Question

Write down the following reactions: (i) Carbylamine reaction (ii) Reaction between benzene diazonium chloride and phenol in basic medium

Hint:

Carbylamine reaction is a confirmatory test for primary amines. Azo coupling reactions are carried out in cold alkaline medium.

Answer 1

(i) Carbylamine reaction: When a primary amine is heated with chloroform and alcoholic KOH, a foul-smelling isocyanide is formed: \[ \text{RNH}_2 + \text{CHCl}_3 + 3\text{KOH} \rightarrow \text{RNC} + 3\text{KCl} + 3\text{H}_2\text{O} \] (ii) Reaction between benzene diazonium chloride and phenol in basic medium: Phenol reacts with benzene diazonium chloride in alkaline medium to form an azo dye (p-hydroxyazobenzene): \[ \text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^- + \text{C}_6\text{H}_5\text{OH} \xrightarrow{\text{NaOH}} \text{C}_6\text{H}_5{-}\text{N=N}{-}\text{C}_6\text{H}_4\text{OH} \]