Reaction Of Carbonate Research Articles

Polyetheretherketone fiber-supported TBD as an efficient fibrous superbase catalyst for organic conversions in continuous-flow processing

The development of clean catalytic technologies in continuous-flow processing for efficient organic conversions has a positive influence on the fine chemicals and pharmaceutical manufacturing. Herein, the commonly used organic superbase 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was immobilized on the commercially available ultra-high strength textile fiber polyetheretherketone (PEEK) to report a polymer-supported basic catalyst (PEEK-TBD) for three types of organic conversions in cleaner continuous-flow processing. The fiber catalyst was prepared through an improvement strategy and verified as a heterogeneous fibrous superbase catalyst in the microtubule reactor to mediate the Knoevenagel condensation-cyclization between salicylaldehydes and activated nitriles for the synthesis of iminocoumarins in ethanol (10 samples, yields 91–97%) after turning the flow rate, substrate concentration, and catalyst padding quantity, additionally, PEEK-TBD was also effective for the cyanosilylation of carbonyl compounds for the synthesis of cyanogen compounds in acetonitrile, as well as the substitution reaction of aniline and carbonate for the synthesis of N,N’-substituted urea in toluene in continuous-flow processing. Moreover, the resulting fiber samples were characterized in detail by sorts of analytical methods and techniques to further confirm the dependability of this methodology, and the clean and valid gram-scalable procedure of PEEK-TBD in continuous-flow processing has extensive application prospects on the chemical productions.

A simple method to determine the reactivity of calcium carbonate in soils

AbstractDetermination of soil carbonate is important for numerous chemical and physical soil processes in arid and semi‐arid zones. Here, we modify a conventional method to more easily determine active CaCO3 (ACC) fraction in soils. Unlike the conventional method where the oxalate used up after reaction with carbonate is determined by titration with KMnO4, the proposed method uses the difference between total carbonate analyzed before and after reaction with oxalate to determine ACC. The method compared well to the conventional approach; the procedure was faster, did not require KMnO4, and appeared to be unaffected by exchangeable Ca. The proposed method is well‐suited for samples across a wide range of total carbonate.

Palladium-catalyzed regioselective synthesis of mono and bis(arylthiol) alkenes from propargyl carbonate and thiophenol.

A palladium catalyzed regioselective reaction of propargylic carbonate with thiophenols and benzene selenol is described. Atom-economic addition of thiols to propargylic carbonates provides an excellent opportunity for effective processes. The reaction proceeds via hydrothiolation to produce mono(arylthiol) alkenes and hydrothiolation followed by Tsuji-Trost type substitution to form bis(arylthiol) alkenes through single and double sequential attack by soft thio nucleophiles by control of the equivalence of thiophenols. This coupling reaction with good tolerance towards functional groups in both propargylic carbonates and thiols furnished a variety of highly functionalized alkenylation products in moderate to excellent yields via the formation of new C-S and C-Se bonds.

A Sc(OTf)3-catalyzed one-pot two-step approach for spiro-oxindole dihydropyridine derivatives initiated by N-olefination of MBH carbonates

An efficient one-pot, two-step, three-component reaction of isatin-derived MBH carbonates, sulfilimines, and epoxides was achieved, thus affording pharmaceutically important spiro-oxindole dihydropyridines.

Pd-catalysed cross-coupling of allenylic carbonates with gem-diborylalkanes: efficient synthesis of isoprenylboronates.

A simple and novel Pd-catalysed cross-coupling reaction of allenylic carbonates with different gem-diborylalkanes was developed. Under mild reaction conditions, synthetically useful and versatile isoprenylboronates could be obtained selectively in moderate to high yields. Furthermore, the utility of the novel isoprenylboronate is demonstrated through isoprenylboration and homologation.

Elucidating the mechanism and regioselectivity of phosphine-catalyzed transformation of MBH carbonate

A general mechanistic map of the PPh3-catalyzed transformation reaction of MBH carbonate has been theoretically studied and the NCI and ELF analyses are performed to disclose the origins of selectivities and the role of catalyst, respectively.

