Organic Lab Reactions 27

Organic Lab Reactions 27 - 22 THE CLAISEN REARRANGEMENT r...

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22 THE CLAISEN REARRANGEMENT r methylhydroquinone yield LXXVIII, and the same product is obtained from the hydroquinone and crotyl alcohol. 93 CH 3 ,OH 'cH 2 CH=CHCH 3 CH 3 LXXVIII In summary, it can be said that the 7-substituted allylphenols can be prepared by Oalkylation of the sodium salt of the phenol in benzene, and -they usually cannot be prepared by the Claisen rearrangement. The condensation of free phenols with allylic halides, allylic alcohols, and dienes may give allylphenols, but frequently yields other products.*- ** EXPERIMENTAL CONDITIONS AND PROCEDURES Preparation of Allyl Ethers The most widely used method f of preparing allyl aryl ethers consists in refluxing the phenol with allyl bromide and anhydrous potassium carbonate in acetone for several hours; allyl bromide may be replaced advantageously by allyl chloride and sodium iodide, 76 ' 9B and acetone may be replaced by the higher-boiling methyl ethyl ketone. The method , usually gives very good yields but is unsatisfactory for weakly acidic
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