Which among the following represent reagent ‘A’?

Reactants:

1. 1-Naphthol (C₁₀H₇OH): A naphthalene derivative containing a hydroxyl (-OH) group at position 1, making it an electron-rich aromatic compound.
2. Benzene diazonium chloride (C₆H₅N₂⁺Cl⁻): A diazonium salt formed by diazotization of aniline (C₆H₅NH₂) using sodium nitrite (NaNO₂) and hydrochloric acid (HCl).

Conditions:

The reaction occurs in a basic medium, typically sodium hydroxide (NaOH), to activate the hydroxyl group on 1-naphthol and facilitate electrophilic substitution.

Mechanism:

1. In the basic medium, the hydroxyl group of 1-naphthol deprotonates to form the phenoxide ion, which is more nucleophilic.
2. The diazonium cation (C₆H₅N₂⁺) acts as an electrophile.
3. An electrophilic substitution reaction occurs, where the diazonium cation couples with the activated aromatic ring of 1-naphthol.
4. The azo product (C₆H₅N=N-C₁₀H₆OH) is formed, with the diazo (-N=N-) group linking the two aromatic systems.

Product:

The product is an azo compound where the naphthol ring is connected to a phenyl ring through an azo (-N=N-) linkage. This compound is often brightly colored and used in dyes.