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A novel approach is reported to prepare 3D-printed polymers that incorporate metal-organic frameworks (MOFs) through a one-pot growth process, involving covalent grafting and growth onto 3D polymeric surfaces. The resulting hybrid materials were subjected to comprehensive characterization using techniques such as SEM, XRD, FTIR, Raman, and XPS. The findings demonstrated an excellent dispersion of the inorganic units on the polymer matrix while preserving their metal-organic structure. The hybrid materials exhibited the presence of Lewis acid and basic groups within the MOF. The catalytic performance of these hybrid materials was evaluated in the mild cycloaddition reaction of carbon dioxide (CO2) to epoxides. Notably, the polymers incorporating UiO-67 MOFs displayed remarkable activity, even at low CO2 pressures and in the absence of auxiliary co-catalysts or additives. The catalytic activity of these hybrid materials exhibited a significant improvement, up to two orders of magnitude higher than analogous bulk MOFs. This observation highlights the superior performance of the 3D-printed polymer/MOF hybrids in this catalytic transformation.

Polymeric foams are widely used in many industrial applications due to their light weight and superior thermal, mechanical, and optical properties. Currently, increasing research efforts is being directed towards the development of greener foam formulations that circumvent the use of isocyanates/blowing agents that are commonly used in the production of foam materials. Here, a straightforward, one‐pot method is presented to prepare self‐blown polycarbonate (PC) foams by exploiting the (decarboxylative) S‐alkylation reaction for in situ generation of the blowing agent (CO2). The concomitant formation of a reactive alcohol intermediate promotes a cascade ring‐opening polymerization of the cyclic carbonates to yield a cross‐linked polymer network. It is shown that these hydroxyl‐functionalized polycarbonate‐based foams can be easily recycled into films through thermal compression molding. Furthermore, it is demonstrated that complete hydrolytic degradation of the foams is possible, thus offering the potential for zero‐waste materials. This straightforward and versatile process broadens the scope of isocyanate‐free, self‐foaming materials, opening a new pathway for next‐generation environmentally friendly foams. [ABSTRACT FROM AUTHOR]

The biocatalytic kinetic resolution of cyclic carbonates derived from glycerol is reported. A selection of 26 esterases and lipases was tested for the asymmetric hydrolysis of the model substrate (epichlorohydrin carbonate) in aqueous medium. Among them, Pig Liver Esterase and Novozym® 435 showed the best selectivity with E=38 and 49, respectively. Both enzymes were employed for the conversion of 12 glycerol derivatives under optimized conditions. The resolution of halogenated carbonates afforded the unconverted enantiomer in up to >99 : 1 er. Furthermore, Novozym® 435 was successfully recycled 10 times without significant loss of activity. Upscaling and isolation of the chiral carbonate was also demonstrated. Subsequent conversion of this chiral building block allowed the direct one‐pot synthesis of (S)‐Guaifenesin, (S)‐Mephenesin and (S)‐Chlorphenesin in up to 89 % yield and 94 : 6 er. [ABSTRACT FROM AUTHOR]

One of the efficient approaches to achieving net-zero greenhouse gas emissions is the 100% atom-economical conversion of the greenhouse gas carbon dioxide (CO2) to cost-effective, less toxic cyclic carbonates that can act as green solvents and abundant C1 synthon in organic synthesis. In this work, we have synthesized an Indium Metal–Organic Framework (MOF), functionalized with triazole MIL-68(In)-NHTr (Tr = 1-methylene-1,2,4-triazole) as a bifunctional catalyst for the synthesis of cyclic carbonates from epoxides with high yield (96%) and selectivity (100%) under solvent-free ambient reaction conditions (CO2 pressure 1 bar, temperature 50 °C, and reaction time 6 h). The synergistic acid–base effect of Indium SBU and the triazole of MIL-68(In)-NHTr make this a better catalyst than the conventional MIL-68(In)-NH2. This new catalyst was non-leachable and was reusable for six consecutive catalytic cycles without appreciable loss in the catalytic efficiency and crystallinity of the MOF framework. [ABSTRACT FROM AUTHOR]

Benzamide‐derived organochalcogens (chalcogen=S, Se, and Te) have shown promising interest in biological and synthetic chemistry. Ebselen molecule derived from benzamide moiety is the most studied organoselenium. However, its heavier congener organotellurium is under‐explored. Here, an efficient copper‐catalyzed atom economical synthetic method has been developed to synthesize 2‐phenyl‐benzamide tellurenyl iodides by inserting a tellurium atom into carbon‐iodine bond of 2‐iodobenzamides in one pot with 78–95 % yields. Further, the Lewis acidic nature of Te center and Lewis basic nature of nitrogen of the synthesized 2‐Iodo‐N‐(quinolin‐8‐yl)benzamide tellurenyl iodides enabled them as pre‐catalyst for the activation of epoxide with CO2 at 1 atm for the preparation of cyclic carbonates with TOF and TON values of 1447 h−1 and 4343, respectively, under solvent‐free conditions. In addition, 2‐iodo‐N‐(quinolin‐8‐yl)benzamide tellurenyl iodides have also been used as pre‐catalyst for activating anilines and CO2 to form a variety of 1,3‐diaryl ureas up to 95 % yield. The mechanistic investigation for CO2 mitigation is done by 125Te NMR and HRMS studies. It seems that the reaction proceeds via formation of catalytically active Te−N heterocycle, an ebtellur intermediate which is isolated and structurally characterized. [ABSTRACT FROM AUTHOR]

