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The cycloaddition of carbon dioxide to epoxide (CCE) reaction stands out as one of the few feasible chemical processes for catalytically fixing CO2. Traditionally, halide anions were frequently used as cocatalysts for catalysing the CCE reaction owing to their excellent nucleophilic and leaving abilities. However, halides are known for their corrosive effects on process reactors, and their treatment is challenging. Consequently, there is a substantial increase in the demand for halide-free catalysis in the CCE reaction. Herein, a series of bifunctional catalysts were designed for CCE reactions. The reactions were assessed under conditions of 120 °C and 1 MPa employing a catalyst loading of 0.5 mol% over 24 hours. The dual activation mechanism of the catalyst was confirmed through NMR titration and control experiments. As a bifunctional catalyst, the ion pair polarized the oxygen atom of epoxide via H-bonding with N+–H while the phenolate anion activated carbon dioxide simultaneously. This study introduces a pyridinium base binary organocatalyst as a halide-free hydrogen bond donor (HBD) anion organocatalyst with broad applicability for CO2 utilization. [ABSTRACT FROM AUTHOR]

Excessive carbon dioxide (CO2) emissions pose a serious threat to the natural environment; hence CO2 capture and utilization have been widely concerned in industrial production. At present, the high value‐added utilization of CO2 after capture has become a hot issue. Bio‐based carbonate materials with high commercial value can be generated by the reaction of CO2 and bio‐based compounds, which provides a promising, green, and sustainable material synthetic route. Bio‐based carbonate materials, which are suitable for applications in various industries, have excellent thermodynamic and mechanical properties compared with those prepared from petroleum. In this manuscript, the synthesis and utilization of bio‐based carbonates from a variety of bio‐based compounds and CO2 were briefly described, and the existing problems were put forward in the field. It provided a direction for the green utilization of CO2. [ABSTRACT FROM AUTHOR]

A series of calcined Chitosan (CS) photothermal catalysts are prepared by heating the biopolymer at different temperatures. The photothermal conversion (light to heat) ability of these calcined CS materials is evaluated by measuring the temperature change with respect to time and lamp power. The material prepared at 300 °C (Cal‐CS‐300) shows excellent photothermal conversion ability which is explored for the CO2 cycloaddition reaction with epoxides to produce cyclic carbonates under mild reaction parameters (1 atm CO2 pressure, 25 °C). The study reveals the importance of defects present in the material on both photothermal conversion and CO2 fixation efficiency. Under optimized reaction conditions, Cal‐CS‐300 is able to convert a range of epoxides into their respective cyclic carbonates (>97 % selectivity) and retains its catalytic activity (~86 %) for 5 cycles of catalysis without losing its chemical integrity. The use of ubiquitously available biopolymer together with light makes this approach sustainable for preparing value added chemicals. [ABSTRACT FROM AUTHOR]

Polyurethanes (PUs) are a class of materials usually synthesized from isocyanates, diols, and water. Water is essential for producing carbon dioxide (CO2) which is used for the self‐blowing of the foams. Due to safety concerns with the production of isocyanates, alternative chemistries have been evaluated and cyclic carbonate systems have shown great promise. In a recent advancement by Bourguignon, Grignard, and Detrembleur, a cyclic carbonate and diamine system is capable of generating CO2 for self‐blowing through hydrolysis of the carbonate‐based monomer. The authors demonstrate that with a simple variation of the diamine monomer a wide range of physical and thermo‐mechanical properties were achievable. This work represents a significant step towards safer and more environmentally friendly PUs. [ABSTRACT FROM AUTHOR]

