• Bulletin of the Korean Chemical Society
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• 제30권4호
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• pp.825-828
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• 2009

Alum $(KAl(SO_4)_2{\cdot}12H_2O)$ is an inexpensive, efficient, non‐toxic and mild catalyst for the synthesis of bis(indolyl)methanes by the reaction of 1H-indole with various aldehydes/ketones under the influence of ultrasound irradiation in solvent‐free condition. The remarkable advantages of this method are the simple experimental procedures, shorter reaction times, high yields of product and green aspects by avoiding toxic catalysts and solvents.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2367-2374
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• 2013

Lysine (Lys) immobilized on zeolite 4A was prepared by a simple adsorption method. The physical and chemical properties of Lys/zeolite 4A were investigated by X-ray diffraction (XRD), FT-IR, Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis. The obtained organic-inorganic composite was effectively employed as a heterogeneous basic catalyst for synthesis of ${\alpha},{\beta}$-unsaturated carbonyl compounds. No by-product formation, high yields, short reaction times, mild reaction conditions, operational simplicity with reusability of the catalyst are the salient features of the present catalyst.

• 대한화학회지
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• 제64권1호
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• pp.7-18
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• 2020

An efficient and facile procedure has been developed for the synthesis of novel bichalcone derivatives (4a, 4b). The key step contains the solvent-free aldol synthesis of bichalcones based on quinones. Bichalcones (4a, 4b) were used as precursors for the synthesis of some interesting heterocyclic compounds like, diazepines (5a, 5b), pyrazolo-pyrimidines (7a, 7b), and pyrazoline derivatives (8a, 8b). Moreover, new thioxopyrimidine derivatives (9a, 9b) were furnished and used as a functionalizing agent to produce the triazole-pyrimidines (11, 12) and the carbonitrile derivative (14). All the synthesized compounds were fully characterized using physical and spectral data like, FT-IR, ¹H NMR, ¹³C NMR, and MS. Bichalcones (4a, 4b) and diazepines (5a, 5b) were screened for their anticonvulsant activity, where compounds (4a, 5a, and 5b) revealed potent anticonvulsant activity compared to diazepam. On the other hand, some of the prepared compounds were screened for their antiproliferative activity and they showed significant cytotoxic effects on most of the cancer cell lines with regard to broad spectrum antitumor activity.

• 대한화학회지
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• 제53권5호
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• pp.536-541
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• 2009

무용제하에서 $\alpha$-히드록시 인산염을 합성하기 위해 술팜산은 비용효율이 높고 일반적인 산들의 친환경적인 대안으로 활용되었다. 초음파 조사를 이용하여 더 나은 수율을 얻었고 반응시간이 짧았다.

• 분석과학
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• 제30권3호
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• pp.138-145
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• 2017

Microwave-assisted organic synthesis has gained a remarkable interest over the past years because of its advantages - (i) rapid energy transfer and superheating, (ii) higher yield and rapid reaction, (iii) cleaner reactions. Ionic liquids are well known for their unique properties such as negligible vapor pressure and high thermal stability. With these properties, ionic liquids have gained increasing attention as green, multi-use reaction media. Recently, ionic liquids have been applied as reaction media for biocatalysis. Lipase-catalyzed reactions in ionic liquids provide high activity and yield compared to conventional organic solvents or solvent free system. Since polar molecules are generally good absorbent to microwave radiation, ionic liquids were investigated as reaction media to improve activity and productivity. In this study, therefore, the effect of microwave irradiation in ionic liquids was investigated on lipase catalyzed reactions such as benzyl acetate synthesis and caffeic acid phenethyl ester synthesis. Comparing to conventional heating, microwave heating showed almost the same final conversion but increased initial reaction rate (3.03 mM/min) compared to 2.11 mM/min in conventional heating at $50^{\circ}C$.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.153-160
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• 2018

An environmentally favorable (chlorine-free) solid oxidizer, guanidinium dinitramide [GDN; $NH_2C(NH_2)NH_2N(NO_2)_2$], was newly synthesized from guanidine carbonate [$NH_2C(=NH)NH_2{\cdot}1/2H_2CO_3$]. Two different crystalline forms (${\alpha}-type$ and ${\beta}-type$) appeared according to the applied solvents and synthesis conditions. Moisture, during extraction, might become trapped in a crystal between inner molecules. Therefore, despite having the same chemical composition, Raman-IR and TGA-DSC revealed different physical characteristics of the two forms. Peaks of Raman shift near $1000cm^{-1}$ implied different chemical structures. Thermal analysis revealed an exothermic temperature $155.7^{\circ}C$ for ${\alpha}-type$ but one of $191.6^{\circ}C$ for ${\beta}-type$. The caloric value of ${\alpha}-type$ was 536.4 J/g, which was 2.5 times larger than that of the ${\beta}-type$, which was 1310 J/g. While the synthesized GDN of ${\alpha}-type$ showed a steep exothermic decomposition, the ${\beta}-type$ was slowly decomposed after melting through an endothermic process. This work implied that despite of the same molecular formula some different core thermal properties would appear depending on synthesis conditions.

