Question

how to convert p- toluidine into m- bromotoluene

Answer 1

Toluene + HNO₃/H₂SO₄ --> p-nitrotoluene (para directed nitration) 

p-nitrotoluene + Zn/HCl --> p-aminotoluene (changing NO₂ to NH₂ by reduction) 

p-aminotoluene +Br₂ --> bromination ortho to NH₂.

Remove NH₂ via diazonium salt and decomposition with 1) HONO (which is NaNO₂+HCl), 2) H₃PO₂ for the final product.