• Title, Summary, Keyword: phase transfer catalyst

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An Expeditious Oxidative Aromatization of Hantzsch 1,4-Dihydropyridines to Pyridines Using Cetyltrimethylammonium Peroxodisulfate: A Phase Transferring Oxidant

  • Kumar, Parvin;Kumar, Ashwani
    • Bulletin of the Korean Chemical Society
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    • v.31 no.8
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    • pp.2299-2303
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    • 2010
  • A new approach to the use of potassium peroxodisulphate as an oxidizing reagent is proposed and applied to the case of oxidative aromatization of 1, 4-dihydropyridines with cetyltrimethylammonium peroxodisulfate, a phase transfer oxidant. We demonstrate how it is possible to increase the reactivity of potassium peroxodisulphate in the presence of phase transfer catalyst. Dealkylation in case of 4-n-alkyl/n-alkenyl was not obtained.

Long Chain Dicationic Phase Transfer Catalysts in the Condensation Reactions of Aromatic Aldehydes in Water Under Ultrasonic Effect

  • Esen, Ilker;Yolacan, Cigdem;Aydogan, Feray
    • Bulletin of the Korean Chemical Society
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    • v.31 no.8
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    • pp.2289-2292
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    • 2010
  • Long chain dicationic ammonium salts were used successfully as phase transfer catalyst in the condensation reactions of aromatic aldehydes in water under ultrasonic irradiation for the first time. The quaternary salt having longer distance between the cation centers was more effective than the mono- and dicationic ones having short chain.

Phase Transfer Catalyst (PTC) Catalyzed Alkylations of Glycinamides for Asymmetric Syntheses of $\alpha$-Amino Acid Derivatives

  • Park, Seon Yeong;Kim, Hyeon Ju;Im, Dong Yeol
    • Bulletin of the Korean Chemical Society
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    • v.22 no.9
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    • pp.958-962
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    • 2001
  • The chiral amine auxiliary mediated stereoselective alkylation reactions of glycinamides 1-6 and 15-17 using phase transfer catalyst (PTC) for liquid-solid extraction are described. The secondary N-(diphenylmethylene) glycinamides 1, 2 and 3 give better selectivities and yields than tertiary N-(diphenylmethylene) glycinamides 4, 5 and 6. Alkylation of the glycinamide 1 and 2 using 18-Crown-6 as a PTC in toluene at $-40^{\circ}C$ gives best selectivities and yields. Alkylations of N-(4-chlorophenylmethylene)glycinamides 15, 16 and 17 under same PTC conditions give $\alpha$, $\alpha-disubstituted$ amino acid derivatives 18, 19 and 20 with low diastereoselectivities.

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Development of Analysis Model for Down Scaled Two Phase Catalytic Reactor (초소형 촉매 이상 분해 반응기 해석 모델 개발)

  • Lee, Dae-Hoon;Kwon, Se-Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.1
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    • pp.24-30
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    • 2004
  • Analysis model for the two-phase catalytic reactor is presented. With the progress in development of micro thermofluidic devices, needs fur understanding of the phenomena in two phase reaction in cm scale has been arisen. To investigate thermal and reactive performance of down scaled two phase reactor simple analysis model that is a kind of lumped flow model is proposed. Analysis model presented is based on the experiment on mm scale model reactor. Target experiment is catalytic decomposition of 70wt% hydrogen peroxide with existence of perovskite L $a_{0.8}$S $r_{0.2}$Co $O_3$ catalyst. It is composed of balance equations of mass and energy. Each phase is considered to be a species fur the simplicity. Axial diffusion and transversal distribution of properties are neglected. Two phase catalytic reaction is modeled as successive gasification of liquid lump around catalyst and reaction in gas phase. Heat transfer is modeled by model function ofNu number. Modeled Nu is expressed as Nu=N $u_{0}$ (1+ $a_1$( $a_2$ $T^{-}$ $a_3$)exp( $a_4$ $T^{-1}$)exp( $a_{5}$ z). Transfer coefficients are determined by the comparison of experimental results. With the model, heat transfer characteristics are investigated. Also by the mass transfer coefficient, characteristics in mass transfer is investigated. With the result basic understanding on design and analysis of mm scale two-phase reactive device is obtained. Also it can be further applied to micro scale reactive device fabricated by micromachining.ing..

