OK, Let's isolate 4-bromoaniline* from the solution which contains it.
An acidic aqueous solution contains the salt* of 4-bromoaniline, 4-bromoanilinium chloride*.
You want to change 4-bromoaniline hydrochloride (salt of an organic base*) to the water-insoluble 4-bromoaniline (organic base) by converting the salt to a non-protonated* form.
Which solution will you add?
Organic Web Chem University of Alberta