Acetone-water Mixtures Research Articles

Fenton oxidation of 2,4- and 2,6-dinitrotoluene and acetone inhibition

The performances and kinetic parameters of Fenton oxidation of 2,4- and 2,6-dinitrotoluene (DNT) in water-acetone mixtures and explosive contaminated soil washing-out solutions were investigated at a laboratory scale. The experimental results show that acetone can be a significant hydroxyl radical scavenger and result in serious inhibition of Fenton oxidation of 2,4- and 2,6-DNT. Although no serious inhibition was found in contaminated soil washing-out solutions, longer reaction time was needed to remove 2,4- and 2,6-DNT completely, mainly due to the competition of hydroxyl radicals. Fenton oxidation of 2,4- and 2,6-DNT fit well with the first-order kinetics and the presence of acetone also reduced DNT’s degradation kinetics. Based on the comparison and matching of retention time and ultraviolet (UV) spectra between high performance liquid chromatography (HPLC) and standards, the following reaction pathway for 2,4-DNT primary degradation was proposed: 2,4-DNT → 2,4-dinitro-benzaldehyde → 2,4-dinitrobenzoic acid → 1,3-dinitrobenzene → 3-nitrophenol.

The Number of Water-Water Hydrogen Bonds in Water-Tetrahydrofuran and Water-Acetone Binary Mixtures Determined by Means of X-Ray Scattering

The liquid structures of water-tetrahydrofuran (THF) and water-acetone binary mixtures were investigated by the X-ray scattering method. Comparison of the X-ray scattering data revealed that only one kind of intermolecular water-organic molecule interaction is commonly involved throughout all mole fractions of these liquid mixtures, in addition to the intermolecular water-water and organic molecule-organic molecule interactions, which are present in neat water and organic liquids, respectively. On the basis of this finding, we proposed a new analytical method for studying liquid mixtures. By this method the structural information on the intermolecular water-organic molecule interaction as well as the concentrations of the intermolecular water-water, water-organic molecules, and organic molecule-organic molecule interactions were obtained. Combining the concentrations of the intermolecular water-water interaction with the concentrations of water in the liquid mixtures, the number of water-water hydrogen bonds at various mole fractions was experimentally determined for the first time. From the dependence of the number of water-water hydrogen bonds on the composition of the liquid mixtures, the change of the size of the self-associated water-water clusters was deduced.

Complex formation of crown ethers with cations in water–organic solvent mixtures: Part X. Thermodynamics of interactions between Na + ion and 15-crown-5 ether in acetone–water mixtures at 298.15 K

The thermodynamic functions of complex formation of 15-crown-5 ether (15C5) with sodium cation (Na +) in the mixtures of water with acetone at 298.15 K have been calculated. The equilibrium constants of complex formation of 15C5 with Na + have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured by the calorimetric method. The complexes are enthalpy-stabilized but entropy-destabilized in acetone–water mixtures. The effects of hydrophobic hydration, preferential solvation of 15C5 by a molecule of organic solvent and solvation of Na + on the complex formation processes have been discussed.

RPTLC determination of logPof structurally diverse neutral compounds

A validated reversed-phase thin-layer chromatographic (RPTLC) method is proposed for parallel estimation of the lipophilicity of chemically diverse neutral compounds or weak acids and bases. To cover a wide range of lipophilicity two optimized chromatographic systems were used — one for determination of log P of low or moderately lipophilic compounds (log P = 0–3) and one for highly lipophilic compounds (log P = 3–6). RP-diC 1 silanized silica gel plates were used as stationary phase. Mixtures of water with acetone, acetonitrile, methanol, ethanol, 1-propanol, 2-propanol, and 1,4-dioxane were investigated as mobile phases. Acetone-water mixtures were found to be optimum for both systems in respect of correlation of R M values with octanol-water partition coefficients. Two chemically diverse sets of calibration compounds were selected to cover ranges of moderate and high lipophilicity. Correlation between log P and chromatographic R M data (log P = aR M + b ) was good for both systems; the correlation coef...

Strategies to control the particle size distribution of poly- ε-caprolactone nanoparticles for pharmaceutical applications

In this work turbulent precipitation through solvent displacement for the production of poly- ε-caprolactone (PCL) nanoparticles is investigated; two different PCL molecular weights have been employed, using acetone and water as solvent and anti-solvent, respectively. The main important thermodynamic and kinetic parameters, such as solubility and interfacial tension of PCL in water–acetone mixtures, are determined and the effect of the process operating conditions on the final particle size distribution is also investigated. Particles produced under different conditions into a Confined Impinging Jets Reactor (CIJR) were characterized by Dynamic Light Scattering, Zeta potential measurements and Scanning Electronic Microscopy. Results clearly show the strong effect of mixing on the particle size distribution and how mixing must be controlled in order to obtain a product with particular characteristics. Eventually the measured thermodynamic and kinetic parameters are used to interpret the obtained experimental data.

