Mole Of Solvent Research Articles

Study to reconnoiter solvation consequences of l-arginine/l-histidine and sodium salicylate in aqueous environment probed by physicochemical approach in the temperature range (293.15–318.15) K

Abstract The densities, ρ, ultrasonic speeds, u and viscosities, η of l-arginine and l-histidine in aqueous-sodium salicylate (1% and 2% sodium salicylate in water, w/w) solvents were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure in seven different concentrations. The experimental density data have been used to calculate the apparent molar volume, Vϕ, limiting apparent molar volume, Vϕ° and transfer volume, Vϕ, tr°. Likewise from the ultrasonic speed data, different thermo-acoustical parameters, such as apparent molar compressibility, Ks,ϕ, limiting apparent molar compressibility, Ks, ϕ° and transfer compressibility, Ks, ϕ, tr° have been evaluated. The viscosity data have been used to determine Falkenhagen Coefficient, A, Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δμ1°# and solute, Δμ2°#, entropies, ΔS°# and enthalpies, ΔH°# of activation of viscous flow. These parameters have been discussed in light of solute-solute and solute-solvent interactions prevailing in these solutions and their variations are revealed to get the basic picture of the molecular interactions occurring in the systems studied. The negative values of dB/dT favour structure making behavior of amino acids in aqueous solutions of sodium salicylate. The free energy parameters indicate the formation of transition state in the presence of amino acids.

Correlation between physicochemical properties and non-covalent interactions involving l-arginine/l-histidine and semicarbazide hydrochloride at temperatures from 293.15 to 318.15 K

Physicochemical properties and the nature of interaction of drug-amino acid have been investigated from the experimentally measured values of densities, ρ, ultrasonic speed, u and viscosities, η of l-arginine and l-histidine in aqueous-semicarbazide hydrochloride (1 wt% and 2 wt% semicarbazide hydrochloride in water, w/w) solvents over the temperature range of 293.15 K to 318.15 K at an interval of 5 K and at atmospheric pressure. From the experimental densities, the apparent molar volume, Vφ, limiting apparent molar volume, Vϕo and transfer volume, Vϕ,tro were obtained. Further from the ultrasonic data, thermo-acoustical parameters, such as apparent molar compressibility, Ks,ϕ, limiting apparent molar compressibility, Ks,ϕo and transfer compressibility, Ks,ϕ,tr° have been evaluated. The viscosity data have been used to determine Falkenhagen Coefficient, A, Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δμ1o# and solute, Δμ2o#, entropies, ΔSo# and enthalpies, ΔHo# of activation of viscous flow. The results have been interpreted in terms of plausible molecular interactions. The cosphere overlap model has been used to interpret the positive Vϕ,tro values. These amino acids act as structure maker in aqueous-semicarbazide hydrochloride solvents.

Study of solvation behaviour and interactions of drug betaine hydrochloride in aqueous-D-xylose/L-arabinose solutions at different temperatures by using volumetric, acoustic and viscometric methods

The densities, ρ, ultrasonic speeds, u and viscosities, η of the drug betaine hydrochloride in water and in aqueous−D-xylose/L-arabinose (5 wt% and 10 wt% D-xylose/L-arabinose in water) solvents at various temperatures (293.15–318.15) K and at atmospheric pressure of 101 kPa have been measured by using digital vibrating tube density and sound analyser and micro viscometer. The experimental data have been used to evaluate the apparent molar volumes, Vϕ, limiting apparent molar volumes, Vϕo, apparent molar compressibilities, Ks,ϕ, limiting apparent molar compressibilities, Ks,ϕo, apparent specific volume, Vϕ,sp, transfer volumes, Vϕ,tro and transfer compressibilities, Ks,ϕ,tro. The viscosity A and B coefficients, Gibbs free energies of activation of viscous flow per mole of solvent, Δμ1o# and of solute, Δμ2o#, enthalpies, ΔHo# and entropies, ΔSo# of viscous flow, were obtained using the viscosity data. The effect of concentration, temperature, taste behaviour and solute structure were discussed in terms of solute–solvent and solute–solute interactions prevailing in these systems.

