Cyclic Carbonates Research Articles

Zinc bioinspired catalytic system for the valorisation of CO2 into cyclic carbonates

Cyclic organic carbonates are defined as key compounds for a sustainable chemical economy. Their synthesis from CO2 under mild conditions is a useful way to valorise this greenhouse gas as carbon source. Even if a wide range of catalysts were described to promote the carbon dioxide cycloaddition into epoxides, only few ones concern enzymatic systems. The zinc/L‐histidine active site of carbonic anhydrase inspired the present work, pointing out that the imidazole moiety of the amino acid ligand has a crucial role. An extensive study was undertaken to establish the structure‐activity relationship of imidazole derivatives, zinc salts and their respective catalytic activity in the CO2 cycloaddition reaction. The effect of aromatic, alkyl or iodine substituents and their position in N‐heterocycles were highlighted. A synergic effect was noted when combining imidazole compounds with zinc salts. The optimisation of reaction conditions emphasised the in‐situ ZnI2/1‐methylimidazole catalytic system is selective towards cyclic styrene carbonates and efficient under solvent‐free mild conditions (50°C, atmospheric CO2 pressure). Once reusing tests confirmed the catalytic system robustness, the reaction scope was enlarged to several epoxides resulting in 84‐99% yields of their corresponding cyclic carbonates.

Systematic study on the hydrogen abstraction reactions from oxygenated compounds by H and HO2

AbstractTo extend the rule‐based approach for hydrogen abstraction reactions from oxygenated compounds, a systematic investigation was performed to examine the reactivity of gas‐phase hydrogen abstraction reactions from alkyl groups (methyl and ethyl groups) bound to oxygen atoms in five types of oxygenated compounds (alcohols, ethers, formate esters, acetate esters, and carbonate esters) by H atoms and HO2 radicals comprehensively considering rotational conformers. Quantum chemical calculations were conducted at the CBS‐QB3 level for stationary points. Rate constants were determined employing conventional transition state theory (TST). For hydrogen abstraction reactions by H, the rotational conformer distribution partition function was employed to approximate partition functions, owing to the similarity in vibrational energy‐level structures among conformers. In hydrogen abstraction reactions by HO2, the vibrational structures of transition‐state (TS) conformers varied significantly due to the hydrogen bonding, leading to an inappropriate evaluation of rate constants when using the lowest‐energy conformer as a representative. Therefore, the rate constants were calculated by the multi‐structural TST. It was revealed that the differences in functional groups containing O atoms mainly affect the bond dissociation energies of the C–H bonds and the activation energies of hydrogen abstraction reactions only when the C atoms are adjacent to the O atoms. Additionally, it was found that hydrogen bonds formed in the TSs show minor effect on rate parameters for the overall rate constants, apart from the reduction of the pre‐exponential factors for the H‐abstraction reactions from the methylene position of ethyl groups. The comparison with the rate constants from previous studies showed reasonable results, indicating that the rate constants in this study, which thoroughly consider rotational conformers, can be the current best estimates.

Two Sustainable Pathways of MOF-Catalyzed Room Temperature Chemical Fixation of CO2 inside Alkynes under Atmospheric Pressure.

The rising atmospheric CO2 levels necessitate the development of effective materials for its mitigation. Utilization of adsorbent materials for the reversible physisorption of CO2 has a significantly less impact. Recognizing this need, herein, we present a nitrogen-rich, aqua-stable, Ag(0)-nanoparticle-doped metal-organic framework (MOF) designed for the irreversible chemical conversion of CO2 into valuable fine chemicals. We demonstrate two sustainable pathways for CO2 fixation, utilizing the catalyst, 1'@Ag NPs. The designed catalyst facilitates the cyclization of propargylic amines and alcohols under ambient temperature and pressure conditions. Remarkably, this is the first MOF-based catalyst that allows for quantitative conversion of propargylic amines into 2-oxazolidinones at room temperature with atmospheric CO2 pressure. The process successfully transforms various propargylic amines and alcohols into 2-oxazolidinones and α-alkylidene cyclic carbonates under the CO2 atmosphere. Additionally, the catalyst shows excellent recyclability, maintaining its activity and structural integrity across multiple reuse cycles. Control experiments revealed that the catalytic efficiency of 1'@Ag NPs is attributed to the highly exposed alkynophilic Ag(0) sites on its pore walls. Computational studies further elucidate the mechanistic pathway for CO2 fixation. This work highlights the potential of 1'@Ag NPs to enhance environmental sustainability by converting CO2 into valuable bioactive chemicals under mild conditions.

