Acid In Mixed Solvents Research Articles

Solubility of 5-(Dithiolan-3-yl)pentanoic Acid in the Mixed Solvents of Cyclohexane + Ethyl Acetate, Heptane + Ethyl Acetate, and Hexane + Ethyl Acetate

The solubility of α-5-(dithiolan-3-yl)pentanoic acid in mixed solvents (cyclohexane + ethyl acetate, heptane + ethyl acetate, and hexane + ethyl acetate) was experimentally studied by an analytical method. The data obtained were correlated by a semiempirical equation. Results showed that the solubility of 5-(dithiolan-3-yl)pentanoic acid increased with increasing temperature. In the same solvent systems, the molar fraction solubility increased with a decreasing solvent volume ratio.

Dissociation constants of some derivatives of 5-amino isophthalic acid in mixed solvents

The dissociation constants of some derivatives of 5-amino isophthalic acid have been measured by Calvin Bjerrum pH titration method in DMF-water and DMSO-water (60: 40 v/v) systems at 308.15 K. It is observed that dissociation constant depends on the solvent and substituents group present in the compound.

Water-Soluble CdS Nanospheres Assembled from Quantum Dots

Water-soluble CdS nanospheres assembled from CdS quantum dots (QDs) have been prepared using CdCl2 and thioglycolic acid in mixed solvents of glycerine and ethanolamine at an elevated temperature. The size of CdS nanospheres could be controlled through adjusting the experimental parameters. The UV-Visible absorption and photoluminescence spectra of CdS nanospheres were investigated. The deep-trap luminescence at ∼600 nm quenched at elevated temperatures or longer reaction time and exclusive blue luminescence derived from the band-edge emission of aqueous colloid of CdS nanospheres was observed. The formation mechanism of CdS nanospheres assembled from CdS QDs was discussed.

Direct hydroxylation of benzene with hydrogen peroxide over pyridine–heteropoly compounds

Abstract The hybrid catalysts, pyridine (Py) modified molybdovanadophosphates with Keggin structure Pyn–PMo(12−m)VmO40 (n = 1–3, m = 1–3), were prepared and characterized by FT-IR. Among various catalysts, Py1–PMo10V2O40 exhibited the highest yield of phenol (20.5%) with the selectivity of phenol of 98.0% at 353 K for 5 h in the direct hydroxylation of benzene to phenol with H2O2 in the acetic acid and acetonitrile (volume ratio 1:1) mixed solvent. Pyridine plays an important role in the promotion of the catalytic activities, mostly due to the electronic interaction between pyridine and heteropolyacid together with the more remarkable pseudo-liquid-phase behavior. The influences of the reaction temperature, the amount of H2O2, the amount of Py1–PMo10V2O40 and the reaction time on the yield of phenol were investigated to obtain the optimal reaction conditions for phenol formation.

New topic of supercritical fluids: Local activity coefficients of supercritical solvent and cosolvent around solute

The study of inhomogeneity in supercritical fluids (SCFs) is of great importance. In this work, we propose the concept of local activity coefficients in supercritical (SC) solutions, which link thermodynamics and inhomogeneity in SC systems. The local activity coefficients of CO(2)+acetonitrile+phenol blue and CO(2)+acetic acid+phenol blue systems are investigated at 308.15 K in critical region and outside critical region. To do this, the local compositions of CO(2)+acetonitrile and CO(2)+acetic acid mixed solvents around phenol blue are first estimated using UV-visible spectroscopy. Then it is considered that there exist bulk phase and local phase around phenol blue in the systems. The activity coefficients of CO(2) and the cosolvents (acetonitrile or acetic acid) in bulk phase are calculated using Peng-Robinson equation of state. The local activity coefficients of CO(2) and the cosolvents are then calculated on the basis of thermodynamic principles. It is demonstrated that in the critical region the local activity coefficients differ from bulk activity coefficients significantly and are sensitive to pressure. This can explain many unusual phenomena in SC systems in critical region thermodynamically.

