Cycloaddition Reaction Of Epoxides Research Articles

A zinc porphyrin polymer as efficient bifunctional catalyst for conversion of CO2 to cyclic carbonates

AbstractThe design and synthesis of efficient heterogeneous catalysts for catalytic conversion of CO2 are an important challenge. The novel zinc porphyrin polymer reported herein, [ZnPy+CPP‐BTA]I−, is synthesized from trans‐A2B2 porphyrin precursor 5,15‐(4‐carboxyphenyl)‐10,20‐(pyridyl)‐porphyrin (PyCPP) and 1,2,4,5‐benzenetetramine tetrahydrochloride (BTA), employing a sequential post‐synthetic methylation and metalation strategy. The newly synthesized zinc porphyrin polymer was well characterized by Fourier transform infrared spectroscopy (FT‐IR), Ultraviolet–visible spectroscopy (UV–vis), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal gravimetric analysis (TGA), and X‐ray photoelectron spectroscopy (XPS). As bifunctional heterogeneous catalyst incorporated zinc porphyrin and nucleophile I−, [ZnPy+CPP‐BTA]I− shows good catalytic activity and recyclability for the cycloaddition reactions of epoxides and CO2 under lower CO2 initial pressure and cocatalyst‐free conditions.

Porous polymeric metalloporphyrin obtained through Sonogashira coupling: Catalytic performance at CO2 cycloaddition to epoxides

Using metal complexes of (5,10,15,20-tetrakis(p-bromophenyl) porphyrin) (MT4BrPP) (M ​= ​Co, Mn) and 4,4-diethynylbiphenyl as monomers, a porous polymeric metalloporphyrin [PoP(MTPP), M ​= ​Co, Mn] was successfully synthesized by Sonogashira cross-coupling reaction. Their morphology, structure and elements were characterized and analyzed by scanning electron microscopy (SEM), Fourier-Transform infrared spectroscopy (FT-IR), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TG), and brunauer-emmett-teller (BET), which indicated high specific surface area and good thermal stability. Then, using PoP(MTPP) as porous catalyst with two-dimensional structure, the cycloaddition reaction of epoxides and carbon dioxide (CO2), for reducing greenhouse gas emissions, was effectively executed without solvents, and the yield of cyclocarbonate got to 90%. In summary, a novel metalloporphyrin based porous polymers were prepared by coupling reaction, and catalytic active centers were effectively fixed in two-dimensional networks, which improved its stability and excellently enhanced their catalytic performance. It’s a competitively candidates for catalyzing the cycloaddition reaction without solvent.

Nanochannel-based {BaZn}-organic framework for catalytic activity on the cycloaddition reaction of epoxides with CO2 and deacetalization-Knoevenagel condensation.

Herein, the rare combination of BaII (5s) and ZnII (3d) in the presence of the structure-oriented TDP6- ligand generated the nanochannel-based hybrid material {[(CH3)2NH2]2[BaZn(TDP)(H2O)]·DMF·5H2O}n (NUC-51, H6TDP = 2,4,6-tri(2,4-dicarboxyphenyl)pyridine), which possesses excellent physicochemical characteristics such as nanoscopic channels, high porosity, large specific surface area, and high heat/water-resistance. To the best of our knowledge, this is the first 3D [BaIIZnII(CO2)6(H2O)]-based nano-porous host framework, whose activated state possesses the coexistence of Lewis acid-base sites including 4-coordinated Zn2+ ions, 7-coordinated Ba2+ ions, uncoordinated carboxyl oxygen atoms, and Npyridine atoms. Catalytic experiments exhibited that activated NUC-51a possesses a high catalytic activity on the cycloaddition reactions of epoxides with CO2 at 55 °C, which can be ascribed to its structural advantages of nanoscale channels and rich bifunctional active sites. Moreover, NUC-51a could significantly accelerate the deacetalization-Knoevenagel condensation reaction in DMSO solvent at 70 °C.

Nanocage-based {In2Tm2}-organic framework for efficiently catalyzing the cycloaddition reaction of CO2 with epoxides and Knoevenagel condensation

The combination of [In2Tm2(μ2-OH)2(CO2)10(H2O)2] clusters and H5BDCP ligand generated a highly robust nanoporous MOF with high catalytic performance in the cycloaddition reaction of epoxides with CO2 and Knoevenagel condensation.