Geochemical Modelling of the Fracturing Fluid Transport in Shale Reservoirs

Field operations report that at least half of the fracturing fluid used in shale reservoirs is trapped. These trapped fluids can trigger various geochemical interactions. However, the impact of these interactions on well performance is still elusive. We modeled a hydraulic fracture stage where we simulated the initial conditions by injecting the fracturing fluid and shutting the well to allow the fluids to soak into the formation. Our results suggest a positive correlation between the dissolution and precipitation rates and the carbonate content of the rock. In addition, we observed that gas and load recovery are overestimated when geochemical interactions are overlooked. We also observed promising results for sea water as a good alternative fracturing fluid. Moreover, we observed better performance for cases with lower-saline connate water. The reactions of carbonates outweigh the reactions of clays in most cases. Sensitivity analysis suggests that the concentration of SO4, K and Na ions in the fracturing fluid, and the illite and calcite mineral content, along with the reservoir temperature, are the key factors affecting well performance. In conclusion, geochemical interactions should be considered for properly modeling the fate of the fracturing fluids and their impact on well performance.

Nucleophilic ring-opening of thiocyclic carbonates: A scheme to prepare sulfhydryl-rich binders for high-performance lithium-sulfur batteries

Problems such as cathode collapse caused by volume change and shuttle effect of lithium polysulfides (LiPSs) limit the commercialization of Lithium-Sulfur (Li-S). Herein, we developed a sulfhydryl-containing multifunctional binder prepared by the nucleophilic ring-opening reaction of thiocyclic carbonates with amino groups. The binders (CNP-T and CNP-F) form sulfur-containing polymers with sulfur through the wet-slurry process, thereby effectively suppressing the shuttle effect. The abundant polar functional groups (e.g., -NH2, -CS(NH)-) in CNP-T and CNP-F can effectively adsorb LiPSs to weaken the shuttle effect, which is confirmed by both density functional theory (DFT) and experimental results. At the same time, their own hyperbranched network structure can also limit the volume change of the sulfur cathode. Therefore, the Li-S battery exhibits an initial specific capacity of 924.02 mAh/g and a decay rate of 0.033% when cycled at 1C for 500 cycles.

DBU-assisted expeditious synthesis of highly stable IL@ZIFs intergrowth composite: A nanocatalyst for EMC production

Methyl ethyl carbonate (EMC) is the primary raw material for the electrolyte of lithium-ion batteries. It is mainly prepared by the transesterification reaction of dimethyl carbonate (DMC) and EtOH. However, homogeneous alkaline catalysts such as sodium alcohol commonly used in industry are easy to deactivate and challenging to separate and recover.Therefore, the alkaline ionic liquid decorated zeolitic imidazolate frameworks (IL@ZIFs) heterogeneous catalysts were prepared using a simple method with DBU as an inducer. In the synthetic route of IL@ZIFs, the ligand of ZIFs can form an ionic liquid with DBU, and deprotonated ligands will rapidly coordinate with metal ions at room temperature. The DBU can also play the structural guidance and stabilizer, which is conducive to the rapid and effective preparation of ZIFs materials. Meanwhile, the DBU, which has a large molecular diameter, will be trapped in the pore cage and can combine with other protic materials (imidazole, triazole, 2-methylimidazole, phenol, etc.) to form alkaline ionic liquids. The prepared DBU-IL@ZIFs were used as heterogeneous catalysts for synthesizing EMC by transesterification reaction. The DBU-PO@ZIF-8 composite with phenol as anion has better catalytic activity. Under the appropriate reaction conditions, the yield of EMC can reach 55.7% with high selectivity of 94.7%.The catalytic mechanism of DBU-PO@ZIF-8 in the transesterification reaction was also explored and revealed.

Comparative study of the isothermal solid-state reaction systems of kaolinite–Na2CO3 and kaolinite–quartz–Na2CO3 for coal gangue activation

