Intermolecular proton transfer in cyclic carbonate synthesis from epoxide and carbon dioxide catalyzed by azaphosphatranes: a DFT mechanistic study

Zhang, Zhiqiang; Xu, Liancai; Feng, Wenkai

doi:10.1039/c4ra11081a

Cited by 24 publications

(21 citation statements)

References 44 publications

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“…So, the effect of substitution on the aromatic rings of complexes was investigated. 10 The experimental results in Table 4 showed that although this series of catalysts had good catalytic performance under optimal conditions (110 o C, 5 h, 2 MPa), the catalytic activity of these catalysts exhibited some difference for different substitutions. Ko's and present works proved that zinc complexes with phenoxide ligands possessed excellent catalytic performance for the coupling reaction of CO 2 and epoxide.…”

Section: Complexesmentioning

confidence: 95%

“…The catalyst was applicable to a variety of terminal epoxides to produce the corresponding cyclic carbonates with 10 excellent yields, with the exception of isobutylene oxide (entry 5) and cyclohexene oxide (entry 6), which was probably due to their higher steric hindrance. 66,67 This steric effect was more likely to hinder the nucleophilic attack of the epoxide rather than its coordination to the Lewis acid metal centre.…”

Section: 9mentioning

confidence: 99%

“…44 A mixture of salicylaldehyde or corresponding salicylaldehyde derivatives (9.51 mmol), benzil 10 (9.51 mmol), and ammonium acetate (20 equivalent) were refluxed for 2 h in glacial acetic acid (30 mL …”

Section: Synthesis Of Ligands L 1 -Lmentioning

confidence: 99%

“…The catalysts were successively charged into the reactor without using any additional solvent. The reactor vessel was sealed and immersed into a oil 10 bath at the desired temperature under stirring. Then, the CO 2 was pressurized into the reactor to the given pressure and the reaction started.…”

Section: 4mentioning

confidence: 99%

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Metal complexes bearing 2-(imidazol-2-yl)phenol ligands: synthesis, characterization and catalytic performance in the fixation of carbon dioxide with epoxides

2015

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A series of metal complexes bearing 2-(imidazol-2-yl)phenol ligands (Zn, Cu, Ni, Co, Pb) were synthesized and their structures were characterized by IR, NMR, elemental analysis and X-ray. The catalytical activities of all complexes for the coupling reaction of CO 2 and epoxide were then detected. The activity influence factors, such as temperature, time, pressure, substituents of ligands and metal 10 centre, were systematically investigated. All these complexes were efficient to catalyze the coupling of CO 2 and epoxide to generate cyclic carbonate in perfect yields (>90%) and selectivities (>99%) under optimized conditions of (2 MPa, 5 h, 110 °C) without any organic solvents. A 99.7% yield and >99% selectivity for propylene carbonate (PC) were obtained with C 7 /n-Bu 4 NI as catalyst system under the optimized conditions. The catalysts were also proved to be applicable to other terminal epoxides. It is 15 worthy noted that the Pb(II) complex was firstly used to catalyze the coupling reaction of epoxides with carbon dioxide. Moreover, these metal catalysts were recyclable with only minor losses in catalytic activity after simple separation. Finally, a plausible mechanism was given. 65 were distilled from CaH 2 .NMR spectra were recorded on a Bruker Al-400 MHz instrument using TMS as an internal standard. IR spectra were recorded on a Perkin-Elmer 2000 FT-IR spectrometer. Elemental analysis was conducted on a PE 2400 series II CHNS/O 70 elemental analyzer. Melting point was obtained from X-4-type digital micro-melting point apparatus. X-ray diffraction studies 65 each cycle, the catalyst C 1 could be easily separated from the product by the addition of ethanol, subsequent filtration and then used for the next run directly. The results in Fig. 5 exhibited that the catalyst C 1 could be reusable for at least 5 times without significant loss of activity, while the selectivity of the product 70 remained the same.

