Solvent Mixture Of Ethanol Research Articles

Water–ethanol solvent mixtures: a promising liquid environment for high quality positively-charged CdTe nanocrystal preparation

In this work, the photoluminescence quantum yield of positively-charged CdTe nanocrystals was brought up to 31% in a water–ethanol solvent mixture.

Solubilities of 1,1′-[1,2-Ethanediylbis(oxy-1,2-ethanediyl)]bis-[3-methyl-1H-imidazolium-1-yl] Dihexafluorophosphate in Water, Methanol, Ethanol, Dimethylformamide, Dimethyl Sulfoxide, and (Acetone + Water) Binary Solvent Mixtures

The chemical structure of a new gemini dicationic imidazolium ionic liquid, 1,1′-[1,2-ethanediylbis(oxy-1,2-ethanediyl)]bis-[3-methyl-1H-imidazolium-1-yl] dihexafluorophosphate ([C6O2(mim)2][PF6]2), was established by 1HNMR. The thermal stability of [C6O2(mim)2][PF6]2 was studied with differential scanning calorimetry and thermogravimetric analyses. With the use of the analytical stirred-flask method at atmospheric pressure, the solubilities of [C6O2(mim)2][PF6]2 in water, methanol, ethanol, dimethylformamide, dimethyl sulfoxide, and (acetone + water) binary solvent mixtures were measured from (283.00 to 323.00) K. The experimental data was correlated with the modified Apelblat equation.

Crystal structure of 8-hy-droxy-quinoline: a new monoclinic polymorph.

In an attempt to grow 8-hy­droxy­quinoline–acetamino­phen co-crystals from equimolar amounts of conformers in a chloro­form–ethanol solvent mixture at room temperature, the title compound, C9H7NO, was obtained. The mol­ecule is planar, with the hy­droxy H atom forming an intra­molecular O—H⋯N hydrogen bond. In the crystal, mol­ecules form centrosymmetric dimers via two O—H⋯N hydrogen bonds. Thus, the hy­droxy H atoms are involved in bifurcated O—H⋯N hydrogen bonds, leading to the formation of a central planar four-membered N2H2 ring. The dimers are bound by inter­molecular π–π stacking [the shortest C⋯C distance is 3.2997 (17) Å] and C—H⋯π inter­actions into a three-dimensional framework. The crystal grown represents a new monoclinic polymorph in the space group P21/n. The mol­ecular structure of the present monoclinic polymorph is very similar to that of the ortho­rhom­bic polymorph (space group Fdd2) studied previously [Roychowdhury et al. (1978 ▶). Acta Cryst. B34, 1047–1048; Banerjee & Saha (1986 ▶). Acta Cryst. C42, 1408–1411]. The structures of the two polymorphs are distinguished by the different geometries of the hydrogen-bonded dimers, which in the crystal of the ortho­rhom­bic polymorph possess twofold axis symmetry, with the central N2H2 ring adopting a butterfly conformation.

Thermodynamic analysis and correlation of solubility of disodium 5′-guanylate heptahydrate in aqueous ethanol mixtures

The solubility of disodium 5′-guanylate heptahydrate (5′-GMPNa2) in water-ethanol binary solvent mixtures was measured at temperatures ranging from 278.15K to 323.15K using a dynamic method. The solubility data were correlated by the Apelblat equation, the Combined Nearly Ideal Binary Solvent/Redlich–Kister (CNIBS/R–K) equation and the modified Jouyban–Acree equation, respectively. Results showed that a reasonable match with experimental data is obtained from the Apelblat equation and CNIBS/R–K equation, while the modified Jouyban–Acree equation contains parameters including both solvent composition and temperature. The thermodynamic functions Gibbs free energy, enthalpy and entropy of solution were also calculated based on solubility data of 5′-GMPNa2 determined in binary water+ethanol solvent mixtures by using van’t Hoff equation. The dissolving process is endothermic and the dissolution driving force converts from enthalpy-driving to entropy-driving.

Polymorphism Control through a Single Nucleation Event

Recently, we identified that the single nucleus mechanism, in which all crystals in the suspension originate from the same parent single crystal, might occur more generally than is currently recognized, even in larger volumes. This has important implications for the control of industrial crystallization processes of polymorphic compounds. In this paper, we used polymorphism as a tool to validate this single nucleus mechanism. Isonicotinamide (INA) crystallizes as form II in ethanol solutions, form I in nitromethane, and form IV in nitrobenzene solutions. The metastable form I and form IV, furthermore, only very slowly transform to the stable form II in solvent mixtures of ethanol–nitromethane and ethanol–nitrobenzene. We performed multiple crystallization experiments in solvent mixtures of ethanol–nitromethane and ethanol–nitrobenzene which all resulted in the formation of either pure form I or pure form II and either pure form II or pure form IV, respectively. In ethyl acetate, 4-hydroxyacetophenone (4HAP) crystallizes as form II at lower concentrations and as form I at higher concentrations. Crystallization of 4HAP as a function of concentration on a 3 mL scale results in either pure form I or pure form II. This can be well explained by the single nucleus mechanism. In terms of polymorphism, the control can be achieved by controlling the primary nucleation event that leads to the single crystal, which in turn defines the crystal form of the secondary nuclei. Seeding approaches using only a single crystal would then lead to the avoidance of primary nucleation and thus control over the polymorph obtained.

