Acetone-water Mixtures Research Articles

Highly stereoselective direct aldol reaction of 4-formylcoumarins with acetone catalyzed by L-proline in water–acetone mixtures

ABSTRACTOrganocatalyzed direct intermolecular aldol reactions have been developed for substituted 4-formylcoumarins with acetone in water using L-proline and phthalimido-prolinamide catalysts without use of additives. Stereoselective products obtained were in excellent yields (up to 97%) with high purity (up to 99%) and enatioselectivities (up to 95%). The isolated compounds were confirmed by infrared, NMR, high-performance liquid chromatography, and mass spectrometry and some of them by single-crystal x-ray crystallography.

Solubility of Fenofibrate in Different Binary Solvents: Experimental Data and Results of Thermodynamic Modeling

Solubility of fenofibrate in ethanol–water and acetone–water mixtures was investigated using dynamic laser monitoring at atmospheric pressure and temperatures between 278.15 and 308.15 K. Solubility increased as temperature and the fraction of organics increased. The solubility data was correlated with the modified Apelblat, NRTL, combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K), and Jouyban–Acree (J–A) models. Solvent composition and temperature correlations were conducted, and the apparent dissolution enthalpy, entropy, and Gibbs free energy change of the fenofibrate were calculated using the modified Apelblat model and the van’t Hoff equation. The results shoLw that the dissolution of fenofibrate is endothermic and nonspontaneous, and that the main contributor in the binary solvents studied is enthalpy.

Unperturbed dimension, interaction parameters, zeta potential and rheology of sodium alginate in binary solvent mixtures

The intrinsic viscosity [η] of sodium alginate having different molecular weights (high molecular weight (type A), medium molecular weight (type B) and low molecular weight (type C)) is measured at 293–303 K temperature in various mixtures of water (good solvent), acetone (ACE, poor solvent) and water-ethoxy ethanol (EE, poor solvent). The observed result particularly the Huggins constant (K H) values shows a significant variation of cosolvency as a function of solvent composition (ΦACE/ΦEE) and the temperature. Unperturbed dimensions (K θ) under non-theta condition have been calculated using various equations in different water-acetone and water-ethoxy ethanol mixtures. The value of K θ obtained from three different methods of measurements viz., Burchard-Stockmayer and Fixman (BSF), Berry and Inagaki-Suzuki-Kurata (ISK) agree well with each other except in a few compositions of solvents. The molecular extension factor (α n) and actual end-to-end distance (α n K θ) have also been computed herein. Further, the shear thinning nature of the sodium alginate solutions (representative illustration: type A) in water and water-acetone mixed systems has been investigated at increasing strain rate. Results show that the viscous modulus G″ predominates over the elastic modulus G′ and the systems behave as viscoelastic fluids under present conditions. Higher value of G′ in acetone-water mixed solvent system compared to that in pure water undoubtedly indicates enhancement of the elasticity in alginate system in the presence of acetone. Finally, zeta potential measurement demonstrates that the polymeric surface of sodium alginate (representative illustration: type A) is essentially negatively charged and the zeta potential of the polymer is more responsive to the composition of ethoxy ethanol than that of acetone in the aqueous-organic mixed solvents.

PLA Chemical Recycling Process Optimization: PLA Solubilization in Organic Solvents

The recycling of used, post-industrial and post-consumer PLA is crucial to reduce both the consumption of renewable resources for the monomer synthesis and the environmental impact related to its production and disposal. Several processes are actually available: among these, there is a particular interest on the chemical recycling of PLA with production of its monomer. The aim of this work is to analyse the PLA dissolution behaviour in different organic solvents (acetone and Ethyl lactate) at different water concentrations in order to optimize the chemical depolymerisation process of PLA. New experimental data are presented and a kinetic model is provided for a first analysis. Preliminary results suggest that acetone based solvents (i.e., acetone water mixtures at various concentrations) are more effective to solubilize the PLA rather than the Ethyl-lactate based solvent. Anyway, an increase of water concentration in the solvent phase, determines both a reduction of the solvent power and a reduction of mass transport coefficient for the two solvents tested.

