Electrophilic Aromatic Substitution Reactions in Phenols

Chemistry

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Electrophilic substitution reaction of phenols

Electrophilic aromatic substitution reactions are the reactions where an electrophile replaces one or more hydrogen atoms attached to the aromatic ring. Phenols are highly prone to electrophilic substitution reactions due to rich electron density. The hydroxyl group attached to the aromatic ring in phenol facilitates the effective delocalization of the charge in the aromatic ring. Thus, it stabilizes the arenium ion through resonance. The hydroxyl group also acts as ortho para directors.

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Halogenation of phenol

Phenols when treated with halogens undergo halogenation readily to form polyhalogen derivatives.

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Sulphonation of phenol

Phenol's can be sulphonated readily at O-(ortho)  and P(para) positions by the action of concentrated sulphuric acid.

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Nitration of phenol

The -OH group present in phenols activates the ring to such extent that some phenols can be nitrated even with dilute nitric acid at low temperature.

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Friedal craft's alkylation of phenol

Phenols undergo Friedal-Crafts alkylation reactions in the presence of anhydrous aluminium chloride to give mixture of O- and P- derivatives.

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Reaction of phenol and ferric chloride

Phenol with ferric chloride forms a complex which give violet colouration, hence this reaction is used for identification of phenol.

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Chemical Properties of Alcohols and Phenols - Reactions involving cleavage of O-H bond

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