Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a stronger than phenol. Why ?

Options

A. the relative resonance stabilization of the carboxylate ion over carboxylic acid is much greater than the relative resonance stabilization of the phenoxide ion over phenol.
B. a carboxylic acid has a greater resonance stabilization than a phenol.
C. the carboxylate ion is more resonace-stabilized than the the phenoxide ion.
D. A carboxylic acid can form a dimer by intermolecular hydrogen bonding but a phenol cannot.

Answer

A

Explanation

Delocalization of the negative charge in the carboxylate anion involves equivalent resonance structures of identical energy content. Moreover, the negative charge is identical energy content.Moreover, the negative charge is `100%` shared by the two highly electronegative `O` atoms, On the other hand, in phenoxide anion. the resonance structure are not. equivalent. The structure involving negative charge on the benzene `C` are higher energy than those in which it is on oxygen.
The relative stabilizartion of the anion, with respect to the undissociated molecule, is thus likely to be less effective with a phenol than with a carboxylic acid, leading to the lower acidic sternth of the former.