Agglomeration Mechanism of Azithromycin Dihydrate in Acetone–Water Mixtures and Optimization of the Powder Properties

The main purpose of this investigation was to investigate the agglomeration mechanism of azithromycin dihydrate in mixed water and acetone systems and improve the powder properties of azithromycin dihydrate. The solubilities and crystallization processes of azithromycin monohydrate and dihydrate in mixed water + acetone systems were measured and investigated. The solubilities of the two hydrates were very close, and the products obtained from water + acetone mixtures were strongly agglomerated. It was found that surface nucleation and growth of dihydrate on monohydrate crystals during the hydrate transformation process were the reasons which caused agglomeration. There was no hydrate transformation during the crystallization process of azithromycin in ethyl acetate, and the products were single crystals. By comparison of the powder properties of agglomerated and nonagglomerated solids, the agglomeration has a serious impact on the crystal size distribution, bulk density, and flowability.

Radiation induced grafting of glycidyl methacrylate on teflon scrap for synthesis of dual type adsorbent: Process parameter standardisation

High energy Co‐60 gamma radiation has been used to graft glycidylmethacrylate (GMA) onto Teflon scrap by mutual radiation grafting technique. Effect of various experimental parameters viz, solvent, solvent mixture, dose, dose rate, monomer concentration, backbone thickness on grafting extent was investigated. The grafting extent decreased with the dose rate and thickness and increased with concentration of GMA. Among the solvent studied acetone–water mixture in which poly(GMA) was soluble was found to be the best solvent for grafting. A kinetic equation Rg = Kg[M] 1.7 D0.1 relating grafting kinetics to monomer concentration and dose rate was deduced. The matrices were characterized for morphology, thermal stability and dye uptake extent. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1367–1373, 2016

GROMOS polarisable model for acetone

ABSTRACTA polarisable model for acetone, COS/A, is proposed that is based on the charge-on-spring (COS) polarisation model and is compatible with the polarisable COS/D2 and COS/G2 models for liquid water. A series of acetone-water mixtures at different acetone mole fractions was simulated using the new model in conjunction with the mentioned polarisable and the non-polarisable SPC and SPC/E water models. The model was parameterised to reproduce the following liquid acetone properties: density, heat of vaporisation, surface tension, dielectric permittivity, self diffusion and heat capacity and subsequently tested in mixtures with water using different water models. For pure liquid acetone the polarisable COS/A model agrees better with experimental data than the non-polarisable Kirkwood-Buff derived force field (KBFF) model, which was parameterised using experimental data for a 0.5 mole fraction acetone-water mixture. For such mixtures the polarisable models yield better agreement with experiment than the non-polarisable models for the heat of vaporisation and dielectric permittivity, while worse agreement for diffusion. The computational cost of simulating the polarisable acetone-water mixtures is a factor of 3 to 4 higher compared with the non-polarisable models due to the increased number of interaction sites and the multiple iterations required to evaluate self-consistently the positions of the COS sites at every simulation step. The COS/A acetone model can be used in biomolecular simulations in conjunction with the mentioned polarisable water models to solvate biomolecules.

The conformational transitions in organic solution on the cress seed gum nanoparticles production

The seeds of Lepidium sativum (garden cress) were selected as a new hydrocolloid source to fabricate cress seed gum nanoparticles (CSGN) by the desolvation method. The intrinsic viscosity of the CSGN solutions was measured to evaluate the conformational differences of the CSG resulted by the various production conditions. The intrinsic viscosity of CSGN solutions was estimated by using various models, i.e. Huggins, Kraemer, Tanglertpaibul–Rao and Higiro, and then the intrinsic viscosity was an objective function aimed at optimizing the conditions for the solubilization of CSG nanoparticles by the response surface method. The results indicated that among the conditions for the preparation of nanoparticles, acetone and gum concentrations had significant effects on the intrinsic viscosity of nanoparticles. Hereby, CSG served as a source of anionic polyelectrolyte molecules in dilute solutions with acetone-water mixtures. This compound goes on to display a coil–globule transition above a certain threshold of acetone.

