Which of the following compound will not undergo Azo coupling coupling reaction?

Nitrobenzene

The correct answer is option 4. Nitrobenzene.

The compound that will not undergo the azo coupling reaction with benzene diazonium chloride is Nitrobenzene.

The azo coupling reaction involves the electrophilic attack of the benzene diazonium cation \((Ar^−N_2^+)\) on a nucleophilic aromatic ring.

Compounds containing electron-donating groups, like \(−NH_2\) (aniline), \(−OH\) (phenol), and \(−OCH_3\) (anisole), activate the aromatic ring towards electrophilic attack and readily participate in the reaction.

Nitrobenzene, however, contains a nitro group \((−NO_2)\), which is a strong electron-withdrawing group. It deactivates the aromatic ring by pulling electron density away from the ring system, making it less susceptible to electrophilic attack by the diazonium cation.

Therefore, nitrobenzene does not undergo the azo coupling reaction due to its electron-withdrawing nitro group.

In summary, the presence of electron-donating groups facilitates the azo coupling reaction, while electron-withdrawing groups hinder it. This explains why nitrobenzene is the only option that would not react with benzene diazonium chloride in this case.