Solute-solvent Molecular Interactions Research Articles

Study the solute-solvent molecular interactions of L-Glutamine and conventional surfactants

The micellar characteristics of the three conventional surfactants such as sodium dodecyl sulfate (SDS), Hexadecyltrimethylammonium bromide (CTAB), and Triton X-100 (TX-100) are changed by the addition biologically active L-Glutamine (Glu) (i.e., 0.005, 0.01 and 0.02 M) were determined from stalagmometric, UV–visible spectroscopy, viscometric, FTIR and fluorescence methods using pyrene as probe. An observed decrease in I1/I3 in all micellar systems confirms the relative hydrophobicity of L-Glu. The CMCs values are reduced with the addition of L-Glu were determined by stalagmometric and it is confirmed by UV–visible and fluorescence methods and differs in the following order: SDS > CTAB > TX-100. The estimation of numerous interfacial parameters have also been done by using stalagmometric measurements including the (ϒCMC), (πCMC), (pC20), (Amin), and (Гmax). The concentration of L-Glu (M) rises, Amin values rise while the Гmax value falls and a significant rise in the surface tension of CMC (ϒCMC) values, with the values being in the range of 0.02 M > 0.01 M > 0.005 M > water. Hydrogen bonds, electrostatic interactions, hydrophobic interactions, and van der Waal interactions are only a few of the diverse types of interactions that were examined using FTIR in the pure surfactants and L-Glutamine mixed systems. To stabilize proteins and prevent protein aggregation, the findings presented here may be applied in pharmaceutical formulations.

Determination of Solubility and Thermodynamic Analysis of Solubility Behavior of 2,5-Furandicarboxylic Acid in Water and Ether Binary Solvent System

2,5-Furandicarboxylic acid (FDCA) is a promising biomass-derived monomer, and the study of FDCA dissolution behavior is of paramount importance to its purification. In this study, the solubility of FDCA in four different ethers (1,4-dioxane, tetrahydrofuran, 1,2-dimethoxyethane, and diethylene glycol dimethyl ether), as well as four binary solvent systems containing these above ethers with water, was measured by a gravimetric method. The solubility of FDCA could be improved in binary solvent systems as compared to corresponding pure solvents. More interestingly, the solubility of FDCA increased first and then gradually dropped back with the increasing mole fraction of water in binary solvent systems. The KAT-LSER model was used to explore the influence of solvent effect on solubility. The Hansen solubility parameter was utilized to probe the solute–solvent molecular interactions. Apelblat equation, van’t Hoff equation, λh equation, Wilson model, and nonrandom two-liquid model were applied to analyze the experimental solubility data in pure ether solvents and binary solvent systems. Furthermore, the dissolution thermodynamic characteristics of FDCA in particular binary solvent systems were analyzed by the van’t Hoff equation, which revealed that the dissolving process of FDCA is endothermic, entropy-driven, and spontaneous in the other three examined solvent systems, with the exception of the 1,4-dioxane/water mixture.

Highly efficient coherent detection of terahertz pulses based on ethanol

Water-based terahertz (THz) coherent detection scheme has been recently proposed, which overcomes the bandwidth limitation or high probe laser power demand in solid-/gas-based schemes. Here, we report a highly efficient THz coherent detection method using ethanol with superior performances under the mechanism of four-wave mixing. We systematically investigate the energy ratios and relative polarizations between the THz-induced second harmonic and control second harmonic (CSH) beams and reveal that ethanol always exhibits significantly higher detection sensitivity than water. The coherent, incoherent, or hybrid detection mode can be flexibly switched by changing the CSH beam polarization. The enhanced sensitivity derives from the much larger third-order nonlinear coefficient and lower ionization potential of ethanol. In addition, for the ethanol–water mixtures with various concentrations, the THz coherent detection signals can always be decomposed into the linear superposition of those from pure ethanol and neat water at the sub-picosecond timescale, indicating the synergistic contribution of ethanol and water molecules in the mixture during the detection process. This work provides a valid method to significantly improve the sensitivity of the liquid-based coherent detection scheme and a research perspective for exploring the solute–solvent molecular interactions.

Experimental analysis and thermodynamic modelling of Nitroxynil solubility in pure solvent and binary solvent

