Q18 / 180 · COMEDK 2026 (9 May Shift 1) · Chemistry
Identify the correct order of the type of reactions taking place in this sequence:
- AOxidation, Coupling, Diazotization
- BReduction, Diazotization, Addition
- Correct answerCReduction, Diazotization, Coupling
- DReduction, Coupling, Diazotization
Solution
Step 1: Nitrobenzene is converted to Aniline using $Sn/HCl$. This involves the removal of oxygen and addition of hydrogen, which is a Reduction reaction.
Step 2: Aniline reacts with $NaNO_2/HCl$ (which forms $HNO_2$ in situ) to form Benzene Diazonium Chloride. The process of conversion of a primary aromatic amine into its diazonium salt is called Diazotization.
Step 3: Benzene Diazonium Chloride reacts with another molecule of aniline in a mildly acidic medium to form $p$-amino Azobenzene. This is an electrophilic aromatic substitution where the diazonium ion acts as an electrophile. This specific type of reaction forming an azo dye is known as a Coupling reaction.
Therefore, the correct sequence of reactions is Reduction, Diazotization, Coupling.
Answer: Reduction, Diazotization, Coupling
Step 2: Aniline reacts with $NaNO_2/HCl$ (which forms $HNO_2$ in situ) to form Benzene Diazonium Chloride. The process of conversion of a primary aromatic amine into its diazonium salt is called Diazotization.
Step 3: Benzene Diazonium Chloride reacts with another molecule of aniline in a mildly acidic medium to form $p$-amino Azobenzene. This is an electrophilic aromatic substitution where the diazonium ion acts as an electrophile. This specific type of reaction forming an azo dye is known as a Coupling reaction.
Therefore, the correct sequence of reactions is Reduction, Diazotization, Coupling.
Answer: Reduction, Diazotization, Coupling
Hence, the correct answer is option: 'C'.