Devulcanization of Vulcanized EPDM Rubber by a Chemical Method (화학적 방법에 의한 가황 EPDM 고무의 탈황처리)

  • Moon, Jae-Ho;Kim, Yang-Soo
    • Elastomers and Composites
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    • v.35 no.4
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    • pp.288-295
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    • 2000
  • It has been tried to decrease the crosslink density of vulcanized EPDM (ethylone-propylene-diene terpolymer) rubber through a chemical devulcanization treatment. Phase transfer catalyst, alkali metal (i.e., sodium), and triphenylphosphine have been used as a chemical agent ul the devulcanization treatment. Also it has been estimated the effect of the devulcanization treatment in the case of utilization of 2-butanol as a devulcanization reaction solvent. In the devulcanization treatment using quaternary ammonium salt as a phase transfer catalyst. the devulcanization effect has been studied with the variation of catalyst molecular weight and the choice of bromide or chloride cation. In the devulcanization treatment using sodium, it has been estimated the devulcanization treatment effect depending upon the variation of reaction variables such as amount of sodium used, reaction temperature, pressure of hydrogen gas, which is used as a reaction environment. The $M_c$ value (number average molecular weight between two crosslink points) has been experimentally estimated by the equilibrium swelling method and it is quantitatively related to the crosslink density. The estimation of devulcanization effect for vulcanized EPDM rubber has been carried out by the comparison of the $M_c$ values between the untreated and the treated specimens.

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The Kinetics of Radical Polymerization of Styrene with Tricaprylymethylammonium Chloride as a Phase-Transfer Catalyst (상이동촉매인 트리카프릴메틸암모니움 클로라이드를 사용한 스티렌 라디칼중합의 동력학적 연구)

  • Park, Sang-Wook;Sohn, In-Joe;Park, Sang-Bo
    • Journal of Adhesion and Interface
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    • v.2 no.2
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    • pp.11-19
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    • 2001
  • The phase-transfer catalyzed radical polymerization of styrene was carried out using tricaprylylmethylammonium chloride as a phase-transfer catalyst in a two-phase system of an aqueous $Na_2S_2O_8$ solution and toluene at $60^{\circ}C$ under nitrogen atmosphere. The initial rate of radical polymerization was expressed as the combined terms of concentrations of quaternary onium cation and peroxydisulfate anion in the aqueous phase rather than the fed concentrations of catalyst and $Na_2S_2O_8$. The observed initial rate of radical polymerization was used to analyze the radical polymerization mechanism with a cycle phase-transfer initiation step in the heterogeneous liquid-liquid system. The viscosity average molecular weight of polystyrene was inversely proportional to concentration of $Na_2S_2O_8$ expressed as $[Q^+]([S_2O{_8}^{2-}]{\alpha}_2)^{1/2}$ derived by the radical polymerization mechanism.

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Asymmetric Michael Reaction of Malonate Derivatives with α, β-Unsaturated Ketones

  • Cho, Min-Je;Cho, Myoung-Gi;Huh, Sun-Chul;Kim, Sung-Min;Lee, Kil-sung;Koh, Kwang-Oh;Mang, Joo-Yang;Kim, Dae-Young
    • Bulletin of the Korean Chemical Society
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    • v.27 no.6
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    • pp.857-862
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    • 2006
  • The catalytic enantioselective Michael reaction promoted by quaternary ammonium salts from Cinchona alkaloids as a phase-transfer catalyst is described. Treatment of malonates with $\alpha$,$\beta$-unsaturated ketones under mild reaction conditions afforded the corresponding Michael adducts in good yields with good to moderate enantiomeric excesses.

Phase Transfer Polymerization. Two Phase Polycondensation of Diphenoxides and 1,6-Dibromohexane in the Presence of Tetrabutylammonium Bromide (狀移動重合. Tetrabutylammonium Bromide 존재하에서 Diphenoxides와 1,6-Dibromohexane의 二狀重縮合反應)

  • Jung-Il Jin;Yong-Woon Jung;Kwang-Sup Lee;Keun-Woo Chung
    • Journal of the Korean Chemical Society
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    • v.23 no.4
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    • pp.259-266
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    • 1979
  • Linear polyethers were prepared by the reaction of diphenoxide anions from 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxylphenyl) sulfide, and bis (khydroxyphenyl) sulfone with 1,6-dibromohexane in aqueous/nitrobenzene heterogeneous phases. Tetrabutylammonium bromide was employed as a phase transfer catalyst. The polymerizations were dependent both on stirring speed and catalyst level, but only up to certain maximum values. Distribution studies demonstrated transference of diphenoxide anions from aqueous phase into nitrobenzene in the presence of the catalyst. Some of polymers were characterized with respect to their intrinsic viscosities (0.09-O.16), number average molecular weight (2400-4800)) and thermal properties. The use of a new terminology, 'phase transfer polymerization?, is proposed to differentiate this type of polymerizations from interfacial polycondensations.

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