• Novel heterogeneous dual-ionic PILs were prepared from readily available starting materials. • The PILs exhibited excellent performance for CO 2 cycloaddition with various epoxides under mild conditions. • The catalyst showed great recyclability and scale-up potential. • Key catalytic active sites were probed and a reasonable mechanism was proposed accordingly. In the context of peaking carbon dioxide emissions and carbon neutrality, development of feasible methods for converting CO 2 into high value-added chemicals stands out as a hot subject. In this study, P[D+COO−][Br−][DBUH+], a series of novel heterogeneous dual-ionic poly(ionic liquid)s (PILs) were synthesized readily from 2-(dimethylamino) ethyl methacrylate (DMAEMA), bromo-substituted aliphatic acids, organic bases and divinylbenzene (DVB). The structures, compositions and morphologies were characterized or determined by nuclear magnetic resonance (NMR), thermal gravimetric analysis (TGA), infrared spectroscopy (IR), scanning electron microscopes (SEM), and Brunauer-Emmett-Teller analysis (BET), etc. Application of the P[D+COO−][Br−][DBUH+] series as catalysts in converting CO 2 into cyclic carbonates showed that P[D+COO−][Br−][DBUH+]-2/1/0.6 was able to catalyze epiclorohydrin-CO 2 cycloaddition the most efficiently. This afforded chloropropylene carbonate (CPC) in 98.4% yield with ≥ 99% selectivity in 24 hr under solvent- and additive-free conditions at atmospheric pressure. Reusability experiments showed that recycling of the catalyst 6 times only resulted in a slight decline in the catalytic performance. In addition, it could be used for the synthesis of a variety of differently substituted cyclic carbonates in good to excellent yields. Finally, key catalytic active sites were probed, and a reasonable mechanism was proposed accordingly. In summary, this work poses an efficient strategy for heterogenization of dual-ionic PILs and provides a mild and environmentally benign approach to the fixation and utilization of carbon dioxide. [Display omitted] [ABSTRACT FROM AUTHOR]

The cycloaddition of CO2 to epoxides to afford versatile and useful cyclic carbonate compounds is a highly investigated method for the nonreductive upcycling of CO2. One of the main focuses of the current research in this area is the discovery of readily available, sustainable, and inexpensive catalysts, and of catalytic methodologies that allow their seamless solvent-free recycling. Water, often regarded as an undesirable pollutant in the cycloaddition process, is progressively emerging as a helpful reaction component. On the one hand, it serves as an inexpensive hydrogen bond donor (HBD) to enhance the performance of ionic compounds; on the other hand, aqueous media allow the development of diverse catalytic protocols that can boost catalytic performance or ease the recycling of molecular catalysts. An overview of the advances in the use of aqueous and biphasic aqueous systems for the cycloaddition of CO2 to epoxides is provided in this work along with recommendations for possible future developments.

This study introduces an efficient strategy for synthesizing polyhydroxyurethane-based multicomponent hydrogels with enhanced rheological properties. In a single-step process, 3D materials composed of Polymer 1 (PHU) and Polymer 2 (PVA or gelatin) were produced. Polymer 1, a crosslinked polyhydroxyurethane (PHU), grew within a colloidal solution of Polymer 2, forming an interconnected network. The synthesis of Polymer 1 utilized a Non-Isocyanate Polyurethane (NIPU) methodology based on the aminolysis of bis(cyclic carbonate) (bisCC) monomers derived from 1-thioglycerol and 1,2-dithioglycerol (monomers A and E, respectively). This method, applied for the first time in Semi-Interpenetrating Network (SIPN) formation, demonstrated exceptional orthogonality since the functional groups in Polymer 2 do not interfere with Polymer 1 formation. Optimizing PHU formation involved a 20-trial methodology, identifying influential variables such as polymer concentration, temperature, solvent (an aprotic and a protic solvent), and the organo-catalyst used [a thiourea derivative (TU) and 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU)]. The highest molecular weights were achieved under near-bulk polymerization conditions using TU-protic and DBU-aprotic as catalyst–solvent combinations. Monomer E-based PHU exhibited higher Mw¯ than monomer A-based PHU (34.1 kDa and 16.4 kDa, respectively). Applying the enhanced methodology to prepare 10 multicomponent hydrogels using PVA or gelatin as the polymer scaffold revealed superior rheological properties in PVA-based hydrogels, exhibiting solid-like gel behavior. Incorporating monomer E enhanced mechanical properties and elasticity (with loss tangent values of 0.09 and 0.14). SEM images unveiled distinct microstructures, including a sponge-like pattern in certain PVA-based hydrogels when monomer A was chosen, indicating the formation of highly superporous interpenetrated materials. In summary, this innovative approach presents a versatile methodology for obtaining advanced hydrogel-based systems with potential applications in various biomedical fields.

The present work focuses on developing heterogeneous catalysts for conversion of CO2 and mono-/di-epoxides to mono-/bis-cyclic carbonates. To achieve this purpose, two types of recyclable solid catalysts, namely polyurethane (PU-BTP) and polyurethane modified on silica gel-solid support (SG-AU-BPT), are synthesized. On these catalysts, the key promoter CaI2 is pre-absorbed. Both catalysts show high catalytic activity under mild conditions. For example, phenyl glycidyl ether (PGE) can be converted to 4-(phenoxymethyl)− 1,3-dioxolan-2-one at 60 °C within 6 h under 1 atm pressure of CO2. PU-BTP and SG-AU-BPT can be recollected by suction filtration and reused for eight times with conversion larger than 81% and 95% respectively. These results indicate that the degree of CaI2 leaching out from the catalysts in each cycle and loss is low.