Design of porous organic polymer catalysts for transformation of carbon dioxide

The transformation of carbon dioxide (CO2) into fuels and chemicals is an interesting topic, which has been paid much attention in recent years. The materials with specific functionalities are highly required for CO2 capture and conversion, which have been widely investigated. As an emerging material platform, porous organic polymers (POPs) have attracted considerable scientific interest due to their distinctive properties such as tailorable functionalization, large surface areas, adjustable porosity, versatile polymerizations, good physicochemical and thermal stability. Our group focuses on designing and synthesizing POPs via introducing CO2-philic groups and organic ligands into the skeletons of the polymers and immobilizing metal active species onto their surface, and a series of POPs with functional groups, such as azo, Tröger's base, fluorine, phenolic –OH, have been prepared for CO2 transformation. In this review article, we mainly introduce our recent work on design of POPs-based catalysts for CO2 transformation, which include POPs-based catalysts for cycloaddition reactions of epoxides and propargylic alcohols with CO2, for reductive transformation of CO2 with H2, for photocatalytic/electrocatalytic reduction of CO2. In addition, the perspectives of the POP-based catalysts for CO2 transformation will be discussed as well.

Highly Robust {Ln4}-Organic Frameworks (Ln = Ho, Yb) for Excellent Catalytic Performance on Cycloaddition Reaction of Epoxides with CO2 and Knoevenagel Condensation

Due to the high electron charge, large ion radius, and plentiful outer hybrid orbitals of LnIII cations, microporous Ln-MOFs can be used as Lewis acidic catalysts with high catalytic activity for a variety of organic reactions, which prompts us to explore cluster-based nanoporous Ln-MOFs by employing structure-oriented ligands. Herein, the exquisite combination of coplanar [Ln4(μ3–OH)2(μ2–HCO2)(H2O)2] clusters (abbreviated as {Ln4}) and the structure-oriented multifunctional ligand of 2,6-bis(2,4- dicarboxylphenyl)-4-(4-carboxylphenyl)pyridine (H5BDCP) led to two isomorphic nanoporous frameworks of {(Me2NH2)[Yb4(BDCP)2(μ3–OH)2(μ2–HCO2)(H2O)2]·5DMF·H2O}n (NUC-38Yb) and {(Me2NH2)[Ho4(BDCP)2(μ3–OH)2(μ2– HCO2)(H2O)2]·6DMF·3H2O}n (NUC-38Ho). To the best of our knowledge, NUC-38Ho and NUC-38Yb are rarely reported {Ln4}-based three-dimensional (3D) frameworks with embedded hierarchical triangular-microporous and hexagonal-nanoporous channels, which are shaped by six rows of coplanar {Ln4} clusters and characterized by plentiful coexisting Lewis acid–base sites on the inner wall including open LnIII sites, Npyridine atoms, μ3–OH, and μ2–HCO2. Catalytic experiments performed using NUC-38Yb as the representative exhibited that NUC-38Yb possessed a high catalytic activity on the cycloaddition reactions of epoxides with CO2 under mild conditions, which can be ascribed to its structural advantages including nanoscale channels, rich bifunctional active sites, large surface areas, and chemical stability. Moreover, NUC-38Yb, as a heterogeneous catalyst, could greatly accelerate the Knoevenagel condensation reactions of aldehydes and malononitrile. Hence, this work paves the way for the construction of functional Ln-cluster-based nanoporous metal–organic frameworks (MOFs) by elaborately designing functional ligands with transnormal connection modes.

Incorporation of linear poly(ionic liquid)s inside acid-base dualistic carbons for CO2 cycloaddition reaction

Boron and nitrogen co-doped carbons (BNCs) were fabricated by the activation of boric acid with waste coffee grounds. The sequential hydrothermal and pyrolysis treatments not only create the porous carbons, but also introduce B- and N-contained functional groups into the frameworks. Porous BNCs can effectively adsorb imidazolium-based ionic liquids, which then in situ polymerized in the channels of BNCs. The heterogeneous PIL@BNC composites were formed by the integration of linear poly(ionic liquid)s (PILs) and BNCs. The composites exhibited excellent catalytic performance for CO2 cycloaddition reaction of epoxide at atmospheric pressure and low temperature. The flexibility of PILs and acid-base sites of BNCs facilitate the cooperative catalysis. Meanwhile, the interactions between electron-rich BNCs and PIL cations can enhance the catalytic activity and stability. This study highlights electron-rich porous carbon is a versatile platform for linear PILs to construct multifunctional heterogeneous catalysts towards CO2 conversion.