A clear understanding of the solid-state reaction of kaolinite (Kln), quartz (Qtz), and sodium carbonate (Na2CO3) is of great significance for the process optimization of coal gangue calcined with Na2CO3. In this work, a comparative study of the isothermal solid-state reaction systems of Kln–Na2CO3 and Kln–Qtz–Na2CO3 was performed by means of X-ray diffraction (XRD), scanning electron microscope, and energy dispersion spectroscopy (SEM-EDS). The results showed that the calcined products both for these reaction systems mainly contain different kinds of sodium aluminum silicates (e.g., NaAlSiO4, Na1.55Al1.55Si0.45O4, and Na1.95Al1.95Si0.05O4) and various kinds of sodium silicates (e.g., Na2Si3O7, Na2SiO3, and Na6Si2O7). The mass percentage of Na2CO3 played a key role in the phase transformation, determining the Na/Al/Si molar ratio of the formed sodium aluminum silicates. Compared with the reaction system of Kln–Na2CO3, the existence of Qtz inhibited the formation of sodium aluminum silicates in the reaction system of Kln–Qtz–Na2CO3. It should be noted that the formed phases both for these reaction systems were slightly different from that of the thermodynamical calculated results of Na2O–SiO2–Al2O3 using FactSage™ software. According to both the experimental and calculated results, a reasonable batching area for coal gangue activation was proposed that the addition of Na2CO3 should be in the range of 20–50% of the total mass of Kln, Qtz, and Na2CO3.

First-Principles Insights on the Formation Mechanism of Innermost Layers of Solid Electrolyte Interphases on Carbon Anodes for Lithium-Ion Batteries.

A solid electrolyte interphase (SEI) plays an essential role in the functionality and service life of ion batteries, where the structure and formation mechanism are still in the midst. Here, we investigate the initial decomposition and reactions of ethylene carbonate (EC) on the surface of a graphite anode using first-principles calculations. EC initially decomposes via the homolytic ring opening with the product of radical anion CH2CH2OCO2−. Bonding with Li, it forms a co-plane structure of CH2CH2OCO2Li, with a binding energy of 1.35 eV. The adsorption energy is −0.91 eV and −0.24 eV on the graphite zigzag edge surface and basal surface, respectively. Two CH2CH2OCO2Li molecules react to form a two-head structure of lithium ethylene dicarbonate (CH2OCO2Li)2, namely LEDC, which further forms a network preferring zigzag edge surfaces. Our results suggest that the first and innermost layers of the solid electrolyte interphase are CH2CH2OCO2Li sticking and networking on the zigzag edges of the surfaces of graphite anodes.

Investigation on Coalbed Methane Fracturing Using Supercritical CO2 Graphene Cement Slurry System

In this study, we innovatively use sulphoaluminate cement slurry and its additives as a fracturing fluid system for supercritical CO2 graphene-permeable cement stone (referred to hereafter as the SCGPCS) fracturing without sand. Utilizing small fluid volumes, small displacement and small pump pressure, we obtain the success of the first field test in an extra-low desorption pressure coal seam. Laboratory experiments have proven that sulphoaluminate cement is suitable as base cements for the SCGPCS system due to their rapid setting and fast hardening characteristics. The reaction of sodium carbonate + aluminum sulfate system and sodium bicarbonate + aluminum sulfate system will generate precipitation to block the internal pore structure of cement stone, leading to a decrease in permeability. Calcium hypochlorite (1.5 wt.%) + urea (0.6 wt.%) system is preferred as a gas-generating agent system for SCGPCS. Sand (30 wt.%) with 300–425 μm particle size is preferred as a structural strength substance for SCGPCS. Graphene poly-gel (referred to hereafter as the GPG) has a high FCI and good CO2 foam stability. GPG (6.0 wt.%) is preferred as a foam stabilizer for SCGPCS. The thickening time of graphene–foam–cement slurry is 138 min at 50 °C, with long pumping time, normal thickening curve and excellent performance. The SCGPCS has a corrosion rate of 11.25 mpy in the formation water and can be stable in the formation. Acid is more corrosive to SCGPCS, and it can be used to improve the permeability of SCGPCS. Field tests have proven that SCGPCS fracturing injected 33 m3 of fluid, of which 27 m3 entered the formation. Graphene–foam–cement slurry was injected into the formation through the casing for 13 m3, with a displacement of 0.4–0.6 m3/min and tubing pressure 8–13 MPa. The formation was fractured with a fracturing crack half-length of 71.58 m, a supported fracturing crack half-length of 56.95 m, and a supported fracturing crack permeability of 56.265 mD.

