Cyclic Carbonates Research Articles

Imidazolium and pyridine bifunctionalized hypercrosslinked polymers as efficient and recyclable catalysts for CO2 cycloaddition

Converting CO2 into precious chemicals is considered to be a fundamental and effective tool for controlling the abundant CO2 emitted. One of the most compelling methods for CO2 conversion is the synthesis of cyclic carbonates by cycloaddition of CO2 with epoxides. However, the development of materials with specific functionalities for CO2 capture and conversion is still considered to be a significant challenge. Herein, a novel imidazolium salts and pyridine skeleton bifunctionalized hypercrosslinked polymers were prepared by FeCl3-catalyted Friedel-Crafts alkylation reaction. Various analytical techniques were used to investigate the properties of the catalysts. The bifunctionalized heterogeneous catalysts exhibited outstanding catalytic performances for CO2 cycloaddition under mild conditions with an excellent yield of up to 99 %. Besides, the catalyst could bear various epoxides and no significant loss of activity after 6 cycles. The properties of metal-free, solvent-free, cocatalyst-free, easy-to-prepare, mild conditions, facility separation and recyclability make the bifunctionalized hypercrosslinked polymers useful for CO2 cycloaddition.

Pyrazolone Containing Azine Based Molybdenum Complexes Having μ‐O{MoO2}2 Core and their Catalytic Applications for the Cycloaddition of CO2 with Epoxides to Cyclic Carbonates

Pyrazolone Containing Azine Based Molybdenum Complexes Having μ‐O{MoO₂}₂ Core and their Catalytic Applications for the Cycloaddition of CO₂ with Epoxides to Cyclic Carbonates

Designing photothermal catalytic systems in multi-component MOFs for enhanced conversion of carbon dioxide.

We integrated a pair of donor-acceptor photothermal units, a Lewis acidic site, and a nucleophilic catalytic site into a multi-component metal-organic framework, resulting in an efficient photothermal catalytic system for the conversion of CO2 to cyclic carbonates.

Ru(II)-Catalyzed Decarboxylative (4 + 2)-Annulation of Benzoic Acids and Benzamides with Propargyl Cyclic Carbonates.

Propargyl cyclic carbonates have emerged as versatile precursors in synthetic chemistry. However, their reactivity has so far been limited to transition metal-catalyzed substitution and cyclization reactions. Herein, we illustrate the successful employment of propargyl cyclic carbonates as coupling partners in Ru(II)-catalyzed C-H annulation of benzoic acids and benzamides. This approach allowed us to access a broad range of biologically relevant isocoumarin and isoquinolinone derivatives in good to excellent yields, utilizing bench-stable and easily accessible precursors. Preliminary mechanistic studies indicated that the C-H metalation step is both reversible and rate-determining in the reaction pathway. Furthermore, the utility of the developed methodology has been illustrated by scale-up and postfunctionalization experiments.

Poly(ethylene oxide) bis(cyclic carbonate) based hydrophilic non-isocyanate polyhydroxyurethanes: Polymer-water interactions and glass transition behavior

Hydrogen bonding, glass transition, water absorption, and plasticization are studied as a function of hydrogen bond donor concentration in the chain of a non-isocyanate polyhydroxyurethane system, synthesized by solvent-free aminolysis of a poly(ethylene oxide) (PEO) based cyclic carbonate. The concentration of hydrogen bond donors is controlled by varying the ratio of diaminobutane (DAB) and triethylenetetramine (TETA) in the amine component. Introduction of secondary amino groups enhances hydrogen bonding and rigidity of the chain, and, as a result, slows down dynamics, as evidenced by an increase in glass transition temperature. Hydroxyurethane groups are the primary hydration sites despite the hydrophilicity of the polyether. Secondary amino groups act as secondary hydration sites which further increases water sorption capacity. The Couchman-Karasz model describes excellently the dependence of glass transition temperature on composition in both dry and hydrated systems.