Carbon dioxide is a cheap, easily available, and practically inexhaustible source of synthetic carbon (C1-synthon). Among various transformations of CO2, the synthesis of cyclic carbonates from epoxides and cyclic carbamates from aziridines can be referred to as priority areas in the development of contemporary chemical synthesis and catalysis. Cyclic carbonates found wide application in modern industry (electrolytes, solvents, reagents, polymers) and their use and production will be constantly increased. The development of effective catalytic processes that would allow the synthesis of carbonates under mild conditions (atmospheric pressure of CO2 or lower, temperature 25°C) and low loads of durable and affordable catalysts is at the forefront of research. In the present review we analyze the existing directions of research on the catalytic systems based earth-abundant metals Al3+, Fe2+(3+), and Zn2+ for the synthesis of cyclic carbonates from epoxides and cyclic carbamates from aziridines. [ABSTRACT FROM AUTHOR]

Development of an effective catalytic system for the cycloaddition of carbon dioxide to epoxides for the preparation of cyclic carbonates under mild conditions is of great importance. Herein, a mixture of zinc iodide, metal chlorides, and strong organic bases is demonstrated to be a useful catalytic system that works at room temperature under atmospheric pressure. The most efficient combination, zinc iodide-niobium chloride-7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (1.2-0.3-3.0 mol%), gave styrene carbonate (95%) from styrene oxide and CO2 (balloon) at 25 °C for 24 h. Another combination, zinc iodide-zinc chloride-1,8-diazabicyclo[5.4.0]undec-7-ene (1.2-0.8-4.0 mol%), kept the catalytic activity for the preparation of propylene carbonate until the fourth run. Therefore, the reaction system was operationally simple, highly efficient, and proceeded under ambient conditions. The catalyst is composed of readily available reagents and is reusable. Thus, the method presented is a powerful tool for utilizing CO2 as the starting material for the production of valuable chemicals. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The reaction of carbon dioxide (CO2) with epoxide to generate cyclic carbonates is one of the most effective chemical fixation methods. The catalytic system significantly affects the carbon fixation efficiency of the reaction. Among the reported catalytic systems, porous materials as heterogeneous catalysts have attracted significant attention. This study aimed to summarize porous materials that catalyzed the conversion of CO2 into cyclic carbonates, including metal organic frameworks, covalent organic frameworks, poly(ionic) liquids, hyper crosslinked polymers, conjugated porous polymers and others. The study analyzed the catalytic properties of these materials and outlined future research directions. [ABSTRACT FROM AUTHOR]

The utilization of CO2 as building block for the production of cyclic carbonate is a promising route to simultaneously mitigate the global warming issue and obtain valuable commercial chemicals. In this work, the activity of nicotinamidium halide catalysts towards the CO2 conversion into cyclic carbonate has been explored by means of density functional theory (DFT) calculations. DFT calculations support the ability, suggested experimentally, of the pyridium α‐C−H proton of the catalysts to activate the epoxide ring via a hydrogen bond. Interestingly, DFT calculations underline the involvement of the n‐octyl substituent of the pyridyl ring in the epoxide activation, while the hydrogen atom of the amide group N−H is rather involved in the stabilization of the iodide trough electrostatic interactions. Moreover, the replacement of the pyridium α‐C−H proton with the bulkier methyl group leads to a different reaction mechanism. The calculated energy barriers well reproduce the experimental trends of the studied catalysts, and the computed activation barrier of 29.0 kcal/mol, relative to the ring opening step of the most active catalyst, is in line with the experimental working temperature of 80 °C. Those results shed light on the CO2 fixation reaction contributing to the development of more efficient catalytic systems. [ABSTRACT FROM AUTHOR]

A one-pot multicomponent green process is investigated for the synthesis of perfluoroalkylated cyclic carbonate which merges the photo-promoted Atom Transfer Radical Addition (ATRA) of a perfluoroalkyl iodide (Rf-I) onto allyl alcohols with the Lewis-base-promoted carboxylative cyclization. The evolution of the complex mixture during the reaction was monitored by in situ ATR-IR and Raman spectroscopies that provided insights into the reaction mechanism. The effect on the kinetics and the carbonate yields of key parameters such as the stoichiometry of reagents, the nature of the Lewis base and the solvent, the temperature and the pressure were evaluated. It was found that high yields were obtained using strong Lewis bases that played both the role of activating the allyl alcohol for the generation of the allyl carbonate in the presence of CO2 and promoting the ATRA reaction through the activation of C4F9I by halogen bonding. This protocol was also extended to various unsaturated alcohols. [ABSTRACT FROM AUTHOR]

The development of efficient methods for the cycloaddition of CX2 (carbon dioxide (X${=}$O) or carbon disulfide (X${=}$S)) with fluorinated epoxides to produce five-membered cyclic carbonates (CCs) or cyclic xanthates (XAs) is a very attractive topic. In this work, the cycloaddition of CX2 with hexafluoropropene oxide (HFPO) was performed in the presence of a lithium bromide (LiBr) catalyst and optimized in terms of temperature, solvent, pressure, and reaction time. Then, the optimized conditions were tried in the cycloaddition of CX2 with 2-(trifluoromethyl)oxirane (TFEO) for reproducibility, leading to the corresponding products in high yields. Finally, two original fluorinated five-membered bis-CCs and bis-XAs were synthesized in high yields (85 and 87%) by reacting CX2 with 1,4-bis($2^{\prime }{,}3^{\prime }$-epoxypropyl) perfluorobutane (BEPFB). All of the resulting compounds were characterized by FTIR, 1H, 19F, and 13C NMR spectroscopy.

The cycloaddition of CO2 to epoxides to afford cyclic organic carbonates is an increasingly relevant non-reductive strategy to convert CO2 to useful products able to serve as high-boiling solvents, chemical intermediates, and monomers for the preparation of more sustainable polymers. The development of efficient and robust heterogeneous catalysts for such transformation is, therefore, crucial and can be carried out by several strategies that often require the preparation of sophisticated and/or expensive organic networks, linkers, or compounds. A different approach to the preparation of heterogeneous catalysts for CO2-epoxide coupling is by applying surface science methodologies to graft molecular fragments or single atoms on various supports leading to well-defined active sites. In this context, surface organometallic chemistry (SOMC), along with comparable methodologies, is a valuable approach for the preparation of efficient, single-site Lewis acids and catalysts for the target cycloaddition reaction on metal oxides, whereas, other grafting methodologies, can be applied to prepare analogous catalysts on different kinds of surfaces. Finally, we discuss very recent advances in the application of surface methodologies for the preparation of single atom catalysts as an increasingly relevant approach towards highly active Lewis acids for the cycloaddition of CO2 to epoxides. Overall, we show that Lewis acids and catalysts prepared by facile surface methodologies hold significant potential for future application in the synthesis of cyclic carbonates from CO2.