• Bulletin of the Korean Chemical Society
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• 제22권1호
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• pp.53-58
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• 2001

Sulfonated poly(phenylene sulfide) (SPPS) polymers were prepared by sulfonation of poly[methyl[4-(phenylthio) phenyl]sulfonium trifluoromethanesulfonate] (PPST) with fumic sulfonic acid (10% $SO_3-H_2SO_4$) and demethylation with aqueous NaOH solution. The equilibrium constants of ion exchange reactions between alkali metal cations ($Li^+,\;Na^+,\;and\;K^+$) and SPPS ion exchanger in organic solvents such as tetrahydrofuran (THF) and dioxane were measured. The equilibrium constants of ion exchange reactions increased as the polarity of the solvent increased, and the reaction temperature decreased. The equilibrium constants of the ion exchange reaction ($K_{eq}$) also increased in the order of $Li^+,\;Na^+,\;and\;K^+$. To elucidate the spontaneity of the exchange reaction in organic solvents, the enthalpy, entropy, and Gibbs free energy were calculated. The enthalpy of reaction ranged from -0.88 to -1.33 kcal/mol, entropy ranged from 1.42 to 4.41 cal/Kmol, and Gibbs free energy ranged from -1.03 to -2.55 kcal/mol. Therefore, the exchange reactions were spontaneous because the Gibbs free energies were negative. The SPPS ion exchanger and alkali metal ion bounding each other produced good ion exchange capability in organic solvents.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1457-1464
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• 2012

An ecofriendly catalytic route for selective synthesis of $N$-substituted azacyclopentanes, nitrogen-containing heterocyclic intermediates for many bioactive compounds, was established by carrying out $N$-heterocyclization (di $N$-alkylation) of primary amines with 1,4-dichloro butane (as dialkylating agent) using catalytic amount of hydrotalcite as solid base catalyst. The hydrotalcite was found to be efficient solid base catalyst for di $N$-alkylation of different primary amines (aniline, benzyl amine, cyclohexyl amine and n-butyl amine) giving 82 to 96% conversion (at optimized reaction condition) of 1,4-dichloro butane and > 99% selectivity of respective $N$-substituted azacyclopentanes within 30 min. under solvent free condition. The reaction parameters significantly influence the conversion of 1,4-dichloro butane to $N$-substituted azacyclopentanes. The nature of substituent present on amino group affects the reactivity of amine substrates for di $N$-alkylation reaction with 1,4-dichloro butane. The 1,4-dichloro butane was found to be highly reactive alkylating agent for di $N$-alkylation of amines as compared to 1,4-dihydroxy butane. The reusability of the catalyst and its chemical stability in the reaction was demonstrated.

• 한국식품과학회지
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• 제36권2호
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• pp.211-216
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• 2004

회분식 반응기(stirred-tank batch reactor)를 사용한 DAG, MAG 함유 기능성유지를 비용매계(solvent-free system) 조건에서 효소적 반응을 이용하여 합성하였다. 48시간 동안 합성된 지질을 HPLC를 사용한 TAG, 1,3-DAG, 1,2-DAG 및 MAG 함량 분석결과 각각 45.05, 16.27, 23.05 및 14.98%로 분석되었으며 체중개선 기능성 유지의 지방산 조성 분석결과 palmitic, palmitoleic, stearic, oleic, linoleic 및 linolenic acid가 13.21, 0.15, 2.02, 34.36, 49.12 및 1.14 mol%로 분석되었다. 합성된 지질의 ${\alpha},\;{\gamma}$ 및 ${\delta}-tocopherol$ 함량을 분석한 결과는 각각 0.014, 0.029 및 0.010%로 분석되었으며 총 tocopherol 함량은 0.053%로 나타났다. 또한 재구성된 지질을 사용하여 산가, 비누화가, 요오드가를 측정하였으며 융점 및 결정화점을 살펴보고 이를 통하여 옥수수유로 유래된 DAG, MAG를 함유한 체중개선 기능성 유지의 이화학적, 물리적 특징을 규명하였다. 체중개선 기능성 유지의 산화 안정성 실험을 시행한 결과 체중개선 기능성 유지가 원료유인 옥수수유보다 높은 과산화물가와 p-anisidine가를 보였으며 각기 달리 혼합한 rosemary추출물(100, 200 및 300ppm)이 체중개선 기능성 유지와 옥수수유의 산화를 감소 시켰다.

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2341-2344
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• 2010

A convenient synthesis of substituted [1,2,4]-triazolo [1',2':1,2]pyrimido[6,5-b]-quinoline 4(a-i) from substituted 2-chloroquinoline-3-carbaldehyde 1(a-i) and 4H-1,2,4-triazol-3-amine 2 by using $SiO_2/K_2CO_3$ under microwave irradiation. This method affords the [1,2,4]-Triazolo [1',2':1,2]pyrimido[6,5-b]-quinoline 4(a-i) under the influence of microwave irradiation in solvent-free conditions within short span (12 - 20 min), & gaves excellent yields (89 - 95%). All the synthesized compounds were further screened for their antibacterial activities. Some of our compounds showed excellent antibacterial activities against control drugs.