Acid In Supercritical Carbon Dioxide Research Articles

Solubility measurements and analysis of binary, ternary and quaternary systems of palm olein, squalene and oleic acid in supercritical carbon dioxide

Through the application of a dynamic method, the solubility of three lipid components with different volatilities and polarities was measured in supercritical carbon dioxide (SC-CO 2). Binary systems of CO 2/squalene (SQ), CO 2/oleic acid (OA) and CO 2/pseudo-component palm olein (PO) were measured at temperatures of 313, 333 and 353 K, and at a pressure range of 10–30 MPa. A ternary system of CO 2/SQ/PO and a quaternary system of CO 2/SQ/PO/OA were also investigated at 313 K and pressures of 10–25 MPa. Comparison of the ternary system with the binary system showed a decrease in the solubility of SQ, with a corresponding rise in the solubility of PO. In the quaternary system, the presence of OA decreased the selectivity of SQ. The data were correlated using Chrastil’s equation in order to examine the general trend of solubility behaviour.

Processing behaviors of thin-film pentacene and benzene-1,4-diboronic acid in supercritical carbon dioxide

This research investigates the feasibility of using supercritical carbon dioxide (scCO 2) as a green solvent for processing organic thin film semiconductor, such as pentacene, and a potential molecular modifier for use in electronic device applications. Benzene-1,4-diboronic acid (BDBA) was selected as a molecular modifier in this work due to its electron deficient nature, which can potentially enhance pentacene's physical, chemical or electronic properties by changing its structure in the solid state. In this study, the solubilities of BDBA and pentacene in scCO 2 are measured as individual compounds and as co-solutes, at 313 K, using ultraviolet (UV) spectroscopy. Methanol co-solvent effects on solubility have also been characterized for each compound. The results show that BDBA is insoluble in pure scCO 2 up to 1.82 × 10 7 Pa. However, with a small amount of methanol added to the mixture, BDBA becomes soluble in solution with a solubility of 3.81 × 10 − 4 mol/l at 9.00 × 10 6-Pa-pressure. In contrast, pentacene is only soluble in scCO 2 at pressures above 1.10 × 10 7 Pa, and its solubility is decreased upon addition of methanol due to the non-polar nature of pentacene. When a pentacene thin film is treated with BDBA in scCO 2/methanol solution, BDBA sorption is observed at pressures as low as 8.80 × 10 6 Pa. Based on these results, it is concluded that treatment of pentacene thin films in scCO 2 is a promising approach that can be optimized for BDBA and other similar molecular modifiers, to produce multi-component organic thin film devices.

Synthesis of Hexanoic Acid in Supercritical Carbon Dioxide

AbstractAm Beispiel der vergleichsweise einfachen autokatalytischen, partiellen Oxidation von Hexanal zu Hexansäure konnten die Vorteile des Einsatzes von CO2 als Lösungsmittel erfolgreich herausgearbeitet werden und in eine Prozessentwicklung münden. Auf der Basis der ermittelten Stoff‐ und Reaktionsdaten wurde ein Prozessdesign erstellt und mittels einer Prozesssimulation Massen‐ und Energiebilanzen für eine Anlagenauslegung berechnet. Schließlich wurden die Kosten für die Herstellung von Hexansäure nach dem vorgeschlagenen Verfahren abgeschätzt.

Solubility of Corosolic Acid in Supercritical Carbon Dioxide and Its Representation Using Density-Based Correlations

The solid solubilities of 2α,3β-dihydroxyurs-12-en-28-oic acid (corosolic acid) in supercritical carbon dioxide (SC-CO2) have been measured using a dynamic method at (308.15, 313.15, 323.15, and 333.15) K over a pressure range of (8 to 30) MPa. Prior to solubility measurements, the accuracy of the experimental apparatus was examined by measuring solubilities of squalene in SC-CO2 and comparing them with literature. The corosolic acid solubilities ranged from a corosolic acid mole fraction of 3.28·10−11 at 333.15 K and 8 MPa to 7.43·10−2 at 333.15 K and 30 MPa. The del Valle and Aguilera and Méndez-Santiago and Teja (density-based) models were used to correlate the experimental data. The calculated solubilities showed good agreement with the experimental data in the temperature and pressure ranges studied.

Equilibrium solubility of pure and mixed 3,5-dinitrobenzoic acid and 3-nitrobenzoic acid in supercritical carbon dioxide

The solid solubility of pure 3,5-dinitrobenzoic acid (3,5-DNBA) and 3-nitrobenzoic acid ( m-NBA) and their equal-weight mixture in supercritical carbon dioxide (SCCO 2) was measured using a flow-type apparatus at 308, 318, and 328 K and in the pressure range of 10.0–21.0 MPa. The solubility enhancement SE of mixed 3,5-DNBA and m-NBA in the ternary system has been observed. The mixture separation factor μ and the separation efficiency HE were investigated. A modified Kumar–Johnston (K–J) model was proposed for correlating the solubility of solid compounds in SCCO 2. The experimental solubility data of pure and mixed solutes in SCCO 2 were successful to be correlated by Chrastil model, the modified Adachi–Lu model, K–J model and new proposed model. Solubility data from 23 different solid compounds were taken from literature. The accuracy of the proposed model was evaluated by correlating 13 binary systems, 13 ternary systems, and 1 quaternary system. The modified K–J model satisfactorily correlated the experimental results for the solubility of all these compounds in SCCO 2 within 5.11% AARD.

ChemInform Abstract: The Suzuki—Miyaura Cross‐Coupling of Bromo‐ and Chloroarenes with Arylboronic Acids in Supercritical Carbon Dioxide.

AbstractA new and convenient method for the Suzuki—Miyauro cross coupling of haloarenes with phenylboronic acid is developed.

Solubility of Small-Chain Carboxylic Acids in Supercritical Carbon Dioxide

The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 ± 0.03) kg·m−3 (T = 323.15 K, p = 8.5 MPa) to (147 ± 0.2) kg·m−3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 ± 0.1) kg·m−3 (T = 333.15 K, p = 10.0 MPa), while the highest solute concentration was (151 ± 2) kg·m−3 (T = 333.15 K, p = 26.7 MPa). Additionally, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant su...

Solubility of 3,5-Dinitrobenzoic Acid in Supercritical Carbon Dioxide with Cosolvent at Temperatures from (308 to 328) K and Pressures from (10.0 to 21.0) MPa

The solid solubility of 3,5-dinitrobenzoic acid in supercritical carbon dioxide with cosolvent, ethanol, ethyl acetate, n-propanol, and ethylene glycol was measured using a flow-type apparatus at temperatures from (308 to 328) K and in the pressure range of (10.0 to 21.0) MPa. The mole fraction of cosolvent was 0.015, 0.035, and 0.055, respectively. The experimental results showed that the equilibrium solubility of 3,5-dinitrobenzoic acid can be effectively enhanced in the presence of all cosolvents. A semiempirical model, the Sovova model, was modified by adding a function of temperature (T). The accuracy of the modified Sovova model was tested and verified by the solubility data of 17 kinds of solid compounds from the literature. In addition, the modified Sovova model was successfully used to correlate the experimental solubility data of 3,5-dinitrobenzoic acid in supercritical carbon dioxide with different cosolvents, and the average absolute relative deviation (AARD) ranged from (2.2 to 8.8) %.

The Suzuki–Miyaura cross-coupling of bromo- and chloroarenes with arylboronic acids in supercritical carbon dioxide

Haloarenes ArHal (Hal = Br, Cl) react with arylboronic acids in supercritical carbon dioxide in the presence of a system comprising Pd(OCOCF 3 ) 2 /Buchwald phosphine ligand/potassium carbonate (phosphate)/18-crown-6 to yield the corresponding cross-coupling products in high yields; all chlorine atoms in di- and tetrachloroarenes are replaced by aryl groups under the proposed conditions.

Solubility of Maleic Acid in Supercritical Carbon Dioxide

The solubility of maleic acid in supercritical carbon dioxide has been measured at (318.15, 333.15, and 348.15) K over a pressure range of (7 to 30) MPa. Measurements were carried out using a static apparatus. The solubility ranged from a maleic acid mole fraction of 1.30·10−5 at 318.15 K and 7 MPa to 59.17·10−5 at 348.15 K and 30 MPa. The Chrastil and Méndez-Santiago and Teja (density-based) models were used to correlate the experimental data.

Levulinic Acid Solubility in Supercritical Carbon Dioxide with and without Ethanol as Cosolvent at Different Temperatures

The solubility of levulinic acid in supercritical carbon dioxide in the absence and presence of ethanol (mole fraction of ethanol x3 = 0.0, 0.027, and 0.051) as a cosolvent was measured with a synthetic method at temperatures from (313.0 to 342.4) K and pressures from (8.0 to 19.0) MPa. It is demonstrated that, at a fixed temperature, the solubility of levulinic acid increases with increasing pressure; at a fixed pressure, it decreases with increasing temperature. When ethanol is added into supercritical carbon dioxide as a cosolvent, the solubility of levulinic acid increases greatly, and it increases with the concentration of the added ethanol. The experimental solubility data can be correlated using the Chrastil model and a modified Chrastil model with four adjustable parameters.

Control of the plasticity of organosilicon rubbers by their modification with polypyrrole

Modification of organosilicon rubbers SKTN and SKTV with polypyrrole was studied. The modifying agent was synthesized directly in the rubbers containing iron trichloride acting as oxidant and catalyst, using the diffusion procedure and impregnation of organosilicon rubbers with pyrrole-2-carboxylic acid in supercritical carbon dioxide. Changes in the ductility and viscosity of the composite materials were analyzed.

Preparation and application of SBA-15-supported palladium catalyst for Suzuki reaction in supercritical carbon dioxide

The external and internal surfaces of SBA-15 were modified by (MeO)3SiPh and a phosphine ligand, (MeO)3SiCH2CH2CH2SCH2C6H4PPh2, before and after the template Pluronic P123 copolymer was removed, respectively. Palladium was then tethered within the cavity of the mesoporous material Ph-SBA-15-PPh3via a ligand-exchange reaction to provide a new supported palladium catalyst Ph-SBA-15-PPh3-Pd. This catalyst was demonstrated to be a robust and active catalyst in Suzuki reaction of a wide range of aryl bromides with arylboronic acids in supercritical carbon dioxide. After the reaction mixtures were treated at 90 °C for 24 h, the crude coupling products were obtained as crystalline solids when the reaction temperature was lowered to room temperature and the carbon dioxide was then slowly released. The pure products can be obtained by simple recrystallization in good to excellent yields. The Ph-SBA-15-PPh3-Pd catalyst has low leaching loss and can be reused at least 7 times without loss of activity.

Microwave Effect for Glycosylation Promoted by Solid Super Acid in Supercritical Carbon Dioxide

The effects of microwave irradiation (2.45 GHz, 200 W) on glycosylation promoted by a solid super acid in supercritical carbon dioxide was investigated with particular attention paid to the structure of the acceptor substrate. Because of the symmetrical structure and high diffusive property of supercritical carbon dioxide, microwave irradiation did not alter the temperature of the reaction solution, but enhanced reaction yield when aliphatic acceptors are employed. Interestingly, the use of a phenolic acceptor under the same reaction conditions did not show these promoting effects due to microwave irradiation. In the case of aliphatic diol acceptors, the yield seemed to be dependent on the symmetrical properties of the acceptors. The results suggest that microwave irradiation do not affect the reactivity of the donor nor promoter independently. We conclude that the effect of acceptor structure on glycosylation yield is due to electric delocalization of hydroxyl group and dielectrically symmetric structure of whole molecule.

Copolymerization of vinylidene fluoride and acrylic acid in supercritical carbon dioxide

AbstractThe free‐radical copolymerization of vinylidene fluoride (VDF) and acrylic acid (AA) was carried out in supercritical carbon dioxide using both precipitation and dispersion techniques in the presence of an ammonium carboxylate perfluoropolyether compound. Formation of a copolymer was confirmed by variable contact time CP MAS NMR spectroscopy. Macromolecular matrices were significantly enriched in AA with respect to the initial feed composition and we found that the nonfluorinated monomer has a much higher reactivity ratio with respect to VDF. The cumulative concentration, crystallinity, and water affinity of the synthesized copolymers could be modified changing the initial feed composition, the density of the polymerization mixture, the specific interfacial area of the polymer phase, and the polymerization time. The solubility of the macromolecular product in water was greatly affected by its composition. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 109–121, 2010

Solubility and density measurements of palmitic acid in supercritical carbon dioxide + alcohol mixtures

Solubility data of palmitic acid (hexadecanoic acid) in supercritical carbon dioxide were measured in the pressure range from 10 to 25 MPa at temperatures of 313 and 318 K. Densities for this binary mixture in the homogeneous phase and at saturation conditions were measured in the same range of temperature. The influence of 3 and 6 mol% ethanol and 2-propanol as co-solvent on the solubility and density data for the CO 2 + palmitic acid mixture was also determined at 313 K. Measurements were carried out in a static-synthetic sapphire cell coupled to a vibrating-tube densitometer. The self-consistency of the data was tested according to the density-based models proposed by Mendez-Santiago and Teja.

Solubilities of palmitic and stearic fatty acids in supercritical carbon dioxide

The solubilities of two fatty acids, namely hexadecanoic acid (palmitic acid) and octadecanoic acid (stearic acid) in supercritical carbon dioxide (SCCO 2), were determined at T = (328 and 338) K from 12.8 MPa to 22.6 MPa. Three models, namely a thermodynamic model based on the Peng–Robinson equation of state with Kwak and Mansoori mixing rules, a model based on dilute solution theory proposed by Mendez-Santiago and Teja and a new reformulated Chrastil equation model, were used to correlate the solubilities. In all the models, the correlation constants are temperature independent. All the models successfully correlated the experimental results for the solubilities of hexadecanoic acid within 3%.

Effect of Chain Length of Alcohol on the Lipase-Catalyzed Esterification of Propionic Acid in Supercritical Carbon Dioxide

The esterification of propionic acid was investigated using three different alcohols, namely, isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol. The variation of conversion with time for the synthesis of isoamyl propionate was investigated in the presence of five enzymes. Novozym 435 showed the highest activity, and this was used as the enzyme for investigating the various parameters that influence the esterification reaction. The Ping-Pong Bi-Bi model with inhibition by both acid and alcohol was used to model the experimental data and determine the kinetics of the esterification reaction.

Stereoselective synthesis of tetrasubstituted olefins via palladium-catalyzed three-component coupling of aryl iodides, internal alkynes, and arylboronic acids in supercritical carbon dioxide

The Pd-catalyzed three-component coupling of readily available aryl iodides, internal alkynes, and arylboronic acids provides a convenient, one-step route to tetrasubstituted olefins in good to excellent yields in scCO 2 using CsOAc as base. The final optimized reaction conditions for the three-component coupling in scCO 2 was determined to be aryl iodides (0.5 mmol), internal alkynes (0.25 mmol), and arylboronic acids (0.5 mmol) in the presence of PdCl 2 (2 mol%) and CsOAc (0.75 mmol) in scCO 2 ( P C O 2 = 7.5 MPa ) at 100 °C for 24 h. The presence of scCO 2 generally substantially improved this Pd-catalyzed system and increased the yields of the desired tetrasubstituted olefins. The reaction involves full cis-addition of internal alkynes and this system in scCO 2 is an effective and environmental friendly alternative to the previous methods involving organic solvent.

Fullerene [60]-Mediated Polymerization of Polyacrylic Acid in Supercritical Carbon Dioxide

A series of fullerene [60]-polyacrylic acid (C60-PAA) conjugates was synthesized through 2,2-azobisisobutyronitrile (AIBN)-initiated in situ polymerization of acrylic acid (AA) under different reaction conditions in supercritical (carbon dioxide (scCO2). This has afforded corresponding C60-PAA conjugates with C60 content ranging from 0.76 to 6.69% and rheoviscosity from 1.183 to 2.349 Mpas (means—in this investigation, fullerene [60] content varied from 0.76 (minimum) to 6.69% (maximum) in synthesized C60-PAA conjugates and rheoviscosity varied from 1.183 (minimum) to 2.349 Mpas (maximum value). The process of in situ polymerization was monitored at concentrations (mole/dL) of AIBN of 304.50–931.5 × 10−3 and AA of 6.94–20.82 × 10−3, temperatures of 50°–90°C, pressures of 1000–2600 psi, and times of 2–26 h. The progress of insitu polymerization was monitored rheoviscometrically in methanol at 25°±1°Cand by gel permeation chromatography. Selected C60-PAA conjugates were characterized by UV-vis, FT-IR, 1H NMR, laser-induced breakdown spectra (LIBS), transmission electron microscopy (TEM), and simultaneous thermogravimetric-differential thermogravimetric analysis-differential scanning calorimetry (TG-DTA-DSC) in nitrogen.