• Title, Summary, Keyword: oxidative coupling

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Synthesis of Dimeric Oligodeoxyribonucleotide (이합체성 올리고디옥시리보핵산의 합성)

  • Song, Jeong-Sup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.6
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    • pp.1566-1571
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    • 2007
  • Oligodeoxyribonucleotide bearing the di-acetylenic linkage has been prepared. Staring from 5-Iodo-2'-deoxyuridine(1), a four-step sequence, consisting of the Pd(0)-catalyzed Heck-type C-C coupling with acetylenic group, protection of 5'-hydroxy group, generation of acetylenic hydrogen, and Glaser oxidative coupling reaction leads to the dimeric oligodeoxyribonucleotide(5).

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Synthesis of Dendrimers from Alkyne-focal Dendrons by Oxidative Homo-coupling of Terminal Acetylene

  • Han, Seung-Choul;Kim, Jong-Sik;Lee, Jae-Wook
    • Bulletin of the Korean Chemical Society
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    • v.32 no.11
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    • pp.3899-3903
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    • 2011
  • General, fast, and efficient fusion methods for the synthesis of dendrimers with 1,3-diynes at a core were developed. The synthetic strategy was employed the oxidative homo-coupling of terminal alkyne. The oxidative homo-coupling reaction of the alkyne-functionalized Frechet-type dendrons 1-Dm was allowed to provide first through fourth generation dendrimers 2-Gm with 1,3-diynes at core. The fusion of the propargylfunctionalized PAMAM dendrons 3-Dm by homo-coupling of terminal alkyne lead to the formation of symmetric PAMAM dendrimers 4-Gm. Their structure of dendrimers was confirmed by $^1H$ and $^{13}C$ NMR spectroscopy, IR spectroscopy, mass spectrometry, and GPC analysis.

Application of Manganese Oxide for the Oxidative Degradation of Bisphenol-A in Aqueous Phase (망간산화물을 이용한 수용액내 Bisphenol-A의 산화 반응성 평가)

  • Jee, Sang-Hyun;Ko, Seok-Oh
    • Journal of Korean Society on Water Environment
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    • v.23 no.5
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    • pp.659-664
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    • 2007
  • The objective of this study is to evaluate the detoxification method for the endocrine disrupting chemicals by manganese oxide. Manganese coated sand and bisphenol-A (BPA) was used as the reactive medium and the contaminant. Results showed that manganese oxide effectively degrades BPA by oxidative coupling reaction. The nonlinear oxidative coupling reaction orders were obtained for BPA and oxide, respectively. The reaction rate of BPA decreased as initial BPA concentration increased, as oxide loading decreased and as pH increased. The higher ionic strength, the higher reaction rate was observed. Divalent cations were adsorbed on the oxide surfaces, resulting in the decreased degradation rate of BPA.

Removal of TNT Reduction Products via Oxidative-Coupling Reaction Using Manganese Oxide (망간산화물을 이용한 TNT 환원부산물의 산화-결합반응에 의한 제거 연구)

  • Kang, Ki-Hoon;Lim, Dong-Min;Shin, Hyun-Sang
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.5
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    • pp.476-485
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    • 2005
  • In this study, abiotic transformation of TNT reduction products via oxidative-coupling reaction was investigated using Mn oxide. In batch experiments, all the reduction products tested were completely transformed by birnessite, one of natural Mn oxides present in soil. Oxidative-coupling was the major transformation pathway, as confirmed by mass spectrometric analysis. Using observed pseudo-first-order rate constants with respect to birnessite loadings, surface area-normalized specific rate constants, $k_{surf}$, were determined. As expected, $k_{surf}$ of diaminonitrotoluenes (DATs) ($1.49{\sim}1.91\;L/m^2{\cdot}day$) are greater about 2 orders than that of dinitroaminotoluenes (DNTs) ($1.15{\times}10^{-2}{\sim}2.09{\times}10^{-2}\;L/m^2{\cdot}day$) due to the increased number of amine group. In addition, by comparing the value of $k_{surf}$ between DNTs or DATs, amino group on ortho position is likely to be more preferred for the oxidation by birnessite. Although cross-coupling of TNT in the presence of various mediator compounds was found not to be feasible, transformation of TNT by reduction using $Fe^0$ followed by oxidative coupling using Mn oxide was efficient, as evaluated by UV-visible spectrometry.

Kinetics of Oxidative Coupling of Methane over NaCl/ZnO/α-Al2O3 Catalyst (NaCl/ZnO/α-Al2O3 촉매상에서 메탄의 Oxidative Coupling의 속도론적 고찰)

  • Kim, Sang-Chai;Seo, Ho-Joon;Sunwoo, Chang-Shin;Yu, Eui-Yeon
    • Applied Chemistry for Engineering
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    • v.3 no.2
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    • pp.256-265
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    • 1992
  • The kinetics for the oxidative coupling of methane over NaCl(30wt%)/ZnO(60wt%)/${\alpha}-Al_2O_3$ catalyst was investigated, and then the active oxygen species were discussed. The conversion rate of methane was measured at the atmospheric pressure with various combinations of partial pressure of methane and oxygen at temperature range of $650^{\circ}C{\sim}750^{\circ}C$, at conversions less than with 10%. These rate data were then used to verify the proposed Langmuir-Hinshelwood kinetic equation. The rate limiting step appeared to be the formation of the methyl radicals by the reactin of the adsorbed methane and the adsorbed oxygen, which were adsorbed on the different active sites of the catalyst. The activation energy of the methyl radical formation was estimated to be ca. 39 kcal/mol. From the kinetic studies, the oxygen species respolsible for the formation of methyl radicals was proposed to be diatomic oxygen such as $O{_2}{^{2-}}$ or $O_2{^-}$ on the surface.

