Combining bio- and chemo-catalysis for cyclic carbonate synthesis at very low pressure: Efficient “online” utilization of CO2 obtained directly from the fermentation of sugars

Binary and Halide-free Catalyst Systems Based on Al/Ga/In Aminopyridylbisphenolate Complexes for the Cycloaddition of Epoxides and CO2

“…Initially, all six of the available compounds were studied at 8.0 bar of CO 2 pressure, 0.25 mol % of catalyst, and 1.25 mol % of TBAI, at room temperature. We chose a molar ratio of 1:5 (catalyst/cocatalyst) as this has previously been found to be optimal with the gallium aminotrisphenolate catalysts . It was found that both aluminum complexes (Cl and Br) provided very similar results, 13 and 14%, respectively (Table , entries 1 and 2).…”

“…With the experimental results in hand, we turned to DFT calculations to elucidate the underlying operative mechanisms in order to understand the distinct activities shown by the gallium and indium catalysts ( GaL-I vs InL-Cl ). Given the similarities to the aminotrisphenolate catalysts previously studied, we expected to be able to directly translate the mechanism to this new binary catalyst system, and in part, this was the case.…”

“…Within these examples, in 2013, Kleij and co-workers reported on a highly active aluminum aminotrisphenolate binary catalysts system (catalyst/ tetra -butylammonium halide) (Figure a) . More recently, in 2021, Whiteoak and co-workers further advanced the field reporting on the first highly active gallium-based binary catalyst system for the synthesis of cyclic carbonates from CO 2 and epoxides (Figure b). , Notably, this catalyst was found in general to be more active than its aluminum congener. With an interest in exploiting the potential catalytic properties of the heavier group 13 elements for the cycloaddition reaction, the same authors explored a range of group 13 complexes bearing a salphen ligand (Figure c) .…”

“…(a,b) Examples of group 13 aminotrisphenolate complexes which have been shown to be active for the cycloaddition reaction. , (c) A recent report comparing the activities of the catalysts based on the heavier group 13 elements against those of aluminum . (d) Examples of aminopyridylbisphenolate complexes which have been successfully applied for cycloaddition/copolymerization of CO 2 and epoxides. − (e) An overview of the work described in this study.…”