• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1154-1158
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• 2012

A room-temperature ionic liquid (RTIL) derived from 1,4-diazabicyclo[2.2.2]octane (DABCO) consisting of tetrafluoroborate anion, 1-butyl-4-(4-sulfonylbutyl)-1,4-diazoniabicyclo[2.2.2]octane hydrogen sulfate tetrafluoroborate ($[C_4DABCOC_4SO_3H][BF_4][HSO_4]$) was synthesized and catalytically evaluated in the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes by cyclocondensation reaction of ${\beta}$-naphthol and aryl aldehydes. This novel RTIL with an acidic $SO_3H$ group showed high catalytic activity with good to excellent yields of the desired products in short reaction times. Moreover, the catalyst could be recovered and reused at least three times with only slight reduction in its catalytic activity.

• Bulletin of the Korean Chemical Society
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• 제21권12호
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• pp.1233-1238
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• 2000

$Mo/{\gamma}-Al_2O_3catalysts$ modified with Fe, Co, and Ni were prepared by impregnation method and catalytic activity for water gas shift reaction was examined. The optimum amount of Mo loaded for the reaction was 10 wt% $MoO_3$ to ${\gamma}-Al_2O_3.$ The catalytic activity of $MoO_3/{\gamma}-Al_2O_3was$ increased by modifying with Fe, Co, and Ni in the order of Co${\thickapprox}$ Ni > Fe. The optimum amounts of Co and Ni added were 3 wt% based on CoO and NiO to 10 wt% $MoO_3/{\gamma}-Al_2O_3$, restectively. The TPR (temperature-programmed reduction) analysis revealed that the addition of Co and Ni enganced the reducibility of the catalysts. The results of both catalytic activity and TPR experiments strongly suggest that the redox property of the catalyst is an important factor in water gas shift reaction on the sulfided Mo catalysts, which could be an evidence of oxy-sulfide redox mechanism.

• Macromolecular Research
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• 제17권3호
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• pp.144-148
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• 2009

Poly(1-oxo-2-phenyltrimethylene) was synthesized by palladium-catalyzed copolymerization of styrene and carbon monoxide in quaternary ammonium ionic liquids. The $[Pd(bipy)_2][PF_6]_2$ compound had relatively more catalytic activity than $[Pd(bipy)_2][BF_4]_2$ in ionic liquids. The catalytic activity of palladium (II) composite catalyst was superior to the catalyst formed in situ from palladium acetate, 2,2-bipyridyl, and $X^-$ ($X^-=PF_6^-$, $BF_4^-$) in ionic liquids. The effects of the volume of ionic liquids, reaction time and benzoquinone content on the copolymerization were also described.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1995년도 춘계학술대회
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• pp.73-73
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• 1995

We investigated the effect of derivatized phospholipid, P-pyridoxyl dipalmiuylphosphatidylethanolamine (P-pyr-DPPE), on the catalytic activity of purified porcine brain glutamate decarboxylase(GAD) which catalyzes the synthesis of GABA known as major inhibitory neurotransmitter in CNS. When the P-pyr-DPPE was incorporated into dipalmitdylphosphatidylcholine(DPPC) or phosphatidylserine(PS) vesicles, these vesicles enhanced the catalytic activity of GAD. P-pyr-DPPE also interacted with apoglutamate decarboxylase(apoGAD) and produced the free pyridoxal-5-phosphate(PLP) which is the natural cofactor of GAD. This result indicated that apoGAD catalyzed the cleavage reaction of the P-pyridoxyl moiety of the derivatized phopholipid to generate free PLP, and then free PLP bound to the apoGAD resulting in restroration of the catalytic activity of the enzyme.

• 대한환경공학회지
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• 제22권5호
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• pp.819-825
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• 2000

본 연구는 자동차 폐촉매의 재활용 가능성을 검토하기 위하여 촉매의 물리화학적 특성 및 acetaldehyde의 연소활성에 관하여 조사하였다. 자동차 폐촉매의 물리화학적 특성을 조사하기 위하여 EA(Elemental analysis), ICP-AES (Inductively coupled plasma-atomic emission spectrophotometer), XRD(X-ray diffraction) 분석을 수행하였다. Carbon 침적량은 촉매의 전반부가 후반부보다 많았으며, 주행거리에 따라 증가하는 경향을 보였다. Pt, Pd, Rh 함유량은 제작사에 따라 구성성분의 차이를 보였다. 모델 VOC로서 acetaldehyde를 선택하였으며, 상압유통식 반응장치를 이용하여 촉매의 연소활성을 조사하였다. 자동차 폐촉매의 후반부가 전반부보다 촉매 활성이 우수하였다. 또한 주행거리의 증가에 따라 촉매활성은 감소하는 경향을 나타내며, 주행거리와 촉매활성은 매우 우수한 상관성을 보였다. 자동차 폐촉매의 acetaldehyde 연소활성은 매우 우수하였으며, 소규모의 배출원 제어에 활용 가능한 것으로 평가된다.

• 대한화학회지
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• 제54권1호
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• pp.131-136
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• 2010

다양한 철 원소의 조성을 갖는 인산알루미늄 철을 합성하여 표면 성질과 벌크 성질을 조사하였다. 벤질 알코올과 디에틸 말론산의 transesterification반응에 의해 촉매 특성을 결정 하였다. 에틸 벤질 말론산과 디벤질 말론산을 유일한 생성물로 얻었다. 철 성분이 0.025 몰 퍼센트인 FeAlP의 경우에 특이한 촉매 특성과 조직상의 특성이 나타난다. 디에스터의 형성은 중간 정도 크기의 산성 자리에서 이루어진다. 물질 안에 수화된 알루미나와 polycondensed인산이 존재할 경우에는 에스터교환 반응에서 인산 알루미늄 철의 촉매 특성이 감소하게 된다.

