Coupling Reaction Of CO2 Research Articles

Bifunctional organoboron-phosphonium catalysts for coupling reactions of CO2 and epoxides.

Recent years have witnessed intensive research activity in exploring novel metal-free organocatalysts for catalyzing the coupling reactions of CO2 and epoxides to afford cyclic or polymeric carbonates. In this direction, herein we report a series of boron-phosphonium organocatalysts for catalyzing the coupling reactions of CO2 and epoxides. These organophosphonium catalysts were synthesized in high yields by following a two step protocol involving Menschutkin and hydroboration reactions in succession. The purity of these organocatalysts was confirmed by spectroscopic techniques like 1H, 13C and 31P NMR, and molecular structures were confirmed by single crystal X-ray diffraction studies. We have also demonstrated that these bifunctional organoboron-phosphonium catalysts are comparatively much less hygroscopic compared to the analogus ammonium catalysts. These phosphonium organocatalysts were shown to catalyze the copolymerization of CO2 and cyclohexene oxide or vinyl cyclohexene oxide to provide polycarbonates with >99% polymer selectivity and carbonate linkages. The coupling reactions of aliphatic epoxides such as PO, having lower energy barrier to cycloaddition formation compared to alicyclic epoxides, preferentially provided cyclic carbonates in good yields. It was demonstrated that these organoboron-phosphonium catalysts are sensitive to chain transfer agents like water, and hence are deactivated in its presence. This is opposite to what is observed for metal based catalysts for these transformations, where water serves as a precursor to the chain-transfer agent diols.

Strategies for tuning the catalytic activity of zinc complexes in the solvent-free coupling reaction of CO2 and cyclohexene oxide

The catalytic activity of various zinc(II) complexes bearing a chelating nitrogen-donor ligand and different ancillary ligands (Cl, acetate, triflate) is investigated for the solvent-free coupling reaction of cyclohexene oxide and CO2. The effect of a co-catalyst is also studied. Whereas the investigated zinc(II) complexes with chloride or acetate as ancillary ligand are inactive, those with triflate are active, allowing the selective formation of polyether or cyclic carbonate controlled by the presence of a suitable amount of [PPN]Cl.

Pentazole (N5H) as a possible catalyst for CO2 activation: Density functional theory (DFT) and ab initio molecular dynamics (AIMD) studies

AbstractThe alarming increase in the atmospheric CO2 concentration is a matter of great concern today. Enormous attention has been devoted to search the novel and innovative approaches to recycle the CO2 evolved from the industries into useful chemicals. However, the thermodynamic stability of CO2 molecule imposes a great challenge in utilizing it as a raw material in chemical reactions. In the present investigation, an attempt has been made to scrutinize pentazole (N5H) as an effective catalyst for the CO2 activation. The fixation reaction of CO2 with ethylene oxide (oxirane) was chosen to be the prototypal model. Both the density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) studies explicitly suggest pentazole to be a promising catalyst for the activation of CO2 molecule. The energy required for the CO2 activation was found to be 35.6 kcal/mol. Also, the proton transfer step is found to be the key step in the reaction. Based on the prototypal reaction, the coupling reaction of CO2 with aziridine, propylene oxide and styrene oxide was also investigated.

Efficient Cycloaddition of CO2 and Aziridines Activated by a Quadruple-Interpenetrated Indium-Organic Framework as a Recyclable Catalyst.

On the basis of the global warming effect, it is of great significance to convert CO2 into the high value-added products oxazolidinones, but investigations on main-group-based metal-organic frameworks (MOFs) as heterogeneous catalysts still have not been reported so far. In this work, a quadruple-interpenetrated porous indium-based MOF, {[NH2(CH3)2][In(CPT)2]·3CH3CN·3DMA}n (1), is constructed from the organic ligand 3,5-bis(4'-carboxyphenyl)-1,2,4-triazole through solvothermal reactions, and N2 adsorption proves that the framework has a high Brunauer-Emmett-Teller surface areas with 2024 m2/g. The catalytic research on CO2 conversion reveals that compound 1 has high reactivity for the cycloaddition of CO2 with aziridines, and the product 3-ethyl-5-phenyloxazolidin-2-one can be obtained with a yield of 99% under mild conditions. In addition, 1 exhibits excellent activity for different kinds of substrates and can be reused at least five cycles without any significant deactivation, suggesting that 1 is a potential candidate for the chemical conversion of CO2 and aziridines. Mechanistic explorations indicate that the high efficiency of 1 is attributed to the indium center in the framework as a Lewis acid site, and the large porosity can enrich substrates. Importantly, 1 behaved as the first main-group MOF-based catalyst in the reported coupling reaction of CO2 with aziridines.