Novel mono- and bimetallic scorpionate aluminum compounds have been designed and characterized by spectroscopic methods. These organometallics complexes, in combination with tetrabutylammonium bromide as cocatalyst, displayed good catalytic activity for the cycloaddition of styrene oxide and CO2 under ambient conditions. Among the compounds tested, monometallic complex 3 featuring diethylamino groups showed the highest catalytic activity. This catalytic system catalyzed the formation of cyclic carbonate products from their corresponding epoxides at room temperature and 1 bar of CO2 pressure in the absence of a solvent in good yields and excellent selectivities.

An effective approach for tuning CO2 adsorption, activation and transformations of various epoxides in CO2 fixation reactions is introducing functional groups into the pores of metal‐organic frameworks (MOFs) through ligand modification. Herein, a novel ionic ligand, 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene‐biphenyl‐4,4′‐dicarboxylic acid (H2BPDC−[TBD]+Br−), was synthesized to construct derivatives of the cationic guanidinium‐containing Zr‐MOF (UiO67‐[TBD]+Br−) with free bromide ions, as multifunctional heterogeneous catalysts. The materials were characterized comprehensively by multiple techniques such as PXRD, FTIR, TGA, SEM, EDS, 1H NMR, 13C NMR, mass spectrometry (MS), elemental analysis, as well as N2 and CO2 adsorption measurements. The synthesized UiO67‐[TBD]+Br− exhibits an efficient heterogeneous catalytic performance in the CO2 fixation reaction with epoxides, with high yield and selectivity, under mild conditions (0.1 MPa CO2, 80 °C, without co‐catalyst and solvent). In addition, these catalysts display good thermal stability, recyclability and could be reused at least five times without a significant decrease in their catalytic performance. [ABSTRACT FROM AUTHOR]

The development of efficient bifunctional organocatalysts for the catalytic conversion of CO2 under mild conditions remains particularly challenging. Inspired by the synergistic mechanism of intramolecular Lewis acid‐base active sites, we report a series of bifunctional cross‐linked epoxy resin organocatalysts containing multiple active sites for the cycloaddition reaction of dilute CO2 with epoxides. These catalysts exhibit high reactivity and product selectivity (10 examples, >99 %) for the cycloaddition reactions of a variety of epoxides and CO2, and surprisingly, epichlorohydrin (ECH), can be converted under ambient temperature and pressure (25 °C, 1.0 bar) without co‐catalysts. 1H NMR, 13C NMR, 19F NMR and in situ IR studies suggest that the simultaneous and efficient activation of CO2 and epoxides is responsible for the improved catalytic activity. Upon an insightful investigation of the catalytic mechanism, this protocol will contribute to the development of efficient and environmentally friendly metal‐free catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Fossil fuel has empowered a remarkable era of prosperity and development of the welfare of human society. However, the resulting large anthropogenic CO 2 emissions had an adverse impact on global temperature. Furthermore, the scarcity of limited fossil fuel resources will eventually force them to look for alternative carbon sources to sustain a sustainable economy. Chemical fixation of CO 2 into fuels and valuable chemicals via renewable energy sources has been attracting human society for not only alleviating CO 2 emissions but also reducing reliance on non-renewable energy sources and minimizing the impact on the environment from displaced fossil fuel fractions. Cyclic carbonate is a valuable CO 2 product that can be used as aprotic solvent, the electrolytic solvent in lithium batteries, degreasing solvents, and intermediates for the synthesis of polycarbonates, drugs, and cosmetics. It can be synthesized via cycloaddition of CO 2 with epoxide under the catalytic condition due to the low reactivity of CO 2 (thermodynamic as well as kinetic inert). An ideal catalyst for this conversion is composed of a Lewis acid to activate the epoxide ring and a Lewis base to open the epoxide ring. Efforts have been done to synthesize various catalytic systems for cyclic carbonate formation. The review is focused on metal-catalyzed cyclic carbonate formation. It begins with carbon capturing, storage, and utilization (CCSU) along with the importance of cyclic carbonate. The mechanism for cyclic carbonate formation was classified into two categories including binary and bifunctional systems based on the presence of nucleophilic moiety either as a separate entity or attached to a catalyst. Various metal catalysts such as metal salen, metal porphyrin, metal salts, metal–organic framework, and zeolitic imidazolate framework are discussed with recent progress in the development. It was believed that homogeneous catalysts showed high catalytic activity but difficult product separation whereas heterogeneous catalysts can be easily separated by simple filtration. Finally, the conclusion and the future outlook in the development of catalysts for cyclic carbonate formation are mentioned. [ABSTRACT FROM AUTHOR]

The fixation of atmospheric CO2 into value‐added products is a promising methodology. A series of novel nickel(II) complexes of the type [Ni(L)(CH3CN)2](BPh4)21–5, where L=N,N‐bis(2‐pyridylmethyl)‐N′, N′‐dimethylpropane‐1,3‐diamine (L1), N,N‐dimethyl‐N′‐(2‐(pyridin‐2‐yl)ethyl)‐N′‐(pyridin‐2‐ylmethyl) propane‐1,3‐diamine (L2), N,N‐bis((4‐methoxy‐3,5‐dimethylpyridin‐2‐ylmethyl)‐N′,N′‐dimethylpropane‐1,3‐diamine (L3), N‐(2‐(dimethylamino) benzyl)‐N′,N′‐dimethyl‐N‐(pyridin‐2‐ylmethyl) propane‐1,3‐diamine (L4) and N,N‐bis(2‐(dimethylamino)benzyl)‐N′, N′‐dimethylpropane‐1,3‐diamine (L5) have been synthesized and characterized as the catalysts for the conversion of atmospheric CO2 into organic cyclic carbonates. The single‐crystal X‐ray structure of 2 was determined and exhibited distorted octahedral coordination geometry with cis‐α configuration. The complexes have been used as a catalyst for converting CO2 and epoxides into five‐membered cyclic carbonates under 1 atmospheric (atm) pressure at room temperature in the presence of Bu4NBr. The catalyst containing electron‐releasing −Me and ‐OMe groups afforded the maximum yield of cyclic carbonates, 34% (TON, 680) under 1 atm air. It was drastically enhanced to 89% (TON, 1780) under pure CO2 gas at 1 atm. It is the highest catalytic efficiency known for CO2 fixation using nickel‐based catalysts at room temperature and 1 atm pressure. The electronic and steric factors of the ligands strongly influence the catalytic efficiency. Furthermore, all the catalysts can convert a wide range of epoxides (ten examples) into corresponding cyclic carbonate with excellent selectivity (>99%) under this mild condition. [ABSTRACT FROM AUTHOR]

