Bifunctional Onium and Potassium Iodides as Nucleophilic Catalysts for the Solvent-Free Syntheses of Carbonates, Thiocarbonates, and Oxazolidinones from Epoxides

The catalytic potential of organo-onium iodides as nucleophilic catalysts is aptly demonstrated in the synthesis of cyclic carbonates from epoxides and carbon dioxide (CO2 ), as a representative CO2 utilization reaction. Although organo-onium iodide nucleophilic catalysts are metal-free environmentally benign catalysts, harsh reaction conditions are generally required to efficiently promote the coupling reactions of epoxides and CO2 . To solve this problem and accomplish efficient CO2 utilization reactions under mild conditions, bifunctional onium iodide nucleophilic catalysts bearing a hydrogen bond donor moiety were developed by our research group. Based on the successful bifunctional design of the onium iodide catalysts, nucleophilic catalysis using a potassium iodide (KI)-tetraethylene glycol complex was also investigated in coupling reactions of epoxides and CO2 under mild reaction conditions. These effective bifunctional onium and potassium iodide nucleophilic catalysts were applied to the solvent-free syntheses of 2-oxazolidinones and cyclic thiocarbonates from epoxides.

Selective formation of a zwitterion adduct and bicarbonate salt in the efficient CO2 fixation by N-benzyl cyclic guanidine under dry and wet conditions

The efficient CO₂ fixation by N-benzyl cyclic guanidine 1 was achieved by bubbling dry CO₂ through CH₃CN at 25 °C for 2 h. In addition, the zwitterion adduct 2 and bicarbonate salt 3 were selectively prepared from 1 under dry (in anhydrous CH₃CN) and wet (in CH₃CN containing an equimolar amount of water for 1) conditions, respectively. Both compounds 2 and 3 were isolated as white solids and their structures were characterized in detail by elemental analysis, FTIR-ATR, solid-state NMR, TGA, and DFT calculation. These analytical results obviously revealed the formation of a zwitterion adduct and bicarbonate salt from N-benzyl cyclic guanidine and CO₂. Especially, the zwitterion adduct of the monocyclic guanidine derivative and CO₂ was isolated and characterized for the first time.

Current advances in the catalytic conversion of carbon dioxide by molecular catalysts: an update

Recent advances (2015–) in the catalytic conversion of CO₂ by metal-based and metal-free systems are discussed.

Recent Developments in the Synthesis of Cyclic Carbonates from Epoxides and CO2

The use of CO₂ as a C1 building block will be of essential importance in the future. In this context the synthesis of cyclic carbonates from epoxides and CO₂ gained great attention recently. These products are valuable compounds in a variety of chemical fields. The development of new catalysts and catalytic systems for this atom-economic, scalable, and industrially relevant reaction is a highly active research field. Over the past 17 years great advances have been made in this area of research. This chapter covers the survey of the important known classes of homogeneous catalysts for the addition of CO₂ to epoxides. Besides pioneering work, recent developments and procedures that allow this transformation under mild reaction conditions (reaction temperatures of ≤100 °C and/or CO₂ pressures of 0.1 MPa) are especially emphasized.

Substituent dependence of imidazoline derivatives on the capture and release system of carbon dioxide

The imidazoline having a cyclic guanidine moiety only captured CO₂ quantitatively, and then the cyclic guanidine derivative gave the guanidinium bicarbonate by CO₂ fixation together with a slight amount of water.

Synthesis and thermal properties of vinyl copolymers with phenyl vinylethylene carbonate and N-substituted maleimides undergoing color change with acid–base switching

The solution of P(PVEC-co-NMI), having an alternating structure, was a red color in basic solvents and the solution color changed with a high sensitively to acid–base switching.

Bifunctional catalysts based on m-phenylene-bridged porphyrin dimer and trimer platforms: synthesis of cyclic carbonates from carbon dioxide and epoxides

Highly active bifunctional diporphyrin and triporphyrin catalysts were synthesized through Stille coupling reactions. As compared with a porphyrin monomer, both exhibited improved catalytic activities for the reaction of CO2 with epoxides to form cyclic carbonates, because of the multiple catalytic sites which cooperatively activate the epoxide. Catalytic activities were carefully investigated by controlling temperature, reaction time, and catalyst loading, and very high turnover number and turnover frequency were obtained: 220 000 and 46 000 h(-1) , respectively, for the magnesium catalyst, and 310 000 and 40 000 h(-1) , respectively, for the zinc catalyst. Results obtained with a zinc/free-base hybrid diporphyrin catalyst demonstrated that the Br(-) ions on the adjacent porphyrin moiety also function as nucleophiles.

Synthesis of cyclic carbonates from CO2 and epoxides using ionic liquids and related catalysts including choline chloride–metal halide mixtures

In this mini-review, progress made in the use of ionic liquid catalysts and related systems for cycloaddition reactions of carbon dioxide with epoxides is described with the primary focus on results from the past eight years.