Transforming Element Sulfur to High Performance Closed‐Loop Recyclable Polymer via Proton Transfer Enabled Anionic Hybrid Copolymerization

AbstractThe utilization of sulfur has been a global issue. Copolymerization of element sulfur (S8) with other monomers is a promising route to convert it to useful materials but is limited by the comonomers. Here, we report anionic hybrid copolymerization of S8 with acrylate and epoxide at room temperature, where S8 does not copolymerize with epoxide in the absence of acrylate. Yet, the proton transfer from the methyne in acrylate to the oxygen anion enables the ring‐opening of the cyclic comonomer and hence the copolymerization. The cyclic comonomers can be expanded to lactone and cyclic carbonate. Specifically, the copolymer of S8 with bisphenl A diglycidyl ether and diacrylate displays mechanical properties comparable to those of most common plastics, namely, it has ultimate tensile strength as high as 60.8 MPa and Young's modulus up to 680 MPa. It also exhibits high UV resistance and good transparency. Particularly, it has excellent UV‐induced self‐healing, reprocessability and closed‐loop recyclability due to the abundant dynamic S−S bonds and ester groups. This study provides an efficient strategy to turn element sulfur into closed‐loop recyclable polymer with high mechanical and optical performances.

Learning Strategies from Nature's Blueprint to Cyclic Carbonate Synthesis.

Nature is a remarkable source of inspiration for developing sustainable and eco-friendly synthetic procedures. In recent years, the synthesis of cyclic carbonates has garnered significant attention due to their versatile applications in various fields, including materials science, pharmaceuticals, and green chemistry. Drawing inspiration from nature, researchers have explored innovative synthetic routes that mimic biological processes to produce cyclic carbonates efficiently and sustainably. This article reviews nature-inspired synthetic procedures for cyclic carbonate formation, highlighting the key strategies and principles employed. Through biomimicry, researchers aim to harness the efficiency and selectivity observed in biological systems to develop greener and more sustainable methods for cyclic carbonate synthesis. Integrating bio-inspired strategies offers opportunities for improving synthetic efficiency and contributes to reducing the environmental impact associated with traditional chemical processes. This review underscores the potential of nature-inspired approaches in advancing the field of cyclic carbonate synthesis toward more sustainable and environmentally benign practices, focusing on recent literature.

Heterogeneous Catalytic Materials for Carbon dioxide Transformation: Efficient Carboxylation Cyclization to Cyclic Carbonates and Oxazolidinones

The exacerbation of environmental issues is increasingly attributed to the anthropogenic emissions of carbon dioxide (CO2) . CO2 is a cost‐effective and readily available C1 source. The conversion of CO2 into value‐added organic chemicals, such as cyclic carbonate and 2‐oxazolidinone, through carboxylation cyclization reactions shows promise in reducing carbon emissions and combating climate change. The use of catalysts can facilitate this process, with heterogeneous catalysts emerging as favorable due to their advantages of easy recovery and structural stability. This paper provides a comprehensive review of heterogeneous catalysts that have been utilized for the carboxylation cyclization of CO2 to afford cyclic carbonates and oxazolidinones in recent years. The catalysts include metal organic frameworks, covalent organic frameworks, super‐crosslinked polymers, conjugated microporous polymers, porous ionic organic polymers, and composite materials. We give a detailed synthesis route for each type of catalysts. Furthermore, the characteristics of the catalysts, such as BET specific surface area, CO2 adsorption capacity, and catalytic performance, is summarized and analyzed to offer insights for improving heterogeneous catalysts for CO2 conversion via carboxylation cyclization reactions in future research.

