Synthesis Of Cyclic Carbonates Research Articles

A Novel POP-Ni Catalyst Derived from PBTP for Ambient Fixation of CO2 into Cyclic Carbonates.

The immobilization of homogeneous catalysts has always been a hot issue in the field of catalysis. In this paper, in an attempt to immobilize the homogeneous [Ni(Me6Tren)X]X (X = I, Br, Cl)-type catalyst with porous organic polymer (POP), the heterogeneous catalyst PBTP-Me6Tren(Ni) (POP-Ni) was designed and constructed by quaternization of the porous bromomethyl benzene polymer (PBTP) with tri[2-(dimethylamino)ethyl]amine (Me6Tren) followed by coordination of the Ni(II) Lewis acidic center. Evaluation of the performance of the POP-Ni catalyst found it was able to catalyze the CO2 cycloaddition with epichlorohydrin in N,N-dimethylformamide (DMF), affording 97.5% yield with 99% selectivity of chloropropylene carbonate under ambient conditions (80 °C, CO2 balloon). The excellent catalytic performance of POP-Ni could be attributed to its porous properties, the intramolecular synergy between Lewis acid Ni(II) and nucleophilic Br anion, and the efficient adsorption of CO2 by the multiamines Me6Tren. In addition, POP-Ni can be conveniently recovered through simple centrifugation, and up to 91.8% yield can be obtained on the sixth run. This research provided a facile approach to multifunctional POP-supported Ni(II) catalysts and may find promising application for sustainable and green synthesis of cyclic carbonates.

Well-dispersed Mn/g-C3N4 as bifunctional catalysts for selective epoxidation of olefins and carbon dioxide cycloaddition

Epoxidation is an important chemical process for the production of epoxides, key building blocks in chemical industry. Despite great efforts being made to facilitate this process, it remains a significant challenge to develop cost-effective, environmental-friendly, and selective catalysts. Herein, we reported a highly dispersed Mn supported by g-C3N4 (Mn/g-C3N4) with Mn loading up to 2.56 wt%. The Mn/g-C3N4 exhibited satisfied catalytic performance for olefin epoxidation with excellent conversion (91%), high selectivity (93%) as well as outstanding recycling stability. Further analysis revealed the importance of Mn-N structure for the generation of active oxo-containing species and subsequent oxygen atom transfer. Besides, an efficient synthesis of cyclic carbonates from styrene epoxide and CO2 has been achieved (88% conversion, 89% selectivity) based on the polar Mn-N coordinated characteristics of Mn/g-C3N4 catalyst.

Tunable and functional phosphonium-based deep eutectic solvents for synthesizing of cyclic carbonates from CO2 and epoxides under mild conditions

Carbon dioxide (CO2) conversion into carbonates is one of the important ways to reduce carbon emissions. In this study, several phosphonium-based functional deep eutectic solvents (DESs) were prepared as catalysts for the synthesis of cyclic carbonates under mild conditions. The research showed that under mild conditions (60 °C, 0.8 MPa, 4 h, and 3.5 mol% catalyst loading), 1-ethylamine-3-butylphosphine bromide−diethylene glycol ([P4,4,4,2NH2][Br]-DEG) DES catalyst can achieve 96% propylene carbonate (PC) yield. In addition, the DES catalyst can be recovered by simple solvent extraction, and the PC yield does not decrease significantly after five cycles. Finally, in situ FT-IR and density functional theory (DFT) were used to provide a potential reaction mechanism for the cycloaddition reaction. Mechanism studies show that synergistic catalysis between quaternary phosphine ionic liquids (ILs) and ethylene glycol (EG)/DEG promotes CO2 conversion to cyclic carbonate.

Synthesis of Cyclic Carbonates from Epoxides Using Silica-Supported Salophens and Salens

Synthesis of Cyclic Carbonates from Epoxides Using Silica-Supported Salophens and Salens

Dihydroxybenzene‐derived ILs as Halide‐Free, Single‐component Organocatalysts for CO2 Insertion Reactions

AbstractA series of dihydroxybenzene‐derived ILs was synthesised via a halide‐free, eco‐friendly methodology and fully characterized. Their activity as single component catalyst towards synthesis of cyclic organic carbonates (COCs) via CO2 insertion into terminal epoxides was evaluated, observing that methyltrioctylammonium hydroquinolate, [N1888][HYD], was the most active catalyst in the proposed optimized conditions ([N1888][HYD] 10 % mol, T=120 °C, t=6 h, p0(CO2)=2.0 MPa, 12 examples, conversion >99 %, yield up to 98 %). Interestingly, [N1888][HYD] was also an active catalyst for CO2 insertion reactions with cyclohexene oxide (CHO), observing formation of both the COC and polycarbonate product. It is proposed that for p0(CO2)≥1.0 MPa, the catalytically active species is the hemicarbonate derivative of the hydroquinolate anion, active towards epoxide ring opening via an unusual hemicarbonate‐alkoxide pathway.

