Reaction Of Carbonate Research Articles

Production and Characterization of Non-Isocyanate Polyurethane/SiO2 Films Through a Sol-Gel Process for Thermal Insulation Applications.

The reaction of cyclic carbonates with amines is the most attractive among the synthesis methods for isocyanate-free polyurethane. Non-isocyanate polyurethane films with SiO2 NPs fabricated by a sol-gel process are reported, where cyclic carbonates (CC) were produced under mild conditions by CO2 insertion in an epoxide complex in the presence of LiCl. A reaction of CC and polyamines was carried out in a low concentration polymer matrix of PVA. The materials were characterized by 1H-NMR, FTIR, UV-Vis, SEM, TGA, DTG, and a KD2 pro technique. polymer FTIR results are consistent with the literature, even with the use of a non-conventional methodology, where the found chemical interactions values were 3330, 2930 and 1637 cm−1. There are differences in the polymers’ morphologies due to the presence and absence of SiO2 NPs according to SEM, where the spherical morphology and homogenous particle size distribution of NPs around 100 nm. According to TGA results, all polymers showed their last stage decomposition after 300 °C and polymers with higher concentration of NPs showed even better stability. Due to the obtained results, the polymers have the potential to be used for thermal insulation without negative effect on the environment.

Characterization of Reverse Micelles Formulated with the Ionic-Liquid-like Surfactant Bmim-AOT and Comparison with the Traditional Na-AOT: Dynamic Light Scattering, 1H NMR Spectroscopy, and Hydrolysis Reaction of Carbonate as a Probe.

The present study investigated how the presence of butylmethylimidazolium cation (bmim+) alters the interfacial properties of reverse micelles (RMs) created with the ionicliquid-like surfactant 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (bmim-AOT), in comparison to sodium 1,4-bis-2-ethylhexylsulfosuccinate (Na-AOT) RMs, employing dynamic light scattering (DLS) and 1H NMR techniques. Moreover, through the hydrolysis reaction of bis(4-nitrophenyl)carbonate inside both RMs as reaction probe, interfacial properties changes were explored in more detail. The kinetic solvent isotope effect was also analyzed. Micellar systems were formed using n-heptane as external nonpolar solvent and water as the polar component. According to the DLS studies, water is encapsulated inside the organized media; however, a different tendency is observed depending on the cationic component of the surfactant. For Na-AOT system, the results suggest that the micellar shapes are probably spherical, while in the case of bmim-AOT, a transition from ellipsoidal to spherical micelles could be occurring when water is added. 1H NMR data show that water is structured differently when Na+ cation is replaced by bmim+; in bmim-AOT RMs, the interaction of water with the surfactant is weaker and the water hydrogen-bonding network is less disturbed than in Na-AOT RMs. Kinetic studies reveal that the hydrolysis reaction in bmim-AOT RMs was much more favorable in comparison to Na-AOT RMs. In addition, when water content decreases in bmim-AOT RMs, the hydrolysis reaction rate increases and the solvent isotope effect remains constant, while for Na-AOT solutions, both the reaction rate and the solvent isotope effect decrease. Our results indicate that bmim+ cation would be located in the surfactant layer in such a way the negative charge density in the interface is less than that in Na-AOT RMs, and the reaction is more favorable. Additionally, as 1H NMR studies reveal, the interfacial water molecules would be more available in bmim-AOT RMs to participate in the nucleophilic attack. Therefore, the present study evidences how the replacement of Na+ counterion by bmim+ alters the composition of the interface of AOT RMs.

Reaction Kinetics and Coreflooding Study of High-Temperature Carbonate Reservoir Stimulation Using GLDA in Seawater

Well stimulation using hydrochloric acid (HCl) is a common practice in carbonate reservoirs to overcome formation damage in the near wellbore area. Using HCl for matrix acidizing has many limitations at high-temperature (HT) conditions, such as tubulars corrosion and face dissolution due to the fast reaction rate. Chelating agents, such as L-glutamic acid-N,N-diacetic acid (GLDA), are alternatives to HCl to overcome these problems. We studied the effect of diluting GLDA in seawater on the reaction kinetics with carbonate rocks under HT conditions at low pH (3.8). Results of the reaction of carbonate at 1000 psi and 150, 200, and 250 °F with GLDA prepared in both fresh and seawater, GLDA/DI and GLDA/SW, respectively, are presented. The reaction kinetics experiments were carried out in HT rotating disk apparatus (RDA) at rotational speeds ranging from 500 to 2000 revolutions per minute (RPM) at a fixed temperature. Indiana limestone and Austin chalk were used to studying the effect of rock facies on the reaction of GLDA with rock samples. In both GLDA/DI and GLDA/SW, the reaction regime of 20 wt% GLDA (3.8 pH) with Indiana limestone was mass transfer limited. The reaction rate and diffusion coefficient were highly dependent on the temperature. For Austin chalk, at 200 °F and 1000 psi the diffusion coefficient of GLDA/SW is an order of magnitude of its value with Indiana limestone using the same fluid. Diffusion coefficients were used to estimate the optimum injection rate for stimulating HT carbonate formation and compared with coreflooding results. The data presented in this paper will support the numerical simulation of the acid flow in carbonate reservoirs.