Ultrasound-Assisted Extraction of Stilbenoids from Grape Stems

A new method for fast determination of stilbenoids from grape stems was developed. Ultrasound-assisted extraction was applied prior to chromatographic determination of stilbenoids in the extracts, and the stability of stilbenoids under extraction conditions was checked. A fractional experimental design was developed to analyze the influence on the extraction process of seven different extraction variables: temperature, ultrasound amplitude, ultrasonic cycle duration, ultrasonic probe type, time, sample-solvent ratio, and solvent (mixtures of ethanol and water). The most important variables for the recovery of major stilbenoids were studied and the final conditions optimized. With this new method, the main stilbenoids found in grape stems can be extracted in 15 min, using 75 °C as the extraction temperature and 80% ethanol as the extraction solvent, and no cleaning step with organic solvent is needed. The optimized method allowed for the analysis of stilbenoid content from 22 grape stem samples, many of them analyzed for the first time.

Solubility of Cefpiramide Sodium in Binary Ethanol + Water and 2-Propanol + Water Solvent Mixtures

The solubility of cefpiramide sodium in binary solvent mixtures of ethanol + water and 2-propanol + water was determined by a steady-state method from (278.2 to 303.2) K and in the initial mole fraction range of alcohol (ethanol or 2-propanol) in the solvent mixture at about 0.4 to 0.8. Cefpiramide sodium exhibits the same order of magnitude of solubility in both binary systems. The solubility decreases with the increase of the initial mole fraction of alcohol and increases with increasing temperature. Dilution crystallization or dilution crystallization incorporated with cooling crystallization will be more suitable than pure cooling crystallization for the purification of cefpiramide sodium. The Jouyban–Acree model, combined with the van’t Hoff equation, was used to correlate the solubility data. The combined model was further simplified so that each item in the model is statistically significant at the 5 % level. The simplified combined model gives a mean relative deviation of 5.3 % for the ethanol + w...

Preparation of protein loaded chitosan microparticles by combined precipitation and spherical agglomeration

Abstract Combined precipitation and spherical agglomeration was carried out in the non-miscible region of ethyl acetate–ethanol–water ternary solvent system. At first, w/o type quasi emulsion was prepared by sequential introduction of aqueous solutions of human serum albumin (HSA), chitosan (CS), and poly(4-styrenesulfonate) (PSS) into an ethyl acetate–ethanol solvent mixture. HSA was used to model a protein type drug, while CS and PSS served as matrix material in the obtained composite particles. PSS also served as chemical precipitation agent for both of the HSA and CS. The solubility of all these substances was reduced by introduction of additional amounts of ethyl acetate–ethanol mixture and/or ethanol as poor solvents. Due to the counter-diffusion of the good and poor solvents between the water rich droplets and the ethyl acetate–ethanol rich continuous phase, the aqueous phase gradually disappeared and partial agglomeration of the precipitated solids and their transfer to the continuous organic phase took place. The paper gives a report on the effect of several process variables on the quality of the obtained microparticles, such as their shape and stability against disintegration. The effects of the composition of the ternary solvent mixture, the route of its variation, the feeding method and composition of the added poor solvents, the stirring rate and the duration of agitation were studied.

Measurement and correlation of solubility of xylitol in binary water+ethanol solvent mixtures between 278.00 K and 323.00K

The solubility of xylitol in ethanol+water solvent mixtures was measured at temperatures ranging from 278.00 K to 323.00 K at atmospheric pressure by using a laser technique. The results of these measurements were correlated by the combined nearly ideal binary solvent CNIBS/Redlich-Kister equation. The experimental solubility and correlation equation in this work can be used as essential data and models in the purification process of xylitol. The variant 2 in the CNIBS/R-K models was confirmed to be more adaptable to predict solubility of xylitol in binary ethanol +water system. Using the experimentally measured solubilities, the thermodynamic properties of dissolution of xylitol, such as Gibbs energy, molar enthalpy of dissolution, and molar entropy of dissolution, were calculated.

