问题：氯化卞与三甲胺反应问题
类型：求助 (悬赏分:3分)
提问：sally110
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版块：有机化学问题(jimuwei,fpcwin1211,netpanda,yjgzfl,Ftian,)
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回复：8
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时间：2009-09-27 10:38:25 编辑加入/取消收藏订制/取消短消息举报该贴

氯化卞与三甲胺反应，甲醇回流，请问甲醇的加入量是多少？（主要想问这个加入量与反应物的量之间有什么关系呢）比如说是加入甲醇的体积占总反应物的体积的多少还是加入甲醇的质量占反应物质量的百分之多少？谢谢！

回复人：stargazer,▲ () 时间：2009-09-27 12:58:56 编辑

1楼

1. Procedure
A 3-l. three-necked flask (flask A) is fitted with a nitrogen inlet, a reflux condenser protected by a soda-lime tube, and
a reflux condenser fitted with a dropping funnel protected by a soda-lime tube.
A second 3-l. three-necked flask (flask B) is fitted with a gas-tight modified Hershberg stirrer (Note 1), a gas inlet
tube, and an appropriately designed gas outlet tube bearing a thermometer and connections leading to a soda-lime tube and
an open-end mercury manometer. All rubber stoppers and connections are wired in place with 16-gauge copper wire.
Sodium (69 g., 3 g. atoms) is introduced into flask A, which had been flushed previously with nitrogen (Note 2).
Ethanol (1.2 kg.) (Note 3) is added at such a rate that a continuous reflux is maintained. After the sodium is completely
dissolved, the solution is allowed to cool to room temperature. During this period the benzyltrimethylammonium chloride is
prepared.
A solution of 379.5 g. (3 moles) of benzyl chloride (Note 4) dissolved in 750 g. of anhydrous ethanol (Note 3) is
placed in flask B. The system is flushed with trimethylamine previously dried by passage through a soda-lime tower. The
gas outlet is closed and connected to the manometer. Over a period of 80 minutes, 195 g. (3.3 moles) of trimethylamine
(Note 5) is introduced with stirring. The reaction is exothermic and must be cooled to keep the temperature below 50°.
After the amine addition is complete, the solution is kept at 50° under an amine pressure of 5 cm. of mercury above
atmospheric pressure for 1 hour. The mixture is then cooled to room temperature under an amine atmosphere.
The inlet tube of flask B is replaced by a rubber stopper bearing a short glass outlet tube and a glass inlet tube which is
connected to an appropriately designed glass siphon outlet tube extending to the bottom of flask A. Gentle suction applied to
the outlet tube of flask B draws the ethoxide solution slowly into flask B. The benzyltrimethylammonium chloride solution is
stirred throughout the addition of the sodium ethoxide. After the transfer of the sodium ethoxide is completed, the finely
divided precipitate of sodium chloride is allowed to settle overnight. When the sodium chloride has completely settled, the
stopper bearing the inlet and outlet tubes is replaced by a stopper bearing a 15-in. length of 19-mm. glass tubing which is
attached in turn by a gum rubber connection to a clean, dry, 1-gal. bottle fitted with an inlet tube and an outlet tube protected
by soda-lime. The bottle is flushed with nitrogen before use. The 15-in. tube is adjusted so that the bottom is approximately
in. above the level of the precipitated sodium chloride. With the open-end manometer sealed off by a screw clamp,
nitrogen pressure is applied through the outlet tube of the flask until 1.7–1.9 kg. of supernatant liquor is forced from the
flask into the bottle (Note 6). This solution contains 24–30% benzyltrimethylammonium ethoxide (2.1–2.7 moles), as
determined by titration with 0.1N hydrochloric acid, using methyl red as indicator. This represents a yield of 70–90%. An
additional 270–400 g. of solution is obtained by filtration of the residual mixture under nitrogen. To ensure rapid filtration,
a filter aid, such as Filtercel (Note 7), must be employed. The filtrate contains 24–30% benzyltrimethylammonium ethoxide
(0.3–0.7 mole). The total yield is 89–100%. The solutions are stored under nitrogen and refrigeration in bottles sealed with
rubber stoppers which are wired in place (Note 8).
Three hundred and thirty-five grams of the 25% ethanolic solution of benzyltrimethylammonium ethoxide (0.43 mole) is
placed under nitrogen in a 3-l. three-necked flask equipped with a gas inlet tube, a gas-tight modified Hershberg stirrer
(Note 1), and a gas outlet tube fitted with a thermometer. All stoppers and rubber connections are wired in place with
16-gauge copper wire. There is obtained by evaporation at 40° (Note 9) under reduced pressure (Note 10) 97 g. (0.40
mole) of the ethoxide containing an equivalent of ethanol. The vacuum is broken with dry nitrogen.
2. Notes
1. The stirrer is of the type designed by Hershberg,2 but it has a single paddle of 16-gauge Nichrome wire.
2. A bubble counter is employed for indicating nitrogen flow.
3. The water content of the ethanol, determined by Karl Fischer analysis, is 0.02–0.10%.
4. Benzyl chloride is redistilled before use. The fraction collected at 40–41° /6 mm. is used.
5. The flask is disconnected periodically from the gas train and stirring mechanism for weighing.
6. In small-scale preparations (approximately 0.5 mole) centrifugation of the total mixture is a convenient method
for separation of the product from sodium chloride.
7. Filtercel is supplied by Johns-Manville Corporation.
8. This method is more satisfactory than storage of the benzyltrimethylammonium ethoxide monoethanolate. The
excess ethanol is removed as necessary.
9. The temperature is maintained by surrounding the flask with a warm water bath. Higher temperatures are not
recommended because of the tendency of the quaternary ammonium ethoxide to decompose.
10. The bulk of the ethanol was removed by using a water pump (40–50 mm.) and collected in 1-l. and 200-ml.
Dry Ice traps connected in series. The remaining ethanol was removed by using an oil pump protected with two
300-ml. Dry Ice traps.
3. Discussion
The procedure described is adapted from the preparation outlined by Meisenheimer.3 The method has been applied by
the authors to the preparation of benzyltrimethylammonium methoxide, dibenzyldimethylammonium methoxide,
bisisopropylbenzyltrimethylammonium methoxide and benzyltriethylammonium ethoxide.
References and Notes
1. Rohm and Haas Company, Philadelphia 37, Pennsylvania.
2. Hershberg, Ind. Eng. Chem., Anal. Ed., 8, 313 (1936).
3. Meisenheimer and Bratring, Ann., 397, 295 (1913).
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
Methyl Red
ethanol (64-17-5)
hydrochloric acid (7647-01-0)
sodium chloride (7647-14-5)
nitrogen (7727-37-9)
mercury (7439-97-6)
sodium (13966-32-0)
sodium ethoxide (141-52-6)
benzyl chloride (100-44-7)
Trimethylamine (75-50-3)
Benzyltrimethylammonium ethoxide,
Ammonium, benzyltrimethyl-, ethoxide (27292-06-4)
benzyltrimethylammonium chloride (56-93-9)
benzyltrimethylammonium ethoxide monoethanolate
ammonium ethoxide
benzyltriethylammonium ethoxide
benzyltrimethylammonium methoxide (122-08-7)
dibenzyldimethylammonium methoxide
bisisopropylbenzyltrimethylammonium methoxide
Copyright © 1921-2007, Organic Syntheses, Inc. All Rights Reserved