Quaternarized chitosan nanofiber and ZIF aerogel composites for synergetic CO2 cycloaddition catalysis

Chemical upcycling of CO2, a major greenhouse gas, is attracting significant attention as a crucial strategy to combat global warming. The production of cyclic carbonate using metal-organic frameworks and their composites using nanofibrous carbohydrate polymer are promising ways to convert CO2 into valuable products. However, the current role of fibrous polymers is restricted to serving as physical substrates. This study seeks to expand the functionality of quaternarized chitosan nanofibers into synergistic catalysts in addition to their physical support role. A novel aerogel composite using Co/Zn-ZIF catalyst and quaternarized chitosan nanofiber (Q-CsNF+) was fabricated, and its hierarchical pore structure was extensively discussed. The obtained ZIF/Q-CsNF+ composite can synergistically convert epoxide to cyclic carbonate by acting as a co-catalyst. Moreover, we determined the predominant factors influencing catalytic activity in CO2 cycloaddition, especially by examining the interplay between CO2 affinity and co-catalyst effects. This research provides fundamental insight into developing CO2 cycloaddition catalysts using nature-derived fibrous polymers, opening new avenues for sustainable and efficient CO2 utilization.

The Reaction between K2CO3 and Ethylene Glycol in Deep Eutectic Solvents.

Understanding intermolecular interactions is important for the design of deep eutectic solvents. Herein, potassium carbonate (K2CO3) and ethylene glycol (EG) are used to form deep eutectic solvents. The interactions between K2CO3 and EG are studied using nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectra. Interestingly, the interaction results indicate that the carbonate anion CO32- can react with EG to form EG-based organic carbonate, which can occur even at room temperature. The possible reaction steps between K2CO3 and EG are presented. As K2CO3 can be prepared from CO2 and KOH, the findings of this work may provide a promising strategy for CO2 capture and conversion.

Nonflammable Fluorinated Electrolyte Realizing High Voltage Anode-Free Zn Dual-Ion Batteries.

Due to the low decomposition potential of H2O and its corrosive effect to Zn foil, the Zn metal battery with aqueous electrolytes operates within a narrow electrochemical window and exhibits low anode utilization ratio. Fluorinated carbonate ester, exhibiting low highest occupied molecular orbital (HOMO) energy level, is suitable for constructing high-voltage batteries, yet its application in Zn metal battery has been scarcely explored. Herein, we propose an electrolyte based on fluorinated solvents and ethoxy (pentafluoro) cyclotriphosphazene (PFPN) additive, which exhibits a high decomposition voltage of 2.75 V in Zn batteries. The fluorinated carbonate esters possess non-flammability and exhibit reduced solvation capacity which in turn promotes the incorporation of anions into Zn2+ solvation shell. Consequently, an anion-derived interface layer is formed on Zn anode, aiding the compact and planar growth of deposited Zn. Therefore, the Zn//Zn cell exhibits an impressive Zn utilization of 91% for 140 h, a level seldom reported previously. Benefitting from the oxidation resistant solvents and cathode-electrolyte interface layer formed by PFPN additive, the Zn//graphite dual-ions battery shows an extended cycling life of 1000 cycles. Furthermore, an anode-free cell was constructed and stably operated for 100 cycles, with a notably high average discharge midpoint voltage of 1.84 V.

Insight into the Enforced Stability of the Solid Electrolyte Interphase on the Graphite Anode by Prelithiation.

Prelithiation in a graphite anode is widely considered as an effective strategy to compensate for the lithium loss due to the formation of the solid electrolyte interphase (SEI), thus improving the cycle life of lithium-ion batteries (LIBs). However, less attention has been paid to the difference of the SEI established by prelithiation from that resulting from the charging process. To address this issue, a prelithiated graphite anode is prepared by thermal contact and its performances are investigated by electrochemical measurements and spectral characterizations. It is found that the significantly improved initial coulombic efficiency (ICE) and cyclic stability of the graphite anode by prelitiation are attributed to the formation of LiF-rich SEI. Different from the charging process that favors decomposition of solvents and results in a SEI mainly consisting of organic and inorganic carbonates, prelithiation is beneficial for the reduction of LiPF6 and results in a LiF-rich SEI that presents high stability and robustness, enabling the graphite anode with significantly improved cyclic stability.

