Question

Which of the following reactions will not give p-amino azobenzene?

• A. 2 only
• B. 1 and 2
• C. 3 only
• D. 1 only

Answer 1

The correct option is A

2 only

Explanation for the correct option:

Option (a):

• The product p-amino azobenzene is formed by the coupling reaction of aniline with the diazonium salt.
• Benzene diazonium chloride reacts with aniline in which the aniline molecule at its para-position is coupled with the diazonium salt to form p-amino azobenzene. This process is called a coupling reaction.
• Among the given options, only (2) does not undergo a coupling reaction.
• 
• Nitrobenzene does not react with any of the given reactants.

Explanation for the incorrect options:

Option (b):

• 
• (1): Nitro benzene reacts with tin and hydrochloride and gets reduced to aniline. Aniline with nitrous acid forms diazonium salt followed by a coupling reaction to give p-amino azobenzene.
• (2): It does not undergo a coupling reaction.
• Since (1) is undergoing the reaction, this is not the correct option.

Option (c):

• 
• (3): Aniline with nitrous acid forms diazonium salt followed by a coupling reaction to give p-amino azobenzene.
• Since (3) undergo the reaction, this is not the correct option.

Option (d):

• (1) undergoes the coupling reaction as already seen. So, this is not the correct option.

Final answer:

Hence, option (a) is the correct answer.