• 제목/요약/키워드: Phase transfer catalysis,

검색결과 22건 처리시간 0.028초

Reactions of Aryl Halides with Phenoxides and Alkoxides by Phase Transfer Catalysis

  • 조봉래;박성대
    • Bulletin of the Korean Chemical Society
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    • 제5권3호
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    • pp.126-129
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    • 1984

  • The reaction of aryl halides with phenoxides and alkoxides were investigated under phase transfer catalytic conditions. 2,4-Dinitro- and 4-nitrohalobenzenes reacted readily with phenoxides in NaOH(aq)-benzene in the presence of Bu4N+Br, affording the products quantitatively. Although the aryl halides did not react with alkoxides under the same condition, the reactions were completed within 2 hours at room temperature when conducted under solid-liquid phase transfenr catalytic condition. The reactivity of aryl halides was in the order, Ar = 2,4-dinitrophenyl > 4-nitrophenyl, and X = F > Cl, consistent with the SNAr mechanism. The reactivity of oxyanions increased with the change of reaction condition from liquid-liquid to solid-liquid phase transfer catalysis. The results were explained with the concentration and the degree of hydration of the anion in benzene.

  • https://doi.org/10.5012/bkcs.1984.5.3.126 인용 PDF

Synthesis of (2,7-dibromo-9,9-dialkyl-substituted-fluorene)s for Poly(dialkylfluorene)s by Phase Transfer Catalytic Reaction

  • Kwon, Seung-Ho;Kim, Jin-Sung;Park, Ji-Ho;Yoo, Jae-Soo
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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    • pp.724-727
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    • 2002

  • 2,7-dibromo-9, 9-dialkyl-substituted-fluorene derivatives were prepared by the alkylation of 2,7-dibromofluorene with various alkyl groups under two-phase phase transfer catalysis (PTC) conditions, as monomers for synthesizing poly(dialkylfluorene)s. Tetra-nbutylammonium hydrogen sulfate (TBAHS) was used as a phase transfer catalyst to enhance nucleophilic substitution. In addition, NaOH in water (25M) was used as a base to generate anions. Compared to conventional alkylation using butyllithium(BuLi), the reaction using the PTC technique attained high selectivity and substantial conversion of reactants, due to the enhanced reaction rate, while the reaction was carried out under moderate conditions. An approximately 90% yield was obtained from the reaction and the reaction time was remarkably reduced. 2,7-dibromo-9,9-dihexyl-fluorene, 2,7-dibromo-9,9-dioctyl-fluorene, and 2,7-dibromo-9,9-di(2-ethylhexyl)-fluorene were effectively synthesized by phase transfer catalytic reaction.

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Stereoselective Transformation of Phytosphingosine to Safingol

  • Kim, Na-Ri;Lee, Sun-Hee;Namgoong, Sung-Keon
    • Bulletin of the Korean Chemical Society
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    • 제30권3호
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    • pp.695-699
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    • 2009

  • A short and efficient synthesis of (2S,3S)-safingol from commercially available D-ribo-(2S,3S,4R)-phytosphingosine is described. The highlights of the synthesis are a stereoselective one-pot transformation of a diol into an epoxide under phase transfer catalytic conditions and a regioselective epoxide-opening reduction with a hydride reagent.

  • https://doi.org/10.5012/bkcs.2009.30.3.695 인용 PDF KSCI

Tetra-n-Butyl Ammonium Chloride에 의한 알코올류의 상전이 반응에 대한 선택 특이성 (A Selectivity Character for the Phase Transfer Reactions of Alcohols by Tetra-n-Butyl Ammonium Chloride)

  • 지종기;최원복;이광필
    • 분석과학
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    • 제8권1호
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    • pp.33-40
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    • 1995

  • 미량의 hydroxide 이온은 Tetra-n-Butyl Ammonium(TBAC)에 의해 수액상에서 유기상으로 추출될 수 있다. 일차 알코올류, 특히 다이올류의 적은 양을 첨가하면 상전이 촉매계의 거동이 급격히 변하고 과량의 염기를 유기상에서 발견할 수 있다. 정량 측정은 유기상에서 1차, 2차 알콕사이드와 다이올 음이온들의 추출한 양에 대해 행하였다. 한편, 일차 알코올류와 벤질 알코올의 추출에 대한 선택상수들은 수액상과 유기상에서 $Q^+RO^-$($Q^+$ : quaternary 양이온, $RO^-$ : 알콕사이드 이온)와 $Q^+Cl^-$과 같은 이온쌍들의 평형상수와 이 두 상간의 분배계수로 분리되었다. 따라서 $Q^+RO^-$의 선택성에 대한 전제 특성을 본 연구결과에서 언급된 여러 상수들에 대하여 자유에너지에 상응하는 값들을 사용해서 더욱 상세하게 논하였다.

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