Phenols
Easychemistry
Phenol is more acidic than ethanol because:
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Solution
Incorrect! Answer:
Phenoxide ion is stabilized by resonance
The relative acidity is determined by the stability of the conjugate base formed after losing a proton.
- Phenol (C6H5OH) forms the Phenoxide ion (C6H5O−). The negative charge on oxygen is delocalized over the ortho and para positions of the benzene ring through resonance.
- Ethanol (C2H5OH) forms the Ethoxide ion (C2H5O−). There is no resonance to stabilize the negative charge; in fact, the +I effect of the ethyl group destabilizes it further.
- Consequently, phenol (pKa ≈10) is significantly more acidic than ethanol (pKa ≈16).
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About This Question
- Subject
- chemistry
- Chapter
- organic compounds containing oxygen
- Topic
- phenols
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
Phenoxide ion is stabilized by resonance
The relative acidity is determined by the stability of the conjugate base formed after losing a proton.
- Phenol (C6H5OH) forms the Phenoxide ion (C6H5O−). The negative charge on oxygen is delocalized over the ortho and para positions of the benzene ring through resonance.
- Ethanol (C2H5OH) forms the Ethoxide ion (C2H5O−). There is no resonance to stabilize the negative charge; in fact, the +I effect of the ethyl group destabilizes it further.
- Consequently, phenol (pKa ≈10) is significantly more acidic than ethanol (pKa ≈16).
This easy difficulty chemistry question is from the chapter organic compounds containing oxygen, covering the topic of phenols. It appeared in the 2025 exam.
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