Facile esterification of carboxylic acid using amide functionalized benzimidazolium dicationic ionic liquids

• Amide functionalized dicationic benzimidazolium based ionic liquids were synthesized.
• Their efficacy as catalysts for esterification has been demonstrated.
• Catalytic activity attributed to the amide functionality of ILs via hydrogen bonding.
• Catalysts were recyclable for seven runs without significant loss in activity.

Herein, we report the synthesis of a new series of amide functionalized dicationic benzimidazolium based ionic liquids (DBimILs) and appraised their efficacy towards perceptive esterification of carboxylic acids with alkyl/allyl/aryl halides in presence of triethylamine. The amide groups present in this new series of DBimILs are expected to form hydrogen bonding with the carboxylic acids and this could facilitate the esterification reactions under mild conditions devoid of any added catalyst or organic solvent. The plausible mechanism for the enhanced catalytic activity in presence of this new series of ILs has been proposed. The corresponding alkyl/allyl/aryl esters isolated from this reaction were of high purity after simple extraction, which wipe out the necessity for further purification. This protocol addresses clean methodology and the efficient recyclability as well as reusability of the catalyst.

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