Comparative Study of High Voltage Spinel∥Lithium Titanate Lithium‐ion Batteries in Ethylene Carbonate Free Electrolytes

AbstractA persistent obstacle towards the realization of high voltage cathodes is electrolyte instability where oxidation and transition metal dissolution manifest in rapid capacity failure with both issues connected to the presence of ethylene carbonate in the electrolyte. Here, alternative electrolyte co‐solvents are investigated and compared, where the cyclic carbonate is replaced with sulfones ethyl methyl sulfone (EMS) and tetra methylene sulfone (TMS) and fluoroethylene carbonate (FEC). The best full cell performance was observed for cells cycled in a FEC/EMC (3/7) and FEC/EMC (1/1) electrolytes which exhibited 84–85 % capacity retention after 500 cycles. TMS/EMC (3/7), was determined to be the best performing sulfone electrolyte and maintained 71 % capacity after 500 cycles. Post‐mortem XPS analysis indicated different film forming mechanisms for the respective co‐solvent. A thicker cathode electrolyte interphase (CEI) on the LNMO was observed for the FEC containing electrolytes (relative to when TMS was used as the co‐solvent) indicating more effective passivation of the reactive cathode surface which correlated well with the enhanced cycling stability observed. For LTO, more evidence of transition metal migration and a thicker solid electrolyte interphase (SEI) layer was observed for the sulfone electrolyte suggesting more parasitic anode‐electrolyte interactions and an inability to mitigate Mn2+/Ni2+ crosstalk.

First Photocatalytic Synthesis of Cyclic Carbonates from CO2 Using Bromide-Functionalized Polyoxometalate without Additional Cocatalyst

First Photocatalytic Synthesis of Cyclic Carbonates from CO₂ Using Bromide-Functionalized Polyoxometalate without Additional Cocatalyst

Iron and Zinc Metallates Supported on Ion Exchange Resins: Synergistic Catalysts for the Solvent‐free Cyclic Carbonate Synthesis from Epoxides and CO2

Despite extensive research into developing efficient and environmentally friendly catalysts for converting CO2 over the last decade, the search for a robust and cost‐effective catalytic system is ongoing. This study describes developing and applying a new catalytic system using inexpensive ferrate and zincate anions immobilized on easily available commercial ion exchange resins (IER) to produce cyclic carbonates from CO2 with high efficiency and low cost. Two polystyrene‐based anion exchange resins, AmberlystTM A26‐Cl (A26‐Cl) and AmberliteTM IRA‐400‐Cl (IRA400‐Cl), were compared. The results demonstrated the catalysts' remarkable activity under mild conditions and demonstrated the synergistic effect between the polystyrene support and the active ammonium metallates, presenting a scalable, eco‐friendly method for cyclic carbonate production using waste CO2. A Design of Experiment approach was implemented to optimize the catalytic cycloaddition of CO2. The reaction scale‐up to produce a 5 g batch of propylene oxide and conducting recycling tests demonstrated that the catalyst retained its activity over four cycles. The research also explored the use of various epoxides and found that terminal epoxides produced very good yields. In summary, this study introduces a cost‐effective, scalable method for converting CO2 into valuable cyclic carbonates, leveraging the synergistic effects of polystyrene supports and active ammonium metallates.

Computational design for enantioselective CO2 capture: asymmetric frustrated Lewis pairs in epoxide transformations.

Carbon capture and utilisation (CCU) technologies offer a compelling strategy to mitigate rising atmospheric carbon dioxide levels. Despite extensive research on the CO2 insertion into epoxides to form cyclic carbonates, the stereochemical implications of this reaction have been largely overlooked, despite the prevalence of racemic epoxide solutions. This study introduces an in silico approach to design asymmetric frustrated Lewis pairs (FLPs) aimed at controlling reaction stereochemistry. Four FLP scaffolds, incorporating diverse Lewis acids (LA), Lewis bases (LB), and substituents, were assessed via volcano plot analysis to identify the most promising catalysts. By strategically modifying LB substituents to induce asymmetry, a stereoselective catalytic scaffold was developed, favouring one enantiomer from both epoxide enantiomers. This work advances the in silico design of FLPs, highlighting their potential as asymmetric CCU catalysts with implications for optimising catalyst efficiency and selectivity in sustainable chemistry applications.

