Volumetric properties of ascorbic acid (vitamin C) and thiamine hydrochloride (vitamin B1) in dilute HCl and in aqueous NaCl solutions at (283.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K

Apparent molar volumes and apparent molar isentropic compressibilities of ascorbic acid (vitamin C) and thiamine hydrochloride (vitamin B₁) were determined from accurately measured density and sound velocity data in water and in aqueous NaCl solutions at (283.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K. These volume and compressibility data were extrapolated to zero concentration using suitable empirical or theoretical equations to determine the corresponding infinite dilution values. Apparent molar expansibilities at infinite dilution were determined from slopes of apparent molar volume vs. temperature plots. Ionization of both ascorbic acid and thiamine hydrochloride were suppressed using sufficiently acidic solutions. Apparent molar volumes at infinite dilution for ascorbic acid and thiamine hydrochloride were found to increase with temperature in acidic solutions and in the presence of co-solute, NaCl. Apparent molar expansibility at infinite dilution were found to be constant over the temperature range studied and were all positive, indicating the hydrophilic character of the two vitamins studied in water and in the presence of co-solute, NaCl. Apparent molar isentropic compressibilities of ascorbic acid at infinite dilution were positive in water and in the presence of co-solute, NaCl, at low molalities. Those of thiamine hydrochloride at infinitive dilution were all negative, consistent with its ionic nature. Transfer apparent molar volumes of vitamins at infinite dilution from water solutions to NaCl solutions at various temperatures were determined. The results were interpreted in terms of complex vitamin-water-co-solute (NaCl) interactions.     

Volumetric and viscosity studies of interactions between sodium phosphate salts and poly(propylene glycol) 400 in aqueous solutions at different temperatures

Density and sound velocity at the 288.15–313.15 K and viscosity at the 298.15–313.15 K temperature range at 5 K intervals for polypropylene glycol (PPG) in aqueous solutions of sodium di-hydrogen phosphate, di-sodium hydrogen phosphate and tri-sodium phosphate with salt mass fractions 0.00, 0.010 and 0.020 are reported at atmospheric pressure. From the experimental density and sound velocity data, the apparent specific volume, excess specific volume, isentropic compressibility and isentropic compressibility deviation values have been determined. The infinite dilution apparent specific volume and isentropic compressibility values of PPG have been obtained and from which the infinite dilution apparent specific volumes of transfer of PPG from water to aqueous sodium phosphate solutions have been obtained for the investigated salt concentrations and temperatures. The excess specific volume, isentropic compressibility and viscosity deviation are negative and decrease in magnitude as temperature, concentration of sodium phosphate and charge on the anion of electrolyte increases.     

(Liquid + liquid) equilibria of (water + butyric acid + esters) ternary systems

(Liquid + liquid) equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {water (1) + butyric acid (2) + ethyl propionate or dimethyl phthalate or dibutyl phthalate (3)} at T = 298.15 K and (101.3 ± 0.7) kPa. The relative mutual solubility of the butyric acid is higher in the layers of esters than in the aqueous layer. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC method. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

(Liquid + liquid) equilibria of (water + lactic acid + alcohol) ternary systems

(Liquid + liquid) equilibrium (LLE) measurements of the solubility (binodal) curves and tie-line end compositions were carried out for {water (1) + lactic acid (2) + octanol, or nonanol, or decanol (3)} at T = 298.15 K and 101.3 ± 0.7 kPa. The relative mutual solubility of lactic acid is higher in the water layers than in the organic layers. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The LLE results for the ternary systems were predicted by UNIFAC method. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

(Liquid + liquid) equilibria of (water + butyric acid + dibasic esters) ternary systems

(Liquid + liquid) equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {water (1) + butyric acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at T = 298.15 K and p = (101.3 ± 0.7) kPa. The relative mutual solubility of the butyric acid is higher in the dibasic esters layers than in the aqueous layer. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC method. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

(Liquid + liquid) equilibria of the (water + butyric acid + dodecanol) ternary system

