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whh8308木虫 (小有名气)
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[交流]
五氟苯硼酸的合成与表征！！！
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求助：五氟苯硼酸的合成与表征！！！ 各位大侠们，又没有人做五氟苯硼酸的阿！！ 参考文献，用五氟溴苯和镁粉合成格试剂，在低温下滴加到硼酸三甲酯反应，但是旋蒸后基本没有东西出来……郁闷中，不知道是哪里出错的，而且也尝试过用丁基锂合成，最终的白色产物也不对劲，检测表征也不对…… 求助,做过类似反应的前辈,能否把操作的具体过程讲述一下. |
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angangang
木虫 (小有名气)
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4楼2007-11-27 10:55:11
whh8308
木虫 (小有名气)
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怎么没人给我回复啊？？救命啊！ 2楼2007-11-26 14:52:08
angangang
木虫 (小有名气)
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★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
whh8308(金币+10,VIP+0):多谢！我会试试你的方法的……如果可以我会再给你十个金币！^_^
whh8308(金币+2,VIP+0):前面那个方法我试过阿，能不能帮忙找找你提供的这个文献？我这里没有啊……
whh8308(金币+2,VIP+0):你给我的资料我试过了~~虽然没什么大的作用，但是还是谢谢你!要是你有有效的方法希望可以告诉我哦！多谢！
whh8308(金币+5,VIP+0):那篇文献我找不到，你能否给我发到邮箱里~~whh8308@163.com
whh8308(金币+10,VIP+0):多谢！我会试试你的方法的……如果可以我会再给你十个金币！^_^
whh8308(金币+2,VIP+0):前面那个方法我试过阿，能不能帮忙找找你提供的这个文献？我这里没有啊……
whh8308(金币+2,VIP+0):你给我的资料我试过了~~虽然没什么大的作用，但是还是谢谢你!要是你有有效的方法希望可以告诉我哦！多谢！
whh8308(金币+5,VIP+0):那篇文献我找不到，你能否给我发到邮箱里~~whh8308@163.com
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A 500-mL, four-necked, round-bottomed flask containing magnesium turnings () is equipped with a mechanical stir, a thermometer, a press-equalizing dropping funnel, a reflux condenser fitted with an nitrogen inlet adapter. The system is dried and flushed with nitrogen. Anhydrous THF () is introduced to cover the magnesium, a crystal of iodine is added. The dropping funnel is filled with a solution fo bromobenzene () in 100-mL THF. Approximately 10 ml of the solution is added to the flask, and the contents are stirred until the Grignard reaction commences. The remainder of the aryl bromide solution is added slowly at a rate such that the mixture reflux(addition time ca. 1 hour). The resulting mixture is stirred refluxing for another 1 hour. The mixture is cooled to approximately -50 ℃ while stirring. A solution of g trimethyl borate in 100 ml THF is added dropwise at a rate such that the mixture temperature maintain -50~-40 ℃ (addition time ca. 1 hour). Following the addition, the mixture was allowed to stir at -50~-40 ℃ for another 1 hour. The resulting mixture is heated slowly to -15 ℃ while stirring. A solution of 10% hydrochloride acid is added to the reactor. After stirring 1 hour, the organic layer is separated and the aqueous layer is extracted with three 100-mL of ethyl acetate. The combined organic layers are washed with water (100mL), and concentrated under reduced pressure to remove most of solvent. The resulting white solid is dissolved in a minimal amount of hot (65°C) ethyl acetate , allowed to cool to room temperature, and then 600 mL of hexane is added. The resulting solution is allowed to stand overnight and then filtered to afford pure boronic acid as white crystals.solid |
3楼2007-11-27 10:52:35
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