Nanomaterials based on tin (IV) oxide (SnO 2) and zinc oxide (ZnO) were investigated in the search for active, environmentally benign, and inexpensive materials for the crucial reaction of CO 2 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, SnO 2 -NPs, served as an active material for the cycloaddition of CO 2 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, SnO 2 -NPs could also be used in the presence of impure CO 2 feeds (20% methane in CO 2) resembling low calorific landfill gas and could be recycled and reused. Overall, SnO 2 -NPs represent a promising, readily available, and inexpensive metal oxide-based material to produce cyclic carbonates under atmospheric CO 2 pressure. • Nanosized oxides of zinc and tin were explored for the synthesis of cyclic carbonates. • SnO 2 -NPs and TBAI catalyze the coupling of CO 2 and epoxides at atmospheric pressure. • Impure CO 2 could be used as the feed gas and the SnO 2 -NPs could be recycled. [ABSTRACT FROM AUTHOR]

The fixation of carbon dioxide with epoxides is one of the most attractive methods for the green utilisation of this greenhouse gas and leads to many valuable chemicals. This process is characterised by 100% atom efficiency; however, an efficient catalyst is required to achieve satisfactory yields. Metal–organic frameworks (MOFs) are recognised as being extremely promising for this purpose. Nevertheless, many of the proposed catalysts are based on ions of rare elements or elements not entirely safe for the environment; this is notable with commercially unavailable ligands. In an effort to develop novel catalysts for CO2 fixation on an industrial scale, we propose novel MOFs, which consist of aluminium ions coordinated with commercially available 1,4-naphthalene dicarboxylic acid (Al@NDC) and their nanocomposites with gold nanoparticles entrapped inside their structure (AlAu@NDC). Due to the application of 4-amino triazole and 5-amino tetrazole as crystallization mediators, the morphology of the synthesised materials can be modified. The introduction of gold nanoparticles (AuNPs) into the structure of the synthesised Al-based MOFs causes the change in morphology from nano cuboids to nanoflakes, simultaneously decreasing their porosity. However, the homogeneity of the nanostructures in the system is preserved. All synthesised MOF materials are highly crystalline, and the simulation of PXRD patterns suggests the same tetragonal crystallographic system for all fabricated nanomaterials. The fabricated materials are proven to be highly efficient catalysts for carbon dioxide cycloaddition with a series of model epoxides: epichlorohydrin; glycidol; styrene oxide; and propylene oxide. Applying the synthesised catalysts enables the reactions to be performed under mild conditions (90 °C; 1 MPa CO2) within a short time and with high conversion and yield (90% conversion of glycidol towards glycerol carbonate with 89% product yield within 2 h). The developed nanocatalysts can be easily separated from the reaction mixture and reused several times (both conversion and yield do not change after five cycles). The excellent performance of the fabricated catalytic materials might be explained by their high microporosity (from 421 m2 g−1 to 735 m2 g−1); many catalytic centres in the structure exhibit Lewis acids’ behaviour, increased capacity for CO2 adsorption, and high stability. The presence of AuNPs in the synthesised nanocatalysts (0.8% w/w) enables the reaction to be performed with a higher yield within a shorter time; this is especially important for less-active epoxides such as propylene oxide (two times higher yield was obtained using a nanocomposite, in comparison with Al-MOF without nanoparticles).

2–(1H–1,2,4–Triazol–3–yl)phenol (CAT–1) was used as an organocatalyst for the coupling reaction of CO2 and epoxides at an ambient temperature and atmospheric CO2 pressure (1 bar). This compound has a structure in which a hydrogen bond donor, a hydrogen bond acceptor, and another hydrogen bond donor are adjacent in sequence in a molecule. The binary catalytic system of CAT–1/nBu4NI showed TON = 19.2 and TOF = 1.60 h−1 under 1 bar CO2 at room temperature within 12 h using 2–butyloxirane. Surprisingly, the activity of CAT–1, in which phenol and 1H–1,2,4–triazole are chemically linked, showed a much greater synergistic effect than when simply mixing the same amount of phenol and 1H–1,2,4–triazole under the same reaction conditions. In addition, our system showed a broad terminal and internal epoxide substrate scope.

Herein, we report the application of four amino-tris(phenolate)-based metal complexes incorporating Ti(IV) or Zr(IV) centres (2a-3b) as homogeneous catalysts for the conversion of CO2 and epoxides into cyclic carbonates. The four complexes were synthesised, characterised and then evaluated in combination with tetrabutylammonium iodide, bromide or chloride as binary catalytic systems for the reaction of CO2 with 1,2-epoxyhexane as epoxide substrate at 12 bar CO2 pressure and 90 °C for 2 h. The catalytic systems comprising the two Ti(IV) complexes (2a and 2b) showed similar performance. One notable exception was the catalytic system consisting of titanium complex 2b, bearing an axial Cl-ligand, and tetrabutylammonium chloride, which displayed higher catalytic activity compared to other titanium-based systems. Even higher activity was achieved with Zr(IV) complex 3a, bearing an axial isopropoxide ligand, which reached turnover numbers (TONmetal) up to 1920 for the reaction of CO2 with 1,2-epoxyhexane at 12 bar CO2 pressure and 90 °C for 2 h. This performance is comparable with that of state-of-the-art catalysts for this reaction. The catalytic system consisting of complex 3a and tetrabutylammonium bromide was explored further by investigating its applicability with a broad substrate scope, achieving quantitative conversion of several epoxides with CO2 into cyclic carbonate products at 90 °C and 12 bar CO2 pressure for 18 h. The selectivity towards the cyclic carbonate products was ≥ 98% for all studied terminal epoxides and ≥ 80% for all examined cyclohexene-type epoxides.

