问题：求助：2-甲基吡啶的氮氧化物的制备
类型：求助 (悬赏分:3分)
提问：guilun
等级：▲
版块：有机化学问题(jimuwei,fpcwin1211,netpanda,yjgzfl,Ftian,)
信誉：0%
回复：9
阅读：1535
时间：2009-03-14 12:04:28 编辑加入/取消收藏订制/取消短消息举报该贴

我按照文献：
将 39 mL(0.4mol)2-甲基吡啶、63mL(0.6mol)30% 的过氧化氢溶液。190mL(3.325mol)冰醋酸加入到500mL三颈瓶中，控温80-90℃回流12h，再补加12mL(0.116mol) 过氧化氢溶液，于80一90℃继续回流反应12h。减压浓缩回收乙酸，剩余物为黄色液体，用30%的氢氧化钠水溶液调pH值至13左右，用氯仿萃取，用无水硫酸钠干燥。次日，滤出干燥剂，减压浓缩，稍冷固化，析出白色固体。用乙醚洗，真空干燥。
做出来的为黄色液体，调PH,氯仿萃取，无水硫酸钠干燥。次日，滤出干燥剂，减压浓缩，稍冷,可是没有东西析出，放在冰箱里一晚，也没有东西出来，还放在真空干燥箱里还是没有东西出来。大家提下建议，看下试验有什么问题，怎么弄出来？
如果谁知道的，告诉我具体操作步骤，在下不胜感激1

回复人：cuihao320,▲ (初学化工，勤于学习) 时间：2009-03-17 23:00:48 编辑	1楼
点板看反应完了就可以了啊...其他的操作也差不多我做的是2-氯吡啶的氮氧化。不过加的双氧水量比你加的要大一些！`而且在收乙酸的时候我还加了几次水，用水带乙酸和没反应完的原料. 楼上的，全是减压收，没问题的.....但是也要注意哈哈我同事就弄炸了一次！剩少量的时候就叫溶剂挥干就行了

回复人：chemwu70,★ (共同进步) 时间：2009-03-16 20:29:07 编辑	2楼
蒸馏不危险吗?若往下做,剩余物黄色液体即可

回复人：大荣,▲▲▲ (低价、污染。精细化工的路在何方？) 时间：2009-03-16 20:10:17 编辑	3楼
纯度不够很难析出，建议蒸一下。如果要往下做不一定要它析出来啊，点板纯就好了。

回复人：claymore,★★★★★ (C-H活化，kumada,suzuki,stille,negishi.cross-coupling.) 时间：2009-03-14 13:31:40 编辑	4楼
文献上是这么说的吗? 次日，滤出干燥剂，减压浓缩，稍冷固化，析出白色固体。用乙醚洗，真空干燥。减压浓缩应该是减压蒸馏收集馏分吧?

回复人：claymore,★★★★★ (C-H活化，kumada,suzuki,stille,negishi.cross-coupling.) 时间：2009-03-14 13:35:00 编辑

5楼

N-氧化吡啶的方法你可以参照下

http://g.zhubajie.com/urllink.php?id=43463312exkovic4tkoo2ao

或者是跟着Organic Synthesis做

In a 1-l. three-necked flask equipped with a stirrer (Note 1), a thermometer, and a dropping funnel is
placed 110 g. (1.39 moles) of pyridine. The pyridine is stirred, and 250 ml. (285 g., 1.50 moles) of 40%
peracetic acid (Note 2) is added at such a rate that the temperature reaches 85° and is maintained there.
After the addition, which requires 50–60 minutes, the mixture is stirred until the temperature drops to
40°.
A. Pyridine-N-oxide hydrochloride. The acetate is converted to the hydrochloride by bubbling a
slight excess over the theoretical amount (51 g.) of gaseous hydrogen chloride into the reaction mixture
by way of a 7-mm. gas inlet tube which replaces the dropping funnel in the reaction flask. The acetic
acid and excess peracetic acid are removed by warming on the steam bath under vacuum (Note 3). The
residual pyridine-N-oxide hydrochloride is purified by heating under reflux for 30 minutes with 300 ml.
of isopropyl alcohol, cooling to room temperature, and filtering. The colorless crystals are washed with
50 ml. of isopropyl alcohol followed by 50 ml. of ether. The yield is 139–152 g. (76–83%) (Note 4),
m.p. 179.5–181°.
B. Pyridine-N-oxide. The acetic acid solution is evaporated on the steam bath under the pressure of
a water aspirator, and the residue (180–190 g.) is distilled at a pressure of 1 mm. or less in an apparatus
suitable for collecting a solid distillate (Note 5). The vacuum pump must be protected with a Dry Ice
trap capable of holding about 60 ml. of acetic acid, which distils as the pyridine-N-oxide acetate
dissociates at low pressure. Heat is provided by an oil bath, the temperature of which is not allowed to
rise above 130° (Note 6). The product is collected at 100–105°/1mm. (95–98°/0.5 mm.). The yield is
103–110 g. (78–83%) of colorless solid, m.p. 65–66° (sealed capillary). The base is deliquescent and must be stoppered immediately.

