Dolbier HW Solutions 593

Dolbier HW Solutions 593 - hydroxyl group d Allyl aryl...

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24.16 Nucleophilic aromatic substitution by the elimination addition mechanism is impossible, owing to the absence of any protons that might be abstracted from the substrate. The addition elimination pathway is available, however. This pathway is favorable because the cyclohexadienyl anion intermediate formed in the rate- determining step is stabilized by the electron-withdrawing inductive effect of its f uorine substituents. 24.17 ( a ) Allyl bromide is a reactive alkylating agent and converts the free hydroxyl group of the aryl compound (a natural product known as guaiacol ) to its corresponding allyl ether. ( b ) Sodium phenoxide acts as a nucleophile in this reaction and is converted to an ether. ( c ) Orientation in nitration is governed by the most activating substituent, in this case the
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Unformatted text preview: hydroxyl group. ( d ) Allyl aryl ethers undergo a Claisen rearrangement on heating. Heating p-acetamidophenyl allyl ether gave an 83% yield of 4-acetamido-2-allylphenol. heat p-Acetamidophenyl allyl ether OCH 2 CH CH 2 CH 3 CNH O 4-Acetamido-2-allylphenol OH CH 3 CNH O CH 2 CH CH 2 OCH 3 CH O HO Vanillin OCH 3 CH O O 2 N HO 4-Hydroxy-3-methoxy-5-nitrobenzaldehyde (83%) HNO 3 acetic acid, heat 1 Sodium phenoxide ONa 3-Chloro-1,2-propanediol ClCH 2 CHCH 2 OH OH 3-Phenoxy-1,2-propanediol (61 – 63%) OCH 2 CHCH 2 OH OH 1 Guaiacol OCH 3 OH K 2 CO 3 acetone Allyl bromide H 2 C CHCH 2 Br 2-Allyloxyanisole (80 – 90%) OCH 3 OCH 2 CH CH 2 HO 2 1 Hexafluorobenzene F F F F F F slow fast F F F F OH F F 2 Pentafluorophenol F 2 F F F OH F F 1 PHENOLS 687...
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This note was uploaded on 10/03/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.

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