Nitroxynil(NIT) is a commonly used anti-liver fluke drug for cattle and sheep, Its solubility is closely related to its preparation. In this work, the molar solubility of NIT in nine pure solvents (methanol, ethanol, 1,2-propanediolethyl, isopropanol, ethyl acetate, acetonitrile, n-butanol, phemethylol) and two kinds of binary mixtures with different ratio(ethanol + phemethylol; ethanol + acetonitrile) was determined by shake flask method over the temperature from 278.15 ∼ 323.15 K at atmosphere pressure. Results show that the solubility of NIT in all tested solvents was increased with raised temperature. In mono-solvents, the mole fraction solubility of NIT was highest in phemethylol and the solubility order is: phemethylol > acetonitrile > ethyl acetate > methanol > n-butanol > ethanol > 1,2-propanediolethyl > isopropanol > water. In binary solvents, the mole fraction solubility increased with increasing ratio of phemethylol/acetonitrile. In mono-solvents, the modified Apelblat equation, λh equation, Van't Hoff model were applied to correlate the solubility data. In binary solvents, the modified Apelblat equation, λh equation, GSM model and Jouyban-Acree model were to correlate the solubility data. Solubility order of NIT in nine pure solvent and two binary solvent systems were analysed by using the Hansen solubility parameter (HSP). Activity coefficient was to access the solute–solvent molecular interactions. In addition, the dissolution of NIT is an endothermic and entropy-friendly process, since thermodynamic parameters such as enthalpy, entropy, and apparent standard Gibbs free energy are all greater than zero. The results will supply some essential data on recrystallization process, purification and formulation development of NIT in pharmaceutical applications.

Measurement, correlation of solubility and thermodynamic properties analysis of 5,5′-bis(2,4,6-trinitrophenyl)-2,2′-bis(1,3,4-oxadiazole) in different mono solvents

In this paper, the solubility of 5,5′-bis(2,4,6-trinitrophenyl)-2,2′-bis(1,3,4-oxadiazole) (TKX-55) in methanol, ethanol, 1-propanol, 2-propanol, formic acid, acetic acid, propionic acid, acetonitrile, ethyl acetate, tetrahydrofuran, nitromethane, 1,2-dichloroethane, benzene and 1,4-dioxane was determined at T = (293.15–333.15) K under atmospheric pressure (P = 0.1 MPa) by a gravimetric method. The results showed that the solubility increases with rise of temperature in all selected solvents. Additionally, the solvent effect on TKX-55 solubility was investigated with Kamlet-Taft parameters. Moreover, Hansen solubility parameter was used for explaining the solubility order of TKX-55 in selected solvents, the consequences showed that solubility order of TKX-55 resulted from the comprehensive function of several solubility parameters. The solubility parameter of Δδt between TKX-55 and solvents reached from 0.17 MPa0.5 to 8.68 MPa0.5. The interaction energy (Einter) between TKX-55 and selected solvents was calculated by molecular simulation to explain the solubility behavior. Activity coefficient was to access the solute-solvent molecular interactions. Besides, the solubility values were correlated by the modified Apelblat equation, λh equation, the polynomial empirical equation, and ideal equation, and the results showed that all models can give a satisfactory correlation. The average root-mean-square deviation (106RMSD) values were 14.57, 33.08, 8.523 and 30.29, respectively. On the basis of the van’t Hoff and Gibbs equations, the thermodynamic properties exhibited by TKX-55 (i.e., standard dissolution enthalpy (ΔdisHo), standard dissolution entropy (ΔdisSo) and standard dissolution Gibbs free energy (ΔdisGo)) in the selected solvents were characterized and then discussed from the experiment data. As revealed from the result, TKX-55 in solvents selected showed a non-spontaneous process. The excess enthalpy of solution was estimated on the basis of λh equation. And solid-liquid surface tension (γ) and surface entropy factor (f) of TKX-55 were estimated by using the experimental solubility data. Furthermore, the experimental solubility values, model parameters, and thermodynamic properties of TKX-55 in different pure solvents will provide the necessary support for its preparation, crystallization process, and further theoretical studies.

Study of the Interactions between MeOH and Daidzein at the Molecular Level.

In this study, the interactions between daidzein and methanol were studied to investigate isoflavone extraction. The complexes of MeOH–daidzein = 1:1, 2:1, 4:1, and 7:1 were studied using DFT/B3LYP-D3. According to the findings of this study, daidzein can act as a hydrogen bond donor as well as an acceptor. Binding energies demonstrate that more MeOH molecules interacting with daidzein could give more stability to the system. The strengths of the hydrogen bonds reveal that daidzein prefers to act as a hydrogen bond donor than an acceptor. The atoms in molecules (AIM) topological analysis was performed to analyze the nature of the hydrogen bonds. Moreover, daidzein, genistein, and glycitein are the most common soybean isoflavones, and their properties during extraction were also studied. The binding energies show that the soy isoflavone genistein is more reactive with the solvent than daidzein, followed by glycitein. The extraction conditions of the three common soy isoflavones in MeOH solution were obtained at 321, 328, and 348 K for genistein, daidzein, and glycitein, respectively. The generalized Kohn–Sham energy decomposition analysis (GKS-EDA) results indicate that the solute–solvent molecular interactions are typical hydrogen bonds with predominantly electrostatic and exchange energies in nature.

Solubility determination and crystallization thermodynamics of an intermediate in different organic solvents

This study reported the solid–liquid equilibrium solubility of 4-nitropyrazole at the temperature ranging 288.15 K to 328.15 K in methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol, 1-pentanol, isoamyl alcohol, acetonitrile, acetone, methyl acetate, ethyl acetate, tetrahydrofuran and water, respectively. All the experiments were performed with the gravimetric method under the ambient pressure of 0.1 MPa. At the temperature