Properties of the Liquid–Vapor Interface of Acetone–Water Mixtures. A Computer Simulation and ITIM Analysis Study

Molecular dynamics simulations of the liquid–vapor interface of acetone–water mixtures of different compositions, covering the entire composition range have been performed on the canonical (N, V, T) ensemble at 298 K, using a model combination that excellently describes the mixing properties of these compounds. The properties of the intrinsic liquid surfaces have been analyzed in terms of the Identification of the Truly Interfacial Molecules (ITIM) method. Thus, the composition, width, roughness, and separation of the subsurface molecular layers, as well as self-association, orientation, and dynamics of exchange with the bulk phase of the surface molecules have been analyzed in detail. Our results show that acetone molecules are strongly adsorbed at the liquid surface, and this adsorption extends to several molecular layers. Like molecules in the surface layer are found to form relatively large lateral self-associates. The effect of the vicinity of the vapor phase on a number of properties of the liquid p...

Calculated third order rate constants for interpreting the mechanisms of hydrolyses of chloroformates, carboxylic Acid halides, sulfonyl chlorides and phosphorochloridates.

Hydrolyses of acid derivatives (e.g., carboxylic acid chlorides and fluorides, fluoro- and chloroformates, sulfonyl chlorides, phosphorochloridates, anhydrides) exhibit pseudo-first order kinetics. Reaction mechanisms vary from those involving a cationic intermediate (SN1) to concerted SN2 processes, and further to third order reactions, in which one solvent molecule acts as the attacking nucleophile and a second molecule acts as a general base catalyst. A unified framework is discussed, in which there are two reaction channels—an SN1-SN2 spectrum and an SN2-SN3 spectrum. Third order rate constants (k3) are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter. These data and kinetic solvent isotope effects, provide the experimental evidence for the SN2-SN3 spectrum (e.g., for chloro- and fluoroformates, chloroacetyl chloride, p-nitrobenzoyl p-toluenesulfonate, sulfonyl chlorides). Deviations from linearity lead to U- or V-shaped plots, which assist in the identification of the point at which the reaction channel changes from SN2-SN3 to SN1-SN2 (e.g., for benzoyl chloride).

Femtosecond mid-infrared study of the dynamics of water molecules in water-acetone and water-dimethyl sulfoxide mixtures.

We study the vibrational relaxation dynamics and the reorientation dynamics of HDO molecules in binary water-dimethyl sulfoxide (DMSO) and water-acetone mixtures with polarization-resolved femtosecond mid-infrared spectroscopy. For low solute concentrations we observe a slowing down of the reorientation of part of the water molecules that hydrate the hydrophobic methyl groups of DMSO and acetone. For water-DMSO mixtures the fraction of slowed-down water molecules rises much steeper with solute concentration than for water-acetone mixtures, showing that acetone molecules show significant aggregation already at low concentrations. At high solute concentrations, the vibrational and reorientation dynamics of both water-DMSO and water-acetone mixtures show a clear distinction between the dynamics of water molecules donating hydrogen bonds to other water molecules and the dynamics of water donating a hydrogen bond to the S═O/C═O group of the solute. For water-DMSO mixtures both types of water molecules show a very slow reorientation. The water molecules forming hydrogen bonds to the S═O group reorient with a time constant that decreases from 46 ± 14 ps at XDMSO = 0.33 to 13 ± 2 ps at XDMSO = 0.95. The water molecules forming hydrogen bonds to the C═O group of acetone show a much faster reorientation with a time constant that decreases from 6.1 ± 0.2 ps at Xacet = 0.3 to 2.96 ± 0.05 ps at Xacet = 0.9. The large difference in reorientation time constant of the solute-bound water for DMSO and acetone can be explained from the fact that the hydrogen bond between water and the S═O group of DMSO is much stronger than the hydrogen bond between water and the C═O group of acetone. We attribute the strongly different behavior of water in DMSO-rich and acetone-rich mixtures to their difference in molecular shape.

