22. Carboxylic Acid Derivatives: NAS

Provide the mechanism for the following reaction.

Which carbonyl group will undergo decarboxylation most readily?

Which of the following compounds decarboxylates when heated?

Which of the following compounds will decarboxylate when heated?

Although metal ions increase the rate of decarboxylation of dimethyloxaloacetate, they have no effect on the rate of decarboxylation of either the monoethyl ester of dimethyloxaloacetate or acetoacetate. Explain why this is so.

3-Amino-2-oxindole catalyzes the decarboxylation of a-keto acids.

a. Propose a mechanism for the catalyzed reaction.

Which of the following compounds will decarboxylate when heated?

a.

b.

In Chapter 19, we will learn about the hydrolysis of t-butyl esters. In the reaction below, the hydrolysis is coupled to the decarboxylation reaction learned in this chapter. Suggest a mechanism for this reaction. [Hint: The formation of t-butanol proceeds by an S_N1 reaction.]

While acidic conditions were used in Assessment 18.68, decarboxylation of esters can also be conducted under basic conditions to give, at least temporarily, the enolate product shown. [We’ll learn more about the chemistry of enolates in Chapter 20.] Suggest a mechanism of this reaction. [Hint: The formation of chloromethane proceeds by an S_N2 reaction.]