Ester Reactions Summary and Practice Problems

This article summarizes the main reactions of esters with associated practice problems. We covered the mechanism and other details about each reaction so, if you need to go over them, click on the corresponding links.

Let’s start with the hydrolysis of esters.

Esters can be hydrolyzed to carboxylic acid by acid base catalysis. The base-catalyzed hydrolysis, also called saponification, has the advantage of being irreversible.

 

 

Esters can be converted into primary, secondary and tertiary amides by an aminolysis reaction with ammonia, primary amine and a secondary amine respectively:

 

 

Esters can be reduced to alcohols or aldehydes using LiAlH4 and DIBAL respectively:

 

 

Reacting esters with excess Grignard reagent produces tertiary alcohols:

 

 

Below is the summary of ester reactions that you can use to work on the practice problems:

 

Practice

1.

Predict the major product(s) for each of the following reactions:

Answer

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2.

Draw a plausible mechanism for the following synthetic transformation:

 

Answer

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3.

Propose a mechanism for the following synthetic transformation:

Answer

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4.

Friedel-Crafts acylation of carboxylic acids is not very common as the carbonyl group is not so electrophilic. One of the ways to activate the acid is the use of TFAA (Trifluoroacetic anhydride). Propose a mechanism for the following Friedel-Crafts acylation and explain the role of TFAA:

 

Answer

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5.

Propose a mechanism for the following Friedel-Crafts acylation reaction.

 

 

Note: H3O+ with heat is used for hydrolyzing the ester into a carboxylic acid. 

Answer

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6.

Chemiluminescence is used for many applications including glow sticks. The principle behind this process is the excitation of fluorescent dyes such as rhodamines, perylenes, anthracenes, and many more using a chemical reaction. In other words, the source of energy for the excitation of the dye is a chemical reaction. Most often the energy is generated as a result of spontaneously decomposing carbon dioxide dimer which, in turn, is produced via the oxidation of diaryl oxalate diesters with hydrogen peroxide:

 

 

Draw a curved arrow mechanism for the formation of the carbon dioxide dimer and explain why perylene is aromatic despite having 20 π electrons.

 

 

Answer

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