Reaction kinetics of the reaction between carbon dioxide and glycidyl methacrylate using tetraoctylammonium chloride as catalyst

Carbon dioxide was absorbed in an organic solutions of glycidyl methacrylate (GMA) in a semi-batch stirred tank with a plane gas-liquid interface at 101.3 kPa to obtain the absorption rate of carbon dioxide, from which the reaction kinetics of the reaction between carbon dioxide and GMA as studied using tetraoctylammonium chloride as catalyst. The reaction rate constants were estimated from the mass transfer mechanism accompanied by the pseudo-first-order reaction with respect to the concentration of carbon dioxide. An empirical correlation formula between the reaction rate constants and the solubility parameters of solvents such as toluene, N-methyl-2-pyrrolidinone, and dimethyl sulfoxide is presented.     

Reaction kinetics of carbon dioxide with glycidyl methacrylate using immobilized trioctylamine supported on poly(styrene-CO-vinylbenzyl chloride) as a catalyst

A soluble polymer-supprted catalyst containing pendant trioctylammonium chloride was synthesized by the radical copolymerization of p-chloromethylated styrene with styrene followed by the addition reaction of the resulting copolymer with trioctylamine. Absorption rate of carbon dioxide into glycidyl methacrylate (GMA) solutions containing the catalyst was measured using a semi-batch stirred tank with a plane gas-liquid interface at 101.3 kPa. The reaction kinetics of the reaction between carbon dioxide and GMA was evaluated using the absorption rate and the mass transfer mechanism of carbon dioxide. Solvents such as toluene, N-methyl-2-pyrrolidinone, and dimethyl sulfoxide influenced the reaction rate constants. Furthermore, this catalyst was compared to the monomeric tetraoctylammonium chloride under the same reaction conditions.     

Facile synthesis of polymers bearing cyclic carbonate structure through radical solution and precipitation polymerizations accompanied by concurrent carbon dioxide fixation

The radical polymerization of glycidyl methacrylate (GMA) was conducted under a carbon dioxide atmosphere (1 atm) in the presence of catalysts for the reaction of carbon dioxide and the oxirane group to afford the five‐membered cyclic carbonate group. The degrees of the carbon dioxide fixation depended on catalysts, concentration, and solvents. In solution reaction, the slower polymerizations resulted in faster carbon dioxide fixation, due to the faster carbon dioxide fixation to GMA than to oxirane moieties in polymers. When the polymerization was conducted in 1,4‐dioxane, which is a good solvent for polyGMA but a poor solvent for the analogous polymer bearing cyclic carbonate moieties, the resulting polymers were precipitated out as the progress of the polymerization and the carbon dioxide fixation. As a result, polymers could be isolated by simple filtration and rinsing with methanol. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3170–3176, 2009     

Tris(tetramethylguanidinyl)phosphine: The Simplest Non-ionic Phosphorus Superbase and Strongly Donating Phosphine Ligand

We report the synthesis and properties of the much sought-after tris(1,1,3,3-tetramethylguanidinyl) phosphine P(tmg)₃, a crystalline, superbasic phosphine accessible through a short and scalable procedure from the cheap and commercially available bulk chemicals 1,1,3,3-tetramethylguanidine, tris(dimethylamino)-phosphine and phosphorus trichloride. The new phosphine exhibits exceptional electron donor properties and readily forms transition metal complexes with gold(I), palladium(II) and rhodium(I) precursors. The formation of zwitterionic Lewis base adducts with carbon dioxide and sulfur dioxide was explored. In addition, the complete series of phosphine chalcogenides was prepared from the reaction of P(tmg)₃ with N₂O and the elemental chalcogens.     

A Study on the Kinetics of the Catalytic Reforming Reaction of CH4 with CO2： Determination of the Reaction Order

The kinetics of the catalytic reforming reaction of methane with carbon dioxide to produce synthesis gas on a Ni/(α-A1203 and a HSD-2 type commercial catalyst has been studied. The results indicate that the reaction orders are one and zero for methane and carbon dioxide, respectively, when the carbon dioxide partial pressure was about 12.5-30.0 kPa and the temperature was at 1123-1173 K. However, when the carbon dioxide partial pressure was changed to 30.0-45.0 kPa under the same temperature range of 1123-1173 K, the reaction orders of methane and carbon dioxide are one. Furthermore, average rate constants at different temperatures were determined.     

