Cycloaddition Of Carbon Dioxide Research Articles

Carbonation of Epoxidized Methyl Soyates in Tetrabutylammonium Bromide-Based Deep Eutectic Solvents.

Carbonated methyl soyates have been successfully prepared by cycloaddition of carbon dioxide (CO2) to epoxidized methyl soyates in tetrabutylammonium bromide (TBAB)-based deep eutectic solvents (DES). Experimental parameters, i.e., reaction temperature, reaction time, CO2 pressure and TBAB concentration were evaluated. The different reaction conditions have a significant influence on the yields of carbonated methyl soyates. The use of TBAB-based DES (tetrabutylammonium bromide/triethylene glycol) significantly shortened the reaction time of the cycloaddition of CO2 to epoxidized methyl soyates. FT-IR and NMR analysis indicated that 95% of the yield of the five-membered cyclic carbonated methyl soyates were obtained at 120°C with 1.0 MPa pressure of CO2.

Cycloaddition of carbon dioxide to epoxides catalysed by supported ionic liquids

Simple hybrid silica-imidazolium based ILs as highly active and selective catalysts for the carbonation of epoxides in batch and continuous flow systems under mild reaction conditions.

H2O-Polyaluminium chloride-TBAB as synergistic catalysts for the synthesis of cyclic carbonate

An efficient catalytic system consisting of H2O, Polyaluminium chloride (PAC) and Tetrabutylammonium bromide (TBAB) was applied to the cycloaddition of carbon dioxide (CO2) to epoxides under mild conditions. Their catalytic cycloaddition activities were found to be well correlated with H2O and polyaluminium chloride, which had a synergetic effect with the halide anion of TBAB. The presence of H2O and PAC could remarkably improve the yield of propylene carbonate (PC) by which the reaction yield is about 4-5 times higher than TBAB. alone.The catalytic system also exhibited excellent cycloaddition activities for various epoxide substrates.

A rare three-dimensional POM-based inorganic metal polymer bonded by CO2 with high catalytic performance for CO2 cycloaddition.

An exceedingly rare three-dimensional CO2-coordinated inorganic polyoxoanion was prepared by a hydrothermal synthesis reaction. The CO2 ligand connects with two Zn-ε-Keggin cores in a linear and symmetrical μ2-η2o,o coordination pattern with a C[double bond, length as m-dash]O bond length of 1.099(112) Å. The new compound reported here exhibits not only appealing structures but also high catalytic activity for the cycloaddition of carbon dioxide with epoxides.

Cross-linked chitosan with a dicationic ionic liquid as a recyclable biopolymer-supported catalyst for cycloaddition of carbon dioxide with epoxides into cyclic carbonates

A dicationc ionic liquid was synthesized and immobilized on chitosan as a catalyst for cycloaddition of CO2 with epoxides for synthesis of cyclic carbonates.

Zn 1,3,5-benzenetricarboxylate as an efficient catalyst for the synthesis of cyclic carbonates fromCO2.

Development of heterogeneous catalysts for the cycloaddition of CO2 with epoxides to produce cyclic carbonates is a hot issue in the field of chemical fixation of carbon dioxide. It is fairly promising as production of by-products is quite low. In this study, the [Zn3(BTC)2]/n-Bu4NBr catalytic system was investigated for the solventless cycloaddition of carbon dioxide with epoxides and had an excellent synergetic effect in promoting the reaction. The reaction parameters were moderate i.e. (130 °C and 13 bar CO2 pressure) and were selected by a study of the catalytic system. Under the optimal reaction conditions, the yield of cyclic carbonate reached 99%. A decrease in the yield of cyclic carbonate was not apparent after [Zn3(BTC)2] was reused three times, indicating that [Zn3(BTC)2] was stable. At the same time, the catalytic activity of the catalyst for other epoxides was also verified. The acidic and alkaline nature of the [Zn3(BTC)2] catalyst did not change obviously after recycling the catalyst three times. In this study it is also verified that the [Zn3(BTC)2] catalytic cycloaddition reaction was closely related to the Lewis acid/base distribution. In addition, a plausible mechanism for the synergistic effect of the catalyst (Lewis acid and base properties) and the co-catalyst was suggested.

Unprecedented NH2-MIL-101(Al)/n-Bu4NBr system as solvent-free heterogeneous catalyst for efficient synthesis of cyclic carbonates via CO2 cycloaddition.