Determination and Correlation of Solubility of Tris(3-hydroxypropyl)phosphine Oxide in Selected Solvents

The solubility of tris(3-hydroxypropyl)phosphine oxide (THPPO) in selected solvents was measured by a static analytic method over the temperature range from (293 to 328) K in methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, acetone, and a binary solvent mixture of ethanol + acetone. Several widely used thermodynamic models, such as the empirical equation and the Buchowski–Ksiazaczak (λh), Scatchard–Hildebrand, Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) equations were applied to represent the measurement results. The binary interaction parameters of the above models were found to have a linear dependency on temperature, and the coefficients were regressed. The results show that all of these models can satisfactorily reproduce the experimental data and the NRTL equation can provide the best correlation with an overall relative standard deviation of 0.46 %.

Lanthanide metal-organic frameworks based on a thiophenedicarboxylate linker: Characterization and luminescence

Three topologically-related lanthanide thiophenedicarboxylate (TDC) metal-organic frameworks were synthesized using an identical metal:linker:solvet ratio. Nd(TDC)3(EtOH)3(H2O)·H2O (1; space group Cc, a = 24.035(2) Å, b = 10.063(1) Å, c = 18.998(1) Å, β = 132.41(1)°) contains the same metal-TDC coordination modes as two other compounds which have the isostructural formula Ln(TDC)3(EtOH)3(H2O)·H2O; Ln = Tb (2; space group P¯ 1, a = 12.807(9) Å, b = 14.557(1) Å, c = 19.128(1) Å, α = 106.66(2)°, β = 105.62(2)°, γ = 93.691(2)°), Dy (3; space group P¯ 1, a = 12.793(8) Å, b = 14.682(1) Å, c = 19.077(1) Å, α = 107.12(1)°, β = 105.54(1)°, γ = 93.518(2)°). An equimolar solvent mixture of water and ethanol causes both types of solvent molecules coordinating to metal centers. The fluorescence spectra of compounds 2 and 3 show characteristic bands related to their respective metal ions, but Dy-based 3 is very weak compared to Tb-based 2, indicating coordinating solvent molecules may be quenching Dy fluorescence.

Experimental and predicted solubilities of 3,4-dichlorobenzoic acid in select organic solvents and in binary aqueous–ethanol mixtures

Experimental solubilities are reported for 3,4-dichlorobenzoic acid dissolved in methyl butyrate, and in 16 alcohol, 5 alkyl acetate, 5 alkoxyalcohol and 6 ether solvents. Solubilities were also measured in nine binary aqueous–ethanol solvent mixtures at 298.15 K. The measured solubility data were correlated with the Abraham solvation parameter model. Mathematical expressions based on the Abraham model predicted the observed molar solubilities to within 0.12 log units.

Statistical mixture design investigation of CO2–Ethanol–H2O pressurized solvent extractions from tara seed coat

Tara (Caesalpinia spinosa) fruit seed coat is an abundant Peruvian agro-industrial residue that could be explored as a raw material for the production of valuable phenolic- and antioxidant-rich extracts. In this work, a mixture design was applied to optimize solvent mixtures for selective extraction of phenolic compounds from tara fruit seed coat. Pressurized solvent extractions (PSE) were performed at 313K and 20MPa, using homogeneous CO2, ethanol (EtOH) and H2O solvent mixtures. Extraction kinetics was obtained and phenolic contents, antioxidant activities (measured by the coupled oxidation of β-carotene and linoleic acid) and anti-inflammatory activities (measured by the lipoxygenase inhibition activity) of extracts were evaluated. A linear mixture model predicted total yields and it was verified that H2O was the most effective solvent to obtain high extraction yields. A quadratic model predicted extracts’ phenolic contents and it was verified that H2O and CO2 had an antagonistic effect and that maximum phenolic contents can be expected for EtOH-rich mixtures. A special cubic model predicted anti-inflammatory activities and the maximum activities were also predicted for EtOH-rich mixtures. For the antioxidant activity, no model revealed to be significant (at a 95% confidence level). Nevertheless, high antioxidant activities were observed after 3h of assay (above 80% of oxidation inhibition for nine out of eleven extracts) and even after 6h of assay (above 70%). The obtained results strongly suggest that tara seed coat is a residue that has great potential to be valorized for the production of phenolic-rich extracts presenting high anti-inflammatory and antioxidant activities.

Separation of polyphenols using porous polyamide resin and assessment of mechanism of retention

A porous polyamide resin is shown to possess hydrogen bond acceptor properties suitable for the separation of polyphenolic solutes such as phenolic acids, flavonols and flavonoids. The separation is achieved in the presence of solvent mixtures of acetic acid and ethanol. The extent of hydrogen bond adsorption is reviewed based on data obtained from the elution behaviour of a variety of simple polyphenolic solutes. Polyamide adsorption chromatography was applied for the purification of resveratrol and polydatin from Polygonum cuspidatum Sieb. & Zucc.

