Quaternary ammonium salts bearing different alkyl chains and hydroxyl groups were synthesized and tested for the first time as co-catalysts in the cycloaddition reaction between CO2 and propylene oxide. Their synergetic catalytic effect together with the known tetranuclear zinc(II) complex [Zn4(μ3-OH)2 (1κO:2κO-HL)4(κO-HL)2(H2O)4] (1), H2L = 3-(2-carboxyphenyl-hydrazone)pentane-2,4-dione, was investigated at 60 °C and 4 MPa. Results obtained highlight the importance of exploring the hydrogen bonding effect via functionalization with hydroxyl groups but show that the length of the alkyl chains of the ammonium cation is a more relevant factor affecting the reaction kinetic for the system studied.
- arylhydrazones of B-diketones
- CO utilization
- ionic liquids
- organic carbonates
- propylene carbonate