回复人：claymore,★★★★★ (C-H活化，kumada,suzuki,stille,negishi.cross-coupling.) 时间：2009-03-14 13:35:51 编辑

6楼

2. Notes
1. A convenient seal for stirring under vacuum (see (Note 3)) is made by running an 8-mm. glass rod,
with propeller or paddle stirrer at the end, through the outside member of an 18/9 spherical joint which
is inserted into a suitable rubber stopper. The inner member of the 18/9 spherical joint is then slipped
over the stirrer and held in place with a piece of rubber tubing. This rotating seal may then be lubricated
with a drop of oil. Alternatively, one may use a Trubore stirring system.
2. Becco peracetic acid (40%) was used. The composition and properties of this commercial preparation
are described fully in Bulletin 4 of the Buffalo Electro-Chemical Company, Buffalo, New York. The
manufacturer's recommendations for storing and handling should be followed. Experiments using
proportionate amounts of 10% or 20% peracetic acid in acetic acid were equally successful. The
strength of the peracetic acid, as well as the progress of the reaction, can be determined iodimetrically.2
3. The vacuum evaporation proceeds much more smoothly and rapidly if the mixture is stirred
mechanically during the process.
4. The submitters report that the same procedure is successful with four times the amounts given here.
With the increased amounts, a water bath is used for cooling during the initial addition, which then
requires about 45 minutes.
5. Caution! Before distillation, absence of peroxide should be established by test with potassium iodide.
The apparatus for distillation of solids in vacuum described in Organic Syntheses3 is satisfactory, as is a
combination of standard taper flasks, short column, and adaptors.
6. It is imperative that the pressure be maintained at 1 mm. or lower. Decomposition is usually extensive
at higher pressures; however, the removal of the acetic acid may be initiated at 5–10 mm. pressure. The
oil-bath temperature must not exceed 130° if decomposition is to be avoided. A fore-run of 15–20 g.,
b.p. 90–98°/0.5 mm., can be saved and redistilled in combination with similar cuts from successive
runs. About 9–10 g. (7%) of additional crystalline pyridine-N-oxide is obtained per run in this manner.
3. Discussion
Pyridine-N-oxide has been prepared by oxidation of pyridine with perbenzoic acid,4 with
monoperphthalic acid,5 with peracetic acid (hydrogen peroxide and acetic acid),6,7 and with hydrogen
peroxide and other carboxylic acids.7.
References and Notes
1. Stanford University, Stanford, California.
2. Smit, Rec. trav. chim., 49, 691 (1930).
3. Org. Syntheses Coll. Vol. 3, 133 (1955).
4. Meisenheimer, Ber., 59, 1848 (1926).
5. Bobranski, Kochanska, and Kowalewska, Ber., 71, 2385 (1938).
6. Ochiai, Ishikawa, and Zai-Ren, J. Pharm. Soc. Japan, 64, 73 (1944) [C. A., 45, 8526h (1951)];
Hertog and Combé, Rec, trav., chim., 70, 581 (1951).
7. Ochiai, Katada, and Hayashi, J. Pharm. Soc. Japan, 67, 33 (1947) [C. A., 45, 9541i (1951)];
Ochiai, J. Org. Chem., 18, 534 (1953).

回复人：guilun,▲ () 时间：2009-03-29 13:06:47 编辑	7楼
我最后的产品氯仿挥发完了，我得到黄色液体，里面有点沉淀，我过滤，用乙醚洗得浅黄固体，我测熔点只有36度，文献值46-50.怎么回事呀？

回复人：claymore,★★★★★ (C-H活化，kumada,suzuki,stille,negishi.cross-coupling.) 时间：2009-03-29 13:46:27 编辑	8楼
不纯

回复人：guilun,▲ () 时间：2009-04-02 15:30:55 编辑

9楼

我把第一步的乙酸和水蒸出一步分，直接用于第二步反应，与醋酐进行酰化反应，再反应液先蒸出一部分醋酐，最后在7mm汞柱蒸馏，可是没东西出来，只有醋酐出来，我加到170，还是只有醋酐，最后反应液变黑了，郁闷!怎么回事? 第一步吡啶氧化物，我也想把它减压蒸出来，可是到了沸点没东西出来，最后碳黑了，怎么回事呀？请教大家

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