Optimization of Energy and Resource Efficiency in a Multistage Drying Process of Phosphate Pellets

The roasting of phosphate pellets is an energy-intensive process the optimization of which can give rise to considerable efficiency improvements. To this purpose, the mathematical modeling and the computer-aided simulation of a multi-stage process of phosphate pellets roasting have been developed. This process includes drying, dissociation reaction of carbonates and a sintering process in a moving, dense, multilayer mass of phosphate pellets in a special horizontal grate apparatus. A theoretical model for the physical-chemical processes of a mass of phosphate pellets moving in a multistage process and subject to external operation variables (i.e., temperatures and flowrates of the drying gas at different positions of the conveyor length) has been developed. By letting these control variables vary over suitable ranges limited by technical constraints, it is possible to construct an algorithm that minimizes the overall energy consumption subject to the attainment of the required quality indicators of the pellets. Therefore, the set of constraints includes bounds on both the operational variables and quality indicators of the final product. A dynamic programming algorithm subject to suitable penalty functions for avoiding constraints violation has been used. The results obtained show that the scientifically based operation described in this paper achieves the goal of attaining considerable energy savings while assuring the quality of the finished pellets. Furthermore, the results highlight the convenience of extending the general strategy developed in this article to other chemical energy engineering processes.

Polyurethanes without Isocyanates and Isocyanates without Phosgene as a New Field of Green Chemistry: Mechanism, Catalysis, and Control of Reactivity

A brief review of studies in the kinetics, catalysis, and reaction mechanisms of new green chemistry processes for polyurethanes performed at the Semenov Institute of Chemical Physics of the Russian Academy of Sciences over the past decade and a half is given. The review centers on the formation of hydroxyurethanes without the use of isocyanates on the basis of the reaction of cyclic carbonates with amines, the phosgene-free production of isocyanates by thermal decomposition of acylazides, and the prospects for using renewable plant-based raw materials for the production of novel polyurethanes.

Bis(dialkylphosphino)ferrocene-Ligated Nickel(II) Precatalysts for Suzuki-Miyaura Reactions of Aryl Carbonates.

Aryl carbonates, a common protecting group in synthetic organic chemistry, are potentially valuable electrophiles in cross-coupling reactions. Here, after performing a thorough evaluation of different precatalysts, we demonstrate that (dcypf)Ni(2-ethylphenyl)(Br) (dcypf = 1,1-bis-(dicyclohexylphosphino)ferrocene) is an efficient precatalyst for Suzuki-Miyaura reactions using a variety of aryl carbonates as substrates. Mechanistic studies indicate that (dcypf)Ni(2-ethylphenyl)(Br), which contains a bidentate phosphine that binds in a trans geometry, is an effective precatalyst for these reactions for two reasons: (i) it rapidly forms the Ni(O) active species and (ii) it minimizes comproportionation reactions between the Ni(O) active species and both the unactivated Ni(II) precatalyst and on-cycle Ni(II) complexes to form catalytically inactive Ni(I) species. In contrast, the state of the art precatalyst (dppf)Ni(o-tolyl)(Cl) (dppf = 1,1-bis(diphenylphosphino)ferrocene), which contains a bidentate phosphine that binds in a cis geometry, forms Ni(I) species during activation and is essentially inactive for aryl carbonate couplings. Although the exact reasons on a molecular level why the dcypf system is more active than the dppf system are unclear, our results indicate that in general Ni catalysts supported by the dcypf ligand will give better performance for catalytic reactions involving substrates which undergo relatively slow oxidative addition, such as aryl carbonates.