Ibuprofen Racemate Separation by Simulated Moving Bed

Ibuprofen racemates were separated in a SMB system with 4 chromatographic columns packed with TBB gels. Retention times of R- and S-enantiomers of ibuprofen were measured in batch chromatography experiments with hexane/TBME/acetic acid mixed solvent. Isotherm parameters of SMB were calculated from the batch chromatography data, and operation flow parameters obtained from m2 and m3 plane of Morbidelli and coworkers (Abel et al., 2004). Experimental results are summarized as purities of raffinate. In order to compare experiments with simulations, ASPEN Chromatography Simulator was adopted. Isotherm and operation parameters were inserted to the dialog box of the simulator and output display data was cropped for comparison of experiments and simulations.

Pretreatment of eucalyptus wood chips for enzymatic saccharification using combined sulfuric acid‐free ethanol cooking and ball milling

A combined sulfuric acid-free ethanol cooking and pulverization process was developed in order to achieve the complete saccharification of the cellulosic component of woody biomass, thereby avoiding the problems associated with the use of strong acid catalysts. Eucalyptus wood chips were used as a raw material and exposed to an ethanol/water/acetic acid mixed solvent in an autoclave. This process can cause the fibrillation of wood chips. During the process, the production of furfural due to an excessive degradation of polysaccharide components was extremely low and delignification was insignificant. Therefore, the cooking process is regarded not as a delignification but as an activation of the original wood. Subsequently, the activated solid products were pulverized by ball-milling in order to improve their enzymatic digestibility. Enzymatic hydrolysis experiments demonstrated that the conversion of the cellulosic components into glucose attained 100% under optimal conditions. Wide-angle X-ray diffractometry and particle size distribution analysis revealed that the scale affecting the improvement of enzymatic digestibility ranged from 10 nm to 1 microm. Field emission scanning electron microscopy depicted that the sulfuric acid-free ethanol cooking induced a pore formation by the removal of part of the lignin and hemicellulose fractions in the size range from a few of tens nanometers to several hundred nanometers.

Solubility of Benzoic Acid in Mixed Solvents

Benzoic acid solubility has been measured in pure water and in the binary mixtures containing different solvents including water, N,N-dimethylformamide (DMF), ethanol, or 1,4-dioxane. The experiments were carried out employing the cell used in Oliveira's dissertation. The temperature dependence of the solubility of an acid in two solvents could be evaluated. There was similar influence of the temperature in the solubility of benzoic acid in mixtures of water + DMF and water + 1,4-dioxane. An increase in acid solubility was observed with temperature in all mixtures. Addition of more ethanol in water favors the solubilization of benzoic acid.

Volumetric, viscometric and refractive index study of amino acids in mixed solvents at 308.15 K

Densities, ρ, viscosities, η and refractive indices n D for solutions of (0.10, 0.20, 0.30, 0.40 and 0.50 M) glycine (Gly), DL-alanine (Ala) and L-serine (Ser) in aqueous 1-propanol (10 and 30% v/v) at 308.15 K have been determined. These data have been used to calculate apparent molar volumes, φv, partial molar volumes, and Falkenhagen and Jones–Dole coefficients, A and B, respectively. Free energies of activation of viscous flow, and per mole of solvent and solute, respectively, were obtained by using transition state theory to the B-coefficient data. The molar refractive indices, R D were calculated from the experimental values of refractive indices for all the three amino acids + aqueous 1-propanol ternary mixtures. These parameters were used to discuss the solute–solute and solute–solvent interactions and also the effect of cosolvent (1-propanol) on these interactions.

Analysis of Membrane Proteins from Human Chronic Myelogenous Leukemia Cells: Comparison of Extraction Methods for Multidimensional LC−MS/MS