Exploring the potential of nanosized oxides of zinc and tin as recyclable catalytic components for the synthesis of cyclic organic carbonates under atmospheric CO2 pressure

Nanomaterials based on tin (IV) oxide (SnO2) and zinc oxide (ZnO) were investigated in the search for active, environmentally benign, and inexpensive materials for the crucial reaction of CO2 cycloaddition to epoxides to afford cyclic carbonates. In particular, nanoparticles (NPs), nanorods (NRs), nanosheets (NSs) and microplates (µPLs) were prepared and used in combination with small amounts of TBAI (tetrabutylammonium iodide) as the nucleophile. Different from the general case of metal oxides, often requiring harsh reaction conditions, the most active compound in this study, SnO2-NPs, served as an active material for the cycloaddition of CO2 to several terminal epoxides under atmospheric pressure at moderate temperatures (60–80 °C) and could also be employed for converting internal epoxides under harsher conditions. Importantly, SnO2-NPs could also be used in the presence of impure CO2 feeds (20% methane in CO2) resembling low calorific landfill gas and could be recycled and reused. Overall, SnO2-NPs represent a promising, readily available, and inexpensive metal oxide-based material to produce cyclic carbonates under atmospheric CO2 pressure.

Environmentally sustainable synthesis of cyclic carbonates from epoxides and CO2 promoted by MCM-41 supported dual imidazolium ionic liquids catalysts

Abstract A type of MCM-41 supported dual imidazolium ionic liquids have been synthesized and efficiently used as catalysts in the sustainable chemical conversion of CO2 and epoxides into cyclic carbonates. It was shown that the highest efficiency was achieved in the cycloaddition of a variety of epoxides and CO2 in the presence of the MCM-41@DILSCN solid catalyst under mild conditions. More interestingly, the catalyst was stable, very active, robust, and displayed good recyclability without significant loss of catalytic activity after six consecutive cycles during the process. Overall, the present protocol of synthesizing cyclic carbonates under solvent free conditions using MCM-41@DILSCN is promising for industrial applications.

Facile integration of hydroxyl ionic liquid into Cr-MIL-101 as multifunctional heterogeneous catalyst for promoting the efficiency of CO2 conversion

Rational integration of functional ionic liquids (ILs) into metal-organic frameworks (MOFs) is an intriguing and challenging strategy for design of fully heterogeneous catalytic systems for the synthesis of cyclic carbonates from cycloaddition of CO2 and epoxides. This study demonstrates a facile and versatile post-synthetic modification approach for incorporating hydroxyl-functionalized imidazolium IL into Cr-MIL-101 (HImBr@Cr-MIL-101) via coordinative bonding interaction between Cr CUS (coordinative unsaturated metal sites) in MOF and electron-rich –SH group in IL. The resultant HImBr@Cr-MIL-101 possesses high surface area, profitable porosity and good CO2 adsorption capacity, rendering it as an efficient heterogeneous catalyst for the cycloaddition reaction under co-catalyst and solvent free conditions. Compared to either pure Cr-MIL-101 or hydroxyl IL, HImBr@Cr-MIL-101 shows largely enhanced catalytic activity, attributing to the synergistic effect of the integrated multiple active sites, involving Cr CUS as Lewis acid, hydroxyl group as hydrogen bond donor, and bromide anion as nucleophilic reagent for ring-opening of epoxide, as well as tertiary N atom as Lewis basic site for activating CO2. This is also evidenced by the activation energy Ea catalyzed by the Cr-MIL-101-based catalysts with different functions. Notably, HImBr@Cr-MIL-101 also significantly outperforms other benchmark MOF-based catalysts. Moreover, benefited from the superb coordinative bonding interaction of the built Cr (III)–S bond, this catalyst exhibits good chemical stability and recyclability, which can be reused for at least seven runs without obvious catalytic activity depletion. This work provides a promising strategy for constructing multifunctional heterogeneous catalyst for CO2 cycloaddition reaction by highlighting the synergistic effect enabled by one host.

