The reaction of phenol with aqueous sodium hydroxide
indicates that phenols are stronger acids than alcohols and water Let us examine how a compound in which hydroxyl group
attached to an aromatic ring is more acidic than the one in
which hydroxyl group is attached to an alkyl group The ionisation of an alcohol and a phenol takes place as follows:
Due to the higher electronegativity of sp
2 hybridised carbon
of phenol to which –OH is attached, electron density decreases
on oxygen This increases the polarity of O–H bond and results
in an increase in ionisation of phenols than that of alcohols