Facile synthesis of zinc halide-based ionic liquid for efficient conversion of carbon dioxide to cyclic carbonates

Efficiency in Carbon Dioxide Fixation into Cyclic Carbonates: Operating Bifunctional Polyhydroxylated Pyridinium Organocatalysts in Segmented Flow Conditions

Novel polyhydroxylated ammonium, imidazolium, and pyridinium salt organocatalysts were prepared through N-alkylation sequences using glycidol as the key precursor. The most active pyridinium iodide catalyst effectively promoted the carbonation of a set of terminal epoxides (80 to >95% yields) at a low catalyst loading (5 mol%), ambient pressure of CO₂, and moderate temperature (75 °C) in batch operations, also demonstrating high recyclability and simple downstream separation from the reaction mixture. Moving from batch to segmented flow conditions with the operation of thermostated (75 °C) and pressurized (8.5 atm) home-made reactors significantly reduced the process time (from hours to seconds), increasing the process productivity up to 20.1 mmol_(product) h^-1 mmol_(cat)^-1, a value ~17 times higher than that in batch mode.

POSS and imidazolium-constructed ionic porous hypercrosslinked polymers with multiple active sites for synergistic catalytic CO2 transformation

In this work, we reported a facile one-pot approach to construct polyhedral oligomeric silsesquioxane (POSS) and imidazolium-based ionic porous hypercrosslinked polymers (denoted as iPHCPs) with multiple active sites towards efficient catalytic conversion of carbon dioxide (CO₂) to high value-added cyclic carbonates. The targeted iPHCPs were synthesized from a rigid molecular building block octavinylsilsesquioxane (VPOSS) and a newly-designed phenyl-based imidazolium ionic crosslinker through the AlCl₃-catalyzed Friedel-Crafts reaction. The desired multiple active sites come from the mixed anions including free Cl^- and Br^- anions, and in situ formed Lewis acidic metal-halogen complex anions [AlCl₃Br]^- within imidazolium moieties and POSS-derived Si-OH groups during the synthetic process. The typical polymer iPHCP-12 possesses a hierarchical micro-/mesoporous structure with a high surface area up to 537 m² g^-1 and shows a fluffy nano-morphology. By virtue of the co-existence of free nucleophilic Cl^- and Br^- anions, the metal complex anion [AlCl₃Br]^- with both electrophilic and nucleophilic characters and electrophilic hydrogen bond donor (HBD) Si-OH groups, iPHCP-12 is regarded as an efficient recyclable heterogeneous catalyst for synergistic catalytic conversion of CO₂ with various epoxides into cyclic carbonates under mild conditions. The present work provides a succinct one-pot strategy to construct task-specific ionic porous hypercrosslinked polymers from easily available modules for the targeted catalytic applications.

Hydroxy acid-functionalized ionic liquids as green alternatives for the efficient catalytic conversion of epoxides to cyclic carbonates under solvent and co-catalyst-free conditions

Environmentally friendly synthesis route of carbonates from CO2 and epoxides catalysed by novel hydroxy acid ionic liquids under metal/halogen/cocatalyst/solvent-free conditions.