Monodisperse mesoporous La2O3 flakes for the synthesis of glycerol carbonate by efficiently catalyzing the transesterification of dimethyl carbonate with glycerol

Monodisperse mesoporous La2O3 flakes were prepared by hydrothermal methods using polyethylene glycol as pore-expanding agent, the catalyst exhibited better catalytic activity than normal La2O3 in the reaction of glycerol and dimethyl carbonate to produce glycerol carbonate. The influence of the molecular weight of polyethylene glycol and the mass ratio of La(NO3)3·6H2O/polyethylene glycol on the catalyst was investigated. The results showed that the morphology of La2O3 was remolded to porous flakes interestingly by the suitable type and dosage of pore-expanding agent, this change made the La2O3 catalyst particles have higher alkalinity, better crystallinity, larger specific surface area and good dispersion, which greatly improved the catalytic performance of the catalyst. In addition, the optimal reaction conditions were studied. As a result, the as-prepared porous La2O3 modified by polyethylene glycol-20000 showed excellent catalytic performance with high glycerol carbonate yield of 99.4% under the optimal reaction conditions as follows: the glycerol/dimethyl carbonate molar ratio was 1:5, the catalyst dosage was 5.0 wt% to glycerol, the reaction temperature was 85 °C and the reaction time was 0.5 h. The catalyst had outstanding stability after six cycle reactions with almost no loss of catalytic activity. Thereby, the catalyst was considered to possess the promising potential in industrial production for catalyzing glycerol to the high value-added chemical glycerol carbonate.

EXPERIENCING A SYNTHESIS ONE-POT OF 1,2,4-OXADIAZOLE MEDIATED BY MICROWAVE OVEN: GREEN CHEMISTRY IN FOCUS

1,2,4-oxadiazoles are compounds that have attracted the attention of many researchers due to their wide range of biological activities, for example, anti-inflammatory, antimicrobial, antitumor etc. The syntheses are based mostly on the use of amidoximes and acylating agents as the initial reactants. This work aims to describe a one-pot reaction for the synthesis of 1,2,4-oxadiazols, mediated by microwave irradiation, employing home-use microwave oven, in the discipline of heterocyclic Chemistry in the postgraduate. The methodology consisted of the reaction of nitriles, hydroxylamine hydrochloride, potassium carbonate and different esters to obtain 1,2,4-oxadiazole. The reactions include two sequential procedures: base-promoted intermolecular addition of hydroxylamine to nitrile to lead to amidoxime, then treatment of the amidoxime with esther to form 1,2,4-oxadiazoles in good yields. This method represents a direct and simple protocol for the synthesis of 3,5-disubstituted 1,2,4-oxadiazoles. It was initially discussed with the students the chemistry of the oxadiazoles, one-pot reactions and green chemistry through atheoretical-expository-dialogue strategy. In the course of the didactic intervention the students, through a thematic seminary, presented the results of the analysis of the spectra from the different techniques used. With the skills acquired from completing this laboratory work, the students become well-prepared to perform spectroscopic analyzes in subsequent experiments encountered in the organic chemistry laboratory.

Synthesis of Arylacetaldehydes by Iridium-Catalyzed Arylation of Vinylene Carbonate with Arylboronic Acids.

The one-step synthesis of arylacetaldehydes by carbon-carbon bond formation between formylmethyl and aryl groups has been realized by the reaction of vinylene carbonate with arylboronic acids in the presence of an iridium/bisphosphine catalyst and a catalytic amount of tetrahydroxydiboron.

Synthesis of Arylacetaldehydes by Iridium‐Catalyzed Arylation of Vinylene Carbonate with Arylboronic Acids

AbstractThe one‐step synthesis of arylacetaldehydes by carbon–carbon bond formation between formylmethyl and aryl groups has been realized by the reaction of vinylene carbonate with arylboronic acids in the presence of an iridium/bisphosphine catalyst and a catalytic amount of tetrahydroxydiboron.

Kinetics Parameters Determination in Non-isothermal Conditions for the Decomposition Reaction of Calcium Carbonate by the True Activation Energy

The true activation energy has been obtained by the trend extrapolation under the differential condition. The frequency factor and the reaction model can be uniquely determined by comparing the result of the model-fitting method with the true activation energy. The result is shown that, the true activation energy can be used to determine the kinetics parameters for the decomposition reaction of calcium carbonate under non-isothermal conditions.