Thermodynamic and transport investigation of aqueous solutions containing choline L-histidinate and some water soluble polymers such as polyethylene glycol di methyl ether, polyethylene glycol and polypropylene glycol: Evaluation of solute-solvent interactions and phase forming ability

Considering to the importance of choline amino acid ionic liquids, [Ch][AA]-ILs, as green biocompatible and biodegradable solvents utilized for separation of proteins through inducing aqueous biphasic systems in the presence of some water soluble polymers, it is vital to elucidate the solute-solute and solute-solvents interactions in water media which may be responsible for phase separation. In this respect, density, sound speed and viscosity of choline L-histidine, [Ch][L-His], in water and aqueous solutions of three polymers containing polyethylene glycol dimethyl ether 250, PEGDME250, polypropylene glycol 400, PPG400, and polyethylene glycol 400, PEG400, have been measured experimentally at T = (288.15 to 318.15) K and 298.15 K under atmospheric pressure, respectively. The obtained data from these measurements were employed for computing the limiting values for apparent molar volume (Vφ0), molar isentropic compressibility (κφ0), transfer molar volume (ΔtransVφ0) and isentropic compressibility (Δtransκφ0) for transferring [Ch][L-His] from water to aqueous polymer solutions, viscosity B-coefficient, transfer viscosity B-coefficient (ΔtransB), free energies of activation per mole of solvent (Δμ10≠) and solute (Δμ20≠). These quantities provide some useful information about [Ch][L-His]-polymer and [Ch][L-His]-water interactions, soluting-out ability of IL and capability of above ternary solutions for separation into two-phases. The results showed that the ΔtransVφ0 values for PPG and PEGDME are negative which indicates that IL-water interactions become stronger in the presence of these polymers. But, in the case of PEG, a positive value of ΔtransVφ0 shows that the IL-water interactions are weaker in the presence of this polymer.

Volumetric, acoustic and viscometric investigation of some choline amino acid ionic liquids in aqueous solutions of polypropylene glycol 400 and polyethylene glycol 400

Present study reports density (ρ), ultrasonic velocity (u), and viscosity (η) for some choline amino acid ionic liquids, [Ch][AA]-ILs, including choline glycine, choline L-valine and choline L-proline in aqueous solutions of two water soluble polymers, i.e. polypropylene glycol 400 (PPG400) and polyethylene glycol 400 (PEG400) with different mass fractions of polymer, w/w = (0.025, 0.050 and 0.075), at 298.15 K under atmospheric pressure (≈85 kPa). The experimental densities and sound speeds were used for calculation the apparent molar volume (Vφ), limiting apparent molar volume (Vφ0), apparent molar isentropic compressibility (κφ), limiting apparent molar isentropic compressibility (κφ0), and also the transfer molar volume (ΔtranVφ0) and isentropic compressibility (Δtranκφ0) of [Ch][AA] from water to aqueous polymer solutions. Moreover, the viscosity B-coefficient, hydration number (nH), transfer viscosity B-coefficient (ΔtranB), free energies of activation per mole of solvent (Δμ10≠) and solute (Δμ20≠) have been computed by the help of experimental viscosities measured for the studied solutions. These quantities are useful for evaluation the ILs solvation behaviour, their structure-making or breaking abilities in the presence of polymer in water medium and also the solute-solute or solute-solvent interactions exists in aqueous ([Ch][AA] + polymer) solutions. The results indicated that the IL-water interactions are more favourable in the presence of PPG400 and follow the order: [Ch][Gly] > [Ch][L-Pro] > [Ch][L-Val]. Inversely, the IL-water interactions become weaker by ILs transferring from water to aqueous PEG400 solutions.

Study on the interactions of drug isoniazid in aqueous-D-xylose/L-arabinose solutions at different temperatures using volumetric, acoustic and viscometric approaches

Volumetric, acoustic and viscometric properties of drug isoniazid in water and aqueous solutions of carbohydrates, D-xylose and L-arabinose (5% and 10% D-xylose/L-arabinose in water, w/w) were studied at various temperatures, T = (293.15–318.15) K and at atmospheric temperature. The apparent molar volumes, Vϕ and apparent molar compressibilities, Ks,ϕ were calculated from the experimentally measured densities and ultrasonic speeds. Limiting apparent molar volumes, Vϕ°, limiting apparent molar compressibilities, Ks,ϕ°, limiting molar expansibilities, Eϕ° and their corresponding transfer volumes, Vϕ,tr° and transfer compressibilities, Ks,ϕ,tr° of drug isoniazid from water to aqueous carbohydrate solutions were also evaluated. Falkenhagen Coefficients, A, Jones-Dole coefficients, B, variation of B with temperature, dB/dT, free energies of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#, enthalpies, ΔH°# and entropies, ΔS°# of activation of viscous flow were calculated from the viscosity measurements. The negative sign of dB/dT indicated the structure making ability of the drug isoniazid. The results obtained have been discussed in terms of solute-solvent interactions in order to understand the solvation behaviour of isoniazid in these aqueous-carbohydrate solutions.

