melamine trisulfonic acid catalyzed regioselective nitration of aromatic compounds under solvent-free conditions

a simple, mild and efficient method for the regioselective nitration of various aromatic compounds usingpoly(4-vinylpyridinium nitrate) (p4vpyn) in the presence of melamine trisulfonic acid (mtsa), is reported.this method provides several advantages such as good selectiveity between ortho and para positions ofaromatic compounds, clean procedure, simple work-up, short reaction times, solvent-free conditions andhigh yields of products. this methodology is useful for nitration of activated and deactivated aromatic rings.