What is the correct sequence of reagents used for converting nitrobenzene into m-dibromobenzene ?
Show Hint
Always check the directing influence of groups. Since we want a {meta} product, we must do the bromination while the meta-directing $-NO_2$ group is still present.
Step 1:Nitrobenzene has an $-NO_2$ group which is meta-directing. So, first brominate with $Br_2/Fe$ to get m-bromonitrobenzene.
Step 2: Reduce the $-NO_2$ to $-NH_2$ using $Sn/HCl$ to get m-bromoaniline.
Step 3: Convert the $-NH_2$ to a diazonium salt using $NaNO_2/HCl$.
Step 4: Replace the diazonium group with $Br$ using the Sandmeyer Reaction ($CuBr/HBr$) to get m-dibromobenzene.