Hybrid non‐isocyanate poly(urethanes) (HNIPUs) are designed from a precursor whose carbonate functionality is derived from epoxy‐functional statistical copolymers. Specifically, a bio‐based diene (β‐myrcene) is copolymerized via conventional free radical polymerization with glycidyl methacrylate (GMA) at different molar ratios, producing flexible copolymers with epoxy pendant groups, which are then reacted with carbon dioxide to yield the precursors with cyclic carbonate functionality. Subsequent addition of an amine‐terminated telechelic poly(propylene glycol) (PPG) forms urethane linkages in the side chains, whose concentration is tuned by varying the GMA initial molar fraction. The NIPUs are end‐capped with silanes to enable moisture curing, resulting in HNIPUs with elongations at break up to 150%, and relatively low elastic moduli varying from 32 kPa to 50 kPa as the number of urethane side linkages increases from 6 to 22. The swelling ratio of the NIPUs is also measured in tetrahydrofuran (THF). As the number of urethane side chains increases, the swelling ratio of the NIPUs decreases (710% to 620%), indicating a higher crosslinking density. All samples have gel contents higher than 50% in THF, indicating non‐crosslinked species in the hybrid samples which confirms the relatively low reported tensile moduli. [ABSTRACT FROM AUTHOR]

For 80 years, polyisocyanates and polyols were central building blocks for the industrial fabrication of polyurethane (PU) foams. By their partial hydrolysis, isocyanates release CO2 that expands the PU network. Substituting this toxic isocyanate‐based chemistry by a more sustainable variant—that in situ forms CO2 by hydrolysis of a comonomer—is urgently needed for producing greener cellular materials. Herein, we report a facile, up‐scalable process, potentially compatible to existing infrastructures, to rapidly prepare water‐induced self‐blown non‐isocyanate polyurethane (NIPU) foams. We show that formulations composed of poly(cyclic carbonate)s and polyamines furnish rigid or flexible NIPU foams by partial hydrolysis of cyclic carbonates in the presence of a catalyst. By utilizing readily available low cost starting materials, this simple but robust process gives access to greener PU foams, expectedly responding to the sustainability demands of many sectors. [ABSTRACT FROM AUTHOR]

For 80 years, polyisocyanates and polyols were central building blocks for the industrial fabrication of polyurethane (PU) foams. By their partial hydrolysis, isocyanates release CO2 that expands the PU network. Substituting this toxic isocyanate‐based chemistry by a more sustainable variant—that in situ forms CO2 by hydrolysis of a comonomer—is urgently needed for producing greener cellular materials. Herein, we report a facile, up‐scalable process, potentially compatible to existing infrastructures, to rapidly prepare water‐induced self‐blown non‐isocyanate polyurethane (NIPU) foams. We show that formulations composed of poly(cyclic carbonate)s and polyamines furnish rigid or flexible NIPU foams by partial hydrolysis of cyclic carbonates in the presence of a catalyst. By utilizing readily available low cost starting materials, this simple but robust process gives access to greener PU foams, expectedly responding to the sustainability demands of many sectors. [ABSTRACT FROM AUTHOR]

Polyurethanes (PUs) are a class of materials usually synthesized from isocyanates, diols, and water. Water is essential for producing carbon dioxide (CO2) which is used for the self‐blowing of the foams. Due to safety concerns with the production of isocyanates, alternative chemistries have been evaluated and cyclic carbonate systems have shown great promise. In a recent advancement by Bourguignon, Grignard, and Detrembleur, a cyclic carbonate and diamine system is capable of generating CO2 for self‐blowing through hydrolysis of the carbonate‐based monomer. The authors demonstrate that with a simple variation of the diamine monomer a wide range of physical and thermo‐mechanical properties were achievable. This work represents a significant step towards safer and more environmentally friendly PUs. [ABSTRACT FROM AUTHOR]

