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Electrophilic Substitution Reactions of Phenol

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Bromination

Phenol reacts with bromine water to give white ppt of 2,4,6-tribromophenol.

Electrophilic substitution of phenol : tribromination of phenol

Reason for tribromo substitution

Phenol in the presence of water is converted into the phenoxide ion (C6H5−O) which is a strong activating species. Hence tribromo-substitution occurs.

Monobromo phenol

Bromine is added to a non-polar solvent like CS2 or CCl4 to form monobromo phenol.

Electrophilic substitution in phenol : monobromination of phenol

Nitration

Phenol reacts with conc. HNO3 to form 2,4,6-trinitrophenol.

Electrophilic substitution in phenol : trinitro of phenol

Dil. HNO3 is used to get mononitro phenols.

Electrophilic substitution in phenol : mononitrophenol of phenol

Reimer-Tiemann reaction

Phenol reacts with chloroform (CHCl3) in base (NaOH or KOH etc.) to form salicylaldehyde.

Electrophilic substitution in phenol : Reimer-Tiemann reaction

If we use CCl4 (carbon tetrachloride) instead of chloroform, salicylic acid is formed.

Electrophilic substitution in phenol : salicylic acid formation in reimerteimann reaction

Kolbe's reaction

The reaction of phenoxide ion with CO2 followed by acidification yields salicylic acid. This reaction is known as Kolbe's reaction.

Electrophilic substitution in phenol : Kolbe's reaction

Coupling reaction

Benzenediazonium salt reacts with phenol in weakly alkaline medium at low temperature (0-5° C) to form coloured products called azo dyes. This reaction is known as coupling reaction.

Electrophilic substitution in phenol : coupling reaction in phenol

Conversion

Convert phenol to acetophenone

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