Organic Chemistry MCAT Practice Exam 2025 – The All-in-One Guide to Master Your Test Preparation!

Question: 1 / 400

Which of the following statements about phenols is true?

They are more acidic than alcohols

Phenols are indeed more acidic than alcohols due to the stability of their conjugate bases. When a phenolic compound donates a proton (H+), it forms a phenoxide ion. This phenoxide ion is resonance-stabilized, as the negative charge on the oxygen can be delocalized onto the aromatic ring. This delocalization increases the stability of the ion compared to that of an alkoxide ion from alcohols, which does not have such resonance stabilization. Consequently, the ability to stabilize the negative charge significantly enhances the acidity of phenols compared to alcohols.

In contrast, carboxylic acids are more acidic than phenols due to their ability to form resonance-stabilized carboxylate ions upon deprotonation. Thus, while phenols are more acidic than alcohols, they remain less acidic than carboxylic acids. The other statements about phenols, including their lack of resonance stabilization and ease in forming esters, do not accurately capture the character of phenols. Therefore, the assertion that phenols are more acidic than alcohols stands as a true statement, underpinned by resonance stabilization phenomena that solidify the conclusions regarding their acidity.

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They are less acidic than carboxylic acids

They do not have resonance stabilization

They can form esters easily

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