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Explain why hydroxyl group attached to an aromatic ring is more acidic than the one in which hydroxyl group is attached to an alkyl group?

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Hydroxyl group attached to an aromatic ring is more acidic than the one in which hydroxyl group is attached to an alkyl group. Phenols are a million times more acidic than alcohols.
In alcohols, $- O H$ group is attached to $C$ atom which is $s p^{3}$ hybridised. In phenols, $- O H$ group is attached to $C$ atom which is $s p^{2}$ hybridised. $s p^{2}$ hybridised $C$ atom is more electronegative than $s p^{3}$ hybridised. Thus electron density on $O$ atom in phenol is lower than the electron density on $O$ atom in alcohol. Hence, the polarity of $- O H$ bond and ionization in phenol is more than that in alcohol.
Also when alcohols lose a proton, the resulting alkoxide ion has negative charge localised on $O$ atom. However when phenols lose a proton, the resulting phenoxide ion has negative charge of $O$ atom delocalised over ortho and para positions of aromatic ring. Hence, phenoxide ion is more stable than alkoxide ion.

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Similar Questions

Q1

Explain why hydroxyl group attached to an aromatic ring is more acidic than the one in which hydroxyl group is attached to an alkyl group?

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Q2

In which of the given reaction the hydroxyl group attached with aromatic ring is removed?

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Q3

Phenols are compounds in which a hydroxyl group is bonded directly to an

s p^{2}

hybridized carbon atom of an aromatic ring. It is more acidic than an alcohol, but less acidic than a carboxylic acid. It is even less acidic than carbonic acid but more acidic than water. Thus, phenol is unable to protonate

H C O_{3}^{-}

anion but easily protonates

O H^{-}

anion. The

O H^{-}

group activates the benzene ring so much that electrophilic substitution takes place readily.

The correct order of acidity of the following substituted phenols is:

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Q4

Which is true about the acidic character of hydroxyl groups of sugars and hydroxyl group of an alcohol ?

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Q5

Name the class of secondary metabolites which is characterized by the presence of the hydroxyl group with an aromatic ring?

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