Highly Active Aluminium Catalysts for the Formation of Organic Carbonates from CO2 and Oxiranes

Abstract

AlIII complexes of amino- tris-phenolate ligand scaffolds have been prepared in order to attain highly Lewis acidic catalysts. Combination of the aforementioned systems with ammonium halides provides highly active catalysts for the synthesis of organic carbonates through addition of carbon dioxide to oxiranes with initial turnover frequencies among the highest reported to date within the context of cyclic carbonate formation. Density functional theory (DFT) studies combined with kinetic data provides a rational for the relative high activity found for these AlIII complexes, and data are consistent with a monometallic mechanism. The activity and versatility of these AlIII complexes has also been evaluated against some state-of-the-art catalysts and the combined results compare favorably in terms of catalyst construction, stability, activity and applicability.