phenols

Question

Phenol is more acidic than ethanol because:

RankGuru · Accepted Answer

The relative acidity is determined by the stability of the conjugate base formed after losing a proton.
- **Phenol** ($C_6H_5OH$) forms the **Phenoxide ion** ($C_6H_5O^-$). The negative charge on oxygen is delocalized over the ortho and para positions of the benzene ring through **resonance**.
- **Ethanol** ($C_2H_5OH$) forms the **Ethoxide ion** ($C_2H_5O^-$). There is no resonance to stabilize the negative charge; in fact, the $+I$ effect of the ethyl group destabilizes it further.
- Consequently, phenol (pKa $\approx 10$) is significantly more acidic than ethanol (pKa $\approx 16$).

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phenols

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