(Liquid + liquid) equilibrium (LLE) data for the (water + butyric acid + dodecanol) ternary system have been determined experimentally at T = (298.2, 308.2 and 318.2) K. Complete phase diagrams were obtained by determining binodal curves and tie lines. The reliability of the experimental tie lines was confirmed by using the Othmer–Tobias correlation. The UNIFAC method was used to predict the phase equilibrium in the ternary system using the interaction parameters determined from experimental data of CH₃, CH₂, COOH, OH and H₂O functional groups. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

(Liquid + liquid) equilibria of (water + propionic acid + dibasic esters) ternary systems

(Liquid + liquid) equilibrium (LLE) data for the solubility curves and tie-line compositions were examined for mixtures of {water (1) + propionic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at T = 298.15 K and atmospheric pressure, (101.3 ± 0.7) kPa. The relative mutual solubility of the propionic acid is higher in the dibasic esters phases than in the aqueous phase. The reliability of the experimental tie-line data were confirmed by using the Othmer–Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC and modified UNIFAC methods. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

Volumetric and transport properties of binary liquid mixtures of N-methylacetamide with lactones at temperatures (303.15 to 318.15) K

The values of density (ρ), viscosity (η) and speed of sound (u) have been measured for binary liquid mixtures of γ-butyrolactone (GBL), δ-valerolactone (DVL), and ε-caprolactone (ECL) with N-methylacetamide (NMA) over the whole composition range at T = (303.15 to 318.15) K and atmospheric pressure. From these data, excess molar volume (V^E), deviation in viscosity (Δη), and deviation in isentropic compressibility (Δκ_s), are calculated. The results are fitted to a Redlich–Kister type polynomial equation to derive binary coefficients and standard deviations.     

Synthesis of 1,2-azidoalcohols from epoxides using a task-specific protic ionic liquid: 1-hydrogen-3-methylimidazolium azide

A task-specific ionic liquid as an environmentally eco-friendly green catalyst has been synthesized and used in the ring opening of epoxides under green conditions. In order to use protic ionic liquids (PIL), we decided to synthesize 1,2-azidoalcohols via a ring opening reaction of epoxides with 1-hydrogen-3-methylimidazolium azide ([Hmim]N₃), which actually acts as a solvent, a reagent and an activator of the epoxide ring. The reaction was carried out in short times (50–70 min) at 70 °C to give 1,2-azidoalcohol in 80–94% isolated yields.     

High-pressure densities and derived volumetric properties (excess, apparent, and partial molar volumes) of binary mixtures of {methanol (1) + [BMIM][BF4] (2)}

The density of seven {(0.0087, 0.0433, 0.1302, 0.2626, 0.4988, 0.7501, and 0.9102) mole fraction of [BMIM][BF₄]} binary {methanol (1) + [BMIM][BF₄] (2)} (1-butyl-3-methylimidazolium tetrafluoroborate) mixtures has been measured with a vibrating-tube densimeter. Measurements were performed at temperatures from (298 to 398) K and at pressures up to 40 MPa. The total uncertainties of density, temperature, pressure, and concentration measurements was estimated to be less than 0.15 kg · m⁻³, 15 mK, 5 kPa, and 10⁻⁴, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95% confidence level with a coverage factor of k = 2. The effect of temperature, pressure, and concentration on the density and derived volumetric properties such as excess, apparent, and partial molar volumes was studied. The measured densities were used to develop a Tait-type equation of state for the mixture. The structural properties such as direct and total correlation function integrals and cluster size were calculated using the Krichevskii function concept and the equation of state for the mixture at infinite dilution.     

Liquid phase equilibria of (water + propionic acid + oleyl alcohol) ternary system at several temperatures

(Liquid–liquid) equilibrium (LLE) data are investigated for mixtures of (water + propionic acid + oleyl alcohol) at 298.15, 308.15 and 318.15 K and atmospheric pressure. The solubility curves and the tie-line end compositions of liquid phases at equilibrium were determined, and the tie-line results were compared with the data predicted by the UNIFAC method. The phase diagrams for the ternary mixtures including both the experimental and correlated tie-lines are presented. The distribution coefficients and the selectivity factors for the immiscibility region are calculated to evaluate the effect of temperature change. The reliability of the experimental tie-lines was confirmed by using Othmer–Tobias correlation. It is concluded that oleyl alcohol may serve as an adequate solvent to extract propionic acid from its dilute aqueous solutions. The UNIFAC model correlates the LLE data for 298.15, 308.15 and 318.15 K with a root mean square deviation of 5.89, 6.46, and 6.69%, respectively, between the observed and calculated mole concentrations.     

