• Archives of Pharmacal Research
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• 제13권4호
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• pp.385-387
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• 1990

3-[(1-Methyl-1H-tetrazol-5-y)thiomethyl] is one of the most important side chains in cephaloporins. This side chain which occures in numerous antibacterial agents, suc as cefamandole, latamoxef, cefoperazone, and cefmenoxime, contributes remarkable potency and broad spectrum. For the continuous work of study on the development of broad spectrum cephalosporins, we become interested in the effect of structural modification of the substituent at the N-1 position of mercaptoterazole toward biological activity because our recent work had demonstraated that the arylsubstituted mercaptotetrazoles (Fig. 1) had favorable effect on the activity against gram-positive bacteria. The main focus of this report was to investigate the relationship between activity and functional groups in the mercaptotetrazole.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.591-594
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• 1995

The influence of protecting groups on the β-sheet-structure-stability of protected peptides was studied in organic solvents. α-amino groups, carboxyl groups and side chain functional groups of model peptides were protected by suitable groups commonly used in peptide synthesis. The difference of the solubilities of model peptides was investigated by the solvent-titration method by using IR absorption spectra. The β-sheet structure of model peptide in CH2Cl2 was easily disrupted by increasing the amounts of DMSO. The β-sheet-structure-stabilizing potentials of each protecting group showed similar behaviors except Npys, Mts and Z2. The result exhibits that the < SPβ > values of protected peptides are almost independent of the kinds of their protecting groups.

• Korean Membrane Journal
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• 제2권1호
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• pp.56-59
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• 2000

The surface charge properties of a polymeric NF and a ceramic UF membranes were characterized in terms of zeta potential and acidity. Both the negative zeta potential and acidity values increased as pH increases due to ionizable acidic functional groups. Increased ionic strength reduced the acidity of the negatively-charged membrane surface as anticipated. Through these results, it can be envisioned are used to reject solutes with ionizable functional groups. Fouling of the negatively-charged membrane with natural organic matter (NOM) having a negative charge density was also investigated with respect to the surface charge. The surface charge of the NF membrane increased negatively when greater NOM adsorption onto the membrane surface occured.

• Bulletin of the Korean Chemical Society
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• 제19권2호
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• pp.243-249
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• 1998

The reaction of alcohol with a solution of thexylborane (ThxBH2) in tetrahydrofuran (THF) provides a new class of mild and selective reducing agents, thexylalkoxyboranes (ThxBHOR: R=Et, i-Pr, i-Bu, s-Bu, t-Bu, Ph). In order to elucidate the effect of the alkoxy group in reduction reactions, the reducing power of ThxBHOR toward selected organic compounds containing representative functional groups under practical conditions (THF, 25°, the quantitative amount of reagent to compound) has been investigated. Generally, the reactivity of ThxBHOR is largely dependent upon the alkoxy substituent. ThxBHOR can be synthesized from a variety of alcohols, thus allowing control of the steric and electronic environment of these reagents.

• 한국염색가공학회지
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• 제28권4호
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• pp.280-289
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• 2016

Silica microgel was prepared by sol-gel process and then functional groups, epoxy group and ethoxy group, were introduced on the particle by coupling treatment with 3-glysidoxypropyltrimethoxysilane. The functional silica microgel(functional SiGel) formation was identified using FT-IR spectrometry. Phase stability for DMF solution of functional SiGel, PU resin and pigment was evaluated by Turbiscan Lab. And physical properties of artificial suede including hand values, morphology and dyeing fastness were investigated. The mean particle size and the specific surface area of the functional SiGel were $0.77{\mu}m$ and $380m^2/g$. Mixture containing the functional SiGel, PU resin and pigment was more stable than the functional SiGel-free mixed solution. Artificial suede prepared by the functional SiGel had appearance and feeling close to natural suede. The migration fastness, the solvent wicking fastness and rubbing fastness of the artificial suede were enhanced to 4~5 grades, 4~5 grades and 3~4 grades, respectively.