Improvements of DRISM calculations: symmetry reduction and hybrid algorithms

We present a symmetry-reduced version of the dielectrically-consistent reference interaction site model (DRISM) equation and an adaptation of the Labík-Malijevský-Vonka hybrid algorithm for its numerical solution. This approach is used for the calculation of site-site correlation functions of water, acetone and a water-acetone mixture. Compared to the traditional Picard iteration of non-reduced DRISM theories, savings of more than 90% in computational time are obtained. The resulting site-site pair-correlation functions are in reasonable agreement with computer simulations.

Catalytic dehydration of fructose into 5-hydroxymethylfurfural by ion-exchange resin in mixed-aqueous system by microwave heating

Catalytic dehydration of fructose into 5-hydroxymethylfurfural by microwave heating was studied in acetone-water mixtures in the presence of a cation exchange resin catalyst. The use of acetone–water reaction media resulted in yields of 5-HMF as high as 73.4% for 94% conversion at 150 °C. It was confirmed that there was no decrease of catalytic activity and selectivity for five reuses of the resin, which was in accordance with the elemental analysis results that showed that sulfonic acid groups attached on the resin were stable at the experimental conditions. A comparison between conventional sand bath heating and microwave heating revealed that the latter had a remarkable accelerating effect not only on fructose conversion, but also on 5-HMF yield. Under the conditions (5 ml of 2 wt% fructose solution, 0.1 g of resin, 150 °C and 10 min), fructose conversion and HMF yields by microwave heating (91.7% and 70.3%, respectively) were higher than those by sand bath heating (22.1% and 13.9% respectively). Therefore, the process that we developed in this study showed that high 5-HMF yields from fructose could be achieved under mild conditions.

<b>ACTIVATION PARAMETERS AND EXCESS THERMODYANAMIC FUNCTIONS OF HYDROXAMIC ACIDS IN ACETONE - WATER MIXTURE AT 303.15 K AND 313.15 K: A VISCOMETRIC APPROACH</b>

Experimental values of density and viscosity of N-arylsubstituted hydroxamic acids were evaluated at T = 303.15 K and 313.15 K in acetone-water mixture as a function of their concentration. The properties of solutes were obtained as an intercept of plots C vs η of solutions. Applying these data, viscosity-B-coefficients, activation parameters (Δμ10≠) and (Δμ20≠) and excess thermodynamic functions, viz., excess molar volume (VE), excess viscosity, ηE and excess molar free energy of activation of flow, (GE) were calculated. The value of interaction parameter, d, of Grunberg and Nissan expression have also been calculated and reported. Analysis of these data suggests that specific interactions are present in the system. KEY WORDS: Activation parameters, N-Arylsubstituted hydroxamic acids, Density, Viscosity, Viscosity-B-coefficients, Excess viscosity Bull. Chem. Soc. Ethiop. 2007, 21(3), 379-387.

Synthesis and properties of a highly soluble dihydoxo(tetra- tert-butylphthalocyaninato)antimony(V) complex as a precursor toward water-soluble phthalocyanines

The title complex cation, [Sb(tbpc)(OH) 2] + (where tbpc denotes tetra( tert-butyl)phthalocyaninate, C 48 H 48 N 8 2 - ), has been prepared by oxidizing [Sb(tbpc)]I 3 with tert-butyl perbenzoate in CH 2Cl 2, CHCl 3, o-dichlorobenzene and also without solvent in the range of 20–80 °C. This species has been isolated as I 3 - salt and characterized by elemental analysis, ESI-MS, FT-IR, optical absorption and emission, and magnetic circular dichroism spectroscopy. This compound is quite well soluble in common polar organic solvents (e.g., CH 2Cl 2, acetonitrile, acetone) without detectable aggregation at least up to ca. 10 −4 M while much less soluble (e.g., benzene, chloronaphthalene) or insoluble (hexane) in non-polar solvents. Although this compound is insoluble in water, it makes hydrophilic colloids in acetone–water mixtures. The most intense absorption band (Q-band) in a specific solvent red-shifts with an increase in the refractive index of the solvent. However, considerable deviation of the Q-band positions in donor-solvents from linear correlation between the positions and Onsager’s solvent polarity function suggests that there are significant specific chemical interactions between the axial hydroxyl groups and the surrounding donor molecules. The low fluorescence quantum yield (ca. 0.01) for [Sb(tbpc)(OH) 2] + suggests that the singlet excited state of this species is considerably quenched by the presence of antimony ion in the chromophore.

