Mannich reaction using acidic ionic liquids as catalysts and solventsElectronic supplementary information (ESI) available: spectral data for the Mannich products, IR spectrum of the acidic ionic liquids. See http://www.rsc.org/suppdata/gc/b3/b309700p/

Abstract

Several Brønsted acidic ionic liquids were synthesized and successfully used as solvents and catalysts of three-component Mannich reactions of aldehdyes, amines, and ketones at 25 °C. The used Brønsted acidic ionic liquids include l-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]+[HSO4]−), l-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 Brønsted acidic ionic liquids. The [Hmim]+Tfa− was reused four times without considerable loss of activity.