Ethylammonium nitrate (EAN)/Tf_2O and EAN/TFAA: Ionic liquid based systems for aromatic nitration

摘要

Acting as in situ sources of triflyl nitrate (TfONO_2) and trifluoroacetyl nitrate (CF_3COONO_2), the EAN/Tf _2O and EAN/TFAA systems, generated via metathesis in the readily available ethylammonium nitrate (EAN) ionic liquid as solvent, are powerful electrophilic nitrating reagents for a wide variety of aromatic and heteroaromatic compounds. Comparative nitration experiments indicate that EAN/Tf_2O is superior to EAN/TFAA for nitration of strongly deactivated systems. Both systems exhibit low substrate selectivity (K _T/K_B = 5-10) in (Figure presented) between values reported for covalent nitrates and preformed nitronium salts.