Question

Which one of the following reaction sequences will give an azo dye?

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

The formation of azo dyes involves the diazotization of aromatic amines followed by coupling with compounds like naphthols. This is an important reaction in dye chemistry.

Answer 1

The Correct Option is A

An azo dye is formed through a reaction called the diazotization reaction, where a primary aromatic amine reacts with sodium nitrite in an acidic medium, forming a diazonium salt. This salt then reacts with an aromatic compound, such as naphthol, to form an azo dye.

The correct reaction sequence for the formation of an azo dye involves the following steps:
1. \( \text{NO}_2 \) (i) \( \text{Sn}/\text{HCl} \) reduces the nitro group (\( \text{NO}_2 \)) to an amine group (\( \text{NH}_2 \)).
2. (ii) \( \text{NaNO}_2/\text{HCl} \) diazotizes the amine group to form a diazonium salt (\( \text{Ar-N}_2^+ \)).
3. (iii) \( \beta \)-naphthol, NaOH reacts with the diazonium salt to form the azo dye.
Thus, the correct reaction sequence that will give an azo dye is option

(1).