An important strategy for "shotgun proteomics" profiling involves solution proteolysis of proteins, followed by peptide separation using multidimensional liquid chromatography and automated sequencing by mass spectrometry (LC-MS/MS). Several protocols for extracting and handling membrane proteins for shotgun proteomics experiments have been reported, but few direct comparisons of different protocols have been reported. We compare four methods for preparing membrane proteins from human cells, using acid labile surfactants (ALS), urea, and mixed organic-aqueous solvents. These methods were compared with respect to their efficiency of protein solubilization and proteolysis, peptide and protein recovery, membrane protein enrichment, and peptide coverage of transmembrane proteins. Overall, approximately 50-60% of proteins recovered were membrane-associated, identified from Gene Ontology annotations and transmembrane prediction software. Samples extracted with ALS, extracted with urea followed by dilution, or extracted with urea followed by desalting yielded comparable peptide recoveries and sequence coverage of transmembrane proteins. In contrast, suboptimal proteolysis was observed with organic solvent. Urea extraction followed by desalting may be a particularly useful approach, as it is less costly than ALS and yields satisfactory protein denaturation and proteolysis under conditions that minimize reactivity with urea-derived cyanate. Spectral counting was used to compare datasets of proteins from membrane samples with those of soluble proteins from K562 cells, and to estimate fold differences in protein abundances. Proteins most highly abundant in the membrane samples showed enrichment of integral membrane protein identifications, consistent with their isolation by differential centrifugation.

Thermodynamic properties of hydrochloric acid in mixed solvents: {HCl( mA) + NaCl( mB)} in {(1 − x)H 2O + xd-fructose} at T = (278.15 to 318.15) K

The thermodynamic properties of system (HCl + NaCl + C 6H 12O 6 + H 2O) were studied by e.m.f. measurement in the cells without liquid junction: (A) Pt , H 2 ( p = 101.325 kPa ) | HCl ( 0.01000 mol · kg - 1 ) | AgCl – Ag (B) Pt , H 2 ( p = 101.325 kPa ) | HCl ( m ) , C 6 H 12 O 6 ( w ) , H 2 O ( 1 - w ) | AgCl – Ag (C) Pt , H 2 ( p = 101.325 kPa ) | HCl ( m A ) , NaCl ( m B ) , C 6 H 12 O 6 ( w ) , H 2 O ( 1 - w ) | AgCl – Ag At constant total ionic strength (0.5, 1.0, 1.5, and 2.0) mol · kg −1, from (5 to 45) °C, where m A and m B are the molalities of HCl and NaCl, respectively, and w is the mass fraction of fructose in the mixed solvent, which is w = 0.1 during all the measurements. The standard electrode potential of Ag | AgCl in the pure water and mixed solvent has been determined from cells (A) and (B). The activity coefficients lg γ A of HCl in the mixed solvent system have been determined from cell (C).The results show that the activity coefficients of HCl in (HCl + NaCl) solutions still obey Harned’s Rule. The standard transfer Gibbs free energies, entropy and enthalpy of HCl have been calculated. The primary, secondary and total medium effect of HCl have been calculated and discussed.

Studies on the relationship between Pitzer’s equation and medium effect: the system of HCl + H 2SO 4 in {0.06455C 2H 5OH + 0.93545H 2O}

The second ionization constant of sulfuric acid in mixed solvent, K 2, was determined by e.m.f. of cell without liquid junction: Pt, H 2(101.325 kPa)| HCl(m 1), H 2 SO 4(m 2),{ ethanol(x=0.06455)+ water(x=0.93545)}| AgCl− Ag over the temperatures (278.15 to 318.15) K, where x is mole fraction. Combining Owen’s definition of medium effect with Pitzer’s equations, the values of combination parameters: ( λ nHS + λ nCl − λ nS )+(3/2) m n ( μ nnHS + μ nnCl − μ nnS ),(1/2)( ξ nHHS + ξ nHCl − ξ nHS ), that represent the interactions between ions and ethanol were obtained at 298.15 K.

Diffusion coefficients of carboxylic acids in mixed solvents of water and 1-butanol

The diffusion coefficients of five carboxylic acids—formic acid, acetic acid, propionic acid, succinic acid, citric acid—in the phases of water saturated by 1-butanol (water-rich phase) and 1-butanol saturated by water (1-butanol-rich phase) at 25 °C were measured. The semi-empirical model suggested by Perkins–Geankoplis was applied to predict the value of the diffusion coefficients, while the equations of Wilke–Chang and Hayduk–Laudie were selected to calculate the diffusion coefficients in water and the models of Scheibel and Lusis–Ratcliff were for the diffusion coefficients in 1-butanol. By comparing the calculated and experimental data, it was found that the diffusion coefficients in the water-rich and 1-butanol-rich phases could be predicted very well with the combination of the equations of Hayduk–Laudie and Scheibel.