Aromatization mechanism of coupling reaction of light alkanes with CO over acidic zeolites: Cyclopentenones as key intermediates

The aromatization of light alkanes (C4-C6) is an important value-added reaction. However, the yield of aromatics is always limited by the simultaneous generation of small alkanes (CH4 and C2H6) due to H/C balance. Herein, we demonstrate that the introduction of CO into light alkanes over zeolites significantly enhanced aromatic selectivity and an aromatics selectivity of 85% was achieved in the case of cyclopentane and CO coupling reaction over H-ZSM-5. Methyl-substituted cyclopentenones were observed and considered as the most important intermediates for aromatics formation. Multiple characterizations revealed the coupling mechanism: (1) CO inserts into carbenium ions to form acylium cations, (2) acylium cations react with olefins to generate unsaturated ketones, (3) unsaturated ketones cyclize to methyl-substituted cyclopentenones, (4) methyl-substituted cyclopentenones convert to monocytic aromatics. Methyl-substituted indanones were also discovered causing the generation of binuclear aromatics, such as naphthalene. Nano-sized ZSM-5 and TEOS modifications were applied to enhance the BTX selectivity.

CO2 coupling reaction with methane by using trimetallic catalysts

This study evaluated the coupling reaction of CO2 with methane via trimetallic catalyst based on ZrO2/TiO2 to produce acetic acid. The catalysts were characterized by various techniques including XRD, BET for textural properties, NH3-TPD and H2-TPR. The surface acidity of trimetallic catalyst was affected by the addition of transition metal oxide of Fe, Cu and Co as well as Al oxide over Zr/Ti oxide. Additionally, incorporation of a third metal of Al and Fe into the Zr/Ti oxide catalyst led to an increase in hydrogen reduction. The methane coupling to ethane and ethylene increased as a result of the incorporation of metals into the Zr/Ti oxide catalyst in the order of Al > Co > Fe > Cu. The utilization of CO2 by insertion reaction with methane molecules proceeded through CH bond activation and C-C reaction with CO2 to produce acetic acid. The yield of acetic acid was affected by the addition of third metal oxides and the catalyst Al/Zr/Ti showed the highest activation of methane over catalyst and produced more acetic acid from C-C coupling reaction than the binary Zr/Ti oxide catalyst and other trimetallic catalysts.

Al(III) phthalocyanine catalysts for CO2 addition to epoxides: Fine-tunable selectivity for cyclic carbonates versus polycarbonates

A sustainable synthetic methodology to prepare bifunctional cationic imidazolyl and neutral tert-butylphenoxy Al(III)-phthalocyanine complexes is described, using ultrasound irradiation to synthesize the phthalonitrile precursors, followed by microwave-assisted cyclotetramerization. The metallophthalocyanine catalysts were applied in the coupling reaction of CO2 with epoxides, where the structure of the phthalocyanine was shown to determine the reaction selectivity towards the formation of cyclic carbonates versus polycarbonates. The cationic imidazolyl phthalocyanines operate as efficient bifunctional catalysts to promote the CO2 cycloaddition to terminal epoxides (styrene oxide, epichlorohydrin, propylene oxide and allyl glycidyl ether), leading to TONs up to 1414 and 100% selectivity for cyclic carbonates, without the need of using any co-catalyst. On the other hand, the neutral 4-tert-butylphenoxy Al(III) phthalocyanine catalyzed the copolymerization reaction between CO2 and cyclohexene oxide, in the presence of PPNCl as co-catalyst, with TON = 814, providing the first example of a metallophthalocyanine catalyst with full selectivity for formation of polycarbonates.

Efficient responsive ionic liquids with multiple active centers for the transformation of CO2 under mild conditions: Integrated experimental and theoretical study

The ideal catalyst for the coupling reaction of CO2 with epoxides is expected to have comprehensive advantages. An appealing ionic liquid, C[CMImBrTMG]2, with multiple active centers is synthesized to accomplish several goals in a single-component catalyst to adsorb CO2 and afford the robust electrophilic and nucleophilic groups. The 98.5 % yield of chloropropylene carbonate (CPC) is achieved at 50 °C under 1 bar CO2 pressure during 6 h. Moreover, C[CMImBrTMG]2 is easy to be simply separated from the catalytic system by washing with ethyl acetate. A new reaction mechanism is constructed by the density functional theory (DFT) along with the 13C NMR confirmation. The contribution of critical groups in C[CMImBrTMG]2 to the catalytic performance is further elucidated by the electrostatic potential (ESP), atoms in molecule (AIM), and electron localization function (ELF).