This work reports on the use of gallium aminotrisphenolate compounds as catalysts for the synthesis of cyclic carbonates from epoxides and CO2. The results show that they are highly active, and more so than the corresponding aluminium congeners. The catalyst system is applicable at low and elevated temperatures across a wide substrate scope including terminal, internal, multiple and fully deuterated epoxides. Applying low catalyst loadings has allowed for a TON of 344,000 to be obtained, highlighting their stability. A DFT investigation has confirmed that the gallium catalysts have lower energetic profiles compared to the aluminium congeners. Measurement of the Lewis acidity of both the gallium and aluminium aminotrisphenolate compounds using the Gutmann‐Beckett method provides the experimental proof that the gallium compounds are more Lewis acidic than their aluminium congeners. Finally, Ab‐Initio Molecular Dynamic (AIMD) simulations have investigated and quantified the dynamic behaviour of the catalytic systems, highlighting an important increase in fluxionality in some cases which helps to explain the increase in catalytic activity. [ABSTRACT FROM AUTHOR]

Waste‐derived fish oil (FO) can be epoxidized and reacted with CO2 to produce a cyclic carbonate containing material. Upon reaction with a bioderived amine, this leads to the formation of nonisocyanate polyurethane materials. The FO used is extracted from the by‐products produced at fish processing plants, including heads, bones, skin, and viscera. Three different methods are used for the epoxidation of the FO: (i) oxidation by 3‐chloroperoxybenzoic acid, (ii) oxidation by hydrogen peroxide and acetic acid, catalyzed by sulfuric acid, and (iii) oxidation by hydrogen peroxide catalyzed by formic acid. Synthesized FO epoxides are reacted with CO2 to yield FO cyclic carbonates with high conversions. The products are characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, thermogravimetric analysis, and viscometry. Using a biomass‐derived amine, nonisocyanate polyurethane materials are synthesized. This process can lead to new opportunities in waste management, producing valuable materials from a resource that is otherwise underutilized. [ABSTRACT FROM AUTHOR]

An aminopyridinium ionic liquid is presented as a green, tunable, and active metal-free one-component catalytic system for the atom-efficient transformation of oxiranes and CO2 to cyclic carbonates. Inclusion of a positively charged moiety into aminopyridines, through a simple single-step synthesis, provides a one-component ionic liquid catalytic system with superior activity; effective in ring opening of epoxide, CO2 inclusion, and stabilization of oxoanionic intermediates. An efficiency assessment of a variety of positively charged aminopyridines was pursued, and the impact of temperature, catalyst loading, and the kind of nucleophile on the catalytic performance was also investigated. Under solvent-free conditions, this bifunctional organocatalytic system was used for the preparation of 18 examples of cyclic carbonates from a broad range of alkyl- and aryl-substituted oxiranes and CO2, where up to 98% yield and high selectivity were achieved. DFT calculations validated a mechanism in which nucleophilic ring-opening and CO2 inclusion occur simultaneously towards cyclic carbonate formation. [ABSTRACT FROM AUTHOR]

Carbon dioxide offers an accessible, cheap and renewable carbon feedstock for synthesis. Current interest in the area of carbon dioxide valorisation aims at new, emerging technologies that are able to provide new opportunities to turn a waste into value. Polymers are among the most widely produced chemicals in the world greatly affecting the quality of life. However, there are growing concerns about the lack of reuse of the majority of the consumer plastics and their after-life disposal resulting in an increasing demand for sustainable alternatives. New monomers and polymers that can address these issues are therefore warranted, and merging polymer synthesis with the recycling of carbon dioxide offers a tangible route to transition towards a circular economy. Here, an overview of the most relevant and recent approaches to CO2-based monomers and polymers are highlighted with particular emphasis on the transformation routes used and their involved manifolds. [ABSTRACT FROM AUTHOR]

We have demonstrated the design of a novel bifunctional catalyst that is based on an N-confused tetraphenylporphyrin (NCTPP) motif for the cycloaddition of an epoxide to carbon dioxide via cooperative activation of the epoxide through a Pd(ii) or Ni(ii) metal center and a peripheral benzoate moiety with percent conversions of up to 99% and TON = 7000. [ABSTRACT FROM AUTHOR]