Solute-solute and solute-solvent interactions of drug sodium salicylate in aqueous-glucose/sucrose solutions at temperatures from 293.15 to 318.15 K: A physicochemical study

Physical properties like ultrasonic speed and compressibility give us an idea about the type of interactions prevailing in the solutions. Keeping this in view, we have measured the densities, ρ, ultrasonic speeds, u and viscosities, η of the drug sodium salicylate in water and in aqueous−D-glucose/d-sucrose (5 wt% and 10 wt% glucose/sucrose in water) solvents at different temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. These experimental values have been used to calculate apparent molar volumes, Vϕ and apparent molar compressibilities, Ks,ϕ, limiting apparent molar volumes, Vϕ° and limiting apparent molar compressibilities, Ks,ϕ°. The transfer volumes, Vϕ,tr° and transfer compressibilities, Ks,ϕ,tr° of sodium salicylate from water to aqueous carbohydrate solutions were also calculated. The co-sphere model has been used to interpret the transfer molar properties. Using the η data, the viscosity A and B coefficients have been calculated. The variation of viscosity B coefficient with respect to temperature, i.e., dB/dT have been investigated, the sign of which is indicative of the structure making/breaking ability of the drug in these media. The free energy of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#, enthalpies, ΔHο# and entropy, ΔSο# of activation of viscous flow, were also obtained from the viscosity data. The results obtained are discussed in terms of solute-solute and solute-solvent interactions prevailing in these solutions.

Viscometric and Conductometric Studies of Doxycycline Hyclate in Water, Aqueous Glycine and L-Alanine Solutions at Different Temperatures

To investigate the behaviour of doxycycline hyclate in water, aqueous glycine and aqueous L-alanine solutions, the viscometric and conductometric studies have been conducted at different temperatures. Viscosity data has been used to derive the Jones-Dole viscosity B-coefficient, temperature derivative of B-coefficient (dB/dT), viscosity B-coefficient of transfer (ΔtrB), free energy of activation of viscous flow per mole of solvent (Δμ1 o*) and solute (Δμ2o*) respectively, activation entropy (ΔS2o*) and activation enthalpy (ΔH2o*). Conductance data has been used to compute Walden product (Λm oηo) and temperature coefficient of Walden product (dΛmoηo/dT) for doxycycline hyclate in water, and in aqueous glycine and aqueous L-alanine solution. The positive values of B-coefficient, ΔtrB indicate the prevailing of hydrophilic-ionic interactions in the systems under examination. The negative values of dB/dT and positive values of temperature coefficient of Walden product infer structure maker tendency of doxycycline hyclate in water, and in aqueous glycine and aqueous L-alanine solution. Transfer energy parameters indicate the breaking of intermolecular bonds in transition state which means that formation of activated complex is unfavourable

Role of Solvent Properties in the High-Pressure Phase Behavior of (Ethylene + Comonomer + n-Hexane + LLDPE) Systems

The lower critical end point temperatures of [ethylene + comonomer + n-hexane + linear low-density polyethylene (LLDPE)] systems are shown to be strongly correlated with solvent average molecular mass and mole fraction-averaged carbon number, but not solvent density or critical temperature. A synthetic-visual method is used to measure vapor–liquid, vapor–liquid–liquid, and liquid–liquid phase boundaries for quasiquaternary (ethylene + comonomer + n-hexane + LLDPE) systems for the 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and 1-decene comonomers, and for quasiternary (ethane/n-decane/4-methyl-1-pentene + n-hexane + LLDPE) systems. The reported data span temperatures of T = (375–465) K and pressures of P = (0.5–15) MPa. In all systems, the mass fraction of the LLDPE (Mw = 199 kg·mol–1; Mw/Mn = 2.62; 2.56 mol % 1-hexene) was kept at 3 wt % and solvent compositions were chosen to represent conditions found in the solution polymerization process. The modified Sanchez–Lacombe equation of state can pr...