• Korean Chemical Engineering Research
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• 제46권2호
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• pp.436-442
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• 2008

수용액에서 음이온을 제거하기 위하여 다양한 종류의 유기/무기 복합음이온교환수지를 제조하였다. 제조된 음이온교환수지들은 질소흡탈착 실험, 적외선분광실험, 원소분석 등을 통하여 그 특성을 조사하였다. 또한 제조된 음이온교환수지의 음이온 교환 특성을 조사하기 위하여 배치(batch) 실험과 키네틱(kinetic) 실험을 수행하였다. 제조된 시료들 가운데 트리메틸암모늄 기능기를 사용했을 때보다 트리부틸암모늄 기능기를 사용하였을 때 더욱 큰 흡착량을 나타내었는데, 이것은 호프마이스터 효과와도 부합된다. 또한, 소수성기를 다량 보유하고 있는 계면활성제인 헥사데실아민도 소수성 음이온에 대한 교환능이 있는 것을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3269-3273
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• 2013

Graphene oxide (GO) has been of particular interest because it provides unique properties due to its high surface area, chemical functionality and ease of mass production. GO is produced by chemical exfoliation of graphite and is decorated with oxygen-containing groups such as phenol hydroxyl, epoxide groups and ionizable carboxylic acid groups. Due to the presence of those functional groups, GO can be utilized as a novel platform for hybrid nanocomposites in chemical synthetic approaches. In this work, GO-$SnO_2$ nanocomposites have been prepared through the spontaneous formation of molecular hybrids. When $SnO_2$ precursor solution and GO suspension were simply mixed, $Sn^{2+}$ was spontaneously formed into $SnO_2$ nanoparticles upon the deoxygenation of GO. Through further chemical reduction by adding hydrazine, reduced GO-$SnO_2$ hybrid was finally created. Our investigation for the electrocapacitive properties of hybrid electrode showed the enhanced performance (389 F/g), compared with rGO-only electrode (241 F/g). Our approach offers a scalable, robust synthetic route to prepare graphene-based nanocomposites for supercapacitor electrode via spontaneous hybridization.

• 한국토양환경학회지
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• 제4권3호
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• pp.85-93
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• 1999

유기 염소계 화합물과 니트로기 방향족 화합물 같은 난분해성 유해물질을 처리함에 있어, 0가 철 분말의 사용은 최근에 가장 활발히 논의되고 있는 기술 가운데 하나이다. 본 연구에서는 나노크기의 0가 철 분말을 실험실에서 만들어 유기 염소계 화합물의 탈염소화 반응과 니트로기 방향족 화합물의 니트로기 변환실험을 혐기성 회분식 반응조에서 실시하였다. 매우 큰 비표면적과 높은 반응성을 가지고 있는 나노크기 0가 철 입자는 10mg/$\ell$로 농도수용액상에 존재하는 TCE, 클로로포름, 니트로 벤젠, 니트로 톨루엔, 디니트로 밴젠, 디니트로 톨루엔등의 물질을 상온.상압의 조건에서 빨리 제거할 수 있었다. 본 연구에서는 반응 시간 30분 안에 TCE는 에탄으로, 클로로포름은 메탄으로 탈염소화 되었고, 니트로기 방향족 화합물의 니트로기는 모두 아민기로 변환되었다. 이러한 결과들은 유기 염소계 화합물과 니트로기 방향족 화합물 같은 난분해성 유해물질로 오염된 지하수나토양을 복원함에 있어, 나노크기의 0가 철 분말을 이용한 화학적 처리기술의 잠재성을 나타내주는 것이다.

