• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.267-276
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• 2020

Poly(epichlorohydrin) copolyol series (PECH copolyols) were synthesized via cationic ring-opening copolymerization (ROCP) of oxirane-based monomers and effects of reaction temperature, solvent type, and initiator were studied. As a comonomer, two types of alkylene oxides were used, and polymerization conditions were conducted both with diethylene glycol (DEG) as an initiator in methylene chloride (MC) solvent and tripropylene glycol (TPG) in toluene solvent. In order to induce the active monomer (AM) mechanism in the ring-opening copolymerization reaction, the monomer was injected by an incremental monomer addition (IMA) method using a syringe pump, and the polymerization was performed at -5 ℃. PECH copolyol, a synthesized ephichorohydrin (ECH)-based copolyol, was converted to glycidyl azide-based energy-containing copolyol (GAP copolyol) by azadizing the ECH unit through a substitution reaction. It was confirmed that the synthesized azide copolyol had little effects on changes of the solvent and the initiator. Also, the molecular weight increased 500 after the azide reaction, thereby the GAP copolyol was polymerized as designed. As the content of the comonomer increased, both the T_g and viscosity tended to decrease due to the influence of the alkyl chain length. It is possible to fundamentally prevent CH₃N₃ amount produced in the azide reaction process, and it is expected that a large-scale process could be achievable.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.309-313
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• 1997

Maillard reaction products (MRPs) added into a culture and the resultant bacterial growth were investigated using response surface methodology. The coefficients of determination $(R^{2})$ of response surface regression equations for bacteria were 0.9544 and 0.9578 in Bacillus subtilis and Bacillus natto, respectively. The MRPs produced at higher reaction temperature and for longer reaction time showed greater antimicrobial effect for Bacillus subtilis. Especially, the MRPs produced at temperature above $150^{\circ}C$ for 8 to 12 hrs showed the strongest antimicrobial effect. The MRPs produced at lower reaction temperature and for shorter reaction time showed greater microbial growth effect for Bacillus natto, but those produced at the reaction temperature higher than $160^{\circ}C$ showed the greatest antimicrobial effect. In the ridge analysis, the growth of Bacillus subtilis was the most significantly inhibited in the presence of MRPs prepared at $159.10^{\circ}C$ and pH 12.21 for 9.67 hrs, and the growth of Bacillus natto was the most significantly inhibited in the presence of MRPs prepared at $169.94^{\circ}C$ and pH 9.66 for 9.22 hrs.

• Resources Recycling
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• v.26 no.5
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• pp.3-11
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• 2017

Solvent extraction is an important process to recover pure gold and silver from various leaching solutions. The present work reviews the aqueous chemistry and solvent extraction separation of gold (I, III) and silver (I) from several leaching systems such as cyanide, thiocyanate, thiosulfate, thiourea and chloride medium. The extraction and separation behavior of gold (I, III) and silver (I) by various single and mixtures was compared on the basis of extraction reaction and the selectivity from these mediums. The chloride medium is recommended for the separation of gold and silver by solvent extraction in terms of extraction and stripping efficiency.

• KOREAN POULTRY JOURNAL
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• v.43 no.9
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• pp.134-137
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• 2011

생물체 내에 다량으로 존재하며 생체에서는 각종 생체물질의 이상적 용매와 생화학반응의 반응물질로서 중요한 역할을 한다. 경기도 화성소재 태영산을 지고 있는 비봉농장은 급수에 중점을 두고 건강한 닭을 통해 안전하고 고품질의 계란을 생산하기 위해 애쓰고 있다. 지난 20여 년 간 큰 규모는 아니지만, 꾸준히 양계업에 애착을 갖고 운영하는 한상훈(비봉농장, 52세) 사장의 비봉농장을 찾아 농장경영과 앞으로의 계획에 대해 들어보았다.