Molecular interactions of gentamicin sulphate in aqueous-l-asparagine/l-glutamine solutions at different temperatures: Volumetric, acoustic and viscometric properties

The solute-solute and solute-solvent interactions are investigated by using the experimental values densities, ρ, ultrasonic speeds, u and viscosities, η of gentamicin sulphate in water and in aqueous l-asparagine/l-glutamine (1% and 2% l-asparagine/l-glutamine in water) solvents at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. The experimental ρ and u data have been used to calculate the apparent molar volumes, Vφ, limiting apparent molar volumes, Vϕ°, apparent molar compressibilities, Ks, ϕ, limiting apparent molar compressibilities, Ks, ϕ°, transfer volumes, Vϕ, tr°, transfer compressibilities, Ks, ϕ, tr° and limiting partial molar expansivity of solute, Eϕ°. Also, the Falkenhagen Coefficients, A and Jones-Dole coefficients, B were evaluated from experimental viscosity data. The Gibbs free energies of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#, entropies, ΔSο and enthalpies, ΔHο of activation of viscous flow were also calculated and discussed in terms of transition state theory. These parameters have been discussed in connection with the electrostatic interactions between the zwitterionic groups of amino acids and drug molecules. The structure-making/breaking ability of the drug in these solutions was also analyzed using the signs and magnitudes of (∂2Vϕ°/∂T2) and dB/dT coefficients.

Similarity and differences of the thermochemical characteristics of l-glutamine dissolution in aqueous solutions of some acetamides and formamides at T = 298.15 K

The enthalpies of l-glutamine dissolution in an aqueous solution of acetamide, N-methylacetamide, and N, N-dimethylacetamide were determined by the calorimetric method at T = 298.15 K and organic solvent mole fractions up to x2 ~ 0.25. The standard enthalpies of solution (ΔsolH°) and transfer (ΔtrH°) of l-glutamine from water to a mixed solvent as well as the enthalpy coefficients of pairwise interactions (hxy) were calculated. The interrelation between enthalpic characteristics of l-glutamine dissolution (transfer) and the composition of water-organic mixtures was determined. The received thermochemical characteristics of intermolecular interactions of l-glutamine with the molecules of acetamides were compared with the analogous characteristics interactions of l-glutamine with the molecules of formamides (formamide, N-methyformamide, and N, N-dimethylformamide).

Front Cover: Resin Swelling in Mixed Solvents Analysed using Hansen Solubility Parameter Space (Chem. Eur. J. 19/2019)

3D Hansen solubility space is used to explain why the ability of binary mixtures of two solvents to swell crosslinked resins does not vary linearly with the solvent mole fractions. The cover artwork, which is loosely based on the famous 1979 poster for the film Alien, shows a series of small eggs at the bottom representing unswollen resin beads each surrounded by a single solvent. The centre of the image shows a much larger egg representing a swollen resin bead, now surrounded by a mixture of two solvents. Coming off the egg is a tripeptide representing the solid-phase peptide synthesis reported in the paper. More information can be found in the Full Paper by M. North et al. on page 4951.

Volumetric, acoustic and viscometric studies of solute-solute and solute-solvent interactions of isoniazid in aqueous-glucose/sucrose solutions at temperatures from 293.15 K to 318.15 K

The densities, ρ, ultrasonic speeds, u and viscosities, η of the drug isoniazid in water and in aqueous–d-glucose/d-sucrose (5 wt% and 10 wt% glucose/sucrose in water) solvents were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. The ρ, u and η data have been used to calculate apparent molar volumes, Vϕ, limiting apparent molar volumes, Vϕ∘, apparent molar compressibilities, Ks,ϕ, limiting apparent molar compressibilities, Ks,ϕ∘, transfer volumes, Vϕ,tr∘ and transfer compressibilities, Ks,ϕ,tr∘. The viscosity data have been used to determine Falkenhagen Coefficients, A and Jones-Dole coefficients, B. The calculated parameters have been discussed in terms of various solute-solute and solute-solvent interactions prevailing in these solutions. The structure making/breaking ability of isoniazid in these solutions has been examined by using the sign of dB/dT. Furthermore, the Gibbs energies of activation of viscous flow per mole of solvent, Δμ1∘# and per mole of solute, Δμ2∘#, enthalpies, ΔH∘ and entropies, ΔSo of activation of viscous flow, were also calculated and discussed in terms of transition state theory.