Halogen bonding catalysis for the [3+2] cycloaddition reactions of epoxides with CO2, and other heterocumulenes

Halogen bonding catalysis was introduced into the [3+2] cycloaddition reactions of epoxides with CO2, and other heterocumulenes. Series of 2-iodoimidazolium halides, a typical halogen bond donor (XBD) featured with C–I bond, were synthesized and evaluated in the [3+2] cycloaddition reactions. An optimal XBD catalyst, 1,3-bis-(2,6-diisopropylphenyl)-2-iodoimidazolium bromide, achieved 96 %, 94 %, and 61 % conversions in the cycloadditions of epoxides with CO2, isocyanates, and CS2, respectively, under 80 °C. Arrays of epoxides were transformed into the corresponding five-membered heterocycles of cyclic carbonates, oxazolidinones, and cyclic dithiocarbonates by high yields and selectivity. 1H NMR and 13C NMR titrations of the XBD catalyst on the styrene oxide indicated that the halogen bond donor coordinated with the substrate through halogen bonding between iodine atom of C–I moiety and oxygen of the epoxide. Possible mechanism was proposed, in which halogen bond donor activated the epoxides by halogen bonding and halide counter anion attacked the carbon of methylene to facilitate the ring-opening of the epoxides. Halogen bonding catalysis was firstly extended to general [3+2] cycloaddition reactions of epoxides with CO2, isocyanates, and CS2.

Cycloaddition of carbon dioxide and epoxides catalyzed by rare earth metal complexes bearing a Trost ligand

Rare earth metal complexes containing Trost ligands were used to catalyze the cycloaddition reaction of epoxides with CO2. A series of epoxides were successfully converted into the corresponding cyclic carbonates under mild conditions.

Catalytic CO2 fixation over a high-throughput synthesized copper terephthalate metal-organic framework

In this study, a porous copper metal-organic framework with terephthalate linker, Cu(TPA), was synthesized in DMF via a high-throughput (gram quantities) solvothermal method. Cu(TPA) that arranged in the C2/m space group upon an innovative controlled thermal treatment through removing coordinated DMF molecules to the Cu(II) center provided large square pores with Lewis acidic Cu(II) sites. Upon a novel activation strategy, DMF molecules in the structure of Cu(TPA) were partially eliminated to act as polar groups to enhance the affinity of CO2 into the catalysts. The synergistic effect of Cu(II) metal center with DMF decorated pores was deliberate in the cycloaddition reaction of epoxides with CO2. The partially activated Cu(TPA), Cu(TPA)′, in treating with CO2 that coordinate to the Cu(II) centers in the two-dimensional tunnels revealed excellent heterogeneous catalytic entitativity in solvent-free conditions toward CO2 fixation to cyclic carbonates. Besides, for several cycles, the Cu(TPA) catalyst under mild conditions was simply recycled and reused with a little loss in catalytic performance.

Cycloaddition Reactions of Epoxides and CO2 by the Novel Imidazolium‐Functionalized Metalloporphyrins: Optimization and Analysis using Response Surface Methodology

AbstractThe production of cyclic carbonates using CO2 and epoxides has received great attention due to 100 % atom utilization. Herein, novel imidazolium‐containing metalloporphyrins were synthesized as bifunctional catalysts for the cycloaddition reactions of epoxides and CO2. The reaction conditions were optimized and analyzed with the response surface methodology. Under the optimum condition using Zn‐porphyrin 1 as the catalyst, the turnover number (TON) and turnover number frequency (TOF) for the cycloaddition of CO2 and ECH were 11,629 and 1,735, respectively. In addition, analysis of the RSM indicated that the CO2 pressure had only a small impact on the yield. Based on this conclusion, the catalytic activity of 1 was further evaluated under mild conditions. Regardless of whether the CO2 pressure is high or ambient, this Zn‐porphyrin exhibited an excellent performance with a high turnover number frequency.

