The conjugate base of benzoic acid is stabilized by electron-withdrawing groups (EWG). This makes the acid more acidic by delocalizing the charge of the carboxylate ion.
Electron-withdrawing groups deactivate the benzene ring to electrophilic attack and make benzoic acids more acidic.
The conjugate base of benzoic acid is destabilized by electron-donating groups (EDG). This makes the acid less acidic by pushing more electron density toward the negative charge in the carboxylate.
Electron-donating groups activate the benzene ring to electrophilic attack and make benzoic acids less acidic.
Several examples of electron donating groups.
- Layne Morsch (University of Illinois Springfield)