Physicochemical study of solute-solute and solute-solvent interactions of homologous series of α-amino acids in aqueous-isoniazid solutions at temperatures from 293.15 to 318.15 K

Drug-amino acid interactions have been investigated in aqueous media from the experimentally measured data of densities, ρ, ultrasonic speeds, u and viscosities, η of glycine, l-alanine, l-valine and l-isoleucine in water and in aqueous-isoniazid (1% and 2% isoniazid in water, w/w) solvents at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. The ρ and u data have been used to calculate the apparent molar volume, Vφ, limiting apparent molar volume, Vϕ°, apparent molar compressibility, Ks,ϕ, limiting apparent molar compressibility, Ks,ϕ°, transfer volume, Vϕ,tr°, and transfer compressibility, Ks,ϕ,tr° and hydration number, nH. The viscosity data have been used to determine Falkenhagen Coefficient, A, Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#. These parameters have been discussed in terms of solute-solute and solute-solvent interactions prevailing in these solutions. A detailed insight into the structure making/breaking ability of the amino acids in these solutions has been retrieved through the close perusal of all these parameters. In addition, the values of Vϕ°, Ks, ϕ°, B and Δμ2°# have been split into groups' contributions of the amino acids. Entropies, ΔS°# and enthalpies, ΔH°#of activation of viscous flow for amino acids in aqueous isoniazid solutions have been used to interpret interactions between the ions of amino acids and isoniazid.

Liquid Extraction of Toluene from Heptane, Octane, or Nonane Using Mixed Ionic Solvents of 1-Ethyl-3-methylimidazolium Methylsulfate and 1-Hexyl-3-methylimidazolium Hexafluorophosphate

Liquid–liquid extractions of toluene from paraffin compounds, using binary ionic solvent mixtures of 1-hexyl-3-methylimidazolium hexafluorophosphate [hmim][PF6] and 1-ethyl-3-methylimidazolium methylsulfate [emim][CH3SO4], have been examined at 313.15 K and an atmospheric pressure of 101 kPa. Based on the experimental liquid–liquid equilibrium data for the pseudoternary systems consisting of heptane, octane, or nonane + toluene + [hmim][PF6] + [emim][CH3SO4], the distribution ratios and selectivity values were calculated and compared to systems using pure ionic liquids or sulfolane. The results showed that the use of a binary mixture of [hmim][PF6] + [emim][CH3SO4] at a solvent mole fraction of 0.9 for [hmim][PF6] improves both the toluene distribution ratio and the selectivity, with respect to those of sulfolane and other pure ionic solvents. Consequently, these mixed ionic liquids could be considered an environmentally benign alternative solvent for the aromatic extraction process. The experimental data...

The effect of the side chain structures on the energy of intermolecular interactions of α-amino acids with some formamides in aqueous solutions at T = 298.15 K

To evaluate the effect of amino acid side chains on the thermodynamics of their interaction with the formamides molecules in aqueous solutions, we expanded the range of amino acids by studying in the present investigation the thermodynamics of the dissolution of glutamine in mixed solvents {water + (formamide, N‑methylformamide and N,N‑dimethylformamide)} at T = 298.15 K and organic solvent mole fractions up to x2 ~ 0.3. The standard enthalpies of solution (ΔsolH°) and transfer (ΔtrH°) of l-glutamine from water to a mixed solvent as well as the enthalpy coefficients of pairwise interactions (hxy) were calculated. The interrelation between enthalpic characteristics of l-glutamine dissolution (transfer) and the composition of water-organic mixtures was determined. Using the enthalpic coefficients of pairwise interactions of l-glutamine and five more amino acids (glycine, dl-α-alanine, l-valine, l-methionine, and l-threonine), the enthalpic contributions of the side chains of these amino acids to their interparticle interactions with the molecules of formamides were calculated.

