Download Addition/elimination under acidic conditions

Nucleophilic Acyl Substitution—weak Nu
Major concepts
 Nucleophilic acyl substitutions can occur with weak nucleophiles under basic conditions, but
only if the carboxylic acid derivative is very reactive
 Nulceophilic acyl substitutions can occur with weak nucleophiles under acidic conditions
 Carboxylic acids can be esterified with alcohols under acidic conditions
Vocabulary
 Fisher esterification
Students should be able to:
 Draw a mechanism for nucleophilic acyl substitution under acidic conditions (Fisher
esterification)
 Determine functional groups that undergo nucleophilic acyl substitution reactions
 Predict the products of nucleophilic acyl substitutions
 Predict the direction of equilibrium and draw energy diagrams for the mechanisms of
nucleophilic acyl substitution taking into account Le Chatlier’s principle

Daily Problems
1. Draw a mechanism for this Fisher esterification. What byproduct is produced?
2. Although the stability of the starting materials and products are about the same in the reaction
above, the equilibrium lies far to the right. Explain how this is possible. How could this reaction be
forced back to the left? (Hint: What is the byproduct of the reaction?)
3. These reactive carboxylic acid derivatives will react with these weak nucleophiles. Predict the
product, and explain what the purpose of the triethylamine (TEA) and pyridine (pyr) is in each reaction.
4. Predict the products of these nucleophilic acyl substitution reactions.
Cumulative problems:
5. Label each reaction as a nucleophilic substitution, a nucleophilic addition, or a nucleophilic acyl
substitution. Then predict the product.