Question

Propose a mechanism for the synthesis of methyl orange.

Short answer

Step 1:

Step 2:

Step 3:

Step-by-step solution

Diazotization

Sulphanilic acid with sodium carbonate converted into sodium salt of p-amino benzene sulphonate. It undergoes diazotization reaction in presence of nitrous acid to form diazonium chloride salt.

Ionisation

Diazonium chloride then ionizes in aqueous solution, giving sodium ion, chloride ion and internal salt.

Coupling

N-N-dimethylaniline hydrochloride added to internal salt, coupling occurs to give methyl orange.