Question

Write a short note on the following.

Coupling reaction

Answer 1

Benzene diazonium chloride reacts with electron-rich aromatic compounds like phenol, aniline to form brightly coloured azo compounds. Coupling generally occurs at the para position. If para position is occupied then coupling occurs at the ortho position. Coupling tendency is enhanced if an electron-donating group is present at the para-position to \[\ce{-\overset{+}{N2}Cl^-}\] group. This is an electrophilic substitution.