1. Br₂, PBг3 2. H₂O H3C OH в незв H3C OH Br The a-bromination of carbonyl compounds by Br₂ in acetic acid is limited to aldehydes and ketones because acids, esters, and amides don't enolize to a sufficient extent. Carboxylic acids, however, can be a-brominated by first converting the carboxylic acid to an acid bromide by treatment with PBr3. Following enolization of the acid bromide, Br₂ reacts in an a-substitution reaction. Hydrolysis of the acid bromide completes the reaction. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions H3C Br :0: Br FO::OH₂ H₂O H3C Br 3 a Br

1. Br₂, PBг3 2. H₂O H3C OH в незв H3C OH Br The a-bromination of carbonyl compounds by Br₂ in acetic acid is limited to aldehydes and ketones because acids, esters, and amides don't enolize to a sufficient extent. Carboxylic acids, however, can be a-brominated by first converting the carboxylic acid to an acid bromide by treatment with PBr3. Following enolization of the acid bromide, Br₂ reacts in an a-substitution reaction. Hydrolysis of the acid bromide completes the reaction. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions H3C Br :0: Br FO::OH₂ H₂O H3C Br 3 a Br

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter21: Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution Reactions

Section21.SE: Something Extra

Problem 75AP: One frequently used method for preparing methyl esters is by reaction of carboxylic acids with...

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