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지식나눔

지식나눔

monobromination을 진행하려합니다.

2017-02-27 org.kosen.entty.User@261cefc7 김성수(zero1521)
  • 1
thiophene의 2 위치에 bromination을 진행하려고 하는데 당량을 딱맞추더라도 2,5 위치의 dibromination으로 많이 진행이 됩니다. 어떻게 하면 monobromination이 많이 진행되게 할수 있을까요? 보호기 다는 방법은 제외하고요
반응 조건은 THF -78도에서 NBS를 dropwising 하였습니다.
  • bromine
지식의 출발은 질문, 모든 지식의 완성은 답변! 
각 분야 한인연구자와 현업 전문가분들의 답변을 기다립니다.
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  • 답변

    김기원님의 답변

    2017-02-28
    • 2
    Ref. Synthesis, (11), 890-1; 1988
    Method B: The flask (see Method A) is charged with thiophene (1; 100.8g, 1.20mol), 48% aqueous HBr (300mL), and Et2O (100mL), and 35% aqueous H2O2 peroxide (100 g, 1.0 mol) is added in ten equal portions over 30 min to the vigorously stirred mixture. The temperature of the mixture, initially - 20 °C, is gradually raised over this period to + 10°C. After addition of the last portion of H2O2 at + 10°C. the mixture is stirred for an additional 15 min at 15-20°C. The layers are then separated and the aqueous phase is extracted with pentane (5 x 50 mL). The combined organic solutions are washed with brine (1 x 200 mL) and are dried (MgSO4). The major part of the solvent is distilled off at ambient pressure, and the remaining liquid is carefully distilled through a 40 cm Widmer column at reduced pressure to give 2- bromothiophene (2). The residue (~ 8 g) consists mainly of 2,5-dibromothiophene (3). 2-Bromothiophene (2), yield 154.8 g (94%). Bp 42 °C/12 Torr.
    답변수정
    Ref. Synthesis, (11), 890-1; 1988
    Method B: The flask (see Method A) is charged with thiophene (1; 100.8g, 1.20mol), 48% aqueous HBr (300mL), and Et2O (100mL), and 35% aqueous H2O2 peroxide (100 g, 1.0 mol) is added in ten equal portions over 30 min to the vigorously stirred mixture. The temperature of the mixture, initially - 20 °C, is gradually raised over this period to + 10°C. After addition of the last portion of H2O2 at + 10°C. the mixture is stirred for an additional 15 min at 15-20°C. The layers are then separated and the aqueous phase is extracted with pentane (5 x 50 mL). The combined organic solutions are washed with brine (1 x 200 mL) and are dried (MgSO4). The major part of the solvent is distilled off at ambient pressure, and the remaining liquid is carefully distilled through a 40 cm Widmer column at reduced pressure to give 2- bromothiophene (2). The residue (~ 8 g) consists mainly of 2,5-dibromothiophene (3). 2-Bromothiophene (2), yield 154.8 g (94%). Bp 42 °C/12 Torr.
    김성수(zero1521) 2017-02-28

    혹시 해당논문좀 부탁드릴수있을까요?

    김기원(mingyu2322) 2017-02-28

    원문을 보내드릴 수 없어서 죄송합니다.

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