Synthesis of 5-hydroxymethylfurfural (HMF) by acid catalyzed dehydration of glucose–fructose mixtures

Synthesis of 5-hydroxymethylfurfural (HMF) from hexoses has been studied extensively in the scientific literature. However, a process has yet to be implemented at industrial scale. In this paper the simultaneous dehydration of glucose and fructose was investigated, in order to develop a process allowing the use of the cheapest available source of fructose: high fructose corn syrup. The dehydration was catalyzed by hydrochloric acid and conducted in acetone–water mixtures, which ensured good selectivity towards HMF and eliminated precipitation of polymer by-products (insoluble humins). Through a detailed experimental investigation a reaction network was proposed, and subsequently the corresponding kinetic model was fitted to experimental data in order to obtain estimates of the reaction kinetic parameters. The kinetic model is capable of predicting the formation of HMF along with the important by-products: soluble humins, glucose dimers, anhydroglucose, and formic acid. The reaction conditions in four different reactor configurations were optimized and compared using the kinetic model. It was found that a recirculating reactor setup is preferable, where the equilibrium controlled by-products (anhydroglucose and glucose dimers) are recirculated to the dehydration reactor. The model predicts an HMF selectivity of close to 70% in a recirculating reactor at conditions where HMF degradation is avoided.

Hedgehog-shaped {Mo368} cluster: unique electronic/structural properties, surfactant encapsulation and related self-assembly into vesicles and films.

The hedgehog-shaped {Mo368} cluster shows unique electronic (extremely high extinction coefficient) and structural features, especially regarding its size, the high number of delocalized electrons which allows to measure the surface enhanced Raman scattering (SERS) spectrum and the option for coordination chemistry inside the cavity. Its relative instability in aqueous solution can be overcome by embedment in a hydrophobic shell of dimethyldioctadecylammonium cations. The resulting hybrid self-assembles into spherical vesicles in acetone-water mixtures, according to a process directed by hydrophobic-hydrophilic interactions. It also forms rather stable Langmuir monolayers while a second layer evolves under higher surface pressure, in accordance with a rather low alkyl surface density.

Comparison of some chemical and physico-chemical properties of natural and model sodium humates and of the biological activity of both substances in tomato water cultures

Natural humate from compost and the model sunstance obtained from p-benzoquinone were dissolved in an acetone-water mixture and subjected to chromatography on a column of aluminium oxide. Similar fractions were obtained which were chemically and spectrophotometrically investigated for the content of functional groups. The particle size of these substances was determined by filtration on Sephadex molecular sieves. Experiments were performed with tomato in water cultures on stagnant nutrient solution. The biological activity of the corresponding fractions of natural and model humates was found to be analogous. The results are discussed and confronted with functional groups content and particle size of the respective substances.

Conversion of racemic allylic hydroperoxides into corresponding chiral 1/2,3-triols by using catalytic OsO$_{4}$ and chiral cinchona ligands in the absence of co-oxidant

For the first time, removal of oxygen atoms from allylic hydroperoxide functionality and reintroduction to the double bond was achieved using catalytic OsO$_{4}$ and chiral cinchona alkaloid derivatives in an acetone-water mixture to give corresponding chiral 1/2,3-triol with an enantioselectivity up to 99% ee. The hydroperoxide group was used as both a co-oxidant and a source of hydroxyl groups. This protocol is thought to have potential to provide opportunities for chiral synthesis of 1/2,3-triols from corresponding allylic hydroperoxides in the absence of co-oxidant in one stage for the first time in the literature.

Preparation of a highly water-selective membrane for dehydration of acetone by incorporating potassium montmorillonite to construct ionized water channel

Novel polymer–inorganic hybrid membrane was prepared by incorporating potassium montmorillonite (K+MMT) into chitosan (CS) for the dehydration of water–acetone mixture. The morphology, chemical and physical structure, as well as the hydrophilicity were characterized. The results showed that MMT uniformly dispersed in the chitosan matrix, formed hydrogen bonds with chitosan, and enhanced the thermal stability of the film. The membrane doped with 10wt% of K+MMT exhibited the highest performance with separation factor of 2200, which was almost 8 times higher than 249 of pristine CS membrane at 50°C for 5wt% of water in the feed. The results suggested that the ionized water channel constructed by MMT intergallery in the hybrid membrane could greatly enhance the separation factor of CS membrane. Moreover, a plausible model for water transportation in the CS-K+MMT hybrid membranes was proposed. The results proved that K+MMT had a potential prospect in application for pervaporation.

