• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.155-157
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• 2011

본 논문에서는 In-situ 전기화학 AFM과 In-situ 전기화학 Raman을 주된 분석방법으로 리튬 이차전지의 흑연 음극과 PC계 전해질 계면에서의 반응을 이해하고자 하였다. In-situ 전기화학 AFM 분석방법을 통하여 PC계 전해질에서 용매화된 리튬의 삽입/탈리반응이 진행되는 것을 확인할 수 있었으며 In-situ 전기화학 Raman 분석방법을 이용하여 PC계 전해질에서는 삼원계 Li-GIC가 생성되는 것을 확인할 수 있었다.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.287-292
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• 1992

The rate constants of the nucleophilic addition reaction of amines (piperidine and diethylamine) to phenylvinylketone in various solvents have been determined by UV spectrophotometry at $25^{\circ}C$. On the basis of the high sensitivity of the rate to the polarity of the medium, it may be concluded that the reaction intermediate has zwitterionic character. The effect of the solvents on the rate of the bimolecular nucleophilic addition reaction is described well by the Kirkwood equation: The transition state of the reaction has a cyclic structure formed through an intramolecular hydrogen bond. The addition reaction of primary and secondary amines to phenylvinylketone in all solvents take place considerably faster than that of tertiary amine and this results also can be explained by the intermediate products in the reaction have a cyclic structure formed through an intramolecular hydrogen bond for the primary and secondary amines but not for the tertiary amine.

• Journal of the Korean Chemical Society
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• v.41 no.1
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• pp.22-46
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• 1997

Kinetic studies on nucleophilic substitution reaction of phenacyl bromide and phenacyl chloride with pyridines were conducted at 25℃ and 35℃ in methanol-acetonitrile solvents mixtures. It was shown that the reaction proceeds via an SN2 reaction mechanism based on the transition state parameters, ΔH≠ and ΔS≠ and Bro nsted β values. Quantum mechanical model predicted a product-like transition state, where bond-formation is much more progressed than bond breaking, upon changing the leaving group to that with a better leaving ability.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.141.1-141.1
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• 2015

탄소나노튜브는 우수한 전기적 특성과 더불어 열전도도, 강도, 높은 화학적 안정성, 바이오 물질과의 친화성 때문에 많은 응용이 가능하며 최근까지도 활발히 연구되는 대표적인 탄소질의 물질이다. 이러한 다중 벽 탄소나노튜브를 제품화시키기 위해서는 특정 용매에서 용이한 분산성을 지닐 수 있도록 기능화 공정이 필수적이고 많은 양의 파우더를 기능화 시킬 수 있는 장비의 구조 및 공정개선이 요구된다. 플라즈마 기술을 이용한 건식의 순환형 나노분산 파우더 플라즈마 반복처리장치를 통하여 기능화 처리된 탄소나노튜브를 습식공정에 비해 간편한 공정으로 재현성 있고 균일한 결과로 많은 양의 확보가 가능하다. 이에 탄소나노튜브의 기능화 결과를 제시함으로써 본 장비를 소개하고자 한다.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.98-99
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• 2000

최근 유전자 공학의 급속한 발전으로 인하여 유전자 조작을 통한 생화합물의 대량 생산, 세포배양에 의한 생화학제품(아미노산, 단백질, 핵산)의 생산이 크게 진보하고 있으나, 이에 비해 생화학제품을 효율적으로 분리 및 정제하는 기술은 상대적으로 발전하지 못했다. 생화합물의 분리 방법은 전통적으로 유기용매에 의한 침전법, 염석법, 탈염법, 크로마토그래피법, 전기영동법, 흡착제를 이용한 흡착법등을 사용하는데 이 방법들은 소규모 및 회분식 공정으로 이루어져 대형화에 따른 분리 공정의 효율이 감소하는 어려움이 있었다. 따라서 연속공정으로서 대형화가 쉽고, 효율적인 생물분리공정의 개발이 요구되고 있다. (중략)

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.224-231
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• 1990

To improve the dispersion of platinum catalyst, the effects of carbon black surface treatment, solvents, surfactants, and ultrasonic homogenizing were examined. Upon introducing the hydrophilic groups acting as an anchorage center of the catalyst on the surface of carbon black by oxidation, the migrating and growing of platinum particles(or ions) during reduction could be restricted. When mixed solvents, surfactants, or ultrasonic homogenizer were used to disperse catalysts on the carbon black, the dispersion of catalyst could be improved, due to the good permeation of chloroplatinic acid through the pore of carbon black. Among the impregnation methods, the method using ultrasonic homogenizer with mixed solvent was the most excellent. Using this method the particle sized could be minimized in less than $30A^{\circ}$ and distributed homogeneously.

• 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.

• Journal of Life Science
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• v.26 no.5
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• pp.603-607
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• 2016

A crude extracellular lipase from solvent-tolerant bacterium Pseudomonas sp. BCNU 106 was highly stable in the broad pH range of 4-10 and at temperature of 37℃. Crude lipase of BCNU 106 exhibited enhanced stability in 25% organic solvents such as xylene (121.85%), hexane (120.35%), octane (120.41 %), toluene (118.14%), chloroform (103.66%) and dodecane (102.94%) and showed excellent stability comparable with the commercial immobilized enzyme. In addition, the stability of BCNU 106 lipase retained above 110% of its enzyme activity in the presence of Cu²⁺, Hg²⁺, Zn²⁺ and Mn²⁺, whereas Fe²⁺ strongly inhibited its stability. The detergents including tween 80, triton X-100 and SDS were positive signals for lipase stability. Because of its stability in multiple organic solvents, cations and surfactants, the Pseudomonas sp. BCNU 106 lipase could be considered as a potential biocatalyst in the industrial chemical processes without using immobilization.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.1
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• pp.46-52
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• 2008

Oils and chlorinated solvents leaking to the subsurface are entrapped in the soil pore and these are called as nonaqueous phase liquids (NAPL). NAPL entrapped in porous media acts as a continuous source for surface and ground water contamination. This study visualized dissolution of trichloroethylene (TCE) entrapped in porous media and quantified the velocity of TCE dissolution using an image analysis technique. As the water velocity increased, the level of dissolution increased. The results imply that a TCE contaminated region having a high infiltration rate and groundwater velocity may result in severe groundwater contamination. Microscopic images of TCE entrapped in porous media showed that TCE present in the preferential flow paths was easily dissoluted into the water phase. However, TCE present in the stagnant flow region was visualized for long time. The results imply that TCE would be still present in the soil if TCE is detected in goundwater.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.423-427
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• 2010

Carbon nano sphere(CNS) and nano bowl of carbon(NBC) containing 1.0 wt% copper were prepared by impregnation method and their catalytic activity was compared in the phenol hydroxylation with hydrogen peroxide in the presence of water and acetonitrile as a solvent, respectively. Cu content of catalysts was determined by EDS, and BET, pore volume, pore size and pore size distribution were compared. For both catalysts, phenol conversion, $H_2O_2$ efficiency and yield of catechol and hydroquinone were higher in the presence of water as a solvent than those in the presence of actonitrile. And catalytic activity such as phenol conversion and $H_2O_2$ efficiency of 1.0 Cu/CNS is about two times higher than that of 1.0 Cu/NBC in water solvent.