Given the large amount of anthropogenic CO2 emissions, it is advantageous to use CO2 as feedstock for the fabrication of everyday products, such as fuels and materials. An attractive way to use CO2 in the synthesis of polymers is by the formation of five‐membered cyclic organic carbonate monomers (5CCs). The sustainability of this synthetic approach is increased by using scaffolds prepared from renewable resources. Indeed, recent years have seen the rise of various types of carbonate syntheses and applications. 5CC monomers are often polymerized with diamines to yield polyhydroxyurethanes (PHU). Foams are developed from this type of polymers; moreover, the additional hydroxyl groups in PHU, absent in classical polyurethanes, lead to coatings with excellent adhesive properties. Furthermore, carbonate groups in polymers offer the possibility of post‐functionalization, such as curing reactions under mild conditions. Finally, the polarity of carbonate groups is remarkably high, so polymers with carbonates side‐chains can be used as polymer electrolytes in batteries or as conductive membranes. The target of this Review is to highlight the multiple opportunities offered by polymers prepared from and/or containing 5CCs. Firstly, the preparation of several classes of 5CCs is discussed with special focus on the sustainability of the synthetic routes. Thereafter, specific classes of polymers are discussed for which the use and/or presence of carbonate moieties is crucial to impart the targeted properties (foams, adhesives, polymers for energy applications, and other functional materials). Make 5CCs from CO2: Renewable scaffolds and CO2 are combined to produce five‐membered cyclic organic carbonates that serve as building blocks for the preparation of ubiquitous polymeric materials, including foams, adhesives, components of solid electrolytes in lithium batteries, and sensors. Recent advances are reviewed herein with a focus on the sustainable synthesis of monomers from renewable starting materials and on polymer applications. [ABSTRACT FROM AUTHOR]

Carbon dioxide is a renewable C1‐feedstock that is exploited for the production of polymers. In this work, we report on the conversion of CO2 into novel bis(oxo‐carbamate)s that are then exploited for the synthesis of degradable non‐isocyanate polyurethanes (NIPUs) bearing acid‐sensitive imine functions within the polymer backbone. Two CO2‐sourced bis(oxo‐carbamate)s were first prepared by the facile catalyst‐free and regioselective aminolysis of an α‐alkylidene cyclic carbonate (prepared by carboxylative coupling of CO2 with a propargylic alcohol) with two secondary diamines, piperazine and N,N'‐dimethyl‐1,6‐hexanediamine. A large diversity of poly(urethane‐co‐imine)s (PUIs) with molar masses ranging from 4500 to 8500 g/mol were then prepared by polycondensation of bis(oxo‐carbamate)s with various primary diamines, and by using Ti(OEt)4 as catalyst and drying agent. Finally, the pH‐responsiveness of PUIs was demonstrated by immersing a representative polymer in aqueous solutions at different pH. This work illustrates that hydrolytically degradable NIPUs can be constructed by polycondensation of novel CO2‐sourced monomers with diamines. [ABSTRACT FROM AUTHOR]

Abstract: To overcome the limitations of metal–organic frameworks (MOFs) for catalysis (e.g., low catalytic activities resulting from blockage of the active metal centers by organic linkers) is of great importance. Herein, we demonstrate the formation of UiO‐66 nanoparticles with ultrasmall size and linker defects with the aid of SnS2 nanosheets. The UiO‐66 nanoparticles supported by SnS2 nanosheets were found to exhibit excellent catalytic activity for the cycloaddition reaction of CO2 with propylene oxide under solvent‐free and co‐catalyst‐free conditions. Outstandingly, the catalytic activity was 11 times higher than that of the pure UiO‐66 catalyst under optimum conditions. We thus provide a promising route to modify MOF particles thus to promote their catalytic performance. [ABSTRACT FROM AUTHOR]

