22. Carboxylic Acid Derivatives: NAS

Show how Fischer esterification might be used to form the following esters. In each case, suggest a method for driving the reaction to completion.

(c) ethyl phenylacetate

Predict the esterification products of the following acid/alcohol pairs.

(a) CH₃CH₂CH₂COOH + CH₃OH

(b) CH₃OH + HNO₃

(c) 2 CH₃CH₂OH + H₃PO₄

When butanoic acid and ¹⁸O-labeled methanol react under acidic conditions, what compounds are labeled when the reaction has reached equilibrium?

a. A student did not obtain any ester when he added 2,4,6-trimethylbenzoic acid to an acidic solution of ethanol. Why? (HINT: Build models.)

b. Would he have encountered the same problem if he had tried to synthesize the methyl ester of 4-methylbenzoic acid in the same way?

Propose a mechanism for the following reaction. (Hint: Number the carbons to help you see where they end up in the product.)

Show how each of the following esters could be prepared using a carboxylic acid as one of the starting materials:

a. methyl butyrate (odor of apples)

Propose a mechanism for the acid-catalyzed reaction of acetic acid with ethanol to give ethyl acetate.

Show how you would accomplish the following syntheses in good yields.

(c)

(d)

Predict the esterification products of the following acid/alcohol pairs.

(d)

(e)

Show how Fischer esterification might be used to form the following esters. In each case, suggest a method for driving the reaction to completion.

(a) methyl salicylate

Suggest the most appropriate reagent for each synthesis, and explain your choice.

(b)

Show how you would convert alanine to the following derivatives. Show the structure of the product in each case.

(a) alanine isopropyl ester

(b) N-benzoylalanine

Show how each of the following compounds can be prepared, using the given starting material:

a.

Show how you would accomplish the following multistep syntheses. You may use any additional reagents and solvents you need.

(f)