Adenine-assisted synthesis of functionalized F-Mn-MOF-74 as an efficient catalyst with enhanced catalytic activity for the cycloaddition of carbon dioxide

The development of a highly efficient renewable heterogeneous catalysts for the synthesis of cyclic carbonates by the cyclic esterification of epoxides and carbon dioxide under relatively mild reaction conditions is of great significance in the territory of chemical fixation of carbon dioxide (CO2). This work comprises on a functional catalytic material F-Mn-MOF-74 using an effective competitive coordination strategy, adenine (Ad) as alkali source and competitive ligand, introduced onto the synthetic Mn-MOF-74. An F-Mn-MOF-74 crystal having a spherical structure and being functionalized is obtained, and lone pair of electrons on the nitrogen atom in the adenine can compete with 2,5-hydroxyterephthalic acid for coordination. The alkalinity exhibited by adenine is beneficial to enhance the catalytic properties of the crystal in the cycloaddition reaction of epoxide with carbon dioxide. Further catalytic experiments showed that the functionalized F-Mn-MOF-74 crystal combined with tetrabutylammonium bromide in the lacking of solvent showed excellent catalytic activity in the cycloaddition reaction of styrene oxide and carbon dioxide. Under the optimal reaction conditions after screening (100 °C and 10 bar CO2 pressure), the yield of cyclic carbonate was as high as 99 %. The excellent catalytic performance for other epoxides also confirmed that F-Mn-MOF-74 catalytic material is universal in its application. The catalytic performance of the catalyst was not significantly decreased after being recycled seven times, attributed to its excellent stability. The possible mechanism for the synergistic effect of Lewis acid-base properties of functionalized F-Mn-MOF-74 catalytic material with cocatalyst is also proposed.

Theoretical study on cycloaddition reaction of epoxides with CO2 catalyzed by metal-porphrin complexes: Reaction mechanisms and structure impacts on catalytic activity

The detailed reaction mechanisms for the coupling reaction of epoxides with CO2 catalyzed by metal-porphyrin complexes were investigated using density functional theory methods. A new concerted insertion process was proposed in this work and in comparison with the insertion step supported by the previous four-step mechanism. On the basis of the coupling reaction mechanisms, the potential relevance of structure and catalytic activity was also discussed. Our theoretical results show that the co-catalyst DMAP has significant effects on the free energy barriers of rate-determining steps by changing the electronic properties of metal centers, it suggested the co-catalyst could promote the catalytic activity as observed experimentally. As for the different metal centers (Co, Al, Mn), the rank of catalytic activity for metal-porphyrin catalysts was predicted to be Co > Al > Mn, which encouraged us to develop more catalytic systems with active metal center. Moreover, the electron-withdrawing substitutions in the meso-position also affect the energy barriers, the catalytic activity of metal-porphyrin catalysts were reduced along with more Br-substitutions in meso-position.

Pyridinium‐functionalized metalloporphyrins as bifunctional catalysts for cycloaddition of epoxides and carbon dioxide

New pyridinium‐functionalized metalloporphyrins MEtPpBr4 (M = Zn2+, Co2+, Ni2+, Cu2+; EtPp = 5, 10, 15, 20‐tetra(4‐(3‐(N‐ethyl‐4‐pyridyl)pyrazolyl)phenyl)porphyrin) were synthesized as bifunctional catalysts for the cycloaddition reactions of epoxides and CO2. The effects of catalyst loading, CO2 pressure, reaction temperature and time on catalytic activity were investigated. ZnEtPpBr4 (1) and CoEtPpBr4 (2) exhibited efficient activities in the cycloaddition reactions of various epoxides with CO2 as at 120 °C under 2 MPa of CO2 pressure without solvent. Most of corresponding cyclic carbonates could be obtained in almost quantitative yields and > 99.9% selectivity with molar ratio of epoxide/catalyst 2222 after 8 hr of reaction.