The role of Ce doping on the activity of La2O2CO3 nanosheets catalysts in synthesis of dimethyl carbonate from propylene carbonate and methanol

Dimethyl carbonate (DMC) production from the transesterification reaction of propylene carbonate (PC) and methanol is an eco-friendly and economical process with propylene glycol (PG) as the high value-added co-product. We report herein the synthesis of Ce-doped La2O2CO3 nanosheets (La1Cex) with varying Ce contents through a solvothermol method. La1Ce0.15 catalyst exhibits superior catalytic performance in the production of DMC by the transesterification of methanol and PC. A remarkable improvement in PC conversion (> 85%) and DMC selectivity (> 98%) can be attributed to an increase in surface O2− base sites caused by increased oxygen interstitials and vacancies through Ce doping.

Iron-Catalyzed Cross-Electrophile Coupling of Inert C–O Bonds with Alkyl Bromides

Iron-Catalyzed Cross-Electrophile Coupling of Inert C–O Bonds with Alkyl Bromides

Stereoconvergent Synthesis of Cyclopentenyl Nucleosides by Palladium‐Assisted Allylic Reaction

AbstractThe Tsuji‐Trost reaction of cyclopentenyl carbonates was explored by experimental studies and computational calculations, in search for the synthetic conditions enabling the stereoconvergent synthesis of cyclopentenyl nucleosides. Under common conditions, cyclopentenyl reagents provide Tsuji‐Trost products only in a weakly stereoconvergent manner. However, changes in the amount of catalyst (up to 1 eq) affect either the regio‐ and stereoselectivity of the reaction, selectively leading to cis configured cyclopentenyl N9‐linked purine nucleosides, regardless the relative configuration (cis or trans) of the starting substrates. DFT studies clarified that this could be due to the low activation energy related to the crucial, Pd‐dependent π‐inversion step.

Comparison of 5- and 6-membered cyclic carbonate-polyisocyanate adducts for high performance coatings

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.

Electrical conductivity of siderite and its implication for high conductivity anomaly in the slab-mantle wedge interface

Carbonate minerals as a dominant carbon host can be transported to the Earth’s deep interior via subduction of the oceanic lithosphere, and their physicochemical behavior potentially has a significant influence on the compositional heterogeneity and physical properties in the deep mantle. In this study, we measured the electrical conductivity of natural siderite at 1–3 GPa and 100–700°C using a complex impedance analyzer in a large volume multi-anvil high-pressure apparatus. A sharp increase in conductivity was observed at ∼400°C under various pressures, and subsequently, the electrical conductivity keeps anomalously high values in the whole temperature range owing to a small quantity of interconnected highly conductive phases (graphite and magnetite) produced from the low degree decarbonation of siderite. The change in electrical conductivity and activation enthalpy suggest that the conduction mechanisms before and after low degree decarbonation of siderite are the small polaron (electron hopping in Fe2+–Fe3+) and highly conductive phases, respectively. Our results indicate the incipient decarbonation temperatures at 1–3 GPa are considerably lower than the decomposition boundary of siderite determined by phase equilibrium experiments, implying the initial decarbonation reaction of Fe-bearing carbonates in the subducting oceanic crust occurs at a shallower depth. The 30 vol.% of siderite is required to enhance the electrical conductivity of (Mg, Fe)CO3 solid solutions. Magnetite and graphite generated from the decarbonation reaction of the siderite component of Fe-bearing carbonate make a significant contribution to the high conductivity anomaly observed in the slab-mantle wedge interface.

Mechanistic Basis for the Iridium-Catalyzed Enantioselective Allylation of Alkenyl Boronates.

Iridium(phosphoramidite) complexes catalyze an enantio- and diastereoselective three-component coupling reaction of alkenyl boronic esters, organolithium reagents, and secondary allylic carbonates. The reaction proceeds through an allylation-induced 1,2-metalate shift of the alkenyl boronate to form non-adjacent stereocenters. Mechanistic investigations outline the overall catalytic cycle and reveal trends in reactivity and selectivity. Analysis of relative stereochemistry in products derived from a variety of 1,1-disubtituted alkenyl boronates provides insight into the transition state of the addition and indicates a concerted pathway. Kinetic analysis of the reaction revealed the kinetic order dependence in boronate, the catalyst, and both the slow- and fast-reacting enantiomer of allylic carbonate as well as the turnover-limiting step of the reaction. Determination of nucleophile-specific parameters N and sN for alkenyl boronate complexes enabled comparison to other classes of nucleophiles. DFT calculations indicate the addition of the alkenyl boronate to the cationic Ir(π-allyl) intermediate and the 1,2-metalate shift occur in a concerted mechanism. The stereoselectivity is determined by ligand-substrate steric repulsions and dispersion interactions in the syn addition transition state. Hammett studies supported the computational results with regard to electronic trends observed with both aryl-derived alkenyl boronates and aryl carbonates.

