Which of the following compound will not undergo azo coupling reaction with benzene diazonium chloride?
1. Aniline
2. Phenol
3. Anisole
4. Nitrobenzene
Hint: Electron withdrawing group containing benzene is the poor substrate.
In an azo coupling reaction, the benzene diazonium salt acts as an electrophile and another reactant is acts as a nucleophile. If the benzene ring contains an electron-donating group is a better nucleophile than the benzene ring containing the electron-withdrawing group. Thus, Nitrobenzene is a poor substrate for the azo coupling reaction.
Hint: Benzene ring containing electron withdrawing group doesnot underogo azo coupling reaction
Nitrobenzene will not undergo azo coupling reaction with benzene diazonium chloride while the other three undergo diazo coupling reaction very easily. Diazonium cation is weak and hence reacts with electron-rich compounds containing electron-donating groups i.e., —OH, —NH2, and —OCH3 groups, and not with compounds containing electron-withdrawing group, i.e., NO2, etc.
