racemic styrene oxide was investigated using an isolated Aspergillus niger sp. for the production of optically pure (S) -styrene oxide. The enantioselectivity and initial hydrolysis rates of racemic substrate were highly dependent on the pH, temperature, and the volume ratio of cosolvent. The experimental sets of pH, temperature, and the volume ratio of cosolvent were designed using central composite experimental design, and the reaction conditions were optimized using response surface analysis. The optimal conditions of pH, temperature, and the volume ration of cosolvent were determined to be 7.78, $28.32^{\circ}C$, and 2.4 %(v/v), respectively, and optically pure (S)-styrene oxide (> 99% ee) could be obtained with the 35 % yield by microbial enantioselective hydrolysis reaction.