Effects of wet carbonation with ethanol solution on the mechanical, durability properties, and microstructure of recycled concrete aggregates and derived block products

The carbonation treatment of recycled concrete aggregates (RCA) can significantly enhance their properties and reusability. To improve carbonation efficiency, a wet cyclic carbonation method using ethanol solution was proposed to treat RCA and a wet carbon curing method was applied to its product, recycled blocks (RB). The results showed that wet carbonation with 30 % ethanol solution for 10 min significantly reduced RCA’s water absorption and crushing index and increased its apparent density. This is attributed to ethanol’s high carbon-solubilizing properties, which allow the RCA to generate more calcium carbonate precipitates to fill the voids and optimize the pore structure. When the concentration of ethanol solution was increased above 50 %, the improvement was inefficient and limited. In addition, the second cycle of wet carbonation can further improve the properties of RCA. Optimally processed RCA was used to make recycled masonry blocks. The 10 min wet carbonation curing proved beneficial to the mechanical properties of RB and also improved its resistance to shrinkage and salt freeze-thaw. This rapid method enhances RCA construction materials' performance and durability, improving industrial use in sustainable construction materials.

Sustainable repurpose of waste melamine foam into bifunctional catalysts for efficient CO2 capture and conversion

Global climate change has driven the scientific community to improve the utilization of a critical C1 resource carbon dioxide (CO2) through carbon capture utilization (CCU) technology. The cycloaddition of CO2 with epoxides provides perfect atom economy and economic feasibility to produce versatile cyclic carbonates used in various industries. However, the stable nature of CO2 and epoxides requires highly active catalysts. In this work, the repurpose of nitrogenous waste melamine foams (MFs) as high-performance catalysts for the cycloaddition of CO2 was explored. The pyrolyzed MF was modified with Cu to prepare a series of acid-base bifunctional porous catalysts (MFC-X-Cu). The results demonstrate that the acid-base synergy of the MFC-X-Cu catalysts increases the efficiency of the cycloaddition of various epoxides, yielding target products at 96–99% under mild conditions. Moreover, the characterization results revealed that the superior performance of MFC-X-Cu stems from its hollow structure and acid-base synergy, which are derived from nitrogen species in the repurposed MF and the post-modified copper component. The catalyst maintained consistent catalytic efficiency over five cycles, highlighting its strong recyclability. This work presents an eco-friendly and sustainable approach towards carbon neutrality by utilizing modified waste materials for CO2 conversion into high-value chemicals.

Fully biobased unsymmetric bisphenols from condensation of lignin-derived monophenols for non-isocyanate polyurethane synthesis

Transforming renewable biomass and CO2 to the high value-added non-isocyanate polyurethanes (NIPUs) was of great significance to the development of sustainable chemistry. Herein, a series of unsymmetric bio-based bisphenols featured with chalcone structure were designed and synthesized by Claisen-Schmidt condensation of lignin-derived monophenols (vanillin and syringaldehyde) and plant methyl ketones (zingiberone, raspberry ketone, and piceol), these phenols and ketones are value-added chemicals from biorefinery process of biofuels. The unsymmetric bio-based bisphenols were consequently transformed into bis-epoxides, bis(cyclic carbonate)s, and finally polyhydroxyurethanes (PHUs). With eco-friendly proline as the catalyst, bio-based bisphenols were prepared in excellent yields (76% − 95%). More than 90% isolated yields of bis(cyclic carbonate)s were obtained from bis-epoxides. All of the bis(cyclic carbonate)s were cured with long-chain amine, i.e. PriamineTM 1074, and the result PHUs, a kind of NIPUs, have thermal stability comparable to bisphenols A-based network according to DSC and TGA. The attempts to one-pot-two-step synthesis of PHUs also exhibited better thermal properties, which bis-epoxides directly conducted successively with carbon dioxide and 1,6-hexamethylenediamine. The bio-based bisphenols appeared to be a promising substitute to bisphenols-A with the aim at synthesizing environmentally friendly PHUs. Therefore, this study provided a valuable route in utilization of carbon dioxide and functional aromatics from fuel process into fully biobased polymeric materials.