Amine-functionalised framework NH2-MIL-101(Al) was synthesized using a solvothermal and microwave method and characterized by PXRD, FT-IR, TGA, SEM-EDX, and BET surface area analysis. The desolvated framework, in the presence of co-catalyst tetrabutylammonium bromide (TBAB), acted as an excellent heterogeneous catalyst for the solvent-free cycloaddition of carbon dioxide (CO2) with epoxides, affording five-membered cyclic carbonates. Using styrene oxide, the NH2-MIL-101(Al)/TBAB system showed more than 99% conversion, affording 96% yield and 99% selectivity with a turn over frequency of 23.5 h-1. This validated the synergistic effect of the quaternary ammonium salt during CO2 cycloaddition. The catalyst could be recycled at least five times without a noticeable loss in activity, while leaching test showed no leached Al3+ ions throughout the reaction. Thorough analysis of the reaction parameters showed that the optimum conditions for obtaining the maximum yield and highest selectivity were 120 °C and 18 bar of CO2 for 6 h. The outstanding conversion and selectivity were maintained for a range of aliphatic and aromatic epoxides, corroborating the duel benefit of the micro-mesoporous system with amine functionality, which offered easy access for reactant molecules with diverse sizes, and provided inspiration for future CO2 cycloaddition catalytic systems. We also propose a rationalized mechanism for the cycloaddition reaction mediated by NH2-MIL-101(Al) and TBAB based on literature precedent and experimental outcome.

Amino-Functional Ionic Liquids as Efficient Catalysts for the Cycloaddition of Carbon Dioxide to Yield Cyclic Carbonates: Catalytic and Kinetic Investigation

Various amino-functional ionic liquids were developed as homogeneous catalysts for the cycloaddition of carbon dioxide to different epoxides yielding the corresponding cyclic carbonates under metal- and solvent-free conditions. The effects of reaction temperature, reaction time, CO2 pressure, and the amount of catalyst on the cycloaddition reaction were investigated. The catalysts could be easily recovered after the reaction and then reused at least eight times without noticeable loss of activity and selectivity. Reaction kinetic studies were undertaken, the reaction was apparently first order with respect to the concentration of epoxide and catalyst. Furthermore, the rate constants were determined over a temperature range of 100–130°C and the activation energy was determined to be 45.9 kJ mol−1. Finally, a possible reaction mechanism was proposed. The amino-functional ionic liquids showed the advantage of high catalytic activity and were easily recyclable for CO2 chemical fixation into valuable chemicals.

Protic Pyrazolium Ionic Liquids: An Efficient Catalyst for Conversion of CO2 in the Absence of Metal and Solvent

A series of novel protic pyrazolium ionic liquids are first synthesized and utilized as catalysts for cycloaddition of carbon dioxide and epoxides to form cyclic carbonates under metal- and solvent-free conditions. The new developed protic pyrazolium ionic liquids present excellent catalytic activity toward the fixation of carbon dioxide. More importantly, they would be prepared by a facile two-step reaction from cheap raw starting materials with a yield more than 90%. The influence of catalyst dosage, reaction temperature, carbon dioxide pressure, and reaction time on the synthesis of cyclic carbonates is investigated to identify the optimal reaction conditions. Under the optimum conditions, the catalyst suitability is studied. Additionally, the possible reaction mechanism is investigated by the double-IL model to elucidate the synergistic effects of electrostatic and weak interaction in the catalytic process.

Synthesis of cyclic carbonates from CO2 and propylene oxide (PO) with deep eutectic solvents (DESs) based on amino acids (AAs) and dicarboxylic acids

A novel synthesis of cyclic carbonates from CO2 and PO with DESs, based on AAs and dicarboxylic acids, was developed. The eutectic mixture of L-proline (L-Pro)/propanedioic acid (PA) system exhibited high activity and selectivity for cycloaddition of carbon dioxide to PO among the prepared DESs. The influencing parameters (reaction temperature, CO2 pressure and time) on yield and selectivity of propylene carbonate (PC) was investigated and optimized. The PC yield of the L-Pro/PA system can reach as high as 98% under optimal conditions. Furthermore, the L-Pro/PA system was readily recovered and reused over 9 times without noticeable decrease in yield and selectivity of PC. The synergistic effect of bromide anion, the AAs and the dicarboxylic acids is perhaps the main reason for the high catalytic activity. In addition, the lengths of carbon chain of dicarboxylic acids play a complicated role in the cycloaddition of CO2 to PO with DESs based AAs and dicarboxylic acids, which may be related hydrogen bond strength.

