Question

Why phenol does not undergo protonation readily? 

Hint:

The resonance of the lone pair on the oxygen in phenol with the benzene ring decreases its availability to accept a proton, making protonation less likely.

Answer 1

Phenol does not undergo protonation readily because the lone pair of electrons on the oxygen of the hydroxyl group is delocalized into the benzene ring through resonance. This reduces the electron density on the oxygen atom, making it less available to accept a proton. As a result, phenol is less basic than alcohols and does not readily undergo protonation.