The efficient and reusable imidazolium-organoboron catalysts for green CO2 insertion reactions in solvent-free under atmospheric and high-pressure conditions

Organoboron compounds that are available in industrial and scientific research were investigated as organocatalysts for the coupling reaction of CO2 into cyclic carbonates as fine chemicals in solvent-free and under sustainable green atmospheric and high-pressure conditions (1 atm and 1.6 MPa, 100 °C, 2 h). This work synthesized a series of imidazolium-organoboron catalysts (IBC1-IBC8) using the eco-friendly and metal-free methodology and characterized by various analysis techniques. These techniques were NMR (1H, 13C, and 11B), UV–Vis, FT-IR, Mass spectrometry, C/H/N analysis, and melting point measurement together with thermal gravimetric analysis (TGA-DTA), respectively. After that, the Lewis acidity of the synthesized imidazolium-organoboron catalysts, which is important for catalytic CO2 conversion studies, was investigated by the traditional Gutmann-Beckett test, and the Lewis acidity order of the target compounds was found at range 54.96–50.36 ppm. In the presence of 0.1 mol% imidazolium-organoboron catalyst (IBC8) and 0.2 mol% DMAP as co-catalyst, 4-chloromethyl-1,3-dioxalan-2-one was obtained as cyclic carbonate from epichlorohydrin in 44.9 % yield and 97.6 % selectivity (1 atm and 100 °C) and in an excellent 97 % yield with 98.9 % selectivity (1.6 MPa and 100 °C) in 2 h without any solvents. After the imidazolium-organoboron catalyst (IBC8) showed efficient catalytic conversion and high selectivity, the effect of different parameters, including the effect of substrate, Lewis acid-base, reaction time, reaction temperature, CO2 pressure, and catalyst amount, was studied for this catalyst. According to the obtained catalytic conversion results, it was also determined that the optimum Cat./ECH ratio for CO2 cycloaddition reactions is 1/1000.

Solvent-free CO2 cycloaddition by one- and two-dimensional sodium coordination polymers based on hydrazonic ligands

We successfully synthesized and characterized four new coordination polymers of sodium: sodium 4-hydroxy-3-{[2-(pyridine-4-carbonyl)hydrazinylidene]methyl}benzene-1-sulfonate (NaL4-Py), sodium 3-[(2-benzoylhydrazinylidene)methyl]-4-hydroxybenzene-1-sulfonate (NaLPh), sodium 3-[(2-acetylhydrazinylidene)methyl]-4-hydroxybenzene-1-sulfonate (NaLMe), and sodium 3-[(2-carbamoylhydrazinylidene)methyl]-4-hydroxybenzene-1-sulfonate (NaLNH2). These polymers were synthesized through a 1:1 condensation reaction of hydrazide derivatives with sodium salicylaldehyde-5-sulfonate monohydrate (NaSalSO3) and were thoroughly characterized using various analytical techniques. The compounds NaLMe and NaLPh, crystallized in the P 1‾ and P21/n space groups, respectively, forming one-dimensional polymers. On the other hand, NaLNH2 and NaL4-Py crystallized in the Cmca and P 1‾ space groups, respectively, forming two-dimensional coordination polymers. The coordination environment of the sodium cation differed among the compounds, with the imine nitrogen atom interfering in NaL4-Py and NaLPh. The sulfonate group exhibited various coordination modes, resulting in the different dimensionalities of the polymers. Compounds NaL4-Py and NaLPh acted as heterogeneous Lewis acid catalysts for the solvent-free cycloaddition reaction of epichlorohydrine and CO2 into valued cyclic carbonate. High selective conversion (68 %) of epichlorohydrin to cyclic carbonate was obtained at mild conditions, 60 °C and 1 bar CO2, after 24 h of reaction.