A MOF@MOF S-scheme Heterojunction with Lewis Acid-Base Sites Synergistically Boosts Cocatalyst-Free CO2 Cycloaddition.

The photocatalytic cycloaddition reaction between CO2 and epoxide is one of the most promising green routes for CO2 utilization, for which high performance photocatalysts are intensely desired. Herein, we have constructed an S-scheme heterojunction of MIL-125@ZIF-67 modified by amino groups, which achieves a cyclic carbonate yield of as high as 99 % without employing any co-catalyst, outperforming the previously reported photocatalysts. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and in-situ electron paramagnetic resonance (EPR) spectroscopy reveal the important role of photogenerated electron migration from Lewis acid (Co) sites to the O atom of epoxide in triggering its ring-opening (the rate-determining step of CO2 cycloaddition reaction) under the assistance of photogenerated hole. Synergistically and concurrently, the Lewis base (amino groups) sites activate CO2 to CO2*, facilitating the following CO2 cycloaddition. Such a synergistic effect provides a most favorable approach to design efficient heterogeneous photocatalysts with dual/multiple-active sites for CO2 cycloaddition reaction.

Mixed-Linker Zr-Metal-Organic Framework with Improved Lewis Acidic Sites for CO2 Fixation Reaction Catalysis.

Applying the mixed-linker strategy in synthesizing metal-organic frameworks (MOFs) has drawn considerable attention as a heterogeneous catalyst owing to their easy synthesis and different functional ligands in their frameworks. Following this strategy, we have developed a mixed linker Zr(IV)-based MOF, [Zr6O4(OH)4(FUM)n(PZDC-NO2)6-n] (PZDC-NO2 = 4-nitro-3,5-pyrazoledicarboxylic acid, FUM = fumaric acid) denoted as MOF-801(PZDC-NO2) synthesized via this strategy which possess an electron-withdrawing group (-NO2) on secondary linkers. The MOF-801(PZDC-NO2) has been fully characterized via various analyses, such as Fourier transform infrared, powder X-ray diffraction, 13C/1H nuclear magnetic resonance, XPS, TGA, and N2 adsorption/desorption, SEM, EDX, etc. By considering the concurrent existence of acid-base active sites and the synergistic role of these sites, this mixed-linker MOF was used as a catalyst for the cycloaddition reaction of CO2 and epoxides under mild without-solvent conditions. MOF-801(PZDC-NO2) displays significant catalytic performance by producing the highest catalytic conversion of epoxide to cyclic carbonate (93%) with a turnover number of 130.7 in 8 h reaction time and 100 °C temperature under low-pressure CO2 pressure. The mixed-linker Zr-MOF exhibits exceptional stability and reusability, maintaining its structure and functionality after consecutive cycles of utilization. Finally, the reaction mechanism was further investigated by density functional theory calculations. The total energy of the reactants, intermediates, and products involved in the process.

Insights on the polymerization kinetics of non-isocyanate polyurethanes (NIPU) using in situ NMR spectroscopy

An in situ characterization method using liquid Nuclear Magnetic Resonance (NMR) spectroscopy has been developed to aid the preparation of highly reactive non-isocyanate polyurethanes (NIPUs) from cyclic carbonate aminolysis. Using this methodology, the aminolysis kinetics and the final polymer structure of a model NIPU obtained by reaction of a 5-membered bis-cyclic carbonate (5CC) and 1,4-diaminobutane have been fully investigated, as a function of the type and concentration of the aminolysis catalyst, and the reaction temperature. Several catalysts already reported in NIPUs syntheses, including 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), have been compared. The kinetics of the 5CC hydrolysis side reaction was also studied. With an activation energy of 29.7 kJ mol−1, TBD was clearly the most efficient catalyst used, allowing 5CC conversion ratio of up to 100 % using a concentration of 0.35 eq5CC. However, under these experiment conditions, TBD concentration also showed to have a non-negligible influence on the hydrolysis rate, representing between 6 and 14 % of the initial 5CC concentrations, at 353 K. Neither the catalyst or the temperature seemed to affect the polymer structure, with secondary hydroxyl-containing isomer proportions of (70 ± 6) %. Finally, this in situ NMR method is paving the way for rapid screening of innovative catalysts for sustainable NIPU synthesis.