Thermodynamic Properties of Dissociation of Amino Acid in Mixed Solvents

Thermodynamic Properties of Dissociation of Amino Acid in Mixed Solvents

Multiple solubility maxima of oxolinic acid in mixed solvents and a new extension of Hildebrand solubility approach.

A new extension of the Hildebrand solubility approach which describes drug solubility in solvent mixtures showing multiple solubility peaks, the chameleonic effect, is proposed. The experimental solubilities of oxolinic acid were measured at 25 degrees C in solvent mixtures of ethanol-water and ethanol-ethyl acetate. A plot of the mole fraction of the drug against the solubility parameter (delta) of the solvent mixtures displays two peaks at delta = 30.78 MPa1/2 (80% v/v of ethanol in water) and at delta = 20.90 MPa1/2 (30% v/v of ethanol in ethyl acetate). The new extension proposed reproduces two solubility peaks. The thermograms of the solid phase before and after equilibration with the solvent mixtures did not show significant changes. The new extension was also tested with experimental data previously reported for drugs showing two solubility peaks of different height. The accuracy of other published models for describing two solubility maxima is also compared.

Chemical behaviour of oxotitanium(IV) phthalocyanine (OTiPc) solutions associated with the preparation of OTiPC monolayers and multilayers

The chemical behaviour of oxotitanium(IV) phthalocyanine (OTiPc) in mixtures of dichloromethane and trihalogenoacetic acids was studied by means of spectroscopic measurements. In dichloromethane–trifluoroacetic acid mixtures, OTiPc was relatively unstable, undergoing gradual decomposition via the radical cation of OTiPc; phtalimide and 3-iminoisoindolin-1-one were isolated. In dichloromethane–trichloroacetic acid mixed solvent, on the other hand, a stable solution of OTiPc was obtained with no formation of the radical cation. A monolayer of OTiPc was formed upon spreading this solution onto the water surface and was deposited on substrates with a horizontal lifting method to form a multilayer film. Polarized visible and near-IR absorption spectra and X-ray diffraction of the film indicated a specific order of molecular orientation.

Study on polymerization of acrylonitrile with methylacrylate and itaconic acid in mixed solvent

Study on polymerization of acrylonitrile with methylacrylate and itaconic acid in mixed solvent

Thermodynamics of the Dissociation of Amino Acid in Mixed Solvents IV. Glycine in (20 Mass% Glucose-Water) at 278.15-318.15 K

Thermodynamics of the Dissociation of Amino Acid in Mixed Solvents IV. Glycine in (20 Mass% Glucose-Water) at 278.15-318.15 K

Thermodynamics of the dissociation of amino acid in mixed solvents. 2. Glycine in 0.1 mole fraction 1,2-propanediol-water, as 278.15-318.15 K

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermodynamics of the dissociation of amino acid in mixed solvents. 2. Glycine in 0.1 mole fraction 1,2-propanediol-water, as 278.15-318.15 KJiazhen Yang, Dian Yuan Men, Chunyu Liang, Litian Zhang, Limin He, and Ailian SunCite this: J. Phys. Chem. 1989, 93, 20, 7248–7252Publication Date (Print):October 1, 1989Publication History Published online1 May 2002Published inissue 1 October 1989https://doi.org/10.1021/j100357a042RIGHTS & PERMISSIONSArticle Views62Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (572 KB) Get e-Alerts

Hydrogen bonded solvation structures in the reaction of car☐ylic acids and anilines in cyclohexane acetic acid solutions

Short range solvation effects have been studied in reactions of car☐ylic acids and primary, secondary and tertiary amine anilines in cyclohexane and cyclohexane-acetic acid mixed solvents. Acetic acid is found to hydrogen bond with the amine protons of primary and secondary anilines. Trichloroacetic acid reacts as a trimeric structure. Acetic acid interferes with reactions of trichloroacetic acid, possibly by forming a tight heterodimer.