Thermally induced release and generation of CO2 and C1–C4 hydrocarbons in Opalinus Clay from Mont Terri (Switzerland)

Claystone formations are candidate host rocks for high-level heat-emitting nuclear waste (HLW). Temperatures from 90 to 150 °C at the canister surface are discussed internationally as potential emplacement and storage conditions. The thermal energy emitted from waste containers will be transported into the host rock formation, accelerating chemical reactions including the release of sorbed and dissolved gases and the generation of new gases. This study investigated gas release and generation in Opalinus Clay from Mont Terri (Switzerland) at elevated temperature and pressure conditions relevant for HLW storage and beyond. Hydrous pyrolysis experiments were conducted in Dickson-type flexible gold-titanium reaction cells and gold capsules in the temperature range of 80–345 °C and at 20 MPa. CO2(g) was the predominant product, followed by C1–C4 hydrocarbons, which decrease in abundance with increasing carbon atom number. Neither CO nor H2S was detected. H2 was generated only in high temperature experiments at 315 °C and 345 °C, respectively. A combination of CO2(g) quantification, stable carbon isotopic composition data, thermodynamic calculations and aqueous fluid composition (dissolved ions, pH) demonstrated that ≥80 % of the measured CO2(g) originated from carbonate mineral dissolution. The model calculations also suggest that the fraction of CO2(aq) in DIC increases from ∼50 % at 80 °C to nearly 100 % at higher temperatures. Thermal transformation of organic matter represented an additional source for CO2(g) and was the predominant process yielding the C1–C4 hydrocarbons. Our findings stress the importance of quantitative geochemical data for the safety assessment of potential host rocks for HLW storage. We demonstrated that two sources are involved in gas release and generation at temperatures relevant for HLW storage, e.g., in the Opalinus Clay – organic matter and carbonate minerals. Our data will contribute to numerical modelling studies and the refinement of feature, events, and processes (FEP) catalogues.

Iron(III) Complexes with Pyridine Group Coordination and Dissociation Reversible Equilibrium: Cooperative Activation of CO2 and Epoxides into Cyclic Carbonates.

Herein, a series of [ONSN]-type iron(III) complexes were synthesized. A binary catalytic system in combination with iron complexes and tetrabutylammonium bromide (TBAB) exhibited high activity for the synthesis of cyclic carbonates from CO2 (1 atm) and terminal epoxides at room temperature. Additionally, single-component iron complexes without using additional TBAB as nucleophiles also showed high activity for the cycloaddition of CO2 and terminal epoxides under 80 °C and 0.5 MPa of CO2. This study demonstrates that single-component iron catalysts provide a competitive alternative to binary catalytic systems for the synthesis of cyclic carbonates from CO2 and epoxides. Mechanistic studies on a single-component iron catalytic system suggest that the temperature serves as a role of responsive switch for controlling the coordination and dissociation of pyridine bearing iron catalysts detected using in situ infrared spectroscopy, and uncoordinated pyridine activates CO2 to form carbamate. Studies of electrospray ionization high-resolution mass spectrometry reveal that an iron center was used as a Lewis acidic site, free halogen anions from the iron center were used as a nucleophilic site, and coordinated pyridine was released from iron complexes to activate CO2.