A cooperative methoxy transfer between orthosilicate esters and organotin oxides was developed for the synthesis of various N-alkyl and N-aryl carbamates from carbon dioxide in up to 97% isolated yield. The reaction is highly selective and N-alkylated amines are not observed. Density functional theory calculations of the reaction were performed and, together with NMR observations, a plausible mechanism featuring the catalytic regeneration of dialkyltin dialkoxide is proposed. [ABSTRACT FROM AUTHOR]

Herein the use of CaI2 in combination with poly(ethylene glycol) dimethyl ether (PEG DME 500) as an efficient catalyst system for the addition of CO2 to epoxides is reported. This protocol is based on a nontoxic and abundant metal in conjunction with a polymeric ligand. Fifteen terminal epoxides were converted at room temperature to give the desired products in yields up to 99 %. Notably, this system was also effective for the synthesis of twelve challenging internal carbonates in yields up to 98 %. [ABSTRACT FROM AUTHOR]

Bifunctional phosphorus-based organocatalysts proved to be highly efficient for the atom-economic reaction of CO2 and epoxidized oleochemicals. Notably, those products are obtained from CO2 and renewable feedstocks only. Structure-activity relationships have been deduced from a screening of 22 organocatalysts in a test reaction. Bifunctional catalysts based on a phosphonium salt bearing a simple phenolic moiety proved to be extraordinarily active under comparatively mild and solvent-free reaction conditions. In the presence of the most active organocatalyst 12 oleochemical carbonates were isolated in excellent yields up to 99 %. This organocatalyzed reaction represents an excellent example for the realization of the 12 Principles of Green Chemistry as well as the 12 Principles of CO2 Chemistry. [ABSTRACT FROM AUTHOR]

A straightforward phosgene-free synthesis of aromatic isocyanates and diisocyanates is disclosed. Theoretical investigations suggested that the insertion of carbon dioxide (CO2) by dialkyltin(IV) dialkoxides could be used to convert aromatic amines into aromatic mono- and dicarbamates. Here we show, that methyl phenylcarbamate (MPC) from aniline using organotin(IV) dimethoxide and CO2 can be formed in high yield of up to 92 %, experimentally corroborating the predictions of density functional theory (DFT) calculations. MPC was then separated from the tin oxide residues and converted into phenyl isocyanate. Furthermore, organotin(IV) alkoxides could be regenerated from the tin oxide residues and reused, paving the way for a continuous industrial process. Extension of the scope to the synthesis of diurethanes from toluene 2,4-diamine and 4,4′-methylenedianiline could potentially allow the efficient production of industrially relevant diisocyanates. [ABSTRACT FROM AUTHOR]

Numerous bifunctional organocatalysts were synthesized and tested for the atom-efficient addition of carbon dioxide and epoxides to produce cyclic carbonates. These catalysts are based on phosphonium salts containing an alcohol moiety in the side chain for substrate activation through hydrogen bonding. In the model reaction, converting 1,2-butylene oxide with CO2, 19 catalysts were tested to determine structure-activity relationships. In total, 28 epoxides were converted with CO2 to give the respective cyclic carbonates in yields of up to 99 %. Even at 45 °C, the most active catalyst was able to produce cyclic carbonates selectively in high yields. The carbonates were generally obtained as analytically pure products after simple filtration over silica gel. This single-component catalyst system works under neat and mild reaction conditions and tolerates several useful moieties. [ABSTRACT FROM AUTHOR]

Controlled routes to prepare polyesters and polycarbonates are of interest due to the widespread application of these materials and the opportunities provided to prepare new copolymers. Furthermore, ring-opening copolymerization may enable new poly(ester–carbonate) materials to be prepared which are inaccessible using alternative polymerizations. This review highlights recent advances in the ring-opening copolymerization catalysis, using epoxides coupled with anhydrides or CO2, to produce polyesters and polycarbonates. In particular, the structures and performances of various homogeneous catalysts are presented for the epoxide–anhydride copolymerization. The properties of the resultant polyesters and polycarbonates are presented and future opportunities highlighted for developments of both the materials and catalysts. [ABSTRACT FROM AUTHOR]