Carboxylic acids are more acidic than phenols because the carboxylate ion, the conjugate base of carboxylic acids, is more stabilized with two equivalent resonance structures, while the phenoxide ion has non-equivalent resonance structures, leading to less effective delocalization and lower stabilization.
Explain the higher acidity of carboxylic acids compared to phenols based on the stabilization of their respective conjugate bases and the role of resonance.
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Carboxylic acids exhibit greater acidity than phenols primarily due to the enhanced stability of their conjugate bases. In carboxylate ions, resonance occurs between the two oxygen atoms, distributing the negative charge across multiple atoms and stabilizing the ion. This resonance delocalization is absent in phenoxide ions, making them less stable. The electron-donating aromatic ring in phenols provides some acidity, but it lacks the extensive resonance stabilization seen in carboxylate ions. Consequently, the resonance effect plays a pivotal role in the higher acidity of carboxylic acids compared to phenols, as it better disperses the negative charge, resulting in a more stable conjugate base.