Hypercrosslinked polymers (HCPs) constructed by Friedel‐Crafts reaction have drawn increasing attention in recent decades, but their multifunctionalization remains a huge challenge. Herein, a series of aluminum‐porphyrin‐based hypercrosslinked ionic polymers have been successfully synthesized by direct knitting approach without additional electrophilic comonomers, which involves the copolymerization of neutral porphyrin monomers and ionic building. By increasing the connected nodes numbers of ionic monomers, the introduction of abundant tetraphenylmethane fragements into the porphyrin backbones endows them with high‐density ionic active sites. Accordingly, the well‐matched molar ratios of aluminum sites to nucleophilic chloride anions that work synergistically for CO2/epoxide coupling can be achieved. Al‐HIP‐2 with flexible ionic pendants and a high Al/Cl ratio allows CO2 cycloaddition to be performed at ambient conditions or with diluted CO2; while Al‐HIP‐3 with rigid ionic moieties and a relatively low Al/Cl ratio exhibits higher specific surface area and stronger CO2 capture ability. Therefore, this co‐condensation strategy provides a simple and feasible pathway for adjusting the reactivity ratios of comonomers via simple structural changes in the knitting process, thus achieving the rational construction of multifunctionalized HCPs for CO2 capture and in‐situ conversion to cyclic carbonates. [ABSTRACT FROM AUTHOR]

Novel polyhydroxylated ammonium, imidazolium, and pyridinium salt organocatalysts were prepared through N-alkylation sequences using glycidol as the key precursor. The most active pyridinium iodide catalyst effectively promoted the carbonation of a set of terminal epoxides (80 to >95% yields) at a low catalyst loading (5 mol%), ambient pressure of CO2, and moderate temperature (75 °C) in batch operations, also demonstrating high recyclability and simple downstream separation from the reaction mixture. Moving from batch to segmented flow conditions with the operation of thermostated (75 °C) and pressurized (8.5 atm) home-made reactors significantly reduced the process time (from hours to seconds), increasing the process productivity up to 20.1 mmol(product) h−1 mmol(cat)−1, a value ~17 times higher than that in batch mode. [ABSTRACT FROM AUTHOR]

Aiming highly efficient conversion of greenhouse gas CO2 to cyclic carbonates, a biomass Ru(III) Schiff base complex catalyst (SalRu) was constructed by employing a derivative of Lignin degradation (5‐aldehyde vanillin). The SalRu catalyst had a remarkable conversion for epoxides into corresponding cyclic carbonates even at atmospheric pressure of CO2 without the presence of co‐catalyst. As the condition at 120 °C and 2 MPa CO2 the conversion reached to 94 % with selectivity at 99 % after 8 h. 32 % cyclic carbonate production was obtained even under 0.2 MPa CO2 pressure. The epoxide activation and ring opening, CO2 insertion and cyclic carbonate formation were illuminated explicitly through the of characteristic absorption peaks changing, which further providing direct and visual evidence for the mechanism proposing. This study has important theoretical significance for the comprehensive utilization of environmental pollutants and energy. [ABSTRACT FROM AUTHOR]

Highlights: PC synthesis was achieved over CaO-MgO as a catalyst. The effects of precipitating agent and Mg/Ca ratio was investigated. Best PC yield and selectivity of 96.8% and 99.8%, respectively were achieved. CaO-MgO catalyst revealed excellent reusability up to 6 cycles. A series of calcium oxide–magnesium oxide (CaO–MgO) catalysts were prepared under the effects of different precipitating agents and using varied Mg/Ca ratios. The physiochemical characteristics of the prepared catalysts were analyzed using XRD, FE-SEM, BET, FTIR, and TG/DTA techniques. Quantification of basic active sites present on the surface of the CaO–MgO catalysts was carried out using the Hammett indicator method. The as-prepared mixed oxide samples were tested for propylene carbonate (PC) synthesis through the alcoholysis of urea with propylene glycol (PG). The effects of the catalyst composition, catalyst dose, reaction temperature, and contact time on the PC yield and selectivity were investigated. The maximum PC yield of 96%, with high PC selectivity of 99% and a urea conversion rate of 96%, was attained at 160 °C using CaO–MgO catalysts prepared using a Mg/Ca ratio of 1 and Na2CO3 as a precipitating agent. The best-performing catalysts also exhibited good reusability without any significant loss in PC selectivity. It is expected that the present study will provide useful information on the suitability of different precipitating agents with respect to the catalytic properties of the oxides of Ca and Mg and their application in the synthesis of organic carbonates. [ABSTRACT FROM AUTHOR]

A novel electrochemical route for efficient cycloaddition of CO 2 and styrene oxide (SO) forming the value-added product of styrene carbonate (SC) was proposed in this manuscript using non-metallic nanocarbon material as the catalyst electrode. The synthesized hollow nanospheres (HNSs) nanocarbon materials exhibited unique advantages of porous structure with thin carbon layer, which effectively facilitated the mass and charge transfer process and promoted the electrochemical reaction kinetics. In addition, correlation between the detailed structure analysis and the catalytic activity evaluation results show that the cooperation of nitrogen and oxygen functionalities on nanocarbon played a vital role in enhancing the catalytic activity of the carbon materials. The optimized HNSs catalyst exhibited high SO conversion of 66.9% and SC selectivity of 99.8% under the chronoamperometry at −0.5 mA for 6 hs, showing great potential in practical applications. The structure-function relations reported here may shed light on the rational design of the nanocarbon catalyst electrode and related reaction system for electrochemical synthesis of SC. [Display omitted] • Electrochemical cycloaddition of CO 2 to value-added SC using non-metallic nanocarbon. • N, O co-doped hollow nanospheres nanocarbon with high mass and electron transport capacity. • N, O co-doped nanocarbon showing SO conversion of 66.9% and SC selectivity of 99.8% at −0.5 mA for 6 hs. [ABSTRACT FROM AUTHOR]

