A new method for the synthesis of 1-methylimidazolium
trifluoroacetate ([Hmi]Tfa), a protic ionic liquid (PIL), under
ultrasonic irradiation has been developed. In addition, the product [Hmi]Tfa
was successfully employed as solvent and catalyst in Biginelli reaction to
prepare 3,4-dihydropyrimidinones (DHPMs) in high yield under mild reaction conditions.