An Indium metal-organic framework with a two-fold-interpenetrating structure for the efficient conversion of CO2

An Indium metal-organic framework {[H3O]2[In2(BDC)3(ox)]·2DMA} based on 1,4-dicarboxybenzene (H2BDC) and oxalic acid (H2ox) has been constructed, exhibiting a two-fold-interpenetrating 3D structure with good stability. Each In3+ ion is eight-coordinated by six carboxylate oxygen atoms from three BDC2− ligands and two carboxylate oxygen atoms of one oxalate anion. The ligands BDC2− are joined by In3+ ions to construct a 1D wavy chain, while ligands BDC2− and ox2− are connected alternatively by In3+ ions to form another wavy chain. These two types of chains are interwoven into a three-dimensional structure. It has been explored as an effectively heterogeneous catalyst for the synthesis of cyclic carbonates by CO2 fixation. Under the reaction condition of 10 ​mg catalyst, 70 ​°C, atmospheric pressure over 24 ​h, the yield of epichlorohydrin carbonate can reach 92.0% with the turnover number (TON) value of 2300.

Cycloaddition of CO2 to Epichlorohydrin over Pyridine, Vinylpyridine, and Poly(vinylpyridine): The Influence of Steric Crowding on the Reaction Mechanism

The cycloaddition of CO2 with epoxides is a 100% atom economical reaction that utilizes CO2 and produces valuable cyclic carbonate products. Organic bases are attractive catalysts for this reaction because of their green characteristics, such as low cost and low toxicity. However, further catalyst development is required to achieve acceptable yields at mild temperatures and pressures. This work aims to establish catalyst structure–performance relationships to accelerate the rational design of high performance organic base catalysts for the cycloaddition reaction. Toward this end, we investigate the influence of steric crowding at the ring nitrogen atom of a series of pyridine-based catalysts on the reaction mechanism and catalyst performance using batch reactor measurements at a mild temperature (57 °C) and atmospheric pressure under solventless conditions combined with in situ infrared spectroscopic characterization of the catalysts. We show that steric crowding at the ring nitrogen atom has a significant influence on the reaction mechanism and catalyst performance. Catalysts with unhindered access to the ring nitrogen atom, such as pyridine, 4-vinylpyridine, 3-vinylpyridine, and poly(4-vinylpyridine), are completely transformed during the cycloaddition reaction by quaternization from the epoxide reactant, producing zwitterionic pyridinium-epoxide adducts and ammonium salts that precipitate out of solution. Catalysts with hindered access to the ring nitrogen atom, such as 2-vinylpyridine and poly(2-vinylpyridine), resist quaternization from the epoxide reactant due to the high degree of steric hindrance at the ring nitrogen atom. The poly(2-vinylpyridine) catalyst in particular displayed high stability, high product selectivity, and high activity for cyclic carbonate synthesis. These molecular-level insights have significant implications for the rational design of active, stable, and metal-free catalysts for cyclic carbonate synthesis by tuning the steric crowding at the active site.

N-heterocyclic carbene-pyridine ligand coordinated Mo(II) complexes catalyzed synthesis of cyclic carbonates from carbon dioxide and epoxides

A variety of zero-valent molybdenum complexes and divalent molybdenum complexes with N-heterocyclic carbenes (NHC)-pyridine ligands were synthesized, and their catalytic activities and performances in the cycloaddition reaction of epoxides and carbon dioxide (CO2) were investigated. It was found that the divalent molybdenum complexes show high catalytic activity in the synthesis of cyclic carbonates from epoxide and CO2 in comparison with zero-valent molybdenum complexes. The divalent molybdenum complexes combined with tetrabutylammonium iodide (TBAI) can effectively transform various terminal epoxides and internal epoxides under 30–80 ℃ and 5–10 bar of CO2 pressure. The mechanic experiments by FT-IR and HRMS spectrometry reveal the reaction pathway of binary system in combination of divalent molybdenum complexes with TBAI.