Nowadays, coatings need to fulfill a variety of requirements such as having excellent mechanical, chemical, and optical properties at low baking temperatures. On a large scale, polyisocyanates, amines or melamines are used as crosslinking agents in the coatings industry. In this work, a new self-crosslinking agent based on a hydroxy functional 6-membered carbonate with high ring tension and thus presumably lower baking temperature was synthesized and the behavior as self-crosslinking agent was compared to the crosslinking agent derived from the commercially available 5-membered glycerol carbonate. The hydroxy functional 6-membered carbonate monomer was synthesized enzymatically under mild reaction conditions from commercially available substances, linked to a hexamethylene diisocyanate trimer and self-polymerized afterward. NMR- and IR-spectroscopy and GC-MS analysis were found to be suitable techniques to characterize monomers and crosslinking agents. DSC measurements were performed to evaluate appropriate reaction parameters for the attachment reaction of the 6-membered cyclic carbonate to the polyisocyanate without ring opening. The progress of self-crosslinking has been followed by characteristic changes in IR spectra as well as time and temperature-dependent changes of storage and loss modulus while oscillating rheological crosslinking. Furthermore, glass transition temperatures of the resulting coating films are determined, and sol gel analysis was performed to estimate the degree of crosslinking. After application on steel, aluminum and glass plates application tests were performed. In addition to excellent mechanical and chemical properties, the coating film showed good adhesion to the surface and was colorless. Combining these properties with relatively low baking temperatures, 6-membered cyclic carbonate crosslinking agents could represent a new technology for the coatings industry. [ABSTRACT FROM AUTHOR]

In recent years, the chemical industry has put emphasis on designing or modifying chemical processes that would increasingly meet the requirements of the adopted proecological sustainable development strategy and the principles of green chemistry. The development of cyclic carbonate synthesis from CO2 and epoxides undoubtedly follows this trend. First, it represents a significant improvement over the older glycol phosgenation method. Second, it uses renewable and naturally abundant carbon dioxide as a raw material. Third, the process is most often solvent-free. However, due to the low reactivity of carbon dioxide, the process of synthesising cyclic carbonates requires the use of a catalyst. The efforts of researchers are mainly focused on the search for new, effective catalysts that will enable this reaction to be carried out under mild conditions with high efficiency and selectivity. Recently, deep eutectic solvents (DES) have become the subject of interest as potential effective, cheap, and biodegradable catalysts for this process. The work presents an up-to-date overview of the method of cyclic carbonate synthesis from CO2 and epoxides with the use of DES as catalysts. [ABSTRACT FROM AUTHOR]

In this study, a new and efficient solvent-less procedure was expanded to synthesize cyclic carbonate derivatives by chemical fixation of CO2 using Cu(II)/hydroxyl terminated triazine-based dendrimer (Cu(II)/TD) as a proficient heterogeneous nano-catalyst. The Cu(II)/TD nano-catalyst was characterized using TEM, TGA, FT-IR, SEM, EDS, and ICP techniques. The application of this new nano-catalyst provides the preparation of assorted cyclic carbonate derivatives in the attendance of 0.045 mol% of nano-catalyst and 0.3 MPa of CO2 pressure at 50 °C under solvent-less situations in outstanding yields. The Cu(II)/TD catalyst was able to be reprocessed and recovered many times without considerable failure of its performance. The findings strongly confirm that Cu(II)/TD can be considered as an environmentally friendly and retrievable catalyst for fixation of CO2 into the valuable products. [ABSTRACT FROM AUTHOR]

By integrating reactive Lewis acid sites and Br− nucleophilic anions, ZnBr 4 -D201 exhibited efficient catalytic activity for CCE reaction under the condition of solvent and co-catalyst free. [Display omitted] • An efficient heterogeneous catalyst ZnBr 4 -D201 for the synthesis of cyclic carbonate from CO 2 was prepared using a simple ion exchange method. • ZnBr 4 -D201 exhibited efficient catalytic activity for CCE reaction under the condition of solvent and co-catalyst free, which is superior to most of hetrogenous catalysts ever reported. • Good catalytic activity was mainly attributable to the synergistic effect of Zn2+ ions as Lewis acid sites and Br− ions as nucleophiles. Integrating reactive Lewis acid sites and nucleophilic anions into porous materials is a promising approach to develop efficient heterogeneous catalysts for the cycloaddition of CO 2 to epoxides (CCE) into cyclic carbonates. In this work, ZnBr 4 2− 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 ZnBr 4 -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, ZnBr 4 -D201 exhibited efficient catalytic activity for CCE reaction. Take the cycloaddition of CO 2 to 1,2-epoxybutane (BO) as an example, ZnBr 4 -D201 gave a BO conversion rate of 97 % and a selectivity of 98 % for cyclic carbonate with a high TOF value at 1 MPa CO 2 and 80 °C for 6 h, which is superior to most of heterogeneous catalysts ever reported. Furthermore, ZnBr 4 -D201 showed good recoverability, and the yield of cyclic carbonate was still up to 82 %. The excellent catalytic performance and convenient preparation process make ZnBr 4 -D201 have great potential for CCE reaction in practical production. [ABSTRACT FROM AUTHOR]