Heteroscorpionate Rare-Earth Catalysts for the Low-Pressure Coupling Reaction of CO2 and Cyclohexene Oxide

Novel heteroscorpionate rare-earth-metal complexes (Y, La, and Lu) have been developed for the coupling reaction of CO2 and cyclohexene oxide under mild conditions. The reaction of an alcohol heter...

Towards constant potential modeling of CO-CO coupling at liquid water-Cu(1 0 0) interfaces

We use density functional theory, molecular dynamics, and metadynamics to study electrochemical *CO–*CO coupling in explicit electrolyte. We consider both the *CO–*CO coupling reaction and the charging process required to keep the potential constant. The charging process consists of transferring explicit cations from the electrolyte and electrons from the potentiostat to the interface. Under constant charge conditions (non-constant electrostatic potential), the *CO–*CO coupling reaction energies are relative insensitive to the charge state at the interface and the electrolyte composition and the reaction occurs with co-adsorption of water. Under constant potential conditions, the *CO–*CO coupling reaction is stabilized at lower potentials because of charging, the reaction is influenced by the electrolyte composition, and water-coadsorption is reduced. The *CO–*CO coupling reaction changes the electrosorption valency by around 0.4–0.5. We propose a simple approach to convert energetics from constant charge to estimates at constant potential. The approach is generally applicable to electrochemical processes.

Ruthenium-Catalyzed Coupling Reactions of CO2 with C2 H4 and Hydrosilanes towards Silyl Esters.

A series of in situ-prepared catalytic systems incorporating RuII precursors and bidentate phosphine ligands has been probed in the reductive carboxylation of ethylene in the presence of triethylsilane as reductant. The catalytic production of propionate and acrylate silyl esters was evidenced by high-throughput screening (HTS) and implemented in batch reactor techniques. The most promising catalyst systems identified were made of Ru(H)(Cl)(CO)(PPh3 )3 and 1,4-bis(dicyclohexylphosphino)butane (DCPB) or 1,1'-ferrocene-diyl-bis(cyclohexylphosphine) (DCPF). A marked influence of water on the acrylate/propionate selectivity was noted. Turnover numbers [mol mol(Ru)-1 ] up to 16 for acrylate and up to 68 for propionate were reached under relatively mild conditions (20 bar, 100 °C, 0.5 mol % Ru, 40 mol % H2 O vs. HSiEt3 ). Possible mechanisms are discussed.

Dual active sites fabricated through atomic layer deposition of TiO2 on MoS2 nanosheet arrays for highly efficient electroreduction of CO2 to ethanol

Ultrathin TiO2/MoS2 nanosheet arrays containing dual active sites could achieve efficient CO2 reduction reaction toward ethanol. A new regulatory mechanism of the CO coupling reaction was proposed based on experimental results and DFT calculations.

Amino acid ionic liquids as efficient catalysts for CO2 capture and chemical conversion with epoxides under metal/halogen/cocatalyst/solvent-free conditions

Biocompatible amino acid ionic liquids (AAILs) were synthesized and efficiently applied in CO2 capture and catalysis for the coupling reaction of CO2 with epoxides under halogen-, cocatalyst- and organic solvent-free conditions.

Halogen-free fixation of carbon dioxide into cyclic carbonates via bifunctional organocatalysts

Bifunctional organocatalysts bearing diamine and carboxylic acid groups efficiently catalyze the coupling reaction of CO2 with epoxides under halogen-free conditions due to a synergy effect.