Grafting of glycidyl methacrylate onto polypropylene using supercritical carbon dioxide

Free-radical grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) films has been studied using supercritical carbon dioxide (SC-CO₂) as a solvent and a swelling agent. As the reaction temperature was below the melting point, PP was modified in the solid phase. The PP film was first soaked with the monomer GMA and benzoyl peroxide (BPO) as an initiator using SC-CO₂ at different experimental conditions of pressure, temperature, and thermal treatment time. After releasing CO₂, film GMA molecules were grafted onto PP in different times. Using this method, the degree of grafting and the morphology could be controlled through the combination of pressure, temperature, and soaking time. FTIR spectra confirmed that GMA had been grafted onto PP and that polypropylene-graft-glycidyl methacrylate (PP-g-GMA) presented a high surface reactivity for conductive polyaniline anchoring. DSC measurements and TG analyses showed that the thermal profiles of the graft copolymer and virgin PP are quite similar and that the graft PP does not exhibit changes in terms of thermal degradation profile and melting temperature, respectively. X-ray data showed that a high degree of grafting leads to a lower degree of crystallinity of polypropylene.     

Stopped‐flow Spectrophotometric Study on the Reaction between Carbon Dioxide and [Co(NH3)4(H2O)2]3+ Ion in Aqueous Solution

Kinetics of the reaction of [tetraamminediaquacobalt(III)] perchlorate ion with carbon dioxide in aqueous solution was studied at various temperatures (5–25 °C), variable concentration of CO₂ (0.005M; 0.01M; 0.015M) and over the pH range 6.04–8.15 at a fixed ionic strength of solution (1 M NaClO₄). Investigations were carried out using stopped‐flow spectrophotometry in the range of 300 – 700 nm. The results enabled determination of the number of steps of the reaction studied. Based on the kinetic equations, rate constants were determined for each step. Finally, the mechanism of carbon dioxide uptake by [tetraamminediaquacobalt(III)] perchlorate ion was proposed and discussed.     

Impact of carbon dioxide on the surface tension of 1-hexanol aqueous solutions

Effects of carbon dioxide presence on the surface tension and adsorption kinetics of 1-hexanol solutions were investigated. Experiments were performed at a range of carbon dioxide vapor pressures and varying concentrations of 1-hexanol aqueous solution. Both dynamic and steady-state surface tensions of 1-hexanol aqueous solution were found to decrease with carbon dioxide pressure, and a linear relationship was observed between the steady-state surface tension and carbon dioxide pressure. To explain the experiments, adsorption and desorption of the two species (1-hexanol and carbon dioxide) from two sides of the vapor-liquid interface were considered. A modified Langmuir isotherm, the modified Langmuir equation of state and the modified kinetic transfer equation were developed. The resulting steady-state and dynamic surface tension data were modeled using the modified Langmuir equation of state and the modified kinetic transfer equation, respectively. Equilibrium constants and adsorption rate constants of 1-hexanol and carbon dioxide were evaluated through a minimization procedure for CO₂ pressures ranging from 0 to 690 kPa. From the steady-state modeling, the equilibrium parameters for 1-hexanol and carbon dioxide adsorption from vapor phase and liquid phase were found unchanged at different pressures of carbon dioxide. From the dynamic modeling, the adsorption rate constants for 1-hexanol and carbon dioxide from vapor phase and liquid phase were found to decrease with carbon dioxide pressure. Some fluctuations in the fitting parameters of the dynamic modeling (adsorption rate constants) were observed. These fluctuations may be due to experimental errors, or more likely the limitations of the model used. A major limitation of the model is related to large differences in adsorption/desorption between initial and final stages of the process, and a single set of property parameters cannot describe both initial and final states of the system. Variations may occur depending on which set of data, of initial or final states, is used in the model predictions over the entire time range.     

Removal of Sulfide and Production of Methane from Carbon Dioxide in Microbial Fuel Cells–Microbial Electrolysis Cell (MFCs–MEC) Coupled System

Removal of sulfide and production of methane from carbon dioxide in microbial electrolysis cells (MECs) at the applied voltage of 0.7 V was achieved using sulfide and organic compound as electron donors. The removal rate of sulfide was 72 % and the Faraday efficiency of methane formation was 57 % within 70 h of operation. Microbial fuel cell (MFCs) can be connected in series to supply power and drive the reaction in MECs. Removal of sulfide and production of methane from carbon dioxide in MFCs–MEC coupled system was achieved. The sulfide removal rates were 62.5, 60.4, and 57.7 %, respectively, in the three anode compartments. Methane accumulated at a rate of 0.354 mL h^?1 L^?1 and the Faraday efficiency was 51 %. Microbial characterization revealed that the biocathode of MEC was dominated by relatives of Methanobacterium palustre, Methanobrevibacter arboriphilus, and Methanocorpusculum parvum. This technology has a potential for wastewater treatments and biofuel production from carbon dioxide.     