回复人：sally110,▲ () 时间：2009-09-27 13:11:24 编辑	2楼
装置不用这么麻烦吧，单口烧瓶加冷凝管就行了。主要想问下溶剂的量这个问题，如题目所述

回复人：stargazer,▲ () 时间：2009-09-27 13:36:17 编辑	3楼
过程说的那么清楚了，都在里面了。跟这外国人走，绝对不会有错的

回复人：gongxping,▲▲ () 时间：2009-09-27 14:06:35 编辑

4楼

楼主是要合成苄基三甲基氯化铵吗？很普通的季铵盐呀！作为表面剂或相转移催化剂用得多，合成工艺也很成熟，随便一本有关有机化合物合成的工具书上都有，而且很详细，如章思规、徐克勋、樊能廷等的书上都有。其实楼主完全用不着自己合成的，很普通的东西，也很容易买到；除非楼主想开发新的合成工艺但看楼的意思又不像是在开发新合成工艺。

回复人：sally110,▲ () 时间：2009-09-27 14:12:49 编辑	5楼
是要合成新的东西，只是那这个反应做引子。恳请能告诉我溶剂的加量，到底和反应物的量有什么关系？谢谢了

回复人：gongxping,▲▲ () 时间：2009-09-27 14:36:56 编辑	6楼
见樊能廷《有机合成事典》P292

回复人：claymore,★★★★★ (C-H活化，kumada,suzuki,stille,negishi.cross-coupling.) 时间：2009-09-27 14:50:25 编辑	7楼
我觉得说了很详细了，有什么疑问吗还？

回复人：sally110,▲ () 时间：2009-09-27 15:06:33 编辑	8楼
我不是做这个反应，但是是同类的，做氯化卞和双叔胺的反应，我觉得可以借鉴这个，反应物的加量知道，我的疑问重点是在溶剂甲醇我应该加多少，我问的是一个关系，题目说得很清楚，但是回答的都偏了啊，还是恳请帮助中

得分人：stargazer :1, gongxping :3,

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