Solvent-free synthesis of bio-based non-isocyanate polyurethane (NIPU) with robust adhesive property and resistance to low temperature

Non-isocyanate polyurethane (NIPU) adhesives represent a cutting-edge advancement in adhesive technology, poised to significantly diminish the dependency on isocyanate-based PU within the industry. In the context of the increasing scarcity of petroleum-based resources and the growing imperative for sustainable environmental practices, the pursuit of a comprehensively sustainable, bio-derived non-isocyanate polyurethane (NIPU) adhesive has swiftly become a pivotal area of interest within the scientific research community. In this study, the cashew phenol cyclic carbonate (CPCC) was synthesized through the addition polymerization process involving cashew phenol glycidyl ether (602A) with carbon dioxide (CO2), followed by a curing step utilizing a diamine extracted from biomass-derived oil to produce bio-based NIPU at ambient temperature. The synthesized NIPU adhesive demonstrated remarkable thermal stability and exceptional adhesion to a variety of substrate materials. Notably, the adhesive showcased superior bonding efficacy at ultra-low temperatures, with steel bonding strength reaching up to 7.78 MPa at −37 °C. This study presents an efficient and accelerated synthesis approach for the preparation of bio-based NIPU, offering a significant contribution to the field. Moreover, it provides a valuable reference for future advancements in NIPU adhesive technology, particularly for the applications requiring robust bonding at low-temperature environments.

Mechanochemical Synthesis of High-Entropy MOF-74 with Multiple Active Sites for CO2 Adsorption and Synergistic Conversion.

Compared with monometallic metal-organic frameworks (MOFs), the synergistic effect of multiple metals significantly enhances the catalytic performance of the CO2 cycloesterification reaction, leading to improved CO2 adsorption and catalytic conversion capabilities. To investigate this concept, a high-entropy MOF-74 (HE-MOF-74) with a uniform distribution of five distinct metal ions (Zn2+, Mg2+, Ni2+, Co2+, and Cu2+) was successfully synthesized using a straightforward mechanical ball milling technique and comprehensively characterized (including structural, morphological, and physicochemical properties). The results reveal that HE-MOF-74 exhibits significantly increased specific surface area and CO2 adsorption capacity compared with those of monometallic MOF-74. The presence of multiple unsaturated metal centers as Lewis acid sites, oxygen atoms linking the metals, and ligand-based hydroxyl groups serving as base sites enable efficient immobilization of CO2 into cyclic carbonate. This study introduces a novel synthetic approach for the green and efficient production of HE-MOF-74 and proposes a new application for CO2 utilization.

Cascade Conversion of CO2 to Ethylene Carbonate under Ambient Conditions.

Ethylene carbonate (EC) is the simplest cyclic carbonate with great industrial significance, most importantly as the vital electrolyte component for lithium-ion batteries. Its conventional synthesis generally involves the use of toxic precursors and requires elevated temperatures and pressures. Herein, we propose a cascade catalytic route for converting CO2 to EC under ambient conditions. Such a hybrid reaction scheme consists of the electrochemical reduction of CO2 to ethylene catalyzed by copper in a membrane electrode assembly reactor, the bromine-mediated conversion of ethylene to bromoethanol catalyzed by WO3 nanoarrays grown on carbon cloth, and the reaction between bromoethanol and CO2 to form EC. By separately optimizing individual catalytic steps and then integrating them together in series, we achieved the conversion of CO2 to EC at a good yield under room temperature and atmospheric pressure. Our study also represents the first demonstration about the successful synthesis of organic carbonates from CO2 as the exclusive carbon source.

Sustainable C-H Methylation Employing Dimethyl Carbonate.

