Cycloadditions to Epoxides Catalyzed by Group III–V Transition‐Metal Complexes

et al. 2018

Greenhouse Gases

Cyclic carbonates were synthesized via the coupling reaction of CO2 with epoxides at ambient pressure. The reaction of atmospheric pressure CO2 with styrene oxide (SO) was selected as the model reaction. The coupling reaction was investigated by varying a simple catalytic system composed of Lewis acid and quaternary ammonium salt, molar ratio of catalyst to substrate, solvent, and temperature. The yield of styrene carbonate (SC) reached 91.5% in the presence of ZnBr2/Bu4NBr at p(CO2)° = 0.1 MPa and 100°C for 4 h. The coupling reactions between CO2 and a series of substrates including aliphatic and aromatic epoxides were also performed efficiently. Yields of cyclic carbonates in the range of 76.4–93.2% were achieved. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

Section: Introductionmentioning

confidence: 99%

Synthesis of cyclic carbonate via the coupling reaction of carbon dioxide with epoxide at ambient pressure

Fan

et al. 2018

Greenhouse Gases

“…The transition metal complex catalysts, which exhibit high activity and stability, have been given intensive attention. Moreover, the catalytic activity of transition metal complex can be electronically and sterically modulated by developing novel ligand design and altering metal center and its valence state …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insights into Cycloaddition of CO₂ with Epoxide Catalyzed by a Bimetallic (Salen)Fe(II)Cl₂ Complex with/without a Cocatalyst

Guo

2020

ChemistrySelect

The cycloaddition of carbon dioxide (CO2) with propylene oxide (PO), with bimetallic (salen)Fe(II)Cl2 complex as the catalyst, was studied by using BP86/TZVP method. The calculated results revealed that the catalytic process exhibited a bimetallic cooperative mechanism, and a synergetic effect was observed between one Fe center and the axial ligand of chloride anion in the PO ring‐opening. The axial ligand of chloride anion acted as a cocatalyst. Moreover, a cocatalyst, i. e., NBu4Cl, has been introduced to the catalytic process. The catalytic process proceeded according to a monometallic mechanism, and chloride anion from NBu4Cl acted as a nucleophile in the PO ring‐opening. In addition, the energetic span model was applied to evaluate the catalytic efficiency of both catalytic systems. This current study provided novel insights into the molecular behavior of transition metal catalysts for the cycloaddition of CO2 with epoxides.

“…In this work, three metal complexes based on 2,6-bis[1-(phenylimino)ethyl] pyridine ( L ), namely [Cu L Cl 2 ] ( 1 ), [Cr L Cl 3 ] ( 2 ), and [Mn L Cl 2 ]·0.5(CH 3 CN) ( 3 ) were constructed, and were investigated in terms of their activity in catalyzing the cycloaddition reaction between propylene oxide and carbon dioxide (Scheme 1) [26,27,28], in the presence of co-catalyst. Furthermore, the relationship between the molecular structures and catalysis performance was analyzed based on experiment and density functional theory (DFT) calculation, and a reaction mechanism is proposed.…”

Section: Introductionmentioning

confidence: 99%

New Coordination Complexes Based on the 2,6-bis[1-(Phenylimino)ethyl] Pyridine Ligand: Effective Catalysts for the Synthesis of Propylene Carbonates from Carbon Dioxide and Epoxides

Liu

et al. 2018

Molecules

We aimed to develop new effective catalysts for the synthesis of propylene carbonate from propylene oxide and carbon dioxide. A kind of Mx+LClx coordination complex was fabricated based on the chelating tridentate ligand 2,6-bis[1-(phenylimino)ethyl] pyridine (L). The obtained products were characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. It was found that the catalytic activity of the complexes with different metal ions, the same ligand differed and co-catalyst, where the order of greatest to least catalytic activity was 2 > 3 > 1. The catalytic system composed of complex 2 and DMAP proved to have the better catalytic performance. The yields for complex 2 systems was 86.7% under the reaction conditions of 100 °C, 2.5 MPa, and 4 h. The TOF was 1026 h−1 under the reaction conditions of 200 °C, 2.5 MPa, and 1 h. We also explored the influence of time, pressure, temperature, and reaction substrate concentration on the catalytic reactions. A hypothetical catalytic reaction mechanism is proposed based on density functional theory (DFT) calculations and the catalytic reaction results.