Organic Chemistry MCAT Practice Exam 2025 - Free MCAT Practice Questions and Study Guide

Phenols are indeed more acidic than typical alcohols, and this is primarily due to the resonance stabilization of their conjugate base. When a phenol loses a hydrogen ion (H⁺), it forms a phenoxide ion. This phenoxide ion benefits from resonance stabilization because the negative charge can be delocalized across the aromatic ring. This delocalization makes the conjugate base more stable compared to that of alcohols, where the negative charge remains localized on the oxygen atom without similar resonance involvement.

On the other hand, alcohols do not have this resonant delocalization when their conjugate bases are formed, meaning their conjugate bases are less stable. The increased stability of the phenoxide ion due to resonance makes phenols more likely to donate a proton, therefore explaining their greater acidity compared to alcohols. This key difference underlies why the correct choice is related to the enhanced resonance stabilization of the phenomenon occurring in phenols, which elevates their acidity relative to standard alcohols.