Reactions of Carboxylic Acids and Derivatives Nucleophilic Acyl Substitution

Ketones, aldehydes, and carboxylic acids all contain the carbonyl group, yet the reactions of acids are quite different from those of ketones and aldehydes. Ketones and aldehydes commonly react by nucleophilic addition to the carbonyl group but carboxylic acids (and their derivatives) more commonly react by nucleophilic acyl substitution, where one nucleophile replaces another on the acyl (C = O) carbon atom. [Pg.957]

Acid derivatives differ in the nature of the nucleophile bonded to the acyl carbon —OH in the acid, —Cl in the acid chloride, —OR in the ester, and —NH2 (or an amine) in the amide. Nucleophilic acyl substitution is the most common method for interconverting these derivatives. We will see many examples of nucleophilic acyl substitution in this chapter and in Chapter 21 ( Carboxylic Acid Derivatives ). The specific mechanisms depend on the reagents and conditions, but we can group them generally according to whether they take place under acidic or basic conditions. [Pg.957]

Nucleophilic Acyl Substitution in the Basic Hydrolysis of an Ester [Pg.957]

Step I Hydroxide ion (strong nucleophile) adds to the carbonyl group, forming a tetrahedral intermediate. [Pg.957]

Step 2 An alkoxide ion leaves, regenerating the C=0 double bond. [Pg.957]