Efficiency in Carbon Dioxide Fixation into Cyclic Carbonates: Operating Bifunctional Polyhydroxylated Pyridinium Organocatalysts in Segmented Flow Conditions
Lorenzo Poletti,
Caterina Rovegno,
Graziano Di Carmine,
Filippo Vacchi,
Daniele Ragno,
Arianna Brandolese,
Alessandro Massi,
Paolo Dambruoso
Affiliations
Lorenzo Poletti
Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy
Caterina Rovegno
Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy
Graziano Di Carmine
Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy
Filippo Vacchi
Institute for Organic Synthesis and Photoreactivity of the Italian National Research Council, CNR Area della Ricerca di Bologna, Via P. Gobetti 101, 40129 Bologna, Italy
Daniele Ragno
Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy
Arianna Brandolese
Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy
Alessandro Massi
Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy
Paolo Dambruoso
Institute for Organic Synthesis and Photoreactivity of the Italian National Research Council, CNR Area della Ricerca di Bologna, Via P. Gobetti 101, 40129 Bologna, Italy
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.
