• Polymer(Korea)
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• v.26 no.2
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• pp.168-173
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• 2002

Poly (vinyl butyral) (PVB) was synthesized by acetalization of poly (vinyl alcohol) (PVA) PVB was prepared in particulate forms in water, and chemical and physical properties of the products were characterized using various techniques. The prepared PVB had size distribution from 100 to 700 $\mu\textrm{m}$ with mean diameter of about 380 $\mu\textrm{m}$. The chemical structure of PVB was characterized using FT/IR and NMR, and the average degree of acetalization was determined to be 77% from the titration measurement. DSC data showed that the crystalline structure of PVA vanished as acetalization reaction proceeded to produce PVB, and the glass transition temperature emerged at about $70^{\circ}C$. TGA data showed that PVB was much more thermally stable than PVA, and showed no degradation up to $300^{\circ}C$. Solubility test showed that PVB was soluble in alcohols but Insoluble in water, being totally different from PVA.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.237-245
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• 1997

A DEAE-chitin was prepared with DEAE HCl in an aqueous alkali-chitin solution. The resulting DEAE-chitin exhibited a highly improved affinity to water and organic solvents, It was N-deacetylated by heating in aqueous 10% sodium hydroxide containing sodium borohydride for 9h at $80^{\circ}C$ to produce DEAE-chitosan. These conditions were milder than those for the N-deacetylation of chitin. In order to increase its cationic character, the DEAE-chitin was treated with ethyl halide to give TEAE-chitin. The structural changes in the chitin derivatives were confirmed by using both FT-IR and $^1H$ NMR, and their flocculating behavior, in kaoline suspension showed the optimum property at a weak alkaline pH and 8 ppm concentration of resin conditions.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.138-142
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• 2012

The ${\epsilon}$ type copper phthalocyanine (${\epsilon}$-CuPc), called as a pigment blue 15 : 6, is a significant material to produce a blue pixel in LCD (Liquid Crystal Display) panel. In this study, ${\epsilon}$-CuPc sample was synthesized at various reaction conditions by applying the seed method using ${\epsilon}$-CuPc nanoparticles as a seed. Adequate synthetic conditions of the samples were selected by analyzing and comparing crystalline structure, crystalline purity, microstructure, and synthetic yield of the samples with ${\alpha}$ and ${\beta}$ crystalline CuPc samples. The chemical and crystalline structure of the samples were tested using FT-IR spectrometer and X-ray diffractometry, respectively. The shape of the particle was examined using field emission scanning electiron microscope while the thermal property was tested utilizing thermogravimetric analysis.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.150-155
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• 1998

Kinetic studies on the reaction of isoquinoline with para-substituted benzylbromides were conducted under various pressures (1 ~1000 bar) in acetonitrile. From the rate constants obtained, the activation parameters such as$\DeltaV^{\neq}, \Delta\beta^{\neq}, \DeltaH^{\neq}, \DeltaS^{\neq}, \DeltaG^{\neq}$ and Ea were evaluated. Reaction rate increasing the pressure and temperature. The activation compressibility coefficient and the activation entropy showed negative values. From the substituent effect and the results, it was found that the reaction proceeds through $S_N2$ mechanism, but the structure of transition state was slightly changed with substituents and pressure.

• Journal of the Korean Chemical Society
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• v.29 no.4
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• pp.448-451
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• 1985

Pseudo first-order rate constants for reactions of seven m- or p- phenyl-ring substituted 3,5-diphenyl 1,2,4-dithiazolium triodides with hydrazine in excess, in pyridine, were determined by a UV spectrophotometry. For these reactions, calculated some activation parameters, identified the reaction products, and investigated the effect of substituent on the reaction rate. These reactions were accelerated by electron-withdrawing substituents and obeyed the Hammett rule. From the observed kinetics, a reaction mechanism was proposed.

• Applied Biological Chemistry
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• v.46 no.2
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• pp.150-153
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• 2003

Methanol extract obtained from Lindera erythocarpa leaves was successively fractionated with n-hexane, ethylacetate, n-butanol, and $H_2O$. From ethylacetate fraction, an active fraction was isolated through repeated silica gel column chromatography and recrystallization, and was identified as a stereoisomer complex of methyllucidone by MS and MMR analyses. The complex showed 85% antifungal activity at 50 {\mu}g/ml$ against the disease wheat leaf rust.

• Applied Biological Chemistry
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• v.46 no.3
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• pp.268-270
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• 2003

Methanol extract obtained from aerial parts of Platycarya strobilacea was successively fractionated with n-hexane, ethylacetate, n-butanol, and water. From ethylacetate fraction, an active compound was isolated through repeated silica gel column chromatography and was identified as 5-hydroxy-2-methoxy-1,4-naphthoquinone by MS and NMR analyses. The compound showed in vivo 76% antifungal activity at $100\;{\mu}g/ml$ against tomato late blight disease.

• Applied Biological Chemistry
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• v.16 no.2
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• pp.53-59
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• 1973

The anthocyanins in Santa rosa plum (widely growing var. in Korea) were extracted with 0.5% methanolic HCl and purified with Amberlite IRC-50 cation exchange resin. The individual pigments were separated by paper chromatography. The two pigments were identified as cyanidin-3-monoglucoside and cyanidin-3-xyloglucoside based on the following evidence: Rf values in various solvents, partical acid hydrolysis, stepwise hydrolysis, sugar moiety, alkaline degradation, and absorption spectra in the visible region. Cyanicin-3-monoglucoside was the abundant pigment of the plum.

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.48-52
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• 2001

The needles of Pinus densiflora, grown in the campus of Kangwon National University were collected, extracted with acetone-$H_2O$ (7:3, v/v) and freeze dried to give 10.4 g of ethylacetate soluble powder. A portion of the freeze dried powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol, and ethanol-hexane mixture as eluents. The extractives contained a large amount of flavan compounds in addition to a small amount of flavonoid derivatives such as kaempferol-3-O-glucopyranoside, and quercetin-(6"-O-acetyl)-glucopyranoside which has not been isolated from this species yet. Some spectrometric analyses such as NMR and FAB-MS were performed to identify the structures of the isolated flavonoid derivatives.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.895-902
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• 1993

The chemical behavior of trivalent lanthanide ($Pr^{3+}\;and\;Dy^{3+}$) and organo ligands (phen' and terpy') complexes was investigated by the use of UV/vis-spectrophotometric, magnetization and electrochemical method. The magnitude of crystal field splitting energy, the pairing energy and spin state was obtained from the spectra of complexes. These complexes were founded to be diamagnetics, delocalization and low spin complexes. The electrochemical behavior of complexes was observed by the use of cyclic voltammetry in aprotic media. These reduction peaks were irreversible two step reduction processes by electron transfer.