Q.Search the pKa or pKb values of ortho, meta and para nitroaniline on internet and arrange them in increasing order of their basic strength.

The amino group is a powerful ortho/para-directing, ring-activating group (its nitrogen lone pair donated into the ring by resonance), so aromatic amines undergo electrophilic aromatic substitution far more readily than benzene. Bromination: aniline + bromine water (room temperature) gives a white precipitate of 2,4,6-tribromoaniline directly (the powerful activation makes it hard to stop at monosubstitution). Nitration: direct nitration of aniline (conc. HNO3+H2SO4) gives a mixture (51% para, 47% meta, 2% ortho), because the strongly acidic medium protonates -NH2 to the meta-directing, deactivating -N(+)H3; to get p-nitroaniline cleanly, -NH2 is first protected by acetylation to acetanilide, then nitrated, then hydro …