Question

If an amine is added to the solution containing a carboxylic acid and phenol, which of the following will occur?

a.) Both acid and phenol will be converted to their conjugate base

b.) Phenol will react more quickly than carboxylic acid.

c.) The carboxylic acid will react more quickly than phenol.

d.) Both will react at roughly equal rate

Answer 1

Hint: Carboxylic acid is stronger acid than phenol as it readily loses hydrogen ions making oxygen electron rich. 

Complete answer:

Statement A states that both acid and phenol will be converted to their conjugate base. It is not true because carboxylic acid is a stronger acid comparatively stronger than phenols. 

Carboxylic acid can easily donate their hydrogen ions and form conjugate base while in phenols negative charge on oxygen obtained after the losing of hydrogen ions will be delocalized over the ring making the ring stable and less reactive in comparison to carboxylic acid.

Statement B states that Phenol will react more quickly than carboxylic acid. This statement is not true as carboxylic acid will readily react with amine and form carboxylate ions. Phenols also react with amine but carboxylic acids are deprotonated easily.

Statement C states that the carboxylic acid will react more quickly than phenol. This statement is true as when amine will be directly reacted with carboxylic it will make the carboxylic acid deprotonated forming a carboxylate ion.

Statement D says both will react at roughly equal rate. This statement is not true as carboxylic acids and phenols have different rates of reactions.

Therefore statement C comes out to be true.

Note: Carboxylic acid is stronger acid in comparison to phenol as carboxylic acid can readily lose hydrogen ions whereas in phenols the negative charge on oxygen after the hydrogen ion will be delocalized over the ring making the ring stable and less reactive comparatively to carboxylic acid.