[tex]\boxed{\sf C_6H_6 \to C_6H_5NO_2 \to C_6H_5NH_2 \to C_6H_2NH_2(Br)_3}[/tex]
[tex]\sf (1)~C_6H_6 + HNO_3 \to C_6H_5NO_2 + H_2O.[/tex]
[tex]\sf (2)~C_6H_5NO_2 + 3H_2 \to C_6H_5NH_2 + 2H_2O.[/tex]
[tex]\sf (3)~C_6H_5NH_2 + 3Br_2 \to C_6H_2NH_2(Br)_3 + 3HBr.[/tex]