Question

Phenol, one of the deadliest acids, contains a hydroxy group directly attached to the aromatic ring. A hydroxy group attached to an aromatic ring is also referred to as a phenolic group. Due to the presence of -OH group, phenols show many reactions similar to those of alcohols. The direct attachment of -OH group to the aromatic ring makes its behaviour very different from that of alcohols. That is why phenol behaves differently from alcohols in many reactions. The chemical reactions of phenol can be categorised as follows: Reactions involving -OH group Reactions involving benzene ring

1. Write the chemical equation for the preparation of phenol from benzene using H₂SO₄ and NaOH.
2. What happens when phenol reacts with Br₂/CS₂ at low temperature?
3. What is observed when phenol is treated with neutral ferric chloride solution?
4. Write the reaction when phenol is treated with conc. HNO₃ in the presence of conc. H₂SO₄.
5. Write the reaction when phenol is treated with chloroform in the presence of aqueous NaOH at 340 K.

Answer 1

1. Equation required with proper catalyst and by product
   \[\ce{Benzene->Benzene sulphonic acid->sodium benzene sulphonate->sodium phenoxide->phenol}\]
2. When phenol reacts with Br₂/CS₂ at low temperature o-bromophenol and p-bromophenol are formed.
3. When phenol is treated with neutral ferric chloride violet/purple colour solution is obtained.
4. 2,4,6 tri nitro phenol is formed when phenol is treated with conc. HNO₃ in the presence of conc. H₂SO₄ .
5. Salicylaldehyde is formed when phenol is treated with chloroform in the presence of aqueous NaOH at 340K.