• Bulletin of the Korean Chemical Society
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• 제15권10호
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• pp.881-888
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• 1994

The approximate rates and stoichiometry of the reaction of excess sodium tris(diethylamino)aluminum hydride (ST-DEA) with selected organic compounds containing representative functional groups under standardized conditions(tetrahydrofuran, $0{\circ}$) were studied in order to characterize the reducing characteristics of the reagent for selective reductions. The reducing ability of STDEA was also compared with those of the parent sodium aluminum hydride (SAH) and lithium tris(diethylamino)aluminum hydride (LTDEA). The reagent appears to be milder than LTDEA. Nevertheless, the reducing action of STDEA is very similar to that observed previously for LTDEA, as is the case of the corresponding parent sodium and lithium aluminum hydrides. STDEA shows a unique reducing characteristics. Thus, benzyl alcohol, phenol and 1-hexanol evolved hydrogen slowly, whereas 3-hexanol and 3-ethyl-3-pentanol, secondary and tertiary alcohols, were essentially inert to STDEA. Primary amine, such as n-hexylamine, evolved only 1 equivalent of hydrogen slowly. On the other hand, thiols examined were absolutely stable. STDEA reduced aidehydes and ketones rapidly to the corresponding alcohols. The stereoselectivity in the reduction of cyclic ketones by STDEA was similar to that by LTDEA. Quinones, such as p-benzoquinone and anthraquinone, were reduced to the corresponding 1,4-dihydroxycyclohexadienes without evolution of hydrogen. Carboxylic acids and anhydrides were reduced very slowly, whereas acid chlorides were reduced to the corresponding alcohols readily. Esters and epoxides were also reduced readily. Primary carboxamides consumed hydrides for reduction slowly with concurrent hydrogen evolution, but tertiary amides were readily reduced to the corresponding tertiary amines. The rate of reduction of aromatic nitriles was much faster than that of aliphatic nitriles. Nitrogen compounds examined were also reduced slowly. Finally, disulfide, sulfoxide, sulfone, and cyclohexyl tosylate were readily reduced without evolution of hydrogen. In addition to that, the reagent appears to be an excellent partial reducing agent: like LTDEA, STDEA converted ester and primary carboxamides to the corresponding aldehydes in good yields. Furthermore, the reagent reduced aromatic nitriles to the corresponding aldehydes chemoselectively in the presence of aliphatic nitriles. Consequently, STDEA can replace LTDEA effectively, with a higher selectivity, in most organic reductions.

• Bulletin of the Korean Chemical Society
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• 제14권4호
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• pp.469-475
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• 1993

The approximate rates and stoichiometry of the reaction of excess lithium tris(diethylamino)aluminum hydride (LTDEA) with selected organic compounds containing representative functional groups under standardized condition (tetrahydrofuran, 0$^{\circ}C$) were examined in order to define the characteristics of the reagent for selective reductions. The reducing ability of LTDEA was also compared with those of the parent lithium aluminum hydride (LAH) and lithium tris(dibutylamino)aluminum hydride (LTDBA). In general, the reactivity toward organic functionalities is in order of LAH${\gg}$LTDEA${\geq}$LTDBA. LTDEA shows a unique reducing characteristics. Thus, benzyl alcohol and phenol evolve hydrogen slowly. The rate of hydrogen evolution of primary, secondary, and tertiary alcohols is distinctive: 1-hexanol evolves hydrogen completely in 6 h, whereas 3-hexanol evolves hydrogen very slowly. However, 3-ethyl-3-pentanol does not evolve any hydrogen under these reaction conditions. Primary amine, such as n-hexylamine, evolves only 1 equivalent of hydrogen. On the other hand, thiols examined are absolutely inert to this reagent. LTDEA reduces aldehydes, ketones, esters, acid chlorides, and epoxides readily to the corresponding alcohols. Quinones, such as p-benzoquinone and anthraquinone, are reduced to the corresponding diols without hydrogen evolution. However, carboxylic acids, anhydrides, nitriles, and primary amides are reduced slowly, where as tertiary amides are readily reduced. Finally, sulfides and sulfoxides are reduced to thiols and sulfides, respectively, without evolution of hydrogen. In addition to that, the reagent appears to be an excellent partial reducing agent to convert esters, primary carboxamides, and aromatic nitriles into the corresponding aldehydes. Free carboxylic acids are also converted into aldehydes through treatment of acyloxy-9-BBN with this reagent in excellent yields.