Benzyl substituted imidazolium ionic liquids as efficient solvent-free catalysts for the cycloaddition of CO2 with epoxides: Experimental and Theoretic study

A series of low-cost and easily prepared benzyl substituted imidazolium ionic liquids are firstly synthesized and employed as catalyst for the cycloaddition of carbon dioxide with epoxides without any solvent and co-catalyst. The synthesized imidazolium ionic liquids are characterized by 1H NMR, HRMS, and MS. The influence of different substituted groups in cation and reaction parameters on catalytic activity is investigated. The highest conversion yield of cyclic carbonate (94.89%) could be achieved with slight amount of catalyst (0.25mol%) under 130°C and 2.0MPa during 4h. Meanwhile, the mechanisms of cycloaddition of carbon dioxide with epoxides catalyzed by four benzyl substituted ionic liquids with different substituted groups are investigated by theoretical calculations. The role of hydrogen bond and other noncovalent interactions played in catalytic process is further uncovered to deeply understand the difference of various catalysts from atomistic level.

A Polyoxovanadate-Resorcin[4]arene-Based Porous Metal-Organic Framework as an Efficient Multifunctional Catalyst for the Cycloaddition of CO2 with Epoxides and the Selective Oxidation of Sulfides.

In this work, we report a new polyoxovanadate-resorcin[4]arene-based metal-organic framework (PMOF), [Co2L0.5V4O12]·3DMF·5H2O (1), assembled with a newly functionalized wheel-like resorcin[4]arene ligand (L). 1 features an elegant porous motif and represents a rare example of PMOFs composed of both a resorcin[4]arene ligand and polyoxovanadate. Remarkably, 1 shows open V sites in the channel, which makes 1 an efficient heterogeneous Lewis acid catalyst for the cycloaddition of carbon dioxide to epoxides with high conversion and selectivity. Strikingly, 1 also exhibits high catalytic activity for the heterogeneous oxidative desulfurization of sulfides. Particularly, the heterogeneous catalyst 1 can be easily separated and reused with good catalytic activity.

Biomimetic PDMS-hydroxyurethane terminated with catecholic moieties for chemical grafting on transition metal oxide-based surfaces

The aim of this work was to synthesize a non-isocyanate poly(dimethylsiloxane) hydroxyurethane with biomimetic terminal catechol moieties, as a candidate for inorganic and metallic surface modification. Such surface modifier is capable to strongly attach onto metallic and inorganic substrates forming layers and, in addition, providing water-repellent surfaces. The non-isocyanate route is based on carbon dioxide cycloaddition into bis-epoxide, resulting in a precursor bis(cyclic carbonate)-polydimethylsiloxane (CCPDMS), thus fully replacing isocyanate in the manufacture process. A biomimetic approach was chosen with the molecular composition being inspired by terminal peptides present in adhesive proteins of mussels, like Mefp (Mytilus edulis foot protein), which bear catechol moieties and are strong adhesives even under natural and saline water. The catechol terminal groups were grafted by aminolysis reaction into a polydimethylsiloxane backbone. The product, PDMSUr-Dopamine, presented high affinity towards inhomogeneous alloy surfaces terminated by native oxide layers as demonstrated by quartz crystal microbalance (QCM-D), as well as stability against desorption by rinsing with ethanol. As revealed by QCM-D, X-ray photoelectron spectroscopy (XPS) and computational studies, the thickness and composition of the resulting nanolayers indicated an attachment of PDMSUr-Dopamine molecules to the substrate through both terminal catechol groups, with the adsorbate exposing the hydrophobic PDMS backbone. This hypothesis was investigated by classical molecular dynamic simulation (MD) of pure PDMSUr-Dopamine molecules on SiO2 surfaces. The computationally obtained PDMSUr-Dopamine assembly is in agreement with the conclusions from the experiments regarding the conformation of PDMSUr-Dopamine towards the surface. The tendency of the terminal catechol groups to approach the surface is in agreement with proposed model for the attachment PDMSUr-Dopamine. Remarkably, the versatile PDMSUr-Dopamine modifier facilitates such functionalization for various substrates such as titanium alloy, steel and ceramic surfaces.

Boron doped graphitic carbon nitride with acid-base duality for cycloaddition of carbon dioxide to epoxide under solvent-free condition

The cycloaddition of CO2 and epoxides to yield cyclic carbonate under solvent-free conditions is an eco-friendly way to utilize CO2 in environmental science and green chemistry. In this paper, we report that boron doped carbon nitride (BCN) is highly active and selective for such reactions. BCN, especially if supported on mesoporous silica SBA-15 (i.e., B0.1CN/SBA-15), shows above 95% conversion and selectivity for cycloaddition of CO2 and styrene oxide (SO) to yield styrene carbonate (SC), even under solvent-free conditions. That is mainly due to the acid-base duality induced by B doping, which enables the co-activation of CO2 and epoxide. A mechanism based on acid-base duality is proposed, where CO2 is activated on the basic >NH sites and SO is on the acidic −B(OH)2 sites through a hydrogen bonding. The co-activated CO2 and SO react with each other to yield the SC. Density functional theory (DFT) calculations were conducted to support the mechanism, which show that the co-adsorption of CO2 and SO on BCN is energetically favorable and the reaction follows the Langmuir-Hinshelwood mechanism. The BCN with acid-base duality provides an option for cheap, green and efficient catalysts for CO2 utilization.

