Non-hygroscopic polystyrene-supported chloroaluminate ionic liquid was prepared from the reaction of Merrifield resin with pyridine followed by reaction with aluminium chloride. This Lewis acidic ionic liquid is an environmentally friendly heterogeneous catalyst for the Knoevenagel condensation of aromatic and aliphatic aldehydes with ethyl cyanoacetate. The catalyst is stable (as a bench top catalyst) and can be easily recovered and reused without appreciable change in its efficiency.

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Polystyrene-supported pyridinium chloroaluminate ionic liquid was prepared from the reaction of Merrifield resin with pyridine followed by reaction with aluminium chloride. This catalyst was used as a new chemoselective Lewis acid catalyst for the exclusive synthesis of 2-substituted benzimidazoles from the reaction of aldehydes with o-phenylenediamines. The catalyst is stable (as a bench top catalyst) and can be easily recovered and reused without appreciable change in its efficiency

The catalyst is synthesized from commercially available Merrifield resin, pyridine and AlCl3 and successfully applied in the Knoevenagel condensation of aromatic and aliphatic aldehydes with ethyl cyanoacetate (I) as well as in the Michael reaction of hydroxycoumarin (X) with benzaldehyde.