Conversions of carbon monoxide oxidation over Pt−Rh alloy catalysts calculated by a new gas chromatographic technique

Summary Catalytic fractional conversions of carbon monoxide to carbon dioxide over Pt−Rh alloy catalysts in the presence of excess oxygen, under steady-state or non steady-state conditions, as well as corresponding rate constants for the CO oxidation reaction were measured by using the reversed-flow gas chromatographic technique. From the variation of the conversions with temperature, maximum values of conversions were found, which depend on the catalysts nature (Pt content), while from the variation of the rate constants with temperature, activation energies for the CO oxidation reaction were determined, which also depend on the catalyst Pt content. The results suggest a synergism between Pt and Rh in the Pt−Rh bimetallic catalysts in accordance with previous works, showing that reversed-flow gas chromatography can be used with simplicity and accuracy for the kinetic study of the CO oxidation reaction, which is of technological importance for the control of air pollution.     

Studies of the rates of thermal decomposition of glycine,alanine, and serine

Rates of thermal decomposition of glycine, alanine, and serine are described by the equation of first order reaction in the temperature range 200–300°C. Apparent rate constants and apparent activation energies of decomposition of α-amino acids were evaluated. It was found that the main gaseos reaction product is carbon dioxide.     

Chromic Oxidation of 2-Deoxy-d-Glucose. Comparative Study with Aldoses. I.

Abstract

A rate law for the oxidation of 2-deoxy-d-glucose (2DG) by Cr(VI) in perchloric acid has been derived. This rate law corresponds to the reaction leading to the formation of 2-deoxy-d-gluconic acid (2DGA). No cleavage to carbon dioxide takes place when a twenty-fold or higher excess of aldose over Cr(VI) is employed. Kinetic constants are interpreted in terms of the absence of an hydroxyl group at C-2 on the stability of the chromic ester formed in the first reaction step. Free radicals formed during the reaction convert Cr(VI) to Cr(V). The latter species was detected by EPR measurements.     

Solid-state radical grafting reaction of glycidyl methacrylate and poly(4-methyl-1-pentene) in supercritical carbon dioxide: surface morphology and adhesion

Solid-state radical grafting of glycidyl methacrylate (GMA) onto poly(4-methyl-1-pentene) (PMP) was performed using supercritical carbon dioxide (scCO(2)) impregnation technology. The polymer films were firstly impregnated in the scCO(2) phase with the GMA using benzoyl peroxide as thermal initiator. The grafting degree and surface morphology of the samples may be controlled by the following factors: time, temperature, and pressure of impregnation. A 2(3) factorial design to evaluate the main and interaction effects of such factors on the grafting of the PMP by GMA (grafting response) was elaborated from FTIR data. The superior and inferior limits of the levels were defined on basis of a P-x-y diagram for binary system CO(2)+GMA that provided the location of the transition curves of such a system. Better grafting response was obtained for pressure of 130 bar, temperature of 70°C and time of 7h. The PMP-g-GMA films exhibited a thermal profile similar to that of the unmodified polymer. Adhesion characteristics of polymer films are dependent on grafting degree of GMA.     

Studies of methyl methacrylate–glycidyl methacrylate copolymers: Copolymerization to low molecular weights and modification by ring-opening reaction of epoxy side groups