• ChTSC@ZIF-67 is successfully designed and fabricated. • The deep eutectic solvent moiety covalently was grafted on ZIF-67. • ChTSC@ZIF-67 is explored as a catalyst for CO 2 fixation reaction. • The reaction was carried out under solvent and co-catalyst free conditions. CO 2 is one of the dominant greenhouse gases that causes global warming and a series of serious environmental problems. The catalytic chemical conversion of CO 2 into value-added products is one of the attractive approaches. A novel zeolitic imidazolate framework (ZIF-67) has been successfully synthesized by incorporating choline chloride and thiosemicarbazide-based deep eutectic solvent onto the surface of ZIF-67, denoted as ChTSC@ZIF-67. The material's textural and physical characteristics were analyzed using powder XRD, TGA, zeta potential, SEM, and BET surface area measurements. The utilization of ChTSC@ZIF-67 as a catalyst for the conversion of epoxides and carbon dioxide into cyclic carbonates, in the absence of a co-catalyst or solvent, was investigated under various experimental conditions. Optimum conditions (3 mg catalyst, 4.0 bar CO 2 pressure, 80 °C, and 3 h reaction time) led to the production of diverse cyclic carbonates with excellent yield and selectivity. The synergistic effect between the active site in ZIF-67 and the deep eutectic solvent may be the main reason for the high catalytic activity. Furthermore, the catalyst retains its heterogeneous nature for more than six cycles, exhibiting no substantial decline in yield. [Display omitted] [ABSTRACT FROM AUTHOR]

There is a limited number of systematic CO 2 conversion studies that provide a clear understanding of the effect of the active sites of catalysts. Hence, this work examines the catalytic activity of 24 organic salts consisting of chloride, bromide or iodide anions and imidazolium, ammonium, or phosphonium-based cations, in the synthesis of hexylene and styrene carbonates from CO 2 , resulting in a diverse range of yields. The findings revealed that high yields depend heavily on catalyst solubility in the reaction medium, but solubility alone does not guarantee reaction success. This finding supports the new hypothesis that catalyst dissociation, reliant on solubility, is a critical factor in defining the catalytic activity. A strong correlation was observed between carbonate yields and the dissociation constants of catalysts, calculated using the COSMO-RS method. This suggests that greater dissociation, reflecting weaker cation-anion interactions, facilitates the anion nucleophilic attack on the epoxide. Also, the relationship between calculated dissociation constant and experimental ionic conductivity was successfully validated. This highlights the significance of organic salt dissociation on catalytic performance and validates the use of computational tools to predict key operational parameters, enhancing the understanding and optimization of CO 2 conversion into cyclic carbonates. [Display omitted] • Systematic study of 24 organic salts to synthesize hexylene and styrene carbonates from CO 2. • Demonstration of the importance of catalyst solubility and dissociation in the epoxide. • Strong correlation between experimental yields and computationally calculated dissociation constants of catalysts. • Consistency between calculated dissociation constants and experimental ionic conductivity. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) utilization as C1 feedstock under metal/co-catalyst-free conditions facilitates the development of eco-friendly routes for mitigating atmospheric CO 2 concentration and producing value-added compounds. In this regard, herein, we designed a bifunctional porous organic polymer (POP-1) by incorporating acidic (-CONH) and CO 2 -philic (-NH/N) sites by judicious choice of organic precursors. Indeed, POP-1 exhibits high heat of interaction for CO 2 (40.2 kJ/mol) and excellent catalytic performance for transforming carbon dioxide to cyclic carbonates, a high-value commodity chemical with high selectivity and yield under metal/cocatalyst/solvent-free atmospheric pressure conditions. Interestingly, an analogous polymer (POP-2) that lacks basic (-NH/N) sites showed lower CO 2 interaction energy (31.6 kJ/mol) and catalytic activity than that of POP-1. The theoretical studies further supported the superior catalytic activity of POP-1 in the absence of Lewis acidic metal and cocatalyst. Notably, POP-1 showed excellent reusability with retention of catalytic performance for multiple cycles of usage. Overall, this work presents a novel approach to metal/cocatalyst/solvent-free utilization of CO 2 under eco-friendly atmospheric pressure conditions. [Display omitted] • Rational design of bifunctional porous organic polymers (POPs) for fixation of CO 2. • The POP-1 exhibits selective CO 2 adsorption with interaction energy of 40.2 kJ/mol. • Metal/cocatalyst/solvent-free CO 2 fixation at ambient conditions is demonstrated. [ABSTRACT FROM AUTHOR]

Chemical conversion of CO 2 to cyclic carbonates is one of the most attractive strategies for CO 2 capture and storage utilization. Herein, a binary organocatalyst of 3-aminobenzylalcohol/ n -Bu 4 NI was used to gently catalyze the insertion of CO 2 into the terminal/internal epoxides to generate cyclic carbonates under metal-free and solvent-free conditions. Twelve representative terminal epoxides reacted with CO 2 to achieve excellent cyclic carbonate yields of up to 98.3 % at 30 °C and 1 atm CO 2 and six low activity internal di-substituted epoxides were converted to corresponding cyclic carbonates with yields of up to 96.2 %. Experiments on actual flue gas and water resistance revealed the potential industrial value of this binary organocatalyst. The yield of cyclic carbonate reached 99 % by using actual flue gas under very mild conditions of 60 °C and 1 atm. The results of 4-fold epoxide amplification experiment showed that the residual CO 2 in the flue gas was only 793 ppm after reaction at 1 atm and 60 °C, indicating the good CO 2 capture and conversion ability. Reaction kinetics and catalytic mechanism of the cycloaddition were investigated in detail. The synergistic effect among functional groups of catalysts on substrates is the essential factor for the high activity of the catalyst. [Display omitted] • A binary organocatalyst was developed to efficiently catalyze the cycloaddition of CO 2 and epoxides under mild conditions. • The binary organocatalyst can be applied to the removal of CO 2 in actual flue gas. • The yield of cyclic carbonate reached 99 % by using actual flue gas. • The binary organocatalyst exhibits excellent water-resistance and reusability. [ABSTRACT FROM AUTHOR]