Poly(ethylene glycol)s as Ligands in Calcium‐Catalyzed Cyclic Carbonate Synthesis

Abstract

Herein the use of CaI in combination with poly(ethylene glycol) dimethyl ether (PEG DME 500) as an efficient catalyst system for the addition of CO to epoxides is reported. This protocol is based on a nontoxic and abundant metal in conjunction with a polymeric ligand. Fifteen terminal epoxides were converted at room temperature to give the desired products in yields up to 99 %. Notably, this system was also effective for the synthesis of twelve challenging internal carbonates in yields up to 98 %.

Synthesis of Bio‐Based Cyclic Carbonates Using a Bio‐Based Hydrogen Bond Donor: Application of Ascorbic Acid to the Cycloaddition of CO2 to Oleochemicals

“…Finally, comparison of entries 1, 2 and 13, 14 of Table shows that readily available and bio‐based ascorbic acid requires slightly higher reaction temperature, but quite lower CO 2 pressure, to produce carbonates 2 a and 2 f than a previously published single‐component organocatalyst based on a synthetic phosphonium‐functionalized phenol prepared from expensive (2‐hydroxyphenyl)diphenylphosphine and carcinogenic (GSH08) 1‐bromopropane. A drawback of the molecular catalytic systems displayed in Table , including ascorbic acid/TBAC, but with the notable exception of CaI 2 /PEG DME 500 (Table , entry 8), is the general lack of recyclability that should be addressed by the coimmobilization of both catalytic components (Lewis acidic or HBD moiety along with the nucleophilic halide) to produce heterogeneous catalysts. Until this is achieved, it is likely that the application of these catalysts will be restricted to the laboratory scale.…”

Diethylene Glycol/NaBr Catalyzed CO2 Insertion into Terminal Epoxides: From Batch to Continuous Flow

“…Both the complexing and HBD activity of polyethylene glycols are indeed widely reported. [23][24][25][26][27][28]34] Overall, Tables 1 and 2 show that an effective and robust batch synthesis of styrene carbonate was achieved. These results were further examined by assessing the performance of NaBr/DEG with respect to that of 7 other recently reported halide-based catalysts, with characteristics in terms of commercial availability and ease of handling comparable to our system.…”

“…The catalytic system was then further optimized using PEG400 dimethyl ether as a complexing agent, allowing a scaling up of the CO 2 insertion reaction starting from 10 g of reacting epoxides. [25][26][27][28][29] In the light of these results, as a part of our long standing interest in sustainable CF reactions, [30][31][32][33] we were prompted to investigate whether mixtures of organic ligands based on oligo-and poly-glycols and alkali/alkaline earth metal halides, could be used for the preparation of COCs in CF mode. This was a substantially unexplored area with major challenges associated to the control of the viscosity of the complexing agent and the design of a liquid/gas biphasic system able to ensure reactants/catalyst miscibility and suitable contact time for the process.…”

The Use of Carbon Dioxide (CO2) as a Building Block in Organic Synthesis from an Industrial Perspective

“…A broad series of substituted cyclic carbonates was also formed in moderate to good yields, from the corresponding oxiranes, whereby also different catalysts are applied (see Table , entries 1–4) . But in all these cases, first the reactive oxiranes must be produced, in order to utilize CO 2 as the building block.…”