Functional ionic liquids based on DABCO: Efficient catalysts for chemical fixation of CO2 into cyclic carbonates

A series of basic functional ionic liquids were prepared from 1, 4-diazabicyclo [2.2.2] octane (DABCO) with various halogenated hydrocarbons, then these functional ionic liquids were used as catalysts for the chemical fixation of CO2 into cyclic carbonates and the influence of the structure of the ionic liquids was investigated. The results showed that the N atom active center, types of anions and hydrogen bond of the catalyst play a key role in the cycloaddition reaction of CO2 with epoxides to cyclic carbonates. Under mild reaction conditions (T = 100 °C, 1 atm CO2), the ionic liquid [DABCO-CH2CH2CH2OH] I showed the best catalytic effect, which has notable advantages such as high catalytic activity, eco-friendly, ease of work-up and convenient reuse.

The Flower-Shaped Co (II) and Cu (II) Phthalocyanine Polymers as Highly Efficient and Stable Catalysts for Chemical Fixation of CO2 to Cyclic Carbonate

New flower-shaped metallophthalocyanine polymers (THB-4-M, M = Co, Cu) have been synthesized by using 1,3,5-Tri(4-hydroxyphenhyl) benzene (THB) as rigid and contorted units to control the morphology under the solvothermal method. The polymers were characterized using FT-IR, UV-vis, SEM, TGA, and XPS. These polymers were applied as heterogeneous catalysts for the chemical fixation of carbon dioxide (CO2) to cyclic carbonates without solvent. The influence of reaction parameters and different metal centers on the catalytic performance were studied in detail. Under optimal conditions, the catalysts showed high conversion (49.9–99.0%), selectivity (over 85%), and reusability at ambient conditions (at 1 bar CO2).

Immobilization of tetrabromidozincate(Ⅱ) anions on ion exchange resin for efficiently catalytic conversion of CO2 to cyclic carbonates

Integrating reactive Lewis acid sites and nucleophilic anions into porous materials is a promising approach to develop efficient heterogeneous catalysts for the cycloaddition of CO2 to epoxides (CCE) into cyclic carbonates. In this work, ZnBr42− coordination anions consisting of Zn2+ ions as Lewis acid sites and Br− ions as nucleophiles were immobilized on the poly (styrene–divinylbenzene) anion-exchange resin D201 containing quaternary ammonium cationic groups through a simple ion-exchange method. The obtained catalyst, named ZnBr4-D201, was characterized by X-ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM) and thermo-gravimetry (TG). Under the condition of solvent and co-catalyst free, ZnBr4-D201 exhibited efficient catalytic activity for CCE reaction. Take the cycloaddition of CO2 to 1,2-epoxybutane (BO) as an example, ZnBr4-D201 gave a BO conversion rate of 97 % and a selectivity of 98 % for cyclic carbonate with a high TOF value at 1 MPa CO2 and 80 °C for 6 h, which is superior to most of heterogeneous catalysts ever reported. Furthermore, ZnBr4-D201 showed good recoverability, and the yield of cyclic carbonate was still up to 82 %. The excellent catalytic performance and convenient preparation process make ZnBr4-D201 have great potential for CCE reaction in practical production.

Ionic Liquid Catalysis in Cyclic Carbonate Synthesis for the Development of Soybean Oil-Based Non-Isocyanate Polyurethane Foams.

A method for obtaining non-isocyanate polyurethane (NIPU) foams from cyclic carbonate (CC) based on soybean oil was developed. For this purpose, cyclic carbonate was synthesized from epoxidized soybean oil and CO2 using various ionic liquids (ILs) as catalysts. Among the tested ILs, the highest selectivity (100%) and CC yield (98%) were achieved for 1-ethyl-3-methylimidazolium ([emim]Br). Without any purification, the resulting cyclic carbonate was reacted directly with diethylenetriamine as a model crosslinking agent to produce NIPU foams. It was found that the soybean oil-based CC synthesized with bromide imidazolium ionic liquids exhibited significantly shorter gelling times (8 min 50 s for [emim]Br and 9 min 35 s for [bmim]Br) compared to those obtained with the conventional TBAB catalyst (26 min 15 s). A shorter gelling time is a crucial parameter for the crosslinking process in foams. The obtained foams were subjected to mechanical tests and a morphology analysis.