The Kinetics of Magnesium Carbonate Crystallization for Traditional Salt Production Wastewater Recovery

The kinetics of crystallization of magnesium carbonate (nesquehonite) at room temperature (27°C) has been examined using an electrical conductivity method during process of nucleation. Magnesium carbonate hydrate from a reaction of magnesium chloride (MgCl2) and sodium carbonate (Na2CO3) in supersaturated condition was analyzed. Variations of batch reactor experimental are magnesium chloride initial concentration (500-3.000 mg/L) and operating pH (8-14). In this paper, we studied the crystallization kinetics of magnesium carbonate via an electrical conductivity method, a concentration monitoring method. By monitoring electrical conductivity during the solution reaction process, changes in [Mg2+] can be measured and an induction period of nucleation could be determined. Crystal has been formed was confirmed with powder X-ray Diffractometer (XRD) analyses. The results show that magnesium carbonate is formed during operating condition pH 10 with magnesium chloride initial concentration 3.000 mg/L. The nucleation process of magnesium carbonate crystallization can be represented by second-order reaction equation with R2 is 0.8. The induction period of magnesium carbonate crystallization is 50 second.

REACTIVE DIVIDING WALL COLUMN (RDWC) PADA PRODUKSI DIETIL KARBONAT

In this era, the needs for chemicals are increasing. One of them is an additive called diethyl carbonate that is produced by the transesterification reaction of dimethyl carbonate and ethanol. To produce diethyl carbonate by conventional distillation with high purity is expensive and requires a lot of energy, so that new breakthroughs and innovations are needed to overcome this problem. The new breakthrough and innovation proposed in this study is Reactive Dividing Wall Column (RDWC). The purpose of this study is to design an RDWC model and optimize the Reactive Dividing Wall Column. In this study, Aspen Plus software was used. The operating unit model used was RadFrac. The thermodynamic model used was the UNIQUAC model. Then using the literature on reactive distillation, the data were validated. After it was valid, the data will be used to design and optimize RDWC. Variables for optimization are: number of reactive trays, number of trays with a wall, total tray number, and DMC feed location. The results showed that RDWC for the production of diethyl carbonate produced a lower value of TAC than conventional methods. The TAC value obtained was $1,310,706,938 / year. The Reactive Dividing Wall Column design for optimum diethyl carbonate production has a total number of 24 reactive stages, a total number of 26 wall stages, 77 total stages and dimethyl carbonate feed locations on the 71 st stage.

Palladium‐Catalyzed Carboxy‐Alkynylation of Propargylic Amines Using Carbonate Salts as Carbon Dioxide Source

A palladium‐catalyzed multicomponent reaction of propargylic amines, alkynyl bromides and cesium hydrogen carbonate to access oxazolidinones is reported. In contrast to previous reports, only a slight excess of cesium hydrogen carbonate is used as a surrogate of carbon dioxide. The reaction gives access to oxazolidinones bearing alkyl‐ and aryl polysubstituted enynes in good yield and very high E stereoselectivity.

Sodium Methyl Carbonate as an Effective C1 Synthon. Synthesis of Carboxylic Acids, Benzophenones, and Unsymmetrical Ketones

Reported is the synthesis of carboxylic acids, symmetrical ketones, and unsymmetrical ketones with selectivity achieved by exploiting the differential reactivity of sodium methyl carbonate with Grignard and organolithium reagents.

Synthesis of scheelite nanoparticles by mechanically assisted solid-state reaction of wolframite and calcium carbonate

Nanostructured scheelite (CaWO4) was synthesized by calcination in air of enriched wolframite (Fe1−xMnxWO4) ore and calcium carbonate (CaCO3). The effects of process parameters such as milling conditions of the solid reactants, calcination in flowing or static air, and use of stoichiometric excess of calcium carbonate on wolframite conversion into scheelite were studied by X-Ray Diffraction (XRD) and field emission gun scanning electron microscopy (FEG SEM). The intimate mixing and associated decrease in the diffusion path by high-energy planetary ball milling (PBM) were responsible for the conversion of most of wolframite into nanostructured scheelite after 2 h at 600 °C, with no need of calcium carbonate stoichiometric excess. Complete conversion of PBM wolframite:CaCO3 mixtures into nanosized scheelite, iron oxide and carbon dioxide was accomplished after 2 h at 700 °C. The nanostructured scheelite obtained from wolframite is expected to be significantly more reactive in subsequent treatments (e.g., leaching) for tungsten extraction.

A Multicomponent Approach to Oxazolidinone Synthesis Catalyzed by Rare‐Earth Metal Amides

AbstractThree‐component reaction of epoxides, amines, and dimethyl carbonate catalyzed by rare‐earth metal amides has been developed to synthesize oxazolidinones. 47 examples of 3,5‐disubstituted oxazolidinones were prepared in 13–97 % yields. This is a simple and most practical method which employs easily available substrates and catalysts, and is applicable to a wide range of aromatic and aliphatic amines, as well as mono‐substituted epoxides. Scope of disubstituted epoxides is rather limited, which requires further study. Preliminary mechanistic study reveals two possible reaction pathways through intermediates of β‐amino alcohols or amides.