The use of CO2 and CO2-derived chemicals offers society sustainable and biocompatible chemistry for a variety of applications, ranging from materials to medicines. In this context, dimethyl carbonate (DMC) stands out owing to its low toxicity, high biodegradability, tunable reactivity, and sustainable production. Further, the ability of DMC to act as an ambient electrophile at varied temperatures and reaction conditions in order to produce methoxycarbonylated (via BAC2) and methylated products (via BAL2) is very promising. While the methylation of hetero-H (N-, O-, and S-methylation) with DMC is established and well-reviewed, the C-H methylation reaction with DMC is limited, and there is no specific literature detailing the C-methylation reaction using DMC, creating new opportunities as well as challenges in the same domain. In this context, the present perspective focuses on the new breakthroughs, recent advances, and trends in C-H methylation reactions employing DMC. A critical analysis of the mechanistic course of reactions under each category was undertaken. We believe this timely perspective will offer an in-depth analysis of existing literature with critical remarks, which will certainly inspire fellow researchers across disciplines to understand and pursue cutting-edge research in the area of C-H methylation (alkylation) using DMC and related organic carbonates.

Exploring the Reactivity of Electrophilic Organic Carbonates and Thiocarbonates as Vehicles to Convert Hydrosulfide into COS and CS2.

Hydrogen sulfide (H2S) and other reactive sulfur species are important small molecules with biological significance. In addition to common reactive sulfur species like H2S, polysulfides, and persulfides, both carbonyl sulfide (COS) and carbon disulfide (CS2) have been postulated to be potential sources of reduced sulfur. To better understand this possible connection, we demonstrate that H2S can be converted to COS and CS2 by reaction with simple organic carbonate and thiocarbonate electrophiles, respectively.

Non-hydrolytic sol-gel synthesis of amine-functionalized silica: Template- and catalyst-free preparation of mesoporous catalysts for CO2 valorization

Carbon dioxide utilization presents an important and topical research topic. However, the performance of catalysts needed for CO2 transformations does not achieve the necessary levels for their widespread application. To this end, we decided to study non-aqueous condensations providing amine-functionalized silica catalysts, possibly active in CO2-epoxide cycloaddition reaction. While non-hydrolytic sol-gel method is well-known for its efficiency in providing highly porous Lewis and Brønsted acid metallosilicates, here we show for the first time its application for the preparation of silica-based catalysts containing basic groups. First, the reaction conditions were screened to reproducibly obtain porous materials with preserved amine moieties. These were identified as follows: silicon tetraacetate and bridging tertiary amine silanes as precursors, toluene as a solvent, and temperature between 160 and 180 °C. In such a way, materials with up to 776 m2 g−1 and 1.58 cm3 g−1 were obtained in one-step process, without any template, after conventional drying step. Next, the amine-functionalized materials were tested in CO2-epoxide coupling providing cyclic organic carbonates with high selectivity (>99 %) and moderate activity (up to 86 % epichlorohydrin conversion after 1 h at 120 °C and 10 bar CO2). The characterization of spent catalysts revealed a presence of cyclic organic carbonates at the catalyst surface as well as conversion of tertiary amine groups to quaternary ammonium moieties.

Molecular Architecture @ MOFs: Designing a Multifunctional Catalyst for the Cascade Reaction of Olefins via Epoxides to Cyclic Carbonates

Employing enzymatic reaction cascade principles to synthesize artificial materials with multiple autonomously operating active sites is one of the holy grails in modern catalysis research. In this regard, metal‐organic frameworks (MOFs) are promising host platforms. Yet, applying MOFs as enzyme‐mimicking catalysts is synthetically challenging. Herein, we present a design strategy for the synthesis of porphyrin‐based MOFs for the cascade catalysis of the conversion of olefins to epoxides and their cycloaddition with CO2 to cyclic carbonates. The MOFs feature tunable dual active sites with synthetically controllable metal variations. A clear dependence of the metal combination on the catalytic performance of the MOF catalysts is shown. This work advances the understanding essential for designing sophisticated, multifunctional porphyrin MOFs for efficient one‐pot cascade catalysis.