Organic Syntheses, CV 5, 924
[Method I]
Submitted by Christer Frisell and Sven-Olov Lawesson
1.
Checked by William G. Dauben and Gilbert H. Berezin..
1. Procedure
A
1-l., three-necked, round-bottomed flask equipped with a
sealed mechanical stirrer, a
reflux condenser, and a
500-ml. pressure-equalized dropping funnel is arranged for conducting a reaction in an atmosphere of
nitrogen by fitting into the top of the condenser a T-tube attached to a low-pressure supply of
nitrogen and to a
mercury bubbler. The flask is dried by warming with a soft flame as a slow stream of
nitrogen is passed through the system. In the cooled flask a solution of
phenylmagnesium bromide is prepared from
13 g. (0.53 g. atom) of magnesium turnings,
79 g. (0.5 mole, 53.6 ml.) of bromobenzene, and
200 ml. of anhydrous ether.
After the preparation of
phenylmagnesium bromide is complete, the ethereal solution is cooled in an
ice bath and
200 ml. of anhydrous ether is added. A solution of
58.3 g. (0.3 mole, 56 ml.) of t-butyl perbenzoate (Note
1) in
120 ml. of anhydrous ether is added, dropwise, with stirring over a 30-minute period, and the stirring is continued for an additional 5 minutes.
The reaction mixture is poured carefully into a cold solution of
40 ml. of concentrated hydrochloric acid in 1 1. of water. The ethereal layer is separated, and the aqueous layer is extracted twice with
150-ml. portions of ether. The combined organic layers are extracted with three
25-ml. portions of 2M sodium hydroxide solution, washed with water until the washings are neutral, and then dried over anhydrous
magnesium sulfate (Note
2) and (Note
3). The dried solution is concentrated and the product distilled under reduced pressure, b.p.
57–59°/7 mm. The yield of
phenyl t-butyl ether is
35–38 g. (
78–84%),
n25D 1.4870–1.4880. This synthetic process is applicable to the preparation of other
t-butyl ethers (Note
4).
2. Notes
1.
t-Butyl perbenzoate is supplied by Lucidol Division, Wallace and Tiernan Inc., Buffalo 5, New York, or L. Light & Co., Ltd., Colnbrook, Bucks, England. The Lucidol product contains
98% t-butyl perbenzoate.
2. The ethereal solution should be tested for peroxides as follows: A few milligrams of
sodium iodide, a trace of
ferric chloride, and
3 ml. of glacial acetic acid are placed in a test tube and
2 ml. of the ether solution added carefully. When unconsumed perbenzoate is present, a yellow ring is formed immediately between the two phases. If a positive test is obtained, the acid and base treatments should be repeated.
3. Discussion
4. Merits of Preparation
The synthesis of
t-butyl ethers by the reaction of Grignard reagents with
t-butyl perbenzoate appears to have considerable generality (Note
4), and the perester is a stable, readily available material.
This preparation is referenced from:
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