Reactivity of calcium carbonate prepared from flue gas desulfurization gypsum

Abstract Reactivity of various calcium carbonate samples for flue gas desulfurization was tested. Two groups of CaCO3 samples were considered; natural limestone containing calcite phase dominantly and samples prepared by the conversion of gypsum with ammonium and carbon dioxide (precipitated CaCO3) containing different amounts of calcite, aragonite and vaterite. Reactivity of precipitated calcium carbonate depends primarily on the particle size, similarly as in case of industrial samples. The initial reaction rate was comparable with the industrial limestones for samples with the average particle size lower than 15 μm. However, the conversion of laboratory samples was significantly higher after 5 min of the reaction. Phase composition of the precipitated calcium carbonate has a minor but noticeable impact on the reactivity. The presence of vaterite slightly increased the reactivity, which is in accordance with its lower compact structure in comparison with calcite and aragonite. Unexpected effect of the increased content of aragonite, which is the most compact phase in comparison with calcite and vaterite, was observed. If calcium carbonate contains up to approximately 30 % of aragonite the reactivity increases, which can be explained by the SEM pictures showing agglomerate composition with relatively high specific surface. At higher contents of aragonite, the reactivity decreases. All the obtained results proved the suitability of precipitated CaCO3 prepared from flue gas desulfurization gypsum to be recycled in the flue gas desulfurization process.

Optimization of magnesium recovery from reject brine for reuse in desalination post-treatment

In this work, the recovery of magnesium from desalination reject brine through reaction with ammonia has been evaluated and statistically optimized using response surface methodology. The process is based on precipitation of magnesium hydroxide by the reaction of MgCO3 in the brine with ammonium hydroxide. A software, which is designed for studying chemical reaction and equilibrium, was employed to perform the thermodynamic analysis of the reaction of magnesium carbonate with ammonia, which was found to be exothermic and spontaneous in the temperature range of 0–22 °C. Central composite design (5-level, 3-factor) was used to optimize the process to obtain the maximum response of magnesium recovery as a function of reaction temperature, brine salinity, and ammonia to magnesium molar ratio. Maximum recovery of 99% was obtained at a temperature of 15 °C, brine salinity of 85 g/L, and a molar ratio of 4.4NH3: 1 Mg. The predicted response was in excellent agreement with the experimental results. The collected solid product at optimum conditions was characterized using X-ray Diffraction, Energy Dispersive Spectra analysis and thermogravimetric analysis. The analysis indicated the high purity of the recovered product in the form of Brucite (Mg(OH)2).

An effect of reduced S-rich fluids on diamond formation under mantle-slab interaction

Experimental study, dedicated to understanding the effect of S-rich reduced fluids on the diamond-forming processes under subduction settings, was performed using a multi-anvil high-pressure split-sphere apparatus in Fe3C-(Mg,Ca)CO3-S and Fe0-(Mg,Ca)CO3-S systems at the pressure of 6.3 GPa, temperatures in the range of 900–1600 °C and run time of 18–60 h. At the temperatures of 900 and 1000 °C in the carbide-carbonate-sulfur system, extraction of carbon from cohenite through the interaction with S-rich reduced fluid, as well as C0-producing redox reactions of carbonate with carbide were realized. As a result, graphite formation in assemblage with magnesiowüstite, cohenite and pyrrhotite (±aragonite) was established. At higher temperatures (≥1100 °C) formation of assemblage of Fe3+-magnesiowüstite and graphite was accompanied by generation of fO2-contrasting melts - metal-sulfide with dissolved carbon (Fe-S-C) and sulfide-oxide (Fe-S-O). In the temperature range of 1400–1600 °C spontaneous diamond nucleation was found to occur via redox interactions of carbide or iron with carbonate. It was established, that interactions of Fe-S-C and Fe-S-O melts as well as of Fe-S-C melt and magnesiowüstite, were С0-forming processes, accompanied by disproportionation of Fe. These resulted in the crystallization of Fe3+-magnesiowüstite+graphite assemblage and growth of diamond. We show that a participation of sulfur in subduction-related elemental carbon-forming processes results in sharp decrease of partial melting temperatures (~300 °C), reducting the reactivity of the Fe-S-C melt relatively to FeC melt with respect to graphite and diamond crystallization and decrease of diamond growth rate.