HALOGEN-FREE ROOM-TEMPERATURE BRONSTED ACIDIC IONIC LIQUID [HMIM]+ HSO4- AS A RECYCLABLE GREEN DUAL REAGENT CATALYSIS FOR THE SYNTHESIS OF TRIARYLMETHANES (TRAMS)

The halogen-free Bronsted acidic ionic liquid methylimidazolium hydrogen sulfate ([Hmim](+) HSO4-) acts as a very efficient catalyst for the one-pot, two-component Baeyer condensation of a variety of aromatic aldehydes with dimethyl or diethyl aniline at room temperature. This green'' reagent behaves as both catalyst and solvent; that is, it exhibits dual-reagent catalysis.'' The room-temperature acidic ionic liquid could be recycled several times with almost no loss in the yield of the reaction. This is the first report of the Baeyer synthesis with a halogen-free ionic liquid.