Sustainable Synthesis of Amides from Carboxylic Acids and Equivalent Amounts of Amines Using a Reusable Bronsted Acidic Ionic Liquid as a Catalyst and a Solvent

The simple and easily prepared Bronsted acidic ionic liquid (BAIL) could act as both the solvent and catalyst and could be easily recovered and reused at least six times without considerable loss in catalytic activity. Moreover, the direct amidation of carboxylic acids and amines in a stoichiometric proportion could be catalyzed efficiently by BAIL with a broad substrate scope, a multigram scale, and a significant sustainability improvement [scalable up to 100 mmol, (process mass intensity) PMI (reaction and purification) < 3]. Notably, the water formed during condensation did not inhibit the direct amidation. This protocol could be used to efficiently, greenly, and sustainably prepare amides and has broad applications in organic chemistry.

Automated summary

The study developed a simple and easily prepared Bronsted acidic ionic liquid (BAIL) that can act as both solvent and catalyst, and can be recovered and reused multiple times without significant loss of catalytic activity. The BAIL efficiently catalyzed the direct amidation of carboxylic acids and amines, with a broad substrate scope and significant sustainability.