Mannich reaction using acidic ionic liquids as catalysts and solvents

Several Bronsted acidic ionic liquids were synthesized and successfully used as solvents and catalysts of three-component Mannich reactions of aldehdyes, amines, and ketones at 25degreesC. The used Bronsted acidic ionic liquids include 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim](+)[HSO4](-)), 1-butyl-3-methylimidazolium dihydrogen phosphate ([Bmim](+)[H2PO4](-)), 1-methylimidazolium p-toluenesulfonic acid ([Hmim](+)Tsa(-)) and 1-methylimidazolium trifluoroacetic acid ([Hmim](+)Tfa(-)). Higher yields were obtained in the presence of [Hmim](+)Tfa(-) in comparison with other Bronsted acidic ionic liquids. The [Hmim](+)Tfa(-) was reused four times without considerable loss of activity.