CO₂ chemical fixation using delocalized charge amine-tethered ionic organocatalysts

Carbon dioxide (CO₂) reduction through chemical fixation has attracted great attention due to its key role in climate change. The conversion of CO₂ to the five-membered cyclic carbonates is the most practical and invaluable process, particularly when using sustainable and green methodologies. Two amine-tethered 4-dimethylamino pyridine ionic organocatalysts were prepared in two different solvents using a simple and cost-effective procedure. The mole ratio and solvent effect on the chemical structure of ionic organocatalysts were investigated. Then, the CO₂ chemical fixation was investigated by the reaction with epoxides in the presence of as-prepared ionic organocatalysts under solvent-free conditions. Moreover, the influence of the ionic organocatalyst chemical structures and reaction conditions on the cycloaddition was studied to find the practical with high efficiency of CO₂ conversion to the valuable cyclic carbonates. The optimized conditions were 80°C and 0.2 MPa to give cyclic carbonates in good to excellent yields and high selectivity. Given the high recyclability of the ionic organocatalyst, the current catalytic CO₂ chemical fixation can be a promising scale-up process.