Each of the following reactions has been carried out under conditions such that disubstitution or trisubstitution occurred. Identify the principal organic product in each case.
(a) Nitration of p-chlorobenzoic acid (dinitration)
(b) Bromination of aniline (tribromination)
(c) Bromination of o-aminoacetophenone (dibromination)
(d) Nitration of benzoic acid (dinitration)
(e) Bromination of p-nitrophenol (dibromination)
(f ) Reaction of biphenyl with tert-butyl chloride and iron(III) chloride (dialkylation)
(g) Sulfonation of phenol (disulfonation)