Volumetric properties of (water + hexamethylphosphoric triamide) from (288.15 to 308.15) K

Densities of (water + hexamethylphosphoric triamide) in the entire mole-fraction composition at five temperatures, from (288.15 to 308.15) K, and atmospheric pressure were measured by using a magnetic float densimeter with an error of ±1.1 · 10^?5 g · cm^?3. Excess molar volumes of the mixtures and apparent molar volumes of the components (down to their infinite dilution) were calculated. The volumetric effects of mixing being very large in magnitude present negative deviations from ideality and become decreasingly negative with increasing temperature. The apparent molar volume of organic co-solvent displays a clearly pronounced minimum in the water-rich region at all the temperatures studied. It has been shown that there is a thermodynamically substantiated interrelation between volume and enthalpy (heat capacity) properties of the mixtures considered.     

Liquid–liquid equilibria of ternary systems (water + carboxylic acid + cumene) at 298.15 K

(Liquid–liquid) equilibrium data for the ternary systems [water + formic acid or acetic acid or propionic acid + cumene (2-phenylpropane, isopropylbenzene)] at 298.15 K are reported. Complete phase diagrams were obtained by determining solubility and the tie-line data. The reliability of the experimental tie-lines was determined through the Othmer–Tobias plots. Distribution coefficients and separation factors were evaluated for the immiscibility region. The tie-line data were compared with the results predicted by the UNIFAC method.     

Density and sound speed study of hydration of 1-butyl-3-methylimidazolium based amino acid ionic liquids in aqueous solutions

Amino acid ionic liquids (AAILs) have huge potential in the field of protein chemistry, enzymatic reactions, templates for synthetic study etc. which is due to their distinctive properties like unique acid-base characteristics, tunable hydrophobicity, hydrogen bonding ability and strong hydration effects. To explore the field of bio-ionic liquids for its real life applications and sustainable technology development, it is essential to have better understanding of these newly researched liquid salts in life’s most chosen medium, i.e. in aqueous medium, through study of their physicochemical properties in aqueous solutions. In this context, we are reporting herewith measurements and analysis of volumetric properties in the temperature range of (293.15 to 313.25) K and acoustic properties at 298.15 K in the concentration range of (0.05 to 0.5) mol · kg⁻¹ for aqueous solutions of 1-butyl-3-methylimidazolium [Bmim] based amino acid ionic liquids, prepared from glycine, l-alanine, l-valine, l-leucine and l-isoleucine. The experimental density and sound speed data were used to obtain apparent, partial and limiting molar volumes as well as isentropic and isothermal compressibility properties. These data have been further used to understand electrostriction as well as concentration dependence of internal pressure. The hydration numbers for AAILs in aqueous medium were estimated from compressibility data using Passynski method and the estimated ionic hydration numbers are compared with those obtained using activity data. The results are explained in terms of cooperative hydration effects, hydrophobic interactions, kosmotropic behavior of AAILs, etc.     

Synthesis,thermal and lyotropic liquid crystalline properties of protic ionic salts

A series of protic ionic salts were synthesised by a simple acid–base reaction from various pyridine derivatives and dodecylbenzenesulfonic acid in a common organic solvent and characterised in terms of their thermal and lyotropic liquid crystalline properties using various experimental techniques. All of them exhibited lyotropic liquid crystalline phases in toluene, methanol, acetonitrile, dimethyl sulfoxide and water. Their critical concentrations for the formation of biphasic solutions and concentrations for the formation of lyotropic solutions were quite broad depending on the dielectric constants of the solvents. Their lyotropic phases were identified as lamellar phases, since their textures exhibited bâtonnets, oily streaks and mosaic textures. They can potentially be used for many organic transformations, which may have implications in green chemistry.