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Section: Complexesmentioning

confidence: 95%

Section: 9mentioning

confidence: 99%

Section: Synthesis Of Ligands L 1 -Lmentioning

confidence: 99%

Section: 4mentioning

confidence: 99%

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Metal complexes bearing 2-(imidazol-2-yl)phenol ligands: synthesis, characterization and catalytic performance in the fixation of carbon dioxide with epoxides

2015

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“…Therefore, appropriate catalysts are required to carry out CO 2 conversion reaction at relatively mild temperature and pressure conditions. Thus, a wide array of catalysts, such as metal oxides, alkali halides, ionic liquids, quaternary ammonium salts, organocatalysts, metal–organic frameworks, and transition metal complexes, [11] has been developed. The transition metal complex catalysts, which exhibit high activity and stability, have been given intensive attention.…”

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

Wang

Guo

2020

ChemistrySelect

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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.

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Coupling Reactions of Alkynyl Indoles and CO₂ by Bicyclic Guanidine: Origin of Catalytic Activity?

Kee

Peh

Wong

2017

Chemistry An Asian Journal

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Density functional theory calculations were used to investigate the three possible modes of activation for the coupling of CO with alkynyl indoles in the presence of a guanidine base. The first of these mechanisms, involving electrophilic activation, was originally proposed by Skrydstrup et al. (Angew. Chem. Int. Ed. 2015, 54, 6682). The second mechanism involves the nucleophilic activation of CO . Both of these electrophilic and nucleophilic activation processes involve the formation of a guanidine-CO zwitterion adduct. We have proposed a third mechanism involving the bifunctional activation of the bicyclic guanidine catalyst, allowing for the simultaneous activation of the indole and CO by the catalyst. We demonstrated that a second molecule of catalyst is required to facilitate the final cyclization step. Based on the calculated turnover frequencies, our newly proposed bifunctional activation mechanism is the most plausible pathway for this reaction under these experimental conditions. Furthermore, we have shown that this bifunctional mode of activation is consistent with the experimental results. Thus, this guanidine-catalyzed reaction favors a specific-base catalyzed mechanism rather than the CO activation mechanism. We therefore believe that this bifunctional mechanism for the activation of bicyclic guanidine is typical of most CO coupling reactions.

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Intermolecular proton transfer in cyclic carbonate synthesis from epoxide and carbon dioxide catalyzed by azaphosphatranes: a DFT mechanistic study

Abstract: The activity of azaphosphatranes, novel types of non-metal and solvent-free catalysts for the synthesis of cyclic carbonates from epoxides and CO2, is unraveled by DFT calculations.

Cited by 24 publications

References 44 publications

Metal complexes bearing 2-(imidazol-2-yl)phenol ligands: synthesis, characterization and catalytic performance in the fixation of carbon dioxide with epoxides

Metal complexes bearing 2-(imidazol-2-yl)phenol ligands: synthesis, characterization and catalytic performance in the fixation of carbon dioxide with epoxides

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

Coupling Reactions of Alkynyl Indoles and CO₂ by Bicyclic Guanidine: Origin of Catalytic Activity?

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Intermolecular proton transfer in cyclic carbonate synthesis from epoxide and carbon dioxide catalyzed by azaphosphatranes: a DFT mechanistic study

Abstract: The activity of azaphosphatranes, novel types of non-metal and solvent-free catalysts for the synthesis of cyclic carbonates from epoxides and CO2, is unraveled by DFT calculations.

Cited by 24 publications

References 44 publications

Metal complexes bearing 2-(imidazol-2-yl)phenol ligands: synthesis, characterization and catalytic performance in the fixation of carbon dioxide with epoxides

Metal complexes bearing 2-(imidazol-2-yl)phenol ligands: synthesis, characterization and catalytic performance in the fixation of carbon dioxide with epoxides

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

Coupling Reactions of Alkynyl Indoles and CO2 by Bicyclic Guanidine: Origin of Catalytic Activity?

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

Coupling Reactions of Alkynyl Indoles and CO₂ by Bicyclic Guanidine: Origin of Catalytic Activity?