Chemical fixation of CO2 to cyclic carbonates using Al(III) β-aminoalcohol based efficient catalysts: An experimental and computational studies

• Al(III) β-aminoalcohol based complexes as active catalysts.
• Cycloaddition reaction of CO2 and epoxides to give commercially important cyclic carbonates.
• With the help of DFT calculations the role of co-catalyst was established.

A series of Al(III) unsymmetrical β-aminoalcohol based complexes 1–6 were synthesized via metalation of the corresponding ligands 1′–6′ those were prepared by the reaction of benzylamine with readily available epoxides viz., styrene oxide, 1,2-epoxy-3-phenoxypropane, 4-tertbutylphenyl glycidyl ether, 4-chlorophenyl glycidyl ether, glycidyl 2-methylphenyl ether and 1,2-epoxyhexane. Among these complexes, the complex 2 was found to be most effective in the cycloaddition of aryloxy/aliphatic terminal epoxides with CO2 under atmospheric pressure to get corresponding cyclic carbonates with high conversion and selectivity (up to >99%) in the presence of tetrabutylammonium bromide as a co-catalyst. The DFT calculations revealed the important role played by counter-ion in the co-catalyst during cycloaddition reaction of CO2 with the substituted epoxides.

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