The copolymerization of methyl methacrylate (MMA) with glycidyl methacrylate (GMA) at 60°C with 2,2′-azobisisobutyronitrile (AIBN) as radical initiator and in the presence of thiophenol (TP) as chain-transfer agent has been investigated. Monomer reactivity ratios for MMA and GMA are found to be r₁ (MMA) = 0.80 ± 0.015 and r₂ (GMA) = 0.70 ± 0.015, from which Q and e values are calculated to be 0.68 and ?0.36 for GMA. The initial rate of copolymerization R_p at 60°C with AIBN (0.02 mole/l.) and TP (0.1, 0.01 mole/l.) were found to increase nonlinearly with increasing GMA concentration in the monomer feed. Homopolymerizations of MMA and GMA monomers were studied in the presence and in the absence of thiophenol. The values of δ (= k_t^1/2/k_p) for MMA and GMA were determined to be 10.25 and 3.00 (mole-sec/l.)^1/2, respectively. Using the values r₁ (MMA), r₂ (GMA), δ₁ (MMA), δ₂ (GMA), and R_p, the cross-termination constants ? for MMA–GMA monomers were determined (average value ? = 0.42). The increase in R_p values with increasing GMA content has been attributed to the cross-termination of MMA–GMA radicals. The transfer constant of TP has also been determined for GMA and found to be 1.00. A MMA–GMA copolymer of low molecular weight, containing 2.01% of oxirane oxygen, was modified by opening of the oxirane ring of GMA by reaction with diethanolamine (DEA). The reaction was carried out at 70 ± 1°C, the copolymer content of epoxy groups and the amine being assumed to be in the molar ratio of 1:4. Addition of a hydrogen-bond acceptor like nitrobenzene decreases, while addition of a hydrogen-bond donor like phenol increases the rate of epoxy ring opening with DEA. This indicates that a hydrogen-bonded intermediate is involved in this reaction and that it weakens the epoxy ring and enhances the rate of its opening with DEA. From the studies of the conversion rates, existence of a “nonspecific” side reaction has been shown which involves the reaction of the terminal epoxy groups of the copolymer and the hydroxyl groups of DEA or formed in the reaction with DEA (involves a chain coupling). DEA can be trifunctional in this reaction. This has been further confirmed from the increase of number-average molecular weights M?_n of the copolymers resulting from this coupling and the nitrogen content in the copolymers after modification with DEA.     

Pyrolysis of nuclear reactor circulator oil in carbon dioxide

The ingress of circulator oil into the carbon dioxide coolant of a nuclear reactor can cause problems such as the deposition of carbon on the fuel elements.This paper describes the first stage of degradation when oil is pyrolysed, in carbon dioxide at temperatures between 600 and 900°C, and in helium at 900°C, for 20s. The degradation products were determined using gas chromatography with either a selective carbon monoxide monitor or a flame ionization detector. The chromatograph was combined with a mass spectrometer for the identification of the degradation produces.Hydrogen, carbon monoxide and a wide range of hydrocarbons are the initial degradation products. The amounts of individual reaction product, and the total amount formed (P) increased with pyrolysis temperature, T, according and the total amount = 1/T. The sensitivity to temperature of product formation varied from one product to another. Formation of carbon monoxide was least sensitive to temperature.It is clear that a chemical reaction takes place between the oil and carbon dioxide since the total amounl of product produced is much greater in carbon dioxide than in helium and the relative amounts of product produced in carbon dioxide differ considerably from those produced by pyrolysis in helium: for example, no carbon monoxide is detected when the oil is pyrolysed in helium.     

Free radical polymerization of glycidyl methacrylate in plasticized Poly(vinyl chloride)

Kinetic of free radical in-situ polymerization of glycidyl methacrylate (GMA), was studied in a complex evolutionary system: poly(vinyl chloride) (PVC) plastisols. A predictive model of conversion-time profile based on free radical mechanism was proposed and structure of the modified PVC system developed was investigated by NMR analyses. In order to elucidate the mechanism of the reaction, model molecules for PVC were used with NMR and MALDI-TOF characterization. It was found that in-situ polymerization of GMA in PVC plastisols leads to both homopolymerization and grafting of GMA onto PVC backbone by hydrogen abstraction. For 33 wt% GMA loaded, grafting efficiency is 67% with an amount of grafted poly-glycidyl methacrylate (pGMA) equals to 22 wt%. Thus, this article discloses a new type of PVC plastisols called reactive plastisols where, in addition to usual plasticizers, PVC is modified by polymerizable GMA monomer.     