Ni(II) complexes of tripodal N4 ligands as catalysts for alkane hydroxylation and O-arylation of phenol: Structural and reactivity effects induced by fluoro substitution

Nickel(II) complexes [NiII(L1-2)(OAc)(H2O)][BPh4] (1–2) and [NiII(L3)(OAc)][BPh4] (3) derived from fluorinated tripodal ligands viz. N-((6-fluoropyridin-2-yl)methyl)(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine (L1 or FTPA), N,N′-bis((6-fluoropyridin-2-yl)methyl)(pyridin-2-yl)methanamine (L2 or F2TPA) and tris((6-fluoropyridin-2-yl)methyl)amine (L3 or F3TPA) have been synthesized and characterized by spectroscopic (UV–visible, FT-IR, paramagnetic NMR), elemental analysis, electrochemistry and X-ray diffraction techniques. In structurally similar complexes 1 and 2, Ni(II) center has a distorted octahedral coordination geometry constituted by all the four N atoms of the ligands, one acetate group and a water molecule. Complex 3 has different structural aspects. It does not have the water molecule in the coordination sphere and contains one acetate group bound with metal center in a bidentate mode. All the complexes exhibit a one-electron oxidation corresponding to the NiII/NiIII redox couple, the potential of which is influenced by the donor functionalities of ligand. These complexes catalyze the oxidation of cyclohexane efficiently (turn over number: 586–698) and selectively (alcohol to ketone ratio: 7.9:1 to 8.4:1). The study also includes the catalysis of adamantane oxidation to a mixture of ketones and alcohols. Catalytic potential of all the three complexes (1–3) has also been screened for CO coupling reactions of phenol with aryl halides. Among them, complex 1 is more efficient than 2 and 3 for such reactions.

Electro-Carboxylation of Furfural By CO2 in γ-Valerolactone

The continuous rise of global warming and depletion of fossil fuel resources has led to the development of new ways of valorization of non petro-sourced chemicals. In this objective, it is important to develop electrochemical valorization processes of CO2, a greenhouse gas, for the synthesis of valuable molecules. When the CO2 electroreduction is performed in aqueous media, the competitive HER will decrease the energetic efficiency and the rapid deactivation of reaction intermediates will lead to side products such as CO, formic acid, oxalic acid and small chain hydrocarbons [1]. To circumvent these issues and create value added chemicals, reductive electro-carboxylation reactions can be performed in polar aprotic solvents (DMF, DMSO, acetonitrile or NMP) in the presence of tetraalkylammonim bromide or chloride as electrolytes [2].In this work, we focused on non-aqueous bio-sourced solvent, the γ-valerolactone (GVL), to perform a carboxylation reaction of bio-sourced molecules like furfural by electroreduction of CO2. The reductive electro-carboxylation of furfural was studied at a Pt/C electrode was studied in a bio-sourced GVL with tributylmethylammonium chloride (TBMACl) as electrolyte. The solvent behavior in the CO2 reduction potential range was studied by in situ FTIRS measurements which indicated that GVL reacted at the electrode in the absence of furfural and/or of CO2, while the presence of furfural and/or of CO2 made the solvent much less reactive. The electrochemical study showed that the CO2 electroreduction started at from the high cathodic potential of −0.8 V vs SCE (saturated calomel electrode) and the coupling of electrochemistry with in situ FTIRS demonstrated that it reacted with furfural.The reductive electro-carboxylation was then performed in an electrolysis cell. The cell voltage was maintained at 2.0 V (corresponding to a cathode potential of -1.9 V vs. SCE) for 24 h. In absence of furfural, gas chromatography coupled with mass spectroscopy (GC–MS) analyses revealed the formation of oxalic acid (coupling reaction of CO2) as main reaction product. In the presence of furfural in the reaction medium, a new carboxylated specie, 2-furyl(hydroxy)acetic acid, was identified as the main reaction product. 1H NMR and LC-MS analyses further confirmed the formation of this compound, demonstrating the potentialities of bio-sourced solvents for reduction electro-carboxylation of a bio-sourced molecule by reduction of CO2[3].[1] Y. Hori, Electrochemical CO2 reduction on metal electrodes, in: C. Vayenas, R. White, M. Gamboa-Aldeco (Eds.), Modern Aspects of Electrochemistry, 42, Springer, NewYork 2008, pp. 89–189[2] R. Matthesses, J. Fransaer, K. Binnemans, D.E. De Vos, Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids, Beilstein J. Org.Chem. 10 (2004) 2484–2500.[3] Florent Boissou, S. Baranton, M. Tarighi, K. De Oliveira Vigier, C. Coutanceau, The potency of γ-valerolactone as bio-sourced polar aprotic organic medium for the electrocarboxlation of furfural by CO2. J. Electroanal. Chem. 848 (2019) 113257

Facile one-pot synthesis of ZnBr2 immobilized ion exchange resin for the coupling reaction of CO2 with propylene oxide

