scholarly journals Gas Antisolvent Fractionation: A New Approach for the Optical Resolution of 4-chloromandelic Acid

2019 ◽  
Vol 63 (2) ◽  
pp. 303-311
Author(s):  
Amit Zodge ◽  
Márton Kőrösi ◽  
János Madarász ◽  
Imre Miklós Szilágyi ◽  
Erzsébet Varga ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Organic Solvent ◽  
Enantiomeric Excess ◽  
Optical Resolution ◽  
Operational Parameters ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Resolution Method ◽  
New Approach ◽  
Gas Antisolvent

A new, rapid optical resolution method of 4-chloromandelic acid is presented using (R)-1-phenylethanamine as the resolving agent. Gas antisolvent fractionation was investigated as the separation method, studying the effect of pressure, temperature and carbon dioxide to organic solvent mass ratio in details. Generally, the method offers green operation using supercritical carbon dioxide as the precipitative agent, and can be less time- and organic solvent-intensive than conventional processes. By upscaling, the possibility of controlling the crystal-morphology might also be improved. At 16 MPa, 40 °C and 7.5 carbon dioxide to methanol ratio 72 % enantiomeric excess was reached in the crystalline product, along a 73 % yield. The resolution efficiency was not affected by any of the operational parameters. Enantiomeric enrichment beyond 90 % can be carried out by repeated resolution of a scalemic mixture of the acid. Solid products were investigated using differential scanning calorimetry, powder X-ray diffraction and scanning electron microscopy confirming the formation of a crystalline (R)-1-phenylethanammonium-4-chloromandelate salt.

scholarly journals Photocatalytic and adsorption properties of TiO2-pillared montmorillonite obtained by hydrothermally activated intercalation of titanium polyhydroxo complexes

2018 ◽  
Vol 9 ◽  
pp. 364-378 ◽  
Author(s):  
Mikhail F Butman ◽  
Nikolay L Ovchinnikov ◽  
Nikita S Karasev ◽  
Nataliya E Kochkina ◽  
Alexander V Agafonov ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Nitrogen Adsorption ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
New Approach ◽  
Pillared Montmorillonite ◽  
Degussa P25 ◽  
Adsorption Desorption ◽  
High Degree

We report on a new approach for the synthesis of TiO2-pillared montmorillonite, where the pillars exhibit a high degree of crystallinity (nanocrystals) representing a mixture of anatase and rutile phases. The structures exhibit improved adsorption and photocatalytic activity as a result of hydrothermally activated intercalation of titanium polyhydroxo complexes (i.e., TiCl4 hydrolysis products) in a solution with a concentration close to the sol formation limit. The materials, produced at various annealing temperatures from the intercalated samples, were characterized by infrared spectroscopy, differential scanning calorimetry (DSC)/thermogravimetric analysis (TGA), X-ray diffraction, dynamic light scattering (DLS) measurements, and liquefied nitrogen adsorption/desorption. The photocatalytic activity of the TiO2-pillared materials was studied using the degradation of anionic (methyl orange, MO) and cationic (rhodamine B, RhB) dyes in water under UV irradiation. The combined effect of adsorption and photocatalysis resulted in removal of 100% MO and 97.5% RhB (with an initial concentration of 40 mg/L and a photocatalyst-sorbent concentration of 1 g/L) in about 100 minutes. The produced TiO2-pillared montmorillonite showed increased photocatalytic activity as compared to the commercially available photocatalyst Degussa P25.

scholarly journals Production of Rosuvastatin Calcium Nanoparticles Using Gas Antisolvent Technique

2021 ◽  
Author(s):  
Mohammad Najafi ◽  
Nadia Esfandiari ◽  
Bizhan Honarvar ◽  
Zahra Arab Aboosadi
Keyword(s):  
Particle Size ◽  
Biological Fluids ◽  
Solute Concentration ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Initial Solute ◽  
Rate Of Dissolution ◽  
Minimum Particle Size ◽  
Gas Antisolvent ◽  
Effects Of Temperature