• Proceedings of the Korean Society of Life Science Conference
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• 2001.02a
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• pp.65-65
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• 2001

• Food Science and Preservation
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• v.8 no.4
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• pp.456-461
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• 2001

To develop the use of natural pigment for food, carotenoids from wasted persimmon peel were extracted with seven organic solvents. Among the solvents, acetone was a high yielding solvent of carotenoids. Extraction trends depending on process variables(temperature, time, solvent ratio to persimmon peel) were explained through response surface which was made by central composite experimental design. Carotenoid contents were increased with the extraction time and solvent ratio but it decreaed in the higher experimental design. Carotenoid contents were increased with the extraction time and solvent ratio but it decreased in the higher extraction temperature. The optimum conditions of extraction process variables were predicted as 29$\^{C}$, 93min. at fixed solvent ratio(1:27).

• Journal of Life Science
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• v.6 no.1
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• pp.66-71
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• 1996

Antioxidative activity of various solvent extracts from freeze dried Kimchi was studied during the oxidation process of linoleic acid mixture system. The aqueous model systems were used for the evaluation of antioxidative activity of solvent extracts during the oxidative reaction at 37$^{\circ}C$ by the determination of peroxide value. The linoleic acid mixture for the aqueous model systems was consisted of linoleic acid (64.6%), oleic acid(27.4%), and other acids in ethanolic phosphate buffer (pH 7.0). Water and methanol extracts of Kimchi had a considerable antioxidative activity with the inhibition of peroxides formation during the autoxidation of linoleic acid mixture in aqueous model systems. Antioxidative activity of 75% methanol extract of 7 day-fermented-Kimchi was relatively higher than that of others, however lower than alpa-tocopherol and butylated hydroxyanisol. The antioxidative effect of 75% methanol extract of 7 day-fermented-Kimchi was increased by the its concentration from 0.5% to 2.5% in the oxidation reactions of aqueous model systems.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.716-726
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• 2013

Enzymatic acylations catalyzed by hydrolytic enzymes, along with enzymatic hydrolysis, are established reactions in the synthesis of fine chemicals such as chiral intermediates and polymerizations in the industry. Those reactions have been carried out mostly in organic media due to the thermodynamic limitations. Recently, there have been reports on enzymatic acylations in aqueous media. They have dealt with the elucidation of reaction mechanisms of hydrolases and acyl transferases based on their X-ray structures, homology comparison of the two kinds of enzymes, substrate engineering of acyl donors and computational design of acyl transferases for enzymatic acylations in aqueous media. Enzymatic acylations play an important role in the combinatorial synthesis of natural products such as polyketides and nonribosomal peptides. In this review, the historic developments of enzymatic acylations and industrial examples are described briefly. In addition, recent developments of enzymatic acylations in the modification of natural products and their prospects will be discussed.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.432-438
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• 2008

Hydrogenation reactions of p-toluidine over Ru/C were performed while varying reaction temperature, the hydrogen pressure, catalyst loading, solvent, and alkali additive and the effects on the reaction rates and product distribution were examined. 4-Methylcyclohexylamine was generated as a main product and bis(4-methyl cyclohexyl)amine was obtained as a resentative side-product for the hydrogenation reaction of p-toluidine. The selectivity of MCHA decreased with reaction temperature and the hydrogen pressure while increased with catalyst loading. IPA was the best solvent for MCHA. A mechanism of hydrogenation reaction of p-toluidine was suggested from the results. It was found that the presence of alkali salt increased MCHA by reducing BMCHA and rates of hydrogen reaction increased.

• Journal of the Korean Chemical Society
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• v.41 no.12
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• pp.639-644
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• 1997

Novel carbonylruthenium (Ⅲ) complex Cp*Ru(CO)Cl2(2, Cp*=η5-C5Me5) was synthesized by the reaction of [Cp*RuCl2]2(1) with CO in toluene. The effective magnetic moment (Veff=1.81 B.M.) derived from the magnetic susceptibility measurement of the complex (2) was consistent with the presence of one "single" unpaired electron. Dibromocarbonylruthenium (Ⅲ) complex Cp*Ru(CO)Br2(3) was obtained by the reaction of complex (2) with KBr in toluene. Complex (2) was easily reduced by the reaction with phosphine in toluene to give the corresponding Ru (Ⅱ) complex Cp*Ru(CO)(PR3)Cl (4a∼4e, PR3=PMe3, PEt3, PMePh2, PPh3, PCy3).