Water and time dependent interaction of iron(III) with indole-3-acetic acid

The influence of water on the interaction between iron(III) and indole-3-acetic acid (IAA) was studied in different organic solutions using rapid-scan stopped-flow spectrophotometry and rapid-freeze/quench Mossbauer spectroscopy. Measurements were also performed in ethanol–water and acetone–water mixtures. The results showed that the interaction between FeIII and IAA resulted in dimeric FeIII–IAA complex within 1 s, followed by a slow second step to give Fe2+ and IAA(oxidized). No such products were formed in the absence of water. The visible and Mossbauer spectra reflect the nature of the organic solvent and that of the anion of iron(III) salts.

Combined Process of Solvent Extraction and Gamma-Ray Radiation for the Extraction of Oil from Oil Shale

Jordanian oil shale kerogen was studied by using several solvents under the gamma radiation condition to extract oil from shale. According to the result obtained, the possibility to extract oil at room temperature and using solvent was successfully obtained. The solvent used in this research study was water, benzene, acetone and kerosene. Experiments was conducted by using a mixture of solvents such acetone water, benzene-acetone, benzene-kerosene, and benzene, kerosene, water alone without mixing. The percentage of yield was found to be with in the range of 13–67. The result showed that acetone-water solvent mixture with 50% of each (vol%) gives the best results. In this study, the particle size was fixed at 1mm size since there was no effect size on extraction yield percentage.

Terpyridine-Based Cruciform−Zn2+ Complexes as Anion-Responsive Fluorophores

The synthesis of a terpyridine-appended, zinc-complexed cruciform, 3-Zn2+, and the anion-reactive modulation of its emissive properties in acetone-water mixtures are reported.

Structure–property relations and cytotoxicity of isosorbide‐based biodegradable polyurethane scaffolds for tissue repair and regeneration

Microporous scaffolds with potential applications for tissue engineering were produced from the biodegradable aliphatic isosorbide-based polyurethane using a combined salt leaching-solvent evaporation-coagulation process. Alkaline sodium phosphate heptahydrate crystals were used as a solid porogene, and acetone-water mixture was used as a nonsolvent-coagulant. The scaffolds used in this study had interconnected pores with sizes in the range of 70-120 microm and a pore-to-volume ratio of 87%. The XPS measurements showed that the residence of the scaffold in an aqueous solution of the alkaline porogene changed its surface atomic composition, that is increased the surface concentration of oxygen and nitrogen and reduced the surface concentration of hydrocarbons relative to the control material. This also enhanced the hydrophilicity of the scaffold's surfaces as assessed from contact angle measurements. The alkaline porogene did not affect the polymer's molecular weight. The MTT cytotoxicity assay showed that the isosorbide-based polyurethane scaffold is noncytotoxic. The amounts of interleukin-6 and interleukin-8 proinflammatory cytokines released from human blood leukocytes exposed to the polyurethane scaffolds in vitro were comparable and/or lower than the amount of the cytokines released by leukocytes exposed to the culture-grade polystyrene control.

Nonideality in diffusion of ionic and hydrophobic solutes and pair dynamics in water-acetone mixtures of varying composition

We have performed a series of molecular dynamics simulations of water-acetone mixtures containing either an ionic solute or a neutral hydrophobic solute to study the extent of nonideality in the dynamics of these solutes with variation of composition of the mixtures. The diffusion coefficients of the charged solutes, both cationic and anionic, are found to change nonmonotonically with the composition of the mixtures showing strong nonideality of their dynamics. Also, the extent of nonideality in the diffusion of these charged solutes is found to be similar to the nonideality that is observed for the diffusion and orientational relaxation of water and acetone molecules in these mixtures which show a somewhat similar changes in the solvation characteristics of charged and dipolar solutes with changes of composition of water-acetone mixtures. The diffusion of the hydrophobic solute, however, shows a monotonic increase with increase of acetone concentration showing its different solvation characteristics as compared to the charged and dipolar solutes. The links between the nonideality in diffusion and solvation structures are further confirmed through calculations of the relevant solute-solvent and solvent-solvent radial distribution functions for both ionic and hydrophobic solutes. We have also calculated various pair dynamical properties such as the relaxation of water-water and acetone-water hydrogen bonds and residence dynamics of water molecules in water and acetone hydration shells. The lifetimes of both water-water and acetone-water hydrogen bonds and also the residence times of water molecules are found to increase steadily with increase in acetone concentration. No maximum or minimum was found in the composition dependence of these pair dynamical quantities. The lifetimes of water-water hydrogen bonds are always found to be longer than that of acetone-water hydrogen bonds in these mixtures. The residence times of water molecules are also found to follow a similar trend.

