• 제목/요약/키워드: coupling reaction

검색결과 519건 처리시간 0.027초

Ligand Effect in Recycled CNT-Pd Heterogeneous Catalyst for Decarboxylative Coupling Reactions

  • Kim, Ji Dang;Pyo, Ayoung;Park, Kyungho;Kim, Gwui Cheol;Lee, Sunwoo;Choi, Hyun Chul
    • Bulletin of the Korean Chemical Society
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    • 제34권7호
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    • pp.2099-2104
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    • 2013
  • We present here an efficient and simple method for preparation of highly active Pd heterogeneous catalyst (CNT-Pd), specifically by reaction of dichlorobis(triphenylphosphine)palladium ($Pd(PPh_3)_2Cl_2$) with thiolated carbon nanotubes (CNTs). The as-prepared CNT-Pd catalysts demonstrated an excellent catalytic activity for the carbon-carbon (C-C) cross-coupling reactions (i.e. Suzuki, Stille, and decarboxylative coupling reactions) under mild conditions. The CNT-Pd catalyst could easily be removed from the reaction mixture; additionally, in the decarboxylative coupling of iodobenzene and phenylpropiolic acid, it showed a six-times recyclability, with no loss of activity. Moreover, once its activity had decreased by repeated recycling, it could easily be reactivated by the addition of phosphine ligands. The remarkable recyclability of the decarboxylative coupling reaction is attributable to the high degree of dispersion of Pd catalysts in CNTs. Aggregation of the Pd catalysts is inhibited by their strong adhesion to the thiolated CNTs during the chemical reactions, thereby permitting their recycling.

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

  • 지상현;고석오
    • 한국물환경학회지
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    • 제23권5호
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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.

Functionalization of Organotrifluoroborates via Cu-Catalyzed C-N Coupling Reaction

  • Lee, Jung-Hyun;Kim, Heejin;Kim, Taejung;Song, Jung Ho;Kim, Won-Suk;Ham, Jungyeob
    • Bulletin of the Korean Chemical Society
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    • 제34권1호
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    • pp.42-48
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    • 2013
  • Potassium N-heterobiaryltrifluoroborates were successfully prepared via a selective Cu-catalyzed C-N coupling reaction. The $BF_3K$ moiety was well tolerated under the reaction conditions involving CuI and dimethyl-ethylenediamine (DMEDA) in the presence of DMSO. The Pd-catalyzed Suzuki-Miyaura cross couplings of potassium N-heterobiaryltrifluoroborates with bromoarenes were studied to prepare the N-heterotriaryl compounds. Moreover, homocoupling, iodination, and hydroxylation of potassium N-heterobiaryltrifluoroborates provided the corresponding products in high yields.

Direct Coloration using Self-assembly Fabrication Method on PET Fibers - Surface diazo coupling reaction -

  • Kim, Byung-Soon;Son, Young-A
    • 한국염색가공학회지
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    • 제19권5호
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    • pp.37-40
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    • 2007
  • The electrostatic layer-by-layer technique provides a convenient way to control the construction of ultrathin films at nano-scale ranges and can be easily obtained. It can be also applicable to fiber substrate with dye compounds. We have fabricated multilayer dye films using diazonium resin and three couplers, which are prepared by self-assembly approach. This method is based on layer-by-layer deposition using electrostatic attraction between oppositely charged ions. Beside, the diazo coupling reaction proceeded to form azo dye layer on the PET fibers the same time. The corresponding results of the multilayer films have been discussed on the level of color strength (K/S).

A Convenient Synthesis of an Anti-Helicobacter Pylori Agent, Dehydrodiconiferyl Alcohol

  • Hu, Kun;Jeong, Jin-Hyun
    • Archives of Pharmacal Research
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    • 제29권7호
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    • pp.563-565
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    • 2006
  • Potential anti-Helicobacter pylori agent dehydrodiconiferyl alcohol was synthesized in 44% overall yield, starting from vanillin which could be commercially available. Carbon extension of vanillin followed by the Horner-Wadsworth-Emmons reaction, a biomolecular radical coupling reaction and DIBAL-H reduction gave dehydrodiconiferyl alcohol.

Tris(2-methoxyphenyl)phosphine as a Highly Active Ligand for the Synthesis of Biaryls by Suzuki Coupling Reaction

  • Kang, Pill-Seong;Ko, Sung-Bo;Ko, Jang-Myoun;Park, Jeong-Ho
    • Bulletin of the Korean Chemical Society
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    • 제30권11호
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    • pp.2697-2700
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    • 2009
  • A $Pd(OAc)_2/(o-MeOPh)_3P$ system has been developed for the catalytic Suzuki coupling of aryl bromides with arylboronic acids. Our catalyst system covers a broad spectrum of commonly available arylboronic acids and aryl bromides to provide biaryls in very good yields. The catalyst system works very well in the synthesis of sterically hindered biaryls.