The activity of pharmaceutical substances crucially depends on the bioavailability of the substances. The bioavailability of drugs in body and their rate of dissolution in the biological fluids are increased if the particle size is decreased. In the present paper, the Gas Anti-Solvent (GAS) method was used to lower the size of rosuvastatin particles. The effects of temperature (313–338 K), pressure (105–180 bar) and initial solute concentration (20–60 mg/ml) were evaluated by Response Surface Methodology (RSM). The optimum initial solute concentration, temperature and pressure were found to be 20 mg/ml, 313 K and 180 bar, respectively which resulted in the minimum particle size. Furthermore, the particles were characterized by Differential Scanning Calorimetry (DSC), Dynamic Light Scattering (DLS), Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-Ray Diffraction (XRD). The analyses showed that the rosuvastatin particles (60.3 nm) precipitated by GAS process become significantly smaller than the initial particles (45.8 µm).

scholarly journals In situ high-energy X-ray diffraction of precipitation and dissolution reactions during heating of Al alloys

2021 ◽  
Author(s):  
Hannes Fröck ◽  
Christian Rowolt ◽  
Benjamin Milkereit ◽  
Michael Reich ◽  
Wolfgang Kowalski ◽  
...  
Keyword(s):  
High Energy ◽  
Al Alloys ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Zero Crossing ◽  
New Approach ◽  
X Ray ◽  
Common Technique ◽  
Equilibrium Phases

AbstractDuring heating of Al alloys, typically a sequence of precipitation and dissolution reactions occurs and the single (partly opposing) reactions superimpose. Differential scanning calorimetry (DSC) is one common technique to analyse the kinetic development of precipitation and dissolution in Al alloys, but the superposition of the exothermic precipitation and endothermic dissolution reactions complicates the DSC signal interpretation, as DSC measures the sum of any heat effect. Synchrotron high-energy X-ray diffraction (HEXRD) allows the kinetic development of phase transformations to be obtained and can support the separation of superimposed DSC signals. HEXRD results from this work offer a new approach to separate part of the superimposed reactions and their kinetic development for the equilibrium phases β-Mg2Si in EN AW-6082 and η-Mg(Zn,Cu,Al)2 in EN AW-7150. Comparing DSC and HEXRD results confirms serious overlap issues. Common DSC evaluation methods alone, using zero crossing between endothermic and exothermic heat flow or peak positions can be misleading regarding individual reaction start and finish temperatures as well as regarding reaction intensities, which can be unambiguously determined by in situ HEXRD.

A Novel Process to Synthesize NiCoMnO4 Nano-Powder for NTC Electro-Ceramics

2012 ◽  
Vol 476-478 ◽  
pp. 913-916 ◽  
Author(s):  
Jun Hua Wang ◽  
Jin Cheng Yao ◽  
Zhao Yang Chen ◽  
Yan Wei Fan ◽  
Dian Zeng Jia
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Solid State Reactions ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Spinel Type ◽  
New Approach ◽  
Nano Powder ◽  
Good Electrical Property ◽  
Controlled Morphology

A pure spinel-type phase was attained by solid state reactions at room temperature, with no intermediate compounds. Its formation and the structural evolutions have been characterized by thermogravimetry-differential scanning calorimetry (TG/DSC) tests, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Related electrical analyses were also performed. The results showed that the powders and ceramics prepared by the solid state reactions at room temperature exhibit a good electrical property because of narrow grain size distribution, controlled morphology, and high purity. Most importantly, this new approach greatly simplifies the preparation processes.

scholarly journals Construction of Mechanically Reinforced Thermoplastic Polyurethane from Carbon Dioxide-Based Poly(ether carbonate) Polyols via Coordination Cross-Linking

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2765
Author(s):  
Gaosheng Gu ◽  
Jincheng Dong ◽  
Zhongyu Duan ◽  
Binyuan Liu
Keyword(s):  
Carbon Dioxide ◽  
Dynamic Mechanical Analysis ◽  
Thermoplastic Polyurethane ◽  
Mechanical Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Dynamic Mechanical ◽  
Chemical Structures ◽  
Vis Spectroscopy