Reactivity and Product Selectivity of Fluoroalkyl Carbonates in Substitution Reactions with Primary Alcohols and Amines.

The present study reports a systematic investigation of the substitution reactions of a series of symmetric and unsymmetric fluoroalkyl carbonates with primary alcohols or amines. The reactivity of the haloalkyl carbonate depends mainly on the electrophilicity and steric crowdedness of the carbonyl group and the leaving ability of the haloalkyl alcohols. Diethyl carbonate as a reference substrate showed no reaction with the alcohol or amine. However, bis(2,2,2-trifluoroethyl) carbonate [(F3-EtO)2CO] having electron-withdrawing trifluoroethyl groups enabled substitution reactions, with relatively higher reactivities to those for diphenyl carbonate [(PhO)2CO]. Furthermore, (F6-iPrO)2CO, bearing two sets of hexafluoroisopropyl groups, showed dramatic acceleration of the reactions, in which the observed reactivities were similar to those for bis(perfluorophenyl) carbonate [(F5-PhO)2CO]. The electrophilicity of the carbonyl group and the leaving ability of the alcohols in the series of haloalkyl carbonates were found to be correlated with the wavenumbers of their carbonyl groups in IR spectra and pKa for the eliminated alcohols, respectively. Since the eliminated fluoroalkyl alcohols exhibit weak affinity with the organic products and have lower boiling points owing to a characteristic property of the fluoroalkyl group, they could be readily removed from the product by simple evaporation below 100 °C with or without reduced pressure.

New Guanidinium and Aminoguanidinim Salts of 2-Hydroxypyridine-3-carboxylic acid: Preparation and spectral, structural, thermal, ADMET, biological, and molecular docking studies

The reaction of guanidine carbonate and aminoguanidine bicarbonate with 2-hydroxypyridine-3-carboxylic acid in various mole ratios (1:1, 1:2, and 2:1) resulted in the formation of the salts [GunH][C6H4NO3]▪H2O (1), [GunH][C12H9N2O6] ▪H2O (2), [GunH]2[C6H3NO3]▪H2O (3), [AmguH][C6H4NO3]▪H2O (4), [AmguH][C12H9N2O6] (5), and [AmguH]2[C6H3NO3]▪H2O (6) [where GunH+- guanidinium (+1) and AmguH+- aminoguanidinium (+1) salts]. Elemental analysis, FT-IR, 1H NMR, and TG-DTA studies were used to identify and characterize the synthesized simple salts. All compounds were polycrystalline in nature, except (1), which was obtained as single crystal. Single-crystal X-ray diffraction studies confirmed the structure of (1), which crystallizes in a monoclinic system with the P21/n space group, with molecular formula C7H12N4O4. FT-IR spectra of the aminoguanidinium salts reveal NN stretching frequencies in the range of 989–914 cm−1, indicating the presence of aminoguanidinium moiety. The NH2 protons of the guanidinium/aminoguanidinium moiety are assigned to the 7–7.5 δ signals in the 1H NMR signals for the simple salts (1)–(6). The thermal reactivity and stability of the as-prepared salts were investigated in air using simultaneous TG-DTA analysis. Except for compounds (5) and (6), the TG-DTA of all the salts showed dehydration followed by continuous decomposition to produce gaseous products. All the salts underwent endothermic decomposition followed by exothermic combustion in the temperatures range from 120 to 450 °C. Furthermore, the salts have appreciable drug-likeness characters according to Lipinski's regulations, as predicted by the in silico ADMET properties. Molecular docking studies of salts also revealed good binding affinity toward 3MIW, 4WM8, and 5IBV proteins. Among the six salts prepared, the diguanidinium salts showed good anticancer activity against human lung adenocarcinoma and human breast adenocarcinoma cell lines. The disk diffusion method was adopted to investigate the antibacterial activities of compounds (1)–(6) in vitro against two bacterial strains. All the salts displayed potential antibacterial activity against Escherichia coli and Staphylococcus aureus.