CO2 Fixation by Dimeric Tb(III) Complexes: Synthesis, Structure, and Magnetism

Two dinuclear complexes, [Tb2(L1)2(piv)2(NO3)2]·H2O (1) and [Tb2(L2)2(CF3CO2)2(H2O)4].2NO3 (2), have been prepared and characterized by single-crystal X-ray diffraction, where each metal ion is doubly phenoxido-bridged by the two phenolato oxygen atoms of the tetradentate Schiff-base ligand. Previous magnetic studies of 1 show that it is not a single-molecule magnet (SMM), while AC magnetic measurements of 2 show that it relaxes quite fast with μSQUID measurements revealing the presence of an interaction operating between the Tb ions. Through DC, μSQUID, and CASSCF calculations, the strength of the interaction in 2 can be quantified, which is of dipolar origin. Both complexes showed efficient catalytic activity toward the carbon dioxide insertion reaction into epoxides for the formation of organic cyclic carbonates. Catalytic synthesis of organic cyclic carbonates smoothly occurred at 60 °C under1 bar carbon dioxide pressure and neat conditions. Exocyclic as well as endocyclic epoxides produced a respective cyclic carbonate product with moderate to high yield (43–100%). Moreover, a high turnover number (7300–10000) along with a high turnover frequency (537.5–5000 h–1) are found in this catalytic reaction.

Stable Engineered Trimetallic Oxide Scaffold as a Catalyst for Enhanced Solvent-Free Conversion of CO2 into Value-Added Products

This work demonstrates the development of mesoporous trimetallic oxide scaffolds (TOSs) as heterogeneous catalysts for the solvent-free transformation of CO2 into various value-added products. The TOS catalyst was prepared using a solution-combustion protocol as a time- and energy-saving method using cobalt, magnesium, and cerium metal nitrate salts as precursors and ethylene glycol as the fuel system and compared with their monometallic counterparts. Characterization suggested strong metal–metal and metal–oxygen interactions in the 3D-interconnected hierarchical porous network, which resulted in substantial alteration in the electronic, structural, and physicochemical properties. This resulted in an appreciable surface area, acid–base cooperative sites, and a larger pore volume in the catalyst. Thereafter, the CoMgCe-TOS catalyst was first used for the solvent-free cyclization of o-phenylenediamines and CO2 to produce benzimidazoles. In the presence of dimethylamine borane as a reductant, benzimidazoles were obtained in 94% yield at 100 °C under pressurized conditions, along with good recyclability for 12 cycles. It was established that selectivity toward benzimidazole improved upon the incorporation of basic metals (Mg and Ce), with Co aiding in the formation of cooperative Lewis acid–base sites. A plausible mechanism was also predicted, wherein the overall conversion of reactants for the N-formylation step was influenced by the number and strength of basic sites, and the cyclization step for selectively obtaining benzimidazole was affected by the acidic site strength. Besides the production of benzimidazole, the catalyst was also highly active for the synthesis of cyclic carbonates using epoxides and CO2 under optimized reaction conditions. This work therefore provides a new and greener route for the synthesis of benzimidazoles and organic carbonates, which can be easily adapted for scale-up applications.

Synthesis of cyclic carbonates from CO2 cycloaddition to bio-based epoxides and glycerol: an overview of recent development.

Anthropogenic carbon dioxide (CO2) emissions contribute significantly to global warming and deplete fossil carbon resources, prompting a shift to bio-based raw materials. The two main technologies for reducing CO2 emissions are capturing and either storing or utilizing it. However, while capture and storage have high reduction potential, they lack economic feasibility. Conversely, by utilizing the CO2 captured from streams and air to produce valuable products, it can become an asset and curb greenhouse gas effects. CO2 is a challenging C1-building block due to its high kinetic inertness and thermodynamic stability, requiring high temperature and pressure conditions and a reactive catalytic system. Nonetheless, cyclic carbonate production by reacting epoxides and CO2 is a promising green and sustainable chemistry reaction, with enormous potential applications as an electrolyte in lithium-ion batteries, a green solvent, and a monomer in polycarbonate production. This review focuses on the most recent developments in the synthesis of cyclic carbonates from glycerol and bio-based epoxides, as well as efficient methods for chemically transforming CO2 using flow chemistry and novel reactor designs.

Enhancement of the catalytic performance of UIO-66 for the CO2 synthesis of cyclic carbonate using natural nanomaterials as a carrier.

One of the environmentally friendly methods is the intelligent utilization of natural one-dimensional nanomaterials as carriers to improve the CO2 catalytic performance of MOF materials. This paper reports an efficient composite catalyst preparation using a cheap and readily available magnesium-aluminosilicate nanometer, attapulgite (ATP), as a carrier for MOF materials. Due to its Lewis acidic site and unique alkaline pore structure, ATP exhibits excellent catalytic activity in the coupling reaction of CO2 with epoxy compounds, and its regular one-dimensional nanorod shape has tremendous potential as a carrier compared to other natural minerals. Given the diversity of MOF material types and structures, the design of this UIO-66/ATP nanocomposite catalyst provides both a new pathway for CO2 capture and conversion and a developmental space for the synthesis of such nanocomposites.