Analysis of Conformer Stability for 1,3,8-Trihydroxynaphthalene: Natural Substrate of Fungal Trihydroxynaphthalene Reductase

1,3,8-Trihydroxynaphthalene is one of the substrates in the fungal melanin biosynthesis pathway. We present theoretical studies on energies of its tautomeric forms and their rotamers. Several theory levels and solvent models have been tested using experimental results obtained in water-acetone mixtures as the reference point. Our results indicate that the best agreement with these data is obtained with density functional theory levels when the continuum solvation model uses the united atom topological cavity. We also noticed a fairly good performance of the semiempirical AM1 method that makes it a promising alternative for studies of large systems.

Preparation of a Functionally Flexible, Three-Dimensional, Biomimetic Poly(L-Lactic Acid) Scaffold with Improved Cell Adhesion

Poly(L-lactic acid) (PLLA) is widely used in tissue-engineering applications because of its degradation characteristics and mechanical properties, but it possesses an inert nature, affecting cell-matrix interactions. It is desirable to modify the surface of PLLA to create biomimetic scaffolds that will enhance tissue regeneration. We prepared a functionally flexible, biomimetic scaffold by derivatizing the surface of PLLA foams into primary amines, activated pyridylthiols, or sulfhydryl groups, allowing a wide variety of modifications. Poly(L-lysine) (polyK) was physically entrapped uniformly throughout the scaffold surface and in a controllable fashion by soaking the foams in an acetone-water mixture and later in a polyK solution in dimethylsulfoxide. Arginine-glycine-aspartic acid-cysteine (RGDC) adhesion peptide was linked to the polyK via creating disulfide bonds introduced through the use of the linker N-succinimidyl-3-(2-pyridylthiol)-propionate. Presence of RGDC on the surface of PLLA 2-dimensional (2-D) disks and 3-D scaffolds increased cell surface area and the number of adherent mesenchymal stem cells. We have proposed a methodology for creating biomimetic scaffolds that is easy to execute, flexible, and nondestructive.

The standard thermodynamic characteristics of resolvation of the K+, Ca2+, Cd2+, and Br− ions in water-acetone mixtures

The standard real and chemical thermodynamic characteristics of transfer of the K+, Ca2+, Cd2+, and Br− ions from water into water-acetone solvents of various compositions were analyzed to study the rules governing the solvation of these ions in mixed solvents and its special features. All calculations were performed within the framework of the vertical jet method at 298.15 K. The energy of resolvation as a function of ion charges and crystallographic radii was found to increase in the series K+ < Ca2+ < Cd2+ < Al3+

The calming effect of oil on water

The calming effect of oil on water has been known since ancient times. Benjamin Franklin was the first to investigate the effect, but the underlying mechanism for this striking phenomenon remains elusive. We used a miniature laser interferometer to measure the amplitude of surface waves to a resolution of ±5nm, making it possible to determine the effect of an oil monolayer on the attenuation of capillary waves and the surface dilational modulus of the monolayer. We present attenuation data on pure water, water covered by olive oil, water covered by a fatty acid, and a water-acetone mixture for comparison. From the attenuation data at frequencies between 251 and 551Hz, we conclude that the calming effect of oil on surface waves is principally due to the dissipation of wave energy caused by the Gibbs surface elasticity of the monolayer, with only a secondary contribution from the reduction in surface tension. Our data also indicate that the surface-dilational viscosity of the oil monolayer is negligible and plays an insignificant role in calming the waves.

Aqueous dispersions of C60 fullerene

Stable aqueous colloidal dispersions of C60 fullerene are prepared. A solvatochromic effect is revealed upon the addition of C60 solution in chlorobenzene to a water-acetone mixture.

Growth and Optical Studies of a Novel Organometallic Complex NLO Crystal: Tetrathiourea Cadmium(II) Tetrathiocyanato Zinc(II)

Tetrathiourea cadmium(II) tetrathiocyanato Zinc(II) (TCTZ) single crystals were grown in acetone-water mixture solvent using slow solvent evaporation technique and their optical property was studied for the first time. Both thiourea and thiocyanate ligands were combined with the transition metal ions Cd2+ and Zn2+. The nonlinear optical (NLO) efficiency of TCTZ crystal was tested and measured using Kurtz and Perry technique. The dielectric behavior of the sample was also studied.