1 Zn-doped ZIF-67 as catalyst for the CO2 fixation into cyclic carbonates

A newly Zn-doped ZIF-67 has been synthesized in water at room temperature for the first time without the aid of any organic solvent. The textural and physical properties of the material were analyzed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption-desorption, scanning electron microscopy (SEM) and ICP-AES. The catalyst showed quantitative conversions and selectivity for the synthesis of cyclic carbonates starting from epoxides and carbon dioxide. Compared with different reported MOFs as heterogeneous catalysts used for the cycloaddition of carbon dioxide to epoxides, this catalyst outperforms all the reported ones till now. The coupling reaction was studied at different pressures and temperatures applying different epoxide substrates. Additionally, no co-catalyst and solvent were required to obtain excellent conversions. The heterogeneous nature of the catalyst was maintained at least up to four catalytic cycles with a slight loss of activity.

Polyimidazolium Salts: Robust Catalysts for the Cycloaddition of Carbon Dioxide into Carbonates in Solvent-Free Conditions.

There is a growing interest in sustainable heterogeneous catalysts based on organic polymers. Here, we describe a series of polyimidazolium salt catalysts, prepared from the direct reaction of arene-bridged bis- and tris-alkyl halides with trimethylsilylimidazole. The polyimidazolium salts were characterized by spectroscopic and analytical techniques and it was found that their morphology and porosity could be controlled by adjusting the steric parameters of the spacer in the alkyl-halide starting materials. Moreover, the polymers are excellent heterogeneous organocatalysts for the cycloaddition of CO2 to epoxides to afford cyclic carbonates at atmospheric pressure under solvent-free conditions. The polymer catalysts exhibit long-term stability and may be recycled and reused at least 10 times.

Zirconium-Catalyzed Cycloaddition of Carbon Dioxide and Epoxides

Zirconium-Catalyzed Cycloaddition of Carbon Dioxide and Epoxides

Carbon Dioxide Oversolubility in Nanoconfined Liquids for the Synthesis of Cyclic Carbonates

AbstractThe physical phenomenon of gas oversolubility in nanoconfined liquids was successfully applied for the catalytic cycloaddition of carbon dioxide to epoxides to generate organic cyclic carbonates. Hybrid adsorbents based on MCM‐41 and SBA‐15 mesoporous silica materials were synthesized, and efficient nucleophile deposition on the surface of the support was achieved through a grafting procedure, which allowed for an effective and durable metal‐free catalytic system. Room‐temperature transformation of styrene and hexene oxides to the corresponding organic carbonates at atmospheric pressure of carbon dioxide was explored.

Catalytic performance of metal azolate frameworks in the solventless synthesis of cyclic carbonates from CO2 and epoxides

Two types of metal azolate frameworks (MAFs) with uncoordinated and coordinated nitrogen atoms composed of zinc coordinated with 3-amino-1,2,4-triazole and 3,5-dimethyl-1,2,4-triazole linkers denoted as MAF-66 and MAF-X5, respectively have been synthesized and characterized using various physicochemical techniques. The uncoordinated N donors present in the MAFs show high adsorption affinity for carbon dioxide. The synthesized MAFs showed promising catalytic activity towards the cycloaddition of carbon dioxide and epoxides under solvent-free conditions with excellent selectivity towards the desired five-membered cyclic carbonates. The importance of uncoordinated N donors and amine groups in the effective catalysis of the cycloaddition of CO2 and epoxides was investigated. Both catalysts were separable by simple filtration and reusable without any considerable loss in the initial activity. Various reaction parameters including temperature, reaction time, and CO2 pressure were studied. A possible reaction mechanism explaining the role of amine groups in the cycloaddition reaction was proposed based on literature and experimental inferences.

DBU as activator for the N-iodosuccinimide promoted chemical fixation of carbon dioxide with epoxides

The combination of N-Iodosuccinimide (NIS) and DBU is developed as an efficient organocatalyst system for the cycloaddition of carbon dioxide (CO2) at atmospheric pressure with epoxides without utilization of additional solvents, forming cyclic carbonates in high yields with a broad substrate scope. DBU functions as a nucleophilic promoter for the activation of NIS to be a more electrophilic iodine species thus being capable of activating the epoxides. On the other hand, NIS also provides a nucleophilic nitrogen species, i.e. succinimide anion for ring-opening of the epoxide.