High-temperature kinetics of thermal decomposition of acetic acid and its products

Kinetics of the thermal decomposition of acetic acid vapor dilute in argon have been studied over the temperature range of 1300–1950 K in a single-pulse shock tube. The acid was found to decompose homogeneously and molecularly via two competing firstorder reaction channels at nearly equal rates, to form methane and carbon dioxide on the one hand, and ketene and water on the other. Fall-off behavior has been taken into account and limiting high-pressure rate constants for both channels have been derived. Ketene was found to decompose both unimolecularly to methylene radicals and carbon monoxide and also by a radical reaction with CH₂ to form ethylene and carbon monoxide. The rate constant derived for the unimolecular reaction was found to be in good agreement with an earlier shock tube measurement by H. G. Wagner and F. Zabel [Ber. Bunsenges Phys. Chem., 75 , 114 (1971)]. The bimolecular reaction of ketene to produce allene and carbon dioxide, important in lower temperature reaction systems, has been found to be unimportant under the present conditions. A computer model for the decomposition kinetics involving 46 reactions of 21 species has been found to simulate the experimental yield data substantially. Sensitivity analyses have been used to identify reactions which make important contributions to the overall mechanism and yields of major products. Methylene radicals play important roles in determining yields of major species.     

Viscosity effects on the thermal decomposition of bis(perfluoro-2-N-propoxypropionyl) peroxide in dense carbon dioxide and fluorinated solvents

The thermal decomposition of the free-radical initiator bis(perfluoro-2-N-propoxyprionyl) peroxide (BPPP) was studied in dense carbon dioxide and a series of fluorinated solvents. For the fluorinated solvents, the observed first-order decomposition rate constants, k(obs), increased with decreasing solvent viscosity, suggesting a single-bond decomposition mechanism. The k(obs) values are comparatively larger in dense carbon dioxide and similar to the "zero-viscosity" rate constants extrapolated from the decomposition kinetics in the fluorinated solvents. The decomposition activation parameters demonstrate a compensation behavior of the activation enthalpy with the activation entropy upon change in solvent viscosity. Comparison of the change in activation parameter values upon change in solvent viscosity for BPPP with two additional initiators, acetyl peroxide (AP) and trifluoroacetyl peroxide (TFAP), further suggests that carbon dioxide exerts a very minimal influence on the decomposition mechanism of these initiators through solvent-cage effects.     

CO2/离子液体体系热力学性质的分子动力学模拟

超临界CO2和离子液体(ILs)是两种绿色溶剂. 离子液体可以溶解超临界CO2, 而超临界CO2不能溶解离子液体. 由此设计构成的CO2/IL二元系统, 同时具备了超临界CO2和离子液体的许多优点: 既可以降低离子液体的粘度, 还便于相分离, 是新型的耦合绿色溶剂. 其物理化学性质对于设计反应、分离等过程非常重要. 因此, 本文以CO2/IL二元系统为研究对象, 通过选择合适的分子力场和系综, 运用分子动力学(MD)模拟方法研究了CO2/[bmim][PF6]、CO2/[bmim][NO3]等体系的热力学性质. 结果表明, CO2对ILs膨胀度的影响非常小, 当CO2摩尔分数为0.5时, ILs膨胀仅为15%. CO2/ILs的扩散系数远小于CO2膨胀甲醇、乙醇溶液的扩散系数. 随着CO2含量的增加, ILs的扩散系数提高, 粘度显著下降, 表明CO2能有效地改善ILs扩散性, 减小其粘度. 因此CO2可用以改善离子液体溶剂体系的传递特性, 增强反应分离过程在其中的进行.     

Profluorescent nitroxides: Sensors and stabilizers of radical-mediated oxidative damage

In this study, three profluorescent nitroxides 1,1,3,3-tetramethyldibenzo[e,g]isoindolin-2-yloxyl (TMDBIO), 1,1,3,3-tetramethyl-2,3-dihydro-2-azaphenalene-2-yloxyl (TMAO) and 5-[2-(4-methoxycarbonyl-phenyl)-ethenyl]1,1,3,3-tetramethylisoindoline-2-yloxyl (MeCSTMIO) were tested as probes for radical-mediated damage in polypropylene arising from both UV and thermally initiated sources. These nitroxides possess a very low fluorescence quantum yield due to quenching by the nitroxide group; however, when the free-radical moiety is removed by reaction with alkyl radicals (to give an alkoxyamine), strong fluorescence is observed. The results obtained from this profluorescent nitroxide trapping technique compare favourably with other methods of monitoring degradation, provided the appropriate probe is chosen for the conditions of oxidation, signalling an indication of damage well before other techniques show any response. The technique was also applied to the monitoring of crosslinked polyester coating resins. Differentiation in the oxidative stability of the resins was evident after as little as 200 min where other monitoring techniques require up to 300 h of accelerated degradation. This highlights the sensitivity of this method as well as demonstrating the scope of this technique to assess polymer stability.