Metal-free protocol for the synthesis of α-bromo ketones from olefins using TsNBr2

TsNBr2 reacts readily with olefins to produce α-bromo ketones at room temperature. The synthesis was carried out by treating an olefin with TsNBr2 in acetone–water mixture in 30:1 ratio. Excellent yield of corresponding α-bromo ketone could be achieved within a short time.

Association/Hydrogen Bonding of Acetone in Polar and Non-polar Solvents: NMR and NIR Spectroscopic Investigations with Chemometrics

This paper reports 1H NMR and NIR spectroscopic analysis of hydrogen bonding in acetone mixtures with water, CHCl3, CCl4, and CDCl3 with varying acetone concentrations (0–100 vol%). Spectroscopic data were chemometrically analyzed using independent component analysis to resolve the spectra of complexes existing in the solutions and to obtain their concentration profiles. Ab initio calculations provided additional information (hydrogen-bond energy and bond distance) about the investigated complexes. We have found that in addition to independent solvent associates, acetone–water mixtures contain three intermolecular complexes with acetone–water ratios of 1:1, 1:2 and 1:3. In less polar solvents with hydrogen or deuterium atoms (CDCl3, CHCl3), acetone does not generate self-associates and forms an intermolecular complex (1:1). In contrast, in aprotic non-polar carbon tetrachloride (CCl4) solutions, where no hydrogen-bonding is possible, self-association (as mentioned above for water–acetone mixtures) of two acetone molecules is preferred. The combination of spectroscopic techniques (1H NMR, NIR) with chemometric modeling and ab initio calculations leads to a better understanding of concentration dependent changes in the structure of acetone solutions. The approach discussed can be used for investigation of hydrogen-bonded interactions in other mixed solvents.

Retraction: Acid-Catalyzed Aquation of Ni(II)-Hydrazone Complexes: Kinetics and Solvent Effect

Complexes of the type [Ni(L)(H2O)]Cl2·nH2O, where L = 2-pyridyl-3-isatinbishydrazone ligands, have been synthesized and characterized on the bases of elemental analysis, molar conductance, IR, electronic spectra, and thermal analysis (TGA and DTA). Acid-catalyzed aquation of the Ni(II) isatin-bishydrazone complexes was followed spectrophotometrically in various water–methanol and water–acetone mixtures at temperature 298 K. Kinetic behavior of the acid aquation is a linear rate law, indicating that the acid-catalyzed aquation of these complexes in water–methanol and water–acetone mixtures follows a rate law with kobs = k2[H+]. The effect of the mole fraction of the ganic solvent, i.e., methanol and acetone, on the acid aquation has been analyzed; the decrease in the rate constant values with increasing of the methanol or acetone ratios is attributable to the effect of the co-organic solvent on the initial states of the acid aquation by the destabilization of the H+ ion.

Improving water selectivity of poly (vinyl alcohol) (PVA) – Fumed silica (FS) nanocomposite membranes by grafting of poly (2-hydroxyethyl methacrylate) (PHEMA) on fumed silica particles

Nanocomposite membranes were prepared by incorporation of PHEMA-grafted FS particles with PVA membrane. The grafted-PHEMA promoted a dispersion of FS particles within PVA matrix as revealed by TEM. As a result, the tensile properties of the nanocomposite membranes including Young’s modulus and strength were enhanced. PHEMA-grafted layer on FS particles also strengthened the adhesion at FS-PVA interface causing a shift of Tg of the nanocomposite membranes to higher temperature compared with Tg of PVA. On complete swelling in water, Tgs of the nanocomposite membranes decreased to approximately that of the water-swollen PVA membrane. Dynamic swelling of the nanocomposite membranes suggested an increase in the water diffusion coefficient with increasing PHEMA-grafted FS loading and PHEMA grafting. Water uptake of PHEMA-grafted FS filled membranes was increased compared with those of unfilled PVA membrane. Employing the pervaporation technique, the dehydration of water–acetone mixture was studied, thus revealing an enhancement of water permeability and selectivity in the presence of PHEMA-grafted FS particles.