Molecular Interactions in L-threonine Aqueous-Lactose Solutions at (293.15–313.15) K on Viscometric Data

Viscosity measurements of L-threonine in the range (0.025–0.2) mol kg–1 in various aqueous-lactose solutions (0–6 wt % of lactose in water) have been carried out at temperatures (293.15–313.15) K. Jones–Dole coefficients, viscosity B-coefficients of transfer, Btr, variation of B with temperature, dB/dT and solvation behavior, B/ $$V_{\phi }^{^\circ }$$ of L-threonine have been obtained. Further, the free energy of activation of viscous flow per mole of solvent, as well as per mole of solute, along with activation enthalpy, and activation entropy has also been evaluated. The results have been interpreted in terms of various molecular interactions prevalent in these systems and moreover, it has been seen that the L-threonine acts as structure maker in all studied solutions.

Volumetric, Viscosity and Conductance Studies of Solute–Solute and Solute–Solvent Interactions of Some Alkali Metal Chlorides in Aqueous Citric Acid at Different Temperatures

Abstract The present study aims for the structure-making and structure-breaking behavior of some electrolytes in aqueous citric acid solution. The density, viscosity and conductance of some alkali metal chlorides lithium chloride (LiCl), sodium chloride (NaCl) and potassium chloride (KCl) in 0.01 m aqueous citric acid have been measured in the concentration range 0.01–0.12 m at 303.15, 308.15, 313.15 and 318.15 K. From these measurements, molar volume, viscosity parameters and molar conductance have been deliberated. Debye Hückel limiting law is used for the assessment of the contributions of various types of solute–solvent interactions. Jones–Dole viscosity equation is used to calculate viscosity B-coefficient for these salts in aqueous citric acid, which is known to provide information concerning the solvation of ions and their effects on the structure of the solvent in the near environment of the solute particles. The free energies of activation of viscous flow per mole of solvent, Δ μ 1 0 ‡ $\Delta \mu _1^{0\ddagger }$ and solute, Δ μ 2 0 ‡ , $\Delta \mu _2^{0\ddagger },$ have also been evaluated by using viscosity data. Using molar volume, the transfer volume Фv o tr has also been computed. The structure making/ breaking behavior of LiCl, NaCl and KCl is inferred from the sign of second derivative of partial molar volume with respect to temperature at constant pressure (d2φv o/dT2)p, Temperature coefficient of B. dB/dT and temperature coefficient of Walden product i.e. d(Λm oηo)/dT values. It has been found from these studies that LiCl, NaCl and KCl behave as structure-breaker in 0.01 m aqueous citric acid solution. The results have been qualitatively used to explain the molecular interaction and structural changes between the components of these mixtures.

Study of Intermolecular Interactions of CTAB with Amino Acids at Different Temperatures: A Multi Technique Approach

Abstract The densities, ρ, viscosities, η and specific conductivities κ, of (0.0002, 0.0004, 0.0006 and 0.0008 m) CTAB in 0.1 m aqueous valine, leucine and isoleucine were measured at different temperatures. The measured data were used to calculate various useful thermodynamic parameters. A complete characterization of any mixture can be performed by means of these thermodynamic properties. The apparent molar volume, ϕv , partial molar volume, ϕ v 0 $\phi _v^0$ and partial molar isobaric expansibilities, ϕ E 0 , $\phi _E^0,$ were calculated using density data. The viscosity data were analyzed using Jones–Dole equation to obtain viscosity coefficients, A- and B-, free energy of activation per mole of solvent, Δμ 1°∗, and solute, Δμ 2°∗, enthalpy, ΔH ∗ and entropy, ΔS ∗ of activation of viscous flow. Measuring the changes in these properties has been found to be an excellent qualitative and quantitative way to obtain information regarding the molecular structure and intermolecular interactions occurring in these mixtures. Various structure-making/breaking ability of solute (cetyltrimethylammonium bromide) in presence of aqueous amino acid solutions were discussed. In addition, fluorescence study using pyrene as a photophysical probe has been carried out, the results of which support the conclusions obtained from other techniques.

Study of viscometric properties of L-ascorbic acid in binary aqueous mixtures of D-glucose and D-fructose

ABSTRACTThe relative viscosities and activation parameters of L-ascorbic acid have been determined in water and binary aqueous mixtures of D-glucose and D-fructose at different temperatures. A and B-coefficients of Jones–Dole equation are determined using density and viscosity data. Gibbs energy of activation of viscous flow per mole of solvent as well as per mole of solute along with activation enthalpy and entropy is also determined using Feakin’s transition-state theory. The obtained results are explained in terms of intermolecular interactions and in this study L-ascorbic acid has been found as structure breaker in binary aqueous mixtures of D-glucose and D-fructose.