Solubility of anthracene in binary alkane + ethanol solvent mixtures at 298.15 K

Experimental solubilities are reported for anthracene in six binary alkane + ethanol solvent mixtures at 298.15 K. The alkane solvents studied were hexane, heptane, octane, cyclohexane, methylcyclohexane and 2,2,4-trimethylpentane. Results of these measurements were used to test a mathematical representation based on the combined nearly ideal binary solvent (NIBS)/Redlich–Kister equation. For the six systems studied, the combined NIBS/Redlich–Kister equation was found to accurately describe the experimental data, with an average absolute deviation between measured and back-calculated values being approximately ±0.5%.

Improving Polymer Nanofiber Quality Using a Modified Co‐axial Electrospinning Process

Based on a modified coaxial electrospinning process and suitable selection of solvent mixtures as sheath fluid, a new strategy is presented for systematically improving polymer nanofiber quality. A concentric spinneret with an indented inner capillary is designed for the modified coaxial electrospinning. With a solution of 12% w/v PVP K60 in ethanol as the core electrospinning fluid, six solvents are used as sheath fluids to investigate the impact of solvent properties on the resultant PVP nanofiber quality. The PVP nanofiber quality is closely related to solvent physical-chemical properties. High quality PVP nanofibers of average diameter 130 ±10 nm with homogeneous structures and smooth surfaces are created using a solvent mixture of acetone, ethanol and DMAc in the ratio of 3:1:1(v/v/v).

The environmental impact of post-combustion CO 2 capture with MEA, with aqueous ammonia, and with an aqueous ammonia-ethanol mixture for a coal-fired power plant

In this paper the authors compare monoethanolamine (MEA) to aqueous ammonia (AA) and a solvent mixture of aqueous ammonia and ethanol (EAA) with respect to their post-combustion CO 2 capture performance and their environmental impact. Simulation of all processes was carried out with Aspen Plus ® and compared to experimental results for CO 2 scrubbing with ammonia. Of special interest was the formation of stable salts, which could be observed in the experimental CO 2 capture with both ammonia solvents. If CO 2 can be captured in the form of ammonium salts, energy requirements are greatly reduced, since no energy is required for solvent regeneration and CO 2 compression. The environmental impact of CO 2 capture was investigated for a 500 MW pulverised coal power plant employing Life Cycle Assessment (LCA) using the software SimaPro ®. For a comprehensive evaluation of this impact, influencing factors such as solvent production and solvent emissions were included. With kinetics taken into account, no salt formation could be observed in CO 2 removal with aqueous ammonia. The necessary reduction of ammonia emissions leads to further energy requirements, and solvent production as well as the remaining ammonia losses to the environment have a more significant environmental impact than CO 2 removal with MEA.

PERFORMANCE OF THE JOUYBAN-ACREE MODEL FOR CORRELATING THE SOLUBILITY OF INDOMETHACIN AND ETHYLHEXYL TRIAZONE IN ETHYL ACETATE + ETHANOL MIXTURES

This work reports the experimental volumetric properties and also the saturated solubility of indomethacin and ethylhexyl triazine in ethyl acetate + ethanol mixtures at 293.15 to 313.15 K and evaluates the validity of the Jouyban-Acree (J & A) model to correlate the solubility of these compounds in ethyl acetate + ethanol solvent mixtures. The solubility correlation is studied as a function of temperature and cosolvent composition. The J & A model requires only the experimental solubility values in the pure solvents at all the temperatures under study. The calculated values by using both compounds deviate as mean in 30% from experimental solubility values.

Measurement and Correlation of Solubilities of Cefpirome Sulfate in Aqueous Alcohol Solution between (278.15 and 308.15) K

The solubilities of cefpirome sulfate in water + (methanol, ethanol, 1-propanol, or 2-propanol) solvent mixtures have been measured using a dynamic method at temperature ranging from (278.15 to 318.15) K at atmospheric pressure. A solubility equation was proposed and verified by experimental results. The dissolution enthalpy and dissolution entropy have been calculated from the solubility data. The interactions between solute and solvent were discussed.

Epoxidation by sodium chlorite with aldehyde-promoted chlorine dioxide formation

An improved method is described for selective room temperature epoxidation of alkenes by sodium chlorite in a solvent mixture of ethanol, acetonitrile, and water buffered at pH 7. In addition, the use of aldehydes as promoters in chlorite oxidations is described for the first time. The amount of sodium chlorite, the solvent mixture, and the addition of formaldehyde as a practical promoter were optimized. Styrene was used as a test substrate in the optimization studies and the generality of the method was assessed by using a variety of nucleophilic and electrophilic substrates. Yields up to 89% were obtained with styrene and other nucleophilic alkenes are readily converted into epoxides.