Ionic Fe(iii)-porphyrin frameworks for the one-pot synthesis of cyclic carbonates from olefins and CO2

This study presents a novel use of carbon dioxide (CO2) in the synthesis of cyclic carbonates from olefins under halogen-free conditions. This green strategy offers the twin advantages of environment friendliness and value-added chemical production.

AgNPs supported over porous organic polymers for the fixation of CO2 on propargyl alcohols and amines under solvent-free conditions

Silver nanoparticle embedded POP was synthesized and used as a heterogeneous catalyst for the synthesis of α-alkylidene cyclic carbonates and acyclic carbamates via CO2 fixation under mild conditions.

Dyes as efficient and reusable organocatalysts for the synthesis of cyclic carbonates from epoxides and CO2

The functionalised RhB-EtOH-I dye was identified as an efficient and reusable organocatalyst for the conversion of CO2 and epoxides into cyclic carbonates under mild conditions.

Group 13 salphen compounds (In, Ga and Al): a comparison of their structural features and activities as catalysts for cyclic carbonate synthesis.

Many complexes based on group 13 elements have been successfully applied as catalysts for the synthesis of cyclic carbonates from epoxides and CO2 and to date these have provided some of the most active catalysts developed. It is notable that most reports have focused on the use of aluminium-based compounds likely because of the well-established Lewis acidity of this element and its cost. In comparison, relatively little attention has been paid to the development of catalysts based on the heavier group 13 elements, despite their known Lewis acidic properties. This study describes the synthesis of aluminium, gallium and indium compounds supported by a readily prepared salphen ligand and explores both their comparative structures and also their potential as catalysts for the synthesis of cyclic carbonates. In addition, the halide ligand which forms a key part of the compound has been systematically varied and the effect of this change on the structure and catalytic activity is also discussed. It is demonstrated that the indium compounds are actually, and unexpectedly, the most active for cyclic carbonate synthesis, despite their lower Lewis acidity when compared to their aluminium congeners. The experimental observations from this work are fully supported by a Density Functional Theory (DFT) study, which provides important insights into the reasons as to why the indium catalyst with bromide, [InBr(salphen)], is most active.

Carbon neutral via catalytic transformation of CO2 into cyclic carbonates by an imidazolium-based ionic zeolitic imidazolate frameworks

On the way toward a carbon–neutral future, anthropogenic chemical recycling of captured carbon dioxide (CO2) into value-added chemicals and reusable materials provides an attractive and promising pathway. A multifunctional zeolitic imidazolate framework (ZIF-9-ImBr) consisting of electrophilic cobalt ions, CO2-philic nitrogen-rich units and nucleophilic imidazolium-based ionic liquids (ILs) was synthesized by simple substitution reaction of amino-functionalized ZIF (ZIF-9-NH2) with 1-(4-bromobutyl)-3-methylimidazolium bromide ([BrBMIM]Br). The obtained ZIF-9-ImBr was employed as heterogeneous catalyst for the solvent-free synthesis of cyclic carbonates from CO2 and epoxides in the absence of any cocatalyst. A certain amount of micropores and abundant nitrogen atoms could facilitate CO2 enrichment and its activation, while the mesopores could enhance the mass transfer of reactant and product molecules. Moreover, the synergistic effect between Lewis-acid cobalt and Lewis-base bromine ions of ZIF-9-ImBr made it promising in the CO2 cycloaddition reaction. As expected, ZIF-9-ImBr displayed good catalytic performance of 93.8 % yield and 98.9 % selectivity of propylene carbonate at 120 °C and 2.0 MPa for 3.5 h. Additionally, the reactions proceeded with a broad substrate scope and high selectivity to give the corresponding cyclic carbonates in good to excellent yields (77.9–95.8 %). Even for the challenging internal epoxide, cyclohexene oxide, a satisfactory 71.4 % yield was obtained by extending the reaction time to 24 h. More importantly, ZIF-9-ImBr can be easily recycled and maintains its reactivity and selectivity after five successive cycles. This work highlights the potential of functional ZIF-based materials for targeting CO2 capture and conversion.