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Kinetic Analysis of Oxidative Coupling of Methane over Na+/MgO Catalyst (Na+/MgO 촉매상에서 메탄의 Oxidative Coupling 반응의 속도론적 해석)

  • Seo, Ho-Joon;Sunwoo, Chang-Shin;Yu, Eui-Yeon
    • Applied Chemistry for Engineering
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    • v.5 no.4
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    • pp.580-587
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    • 1994
  • The oxidative coupling of methane was studied kinetically using $Na^+(50wt%)/MgO$ catalyst at 710, 730, 750, 770 and $790^{\circ}C$ in a fixed bed flow reactor at the atmospheric pressure under differential conversion conditions. Through curve fitting, it was found that the Langmuir-Hinshelwood type mechanism was fitted to this reaction rather than Rideal-Redox type or Eley-Rideal type mechanism. Therefore, it was proposed that the $O_2{^-}$ or $O_2{^{2-}}$ species on the surface was related to the production of $CH_3{\cdot}$. The estimated activation energy of $CH_3{\cdot}$ production was about 39.3kcal/mol. Moreover, as the result of curve fitting, the stoichiometric coefficient of $O_2$ for the production of $CH_3{\cdot}$ to produce $CO_x$was approximately 1.5. Accordingly, it could be concluded that the $CH_3O_2{\cdot}*$ was prouduced through the partial oxidation of $CH_3{\cdot}$ with the surface oxygen.

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Transformation of Nitroaromatics and Their Reduced Metabolites by Oxidative Coupling Reaction (Oxidative Coupling에 의한 Nitroaromatics와 그 환원대사산물의 전환)

  • Ahn, Mi-Youn;Kim, Jang-Eok
    • Korean Journal of Environmental Agriculture
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    • v.17 no.3
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    • pp.239-245
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    • 1998
  • To investigate the formation of bound residue with soil organic materials by oxidative coupling, nitroaromatics and their reduced metabolites, the insecticide parathion and the herbicide asulam were incubated with oxidoreductase, laccase or horseradish peroxidase, in the presence or absence of humic monomers. Most of aminotoluenes and amino-nitrophenols were completely transformed while most of nitrotoluenes and nitrophenols remained unchanged by a lactase or horseradish peroxidase in the presence or absence of humic monomers. Amino-nitrotoluenes were not transformed without humic monomers, but the addition of various humic monomers caused a considerable difference in the transformation of amino-nitrotoluenes by a lactase or horseradish peroxidase. Amino-nitrotoluenes were most transformed in the presence of catechol, syringaldehyde and protocatechuic acid. The insecticide parathion with nitro group and its metabolite were not mostly transformed in the presence or absence of humic monomers. The herbicide asulam with amino group remained unchanged without humic monomers as well, but the stimulating effect on the transformation of asulam was caused by the addition of catechol, syringaldehyde, protocatechuic acid or caffeic acid with a lactase.

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Synthesis of 3,4,5-Trisubstituted Isoxazoles through Gold-Catalyzed Cascade Cyclization-Oxidative Alkynylation and Cyclization-Fluorination of 2-Alkynone O-Methyloximes

  • Song, Doo-Hee;Ryu, Jae-Sang
    • Bulletin of the Korean Chemical Society
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    • v.35 no.9
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    • pp.2635-2644
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    • 2014
  • Gold-catalyzed tandem cyclization-oxidative alkynylation and cyclization-fluorination reactions of 2-alkynone O-methyloximes are described. The reactions proceed smoothly at room temperature in the presence of 10 mol % of $(PPh_3)AuNTf_2$, 2.5 equivalents of selectfluor, and 2 equivalents of $K_3PO_4$. 2-Alkynone O-methyloximes undergo intramolecular oxyauration/cyclization and ensuing oxidative cross-coupling and fluorination process to afford the corresponding 3,4,5-trisubstituted isoxazoles in a cascade manner.

Transformation of Pentachlorophenol by Oxidoreductive Catalysts (산화환원 촉매에 의한 Pentachlorophenol의 Transformation)

  • Park, Jong-Woo;Lee, Yun-Ki;Kim, Jang-Eok
    • Applied Biological Chemistry
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    • v.42 no.4
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    • pp.330-335
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    • 1999
  • Pentachlorophenol(PCP), which is very persistent in soil and water environment, was tried to detoxify with oxidoreductive catalysts(peroxidase, laccase, tyrosinase and birnessite). To find out detoxification of PCP, the transformation of PCP through oxidative coupling was investigated in the presence of various oxidoreductive catalysts. PCP incubated with peroxidase was significantly transformed, however, in case of tyrosinase, the transformation was negligible. Using peroxidase, the optimal reaction condition was pH 5.6 and $16^{\circ}C$. The transformation of PCP was very fast in initiation step until 30 min but, that was not observed after 180 min. The transformation of PCP was increased by increasing peroacidase amount. When the effect of humic monomer was investigated as co-substrate on the transformation of PCP, the transformation of PCP was mostly decreased in the incubation with peroxidase, laccase, and birnessite. The transformation of PCP, however, was slightly increased by the incubation with tyrosinase in the presence of humic monomers as co-substrate, except catechol. On the basis of the results obtained, it may be suggested that PCP is able to be effectively detoxified through oxidative coupling mediated with oxidoreductive catalysts.

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