Heterogeneous Suzuki Cross-Coupling Reaction Catalyzed by Magnetically Recyclable Nanocatalyst

  • Choi, Kwang-Hyun;Shokouhimehr, Mohammadreza;Sung, Yung-Eun
    • Bulletin of the Korean Chemical Society
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    • 제34권5호
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    • pp.1477-1480
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    • 2013
  • The Suzuki cross-coupling reactions proceeded in excellent yields when it was catalyzed by magnetically recyclable nanocatalyst. This nanocatalyst provided very high catalytic activity with low loading level (1 mol %), because the palladium nanoparticles were so small in size (~2 nm) and located on the surface of the nanocomposite. It was also easily recovered from the reaction mixture using a magnet and reused for six consecutive cycles.

Tin-Free Three-Component Coupling Reaction of Aryl Halides, Norbornadiene (or Norbornene), and Alkynols Using a Palladium Catalyst

  • Choi, Cheol-Kyu;Hong, Jin-Who;Tomita, Ikuyoshi;Endo, Takeshi
    • Bulletin of the Korean Chemical Society
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    • 제23권1호
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    • pp.112-118
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    • 2002
  • Good-to-excellent yields of 2,3-Disubstituted norbornenes (or norbornanes) were obtained using a Pd/Cu catalyzed three-component ternary coupling reaction of aryl halides, norbornadiene (or norbornene), and alkynols in toluene at $100{\circ}C$ in the presence of 5.5 M NaOH as a base and benzyltriethylammonium chloride as a phase transfer catalyst. The results of experiments using various aromatic halides suggest that the ternary coupling reaction is promoted by bromide.

고무용(用) azo계(系) 착색제(着色劑)에 관한 연구(硏究) -H-산(酸)의 Coupling반응(反應)에 관한 속도론적(速度論的) 고찰(考察)- (Studies on the Colouring matters for Rubber Industry [I] -Kinetics of the Coupling reaction of H-acid-)

  • 박흥조
    • Elastomers and Composites
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    • 제12권1호
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    • pp.27-32
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    • 1977
  • The kinetics of azo-coupling reaction of N-acetyl-H-acid (1-acetamino-8-hydroxynaphthalene-3, 6-disulfonic acid) with several heterocyclic diasonium compounds such as diazotiged 3-aminopyridine, 3-aminoquinoline, 8-aminoauinoline and aniline was studied. It was found that reactions proceeded at remarkably different rate. Reaction rate was in increasing order; 3-aminopyridine, 3-aminoquinoline, 8-aminoauinoline and aniline. And the activation energies were 9.62, 10.10, 10.39, 10.70 Kcal/mole, respectively. Especially, the rate constant of 3-aminopyridine was 100 times larger than that of benzene diasonium compound even in strong acidity. Hammett plot was also made of the rate constants obtained against the heterocyclic substituent constants reported in the literature. A good linear relationship was obtained and the reaction constant of N-acetyl H-acid was calculated to be 3.14.

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Grignard Coupling Reaction of Bis(chloromethyl)diorganosilanes with Dichloro(diorgano)silanes: Syntheses of 1,3-Disilacyclobutanes

  • 조연석;유복렬;안삼영;정일남
    • Bulletin of the Korean Chemical Society
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    • 제20권4호
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    • pp.427-430
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    • 1999
  • The Grignard coupling reaction of bis(chloromethyl)diorganosilanes [(ClCH2)2SiR1R2: R1 = R2 = Me, la; R1 = Me, R2 = Ph, lb; R1 = R2 = Ph, lc] with diorganodichlorosilanes [(Cl2SiR3R4: R3 = R4 = Me, 2a; R3 = Me, R4 = Ph, 2b; R3 = R4 = Ph, 2c] at THE reflux temperature gave the intermolecular C-Si coupling product of 1,1,3,3-tetraorgano-1,3-disilacyclobutanes 3a-f in poor to moderate yields ranging from 7% to 50% along with polydiorganosilapropanes. The cyclization reaction of la-c with methyl-substituted dichlorosilanes 2a, b gave 1,3-disilacyclobutanes 3a-c, e, d in moderate yields (42-50%), while the same reaction with dichlorodiphenylsilane (2c) to 1,3-disilacyclobutanes 3d, f resulted in low yield (7-18%) probably due to the steric hindrance of two-phenyl groups on the silicon of 2c.