Microwave-assisted one pot-synthesis of amino acid ionic liquids in water: simple catalysts for styrene carbonate synthesis under atmospheric pressure of CO2

Abstract

A novel variety of ionic liquids based on naturally occurring amino acids is expeditiously synthesized in water using microwave energy. The amino acid ionic liquids (AAILs) exhibit eminent catalytic activities towards the synthesis of styrene carbonate from styrene oxide and carbon dioxide at atmospheric pressure. The synergistic interaction of the hydrogen-bonding groups with the nucleophile in the AAIL is believed to be the key factor behind the catalytic cycloaddition. Among the various kinds of AAILs tested, the basic AAILs were found to be the most efficient owing to the presence of extra amino groups that could activate the carbon dioxide molecule by formation of a carbamate salt. The AAILs showed appreciable reusability over four cycles without compromising the selectivity towards styrene carbonate synthesis and hence represents an easily synthesizable series of eco-friendly catalysts for CO₂ fixation.