Abstract The synthesis of cyclic carbonate from CO2 and alkylene oxide is one of the best environment-friendly technologies for converting CO2 to valuable chemicals. In this study, a [ZnX2Cl2]2−immobilized ion exchange resin (ZnX2/IER) was synthesized using four kinds of zinc precursors, ZnX2 (X = Cl, Br, OAc, and NO3) and a chloride-anion exchange resin (IER). The synthesized ZnX2/IER was then used for the cycloaddition reaction of CO2 and propylene oxide (PO) to synthesize propylene carbonate (PC). Among the synthesized catalysts, ZnBr2/IER showed the highest activity, with a 76.7% PC yield achieved at 80 °C for 2 h, and 99.1% after 8 h. The catalytic activity was maintained during 5 times uses. The fresh and used ZnBr2/IER were characterized by FT-IR, SEM-EDS, and ICP-OES, and no noticeable changes in the morphology and zinc concentration were observed. The continuous reaction using a fixed-bed system for 96 h demonstrated that the synthesized catalyst can be employed in commercial PC synthesis processes.

Carbon Monoxide Coupling Reactions: A New Concept for the Formation of Hexahydroxybenzene.

For linear and cyclic coupling reactions of CO, among other products, the formation of the hexapotassium salt of hexahydroxybenzene is of particular interesting. The interaction of metallic potassium and CO offers, via the assumed K[OC≡CO]K as the result of several carbon monoxide coupling reactions, the formation of C6(OK)6 among other products. To date, only speculations exist about the reaction pathway for these products, which were first described by Liebig in 1834. A novel concept is suggested here, which consists of the single steps (i) reductive coupling of CO, (ii) formation of dihetero‐metallacyclopentynes (cis‐2,5‐diheterobutatriene as formal ethylenedione O=C=C=O complexes), (iii) formation of its dinuclear 1‐metalla‐2,5‐dioxo‐cyclopentyne complexes by external coordination of the triple bond, (iv) insertion of CO into the M−C bond of the formed metallacyclopropene, and (v) the reductive elimination of C6(OK)6. The novel aspect of this concept is the formation of dihetero‐metallacyclopentynes (in analogy to the well characterized all‐C‐metallacyclopentynes), which have not been considered in the mechanism of reductive CO coupling reactions. It is expected that the presence of transition‐metal impurities would promote the reaction.

Natural porous nanorods used for high-efficient capture and chemical conversion of CO2

Abstract There are abundant mineral resources in nature, and how to skilfully use natural mineral resources as a novel material for CO2 capture and conversion seems to be one of the most sensible strategies. Therefore, for the first time, we report a natural and inexpensive nano-mineral as a bifunctional material for CO2 efficient capture and conversion. The material is a natural 1D porous nanomaterial, and its unique multi-metal weak alkaline pore structure, not only can capture CO2, but also has the advantages of multi-metal synergistic catalysis. The best catalytic activity is shown in the coupling reaction of CO2 with epoxy compounds compared to other clay minerals reported. The catalyst has a unique pore structure, which makes it exhibit excellent substrate selectivity in the catalytic reaction and has remarkable catalytic activity for the sterically hindered epoxy substrate. In addition, the nano-catalyst prepared by using attapulgite as a carrier in combination with ZIF-8 exhibits best catalytic activity as compared with the use of any of its components alone. This new type of natural nano-catalyst provides an effective way for CO2 capture and conversion.

Design catalytic space engineering of Ag-Ag bond-based metal organic framework for carbon dioxide fixation reactions

Chemical fixation of carbon dioxide (CO2) has been regarded as a C1 source into valuable chemical products using cheap industrial chemicals, owing to its abundant supply from the combustion of fossil fuels. The development of efficient and low energy consumption heterogeneous catalysts for cycloaddition with carbon dioxide to produce five-membered cyclic chemical product without any side products under mild reaction conditions is of great importance, yet remains a great challenge. In this work, the coupling reaction of CO2 with propargylamine derivatives by Ag-MOF in the presence of other additives (e.g. reaction time, base, solvent, temperature and pressure) was studied in different conditions. It was discovered that Ag-MOF had excellent synergetic effect in promoting the reaction, and the Ag-MOF/DBU catalytic system was the most efficient among them. The optimal reaction could be completed in 5 h at room temperature under atmospheric CO2 pressure with very high selectivity. A decrease of the yield of the aim product was not noticeable after Ag-MOF catalyst for recycling experiments revealed the stability of the catalysts after five uses. The Ag-MOF catalytic system was also very active and selective for different size and shape reaction substrates.