Combining amino acids and carbohydrates into readily biodegradable, task specific ionic liquids

Abstract

The growing interest in the application of ionic liquids (ILs) with simultaneous sustainability draws attention to their environmental impact in general and their biodegradability in particular. Considering this, we designed a series of novel bio-ionic liquids based on natural, abundant compounds: a carbohydrate [Carb], as the cation, and amino acids [AA], as the anions; these ILs can serve as viable alternatives to the well-known and utile cholinium AAILs. Several [Carb][AA] ILs were characterized by ¹H and ¹³C NMR, mass spectrometry, thermogravimetry (TGA) and differential scanning calorimetry (DSC). The biodegradability properties of the [Carb][AA] ILs were elucidated as well and showed biodegradation readily occurred, decomposing within 5–6 days. These novel materials were successfully utilized as catalysts for the Knoevenagel condensation reaction, where conversion values of 67–94% were achieved under exceptionally mild conditions using water as the solvent and reaction times as short as 15 minutes. These sugar based ILs were easily separated and recycled.