• Journal of Microbiology and Biotechnology
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• 제26권5호
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• pp.837-845
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• 2016

A novel endodextranase isolated from Paenibacillus sp. was found to produce isomaltotetraose and small amounts of cycloisomaltooligosaccharides with a degree of polymerization of 7-14 from dextran. To determine the active site, the enzyme was modified with 1-ethyl-3-[3-(dimethylamino)-propyl]-carbodiimide (EDC) and α-epoxyalkyl α-glucosides (EAGs), an affinity labeling reagent. The inactivation followed pseudo first-order kinetics. Kinetic analysis and chemical modification using EDC and EAGs indicated that carboxyl groups are essential for the enzymatic activity. Three Asp and one Glu residues were identified as candidate catalytic amino acids, since these residues are completely conserved across the GH family of 66 enzymes. Replacement of Asp189, Asp340, or Glu412 completely abolished the enzyme activity, indicating that these residues are essential for catalytic activity.

• 식품기술
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• 제17권4호
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• pp.98-106
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• 2004

Two mutant enzymes of $\gamma$-glutamylcysteine synthetase ($\gamma$-GCS) which catalyzed the synthesis of $\gamma$-glutamylcysteine from L-glutamic acid and L-cysteine in the presence of ATP, were prepared bypoint mutation of $\gamma$-GCS gene with site-directed mutagensis in E. coli. Conformational structuresand catalytic reaction kinetics of mutant enzymes were compared with wild type $\gamma$-GCS afterpurification. The S495F mutant enzyme (serine at 495 residue was substituted with phenylalanine),which had no catalytic activity for $\gamma$-glutamylcysteine synthesis, rarely folded even in neutral pH.However, the mutant A494V (alanine of 494 residue was replaced by valnine) which showed 50 %increase of activity, had a high folding structure. The folding structure of A494V also more stable athigh temperature and extreme pH compared to wild type and S495F. Reaction kinetics of wild typeand A494V were also investigated, Km value of A494V was smaller than that of wild type, while itshowed a little difference at Vmax values. This result evolved that alanine at 494 may be involved inbinding site of substrate rather than catalytic site. In addition, change of catalytic activity by onepoint mutation was highly correlated with the folding structure of enzyme.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1144-1148
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• 2014

Here we report a facile synthesis of ruthenium (Ru) Nanoparticles (NPs) by chemical co-precipitation method. The calcination of ruthenium hydroxide samples at $500^{\circ}C$ under hydrogen atmosphere lead to the formation of $Ru^0$ NPs. The size and aggregation of Ru NPs depends on the pH of the medium, and type of surfactant and its concentration. The X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope image (TEM) analyses of particles indicated the formation of $Ru^0$ NPs, and have 10 to 20 nm sizes. As-synthesized $Ru^0$ NPs are characterized and investigated their catalytic ability in click chemistry (azidealkyne cycloaddition reactions), showing good results in terms of reactivity. Interestingly, small structural differences in triazines influence the catalytic activity of $Ru^0$ nanocatalysts. Click chemistry has recently emerged to become one of the most powerful tools in drug discovery, chemical biology, proteomics, medical sciences and nanotechnology/nanomedicine. In addition, preliminary tests of recycling showed good results with neither loss of activity or significant precipitation.

• 한국산업융합학회 논문집
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• 제7권1호
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• pp.107-113
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• 2004

Several transition metal complexes, [$M(L)X_2$](M=Pd(II), Ni(II); X=CI, Br) are prepared with aminophosphine ligands such as 1,2-bis{(diphenylphosphino)amino}ethane{$Ph_2PNHCH_2CH_2NHPPh_2$}($L_1$), 1,2-bis{(diphenylphosphino)amino}propane{$Ph_2PNHCH(CH_3)CH_2NHPPh_2$}($L_2$), trans-1,2-bis{(diphenylphosphino)amino}cyclohexane{$Ph_2PNHC_6H_{10}NHPPh_2$}($L_3$) and 1,2-bis{(diphenylphosphino)amino}benzene{$Ph_2PNHC_6H_4NHPPh_2$}($L_4$). The properties of these complexes are characterized by optical spectroscopic methods including UV/vis spectroscopy, CD, IR, $^1H$- and $^{31}P-NMR$ together with conductometer and elemental analysis. All complexes are stable under atmospheric environment. Catalytic reactivity for C-C coupling between [$M(L)X_2$] and Grignard reagents(RMgX; R=phenyl, propyl, buthyl) by thermolysis were investigated utilizing GC/mass, $^1H$- and $^{13}C-NMR$. When mol scale is 1:20 at [$Pd(L)Cl_2$] and Grignard reagents, the high catalytic activity for C-C coupling is apparent. The [$M(L)X_2$](X=Cl, Br) complexes which have strong bond at M-P exhibit high yields for C-C coupling reactions. When the central metal ion is Pd(II), the high catalytic activity for C-C coupling is apparent. The complex coordinated with Br shows higher catalytic activity for C-C coupling reactions compared to Cl.