Cobalt-Salen-Based Porous Ionic Polymer: The Role of Valence on Cooperative Conversion of CO2 to Cyclic Carbonate.

Cobalt-salen-based porous ionic polymers, which are composed of cobalt and halogen anions decorated on the framework, effectively catalyze the CO2 cycloaddition reaction of epoxides to cyclic carbonates under ambient conditions. The cooperative effect of bifunctional active sites of cobalt as the Lewis acidic site and the halogen anion as the nucleophile responds to the high catalytic performance. Moreover, density functional theory results indicate that the cobalt valence state and the corresponding coordination group influence the rate-determining step of the CO2 cycloaddition reaction and the nucleophilicity of halogen anions.

Cycloaddition Reaction of Epoxides or Aziridines with Carbon Dioxide on Metalated Cluster Porphyrins

Key words metal–organic framework - zirconium catalysis - cobalt catalysis - cycloaddition - carbon dioxide

Modification of porous lignin with metalloporphyrin as an efficient catalyst for the synthesis of cyclic carbonates

The conversion of carbon dioxide into useful chemical raw materials is a necessary development for advancing carbon dioxide capture and storage technology. In this work, a Friedel–Crafts reaction of lignin and metalloporphyrin was used to produce a lignin-based porous organic polymer (P-(L-FeTPP)) with a surface area of up to 1153 m2 g−1. P-(L-FeTPP)) efficiently catalyzed the cycloaddition reactions of epoxides and CO2 under solvent-free conditions, with porphyrin iron acting as an active center. The product yield reached up to 99.6% after 12 h under 1 MPa CO2 and 70 °C. A turnover number of 1481 was achieved, indicating that this catalyst is much more active than its homogeneous counterpart and is one of the most efficient lignin-supported heterogeneous catalysts ever reported. This method for the in situ incorporation of a metalloporphyrin into a lignin skeleton greatly improved the stability of the metal catalyst, and P-(L-FeTPP) was readily recycled and reused more than six times without any significant loss of catalytic activity. Thus, this catalyst design is promising for practical applications, including the industrial production of cyclic carbonates.

A novel 2D Cu(II)-MOF as a heterogeneous catalyst for the cycloaddition reaction of epoxides and CO2 into cyclic carbonates

A new 2D Cu(II)-based metal-organic framework, [(Cu2BPDSDC·4DMF)·2DMF]n (namely 1), was constructed by a linker biphenyl-3,3′-disulfonyl-4,4′-dicarboxylic acid (H4BPDSDC) and Cu(II) ion with success. The resultant crystals possess two different coordination modes of Cu(II), which are further linked with carboxylic acids from H4BPDSDC to generate 1D Cu(II) chains. The obtained sample 1 has been accurately characterized and investigated in detail by single crystal X-ray diffraction, elemental analysis of C, H, and N, Fourier-transform infrared spectra (FT-IR), powder X-ray diffractions and thermogravimetric analysis. Due to lots of open Cu(II) metal sites in 1, it is able to be implemented as a heterogeneous Lewis acid catalyst for the solvent-free cycloaddition reaction of epoxides and CO2 into valued cyclic carbonates. More importantly, the resultant sample can be easily separated and reused at least four times almost without any significant activity reduction.

Synthesis of covalent organic frameworks via in situ salen skeleton formation for catalytic applications

A facile synthesis of COF-salen via in situ salen skeleton formation under air atmosphere is described herein. COF-salen–M prepared via metal ion coordination could efficiently catalyse chemical reactions, e.g. styrene epoxidation, epoxide hydration and cycloaddition reactions of epoxides with CO2. More interestingly, both cooperation and isolation effects were observed in COF-salen–M.

Atomic zinc dispersed on graphene synthesized for active CO2 fixation to cyclic carbonates.

CO2 fixation to cyclic carbonates is important but depends on the catalyst. Here, atomic zinc (1.62 at%) dispersed on graphene was synthesized as a high-performance heterocatalyst for the cycloaddition reaction of epoxides and CO2. High yield (99%) and high selectivity (98%) of propylene carbonate with a TOF of 2889 h-1 were achieved. [ZnN3.76±0.2] was the active site, which was proved by advanced characterization, including synchrotron XANES, EXAFS and XPS and comparative performance tests.