Using carbon dioxide-based poly(propylene ether carbonate) diol (PPCD), isophorone diisocyanate (IPDI), dimethylolbutyric acid (DMBA), ferric chloride (FeCl3), and ethylene glycol (EG) as the main raw materials, a novel thermoplastic polyurethane (TPU) is prepared through coordination of FeCl3 and DMBA to obtain TPU containing coordination enhancement directly. The Fourier transform infrared spectroscopy, 1H NMR, gel permeation chromatography, UV−Vis spectroscopy, tensile testing, dynamic mechanical analysis, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis were explored to characterize chemical structures and mechanical properties of as-prepared TPU. With the increasing addition of FeCl3, the tensile strength and modulus of TPU increase. Although the elongation at break decreases, it still maintains a high level. Dynamic mechanical analysis shows that the glass-transition temperature moves to a high temperature gradually along with the increasing addition of FeCl3. X-ray diffraction results indicate that TPUs reinforced with FeCl3 or not are amorphous polymers. That FeCl3 coordinates with DMBA first is an effective strategy of getting TPU, which is effective and convenient in the industry without the separation of intermediate products. This work confirms that such Lewis acids as FeCl3 can improve and adjust the properties of TPU contenting coordination structures with an in-situ reaction in a low addition amount, which expands their applications in industry and engineering areas.

Differential Scanning Calorimetry of Minerals of the Dolomite-Ferroan-Dolomite-Ankerite Series in Flowing Carbon Dioxide

1988 ◽  
Vol 52 (368) ◽  
pp. 627-635 ◽  
Author(s):  
J. V. Dubrawski ◽  
S. St. J. Warne
Keyword(s):  
Carbon Dioxide ◽  
Limit Of Detection ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Total Enthalpy ◽  
Fe Content ◽  
The Individual ◽  
Mg Content ◽  
Ferroan Dolomite

AbstractThe dolomite-ferroan-dolomite-ankerite series of carbonate minerals has been investigated in flowing carbon dioxide using high-temperature DSC. Decomposition products were analysed by X-ray diffraction. The minerals studied included dolomite containing no iron, and members substituted by iron in the molar ratio range of 0.082 to 0.49. Complete resolution of the three main endothermic features was observed and enthalpy values ΔH, determined from each. The individual and total enthalpy values showed a linear dependence upon the Fe and Mg content of the members across the series. A decrease in the enthalpy of decomposition occurs with increasing Fe content. The effect of Fe substitution was readily observed and the estimated limit of detection is less than 1% FeO. Accuracy of the measurements was limited by the purity of the minerals themselves.

scholarly journals Model Building on Selectivity of Gas Antisolvent Fractionation Method Using the Solubility Parameter

2019 ◽  
Vol 63 (2) ◽  
pp. 294-302 ◽  
Author(s):  
Máté Mihalovits ◽  
Attila Horváth ◽  
László Lőrincz ◽  
Edit Székely ◽  
Sándor Kemény
Keyword(s):  
Solubility Parameter ◽  
Model Building ◽  
Linear Models ◽  
Optical Resolution ◽  
Solubility Parameters ◽  
Operational Parameters ◽  
Single Term ◽  
Designed Experiment ◽  
Fractionation Method ◽  
Gas Antisolvent

Solubility parameters are widely used in the polymer industry and are often applied in the high pressure field as well as they give the possibility of combining the effects of all operational parameters on solubility in a single term. We demonstrate a statistical methodology to apply solubility parameters in constructing a model to describe antisolvent fractionation based chiral resolution, which is a complex process including a chemical equilibrium, precipitation and extraction as well. The solubility parameter used in this article, is the Hansen parameter. The evaluation of experimental results of resolution and crystallization of ibuprofen with (R)-phenylethylamine based on diastereomeric salt formation by gas antisolvent fractionation method was carried out. Two sets of experiments were performed, one with methanol as organic solvent in an undesigned experiment and one with ethanol in a designed experiment. The utilization of D-optimal design in order to decrease the necessary number of experiments and to overcome the problem of constrained design space was demonstrated. Linear models including dependence of pressure, temperature and the solubility parameter were appropriate to describe the selectivity of the GASF optical resolution method in both sets of experiments.

scholarly journals A new approach for the polymerization of tetraphenyltetramethylcyclotetrasiloxane by an environmentally friendly catalyst called Maghnite-H+

2018 ◽  
Vol 7 (4) ◽  
pp. 296-305 ◽  
Author(s):  
Djamal Eddine Kherroub ◽  
Mohammed Belbachir ◽  
Saad Lamouri
Keyword(s):  
Ring Opening ◽  
Polymerization Reaction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Average Molecular Mass ◽  
Green Catalyst ◽  
New Approach ◽  
X Ray ◽  
Cationic Ring Opening Polymerization ◽  
C Nmr

Abstract This work is devoted to the study of the cationic ring opening polymerization of tetraphenyltetramethylcyclotetrasiloxane (D4Ph,Me), using a solid green catalyst prepared by the activation of a natural clay by sulfuric acid (Maghnite-H+). This treatment leads to the spacing of the montmorillonite sheets due to the substitution of the existing interlayer cations by the protons of the acid. This consequence is clearly shown on the X-ray diffraction (XRD) spectrum. The polymerization reaction proceeded in bulk and under mild conditions. Various tests were carried out by changing the temperature, the time and the catalyst mass content in order to increase, at the same time, the yield of the reaction and the average molecular mass of the polyphenylmethylsiloxane (PPMS) obtained. The structure of the PPMS obtained was identified by infrared (IR), 1H nuclear magnetic resonance (NMR) and 13C NMR analyses over different periods of time. The thermal behavior was investigated by differential scanning calorimetry (DSC) analysis. At the end, in order to show the role played by the Maghnite-H+ during the various reaction stages, a reaction mechanism was proposed.

Glibenclamide-Nicotinamide Cocrystals Synthesized by The Solvent Evaporation Method to Enhance Solubility and Dissolution Rate of Glibenclamide

2019 ◽  
Vol 9 (01) ◽  
pp. 21-26
Author(s):  
Arif Budiman ◽  
Ayu Apriliani ◽  
Tazyinul Qoriah ◽  
Sandra Megantara
Keyword(s):  
Solvent Evaporation ◽  
Physical Mixture ◽  
Dissolution Profile ◽  
Solvent Evaporation Method ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Evaporation Method ◽  
Dissolution Properties ◽  
Mixture Characterization

Purpose: To develop glibenclamide-nicotinamide cocrystals with the solvent evaporation method and evaluate their solubility and dissolution properties. Methods: Cocrystals of glibenclamide-nicotinamide (1:2) were prepared with the solvent evaporation method. The prediction of interactive cocrystals was observed using in silico method. The solubility and dissolution were performed as evaluation of cocrystals. The cocrystals also were characterized by differential scanning calorimetry (DSC), infrared spectrophotometry, and powder X-ray diffraction (PXRD). Result: The solubility and dissolution profile of glibenclamide-nicotinamide cocrystal (1:2) increased significantly compared to pure glibenclamide as well as its physical mixture. Characterization of cocrystal glibenclamide-nicotinamide (1:2) including infrared Fourier transform, DSC, and PXRD, indicated the formation of a new solid crystal phase differing from glibenclamide and nicotinamide. Conclusion: The confirmation of cocrystal glibenclamide-nicotinamide (1:2) indicated the formation of new solid crystalline phases that differ from pure glibenclamide and its physical mixture

Nano-Folded Gold Electrocatalysts Enhance the Selectivity of Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kam Sang Kwok ◽  
Yuxuan Wang ◽  
Michael Cao ◽  
Hao Shen ◽  
Weinan Xu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Mass Transport ◽  
Gold Film ◽  
X Ray Diffraction ◽  
Thin Gold Film ◽  
Faradaic Efficiency ◽  
X Ray ◽  
Transmission Electron ◽  
Carbon Monoxide Formation ◽  
Catalytic Interfaces

<p>The local structure and geometry of catalytic interfaces can influence the selectivity of chemical reactions. Here, using a pre-strained polymer, we uniaxially compress a thin gold film to form a nano-folded catalyst. We observe two kinds of folds and can tune the ratio of loose to tight folds by varying the extent of pre-strain in the polymer. We characterize the nano-folded catalysts using x-ray diffraction, scanning, and transmission electron microscopy. We observe grain reorientation and coarsening in the nano-folded gold catalysts. Electroreduction of carbon dioxide with these nano-folded catalysts reveals an enhancement of Faradaic efficiency for carbon monoxide formation by a factor of about four. This result suggests that electrolyte mass transport limitations and an increase of the local pH in the tight folds of the catalyst outweigh the effects of alterations in grain characteristics. Together, our studies demonstrate that nano-folded geometries can significantly alter grain characteristics, mass transport, and catalytic selectivity. </p>

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