In first step, NO2 group is electron withdrawing group, it decreases the electron density in meta position and bromination occur in meta position. In second step, Sn∕HCl used for reduction to convert −NO2 to −NH2 and form aniline. In next step, diazonium salt is formed and at last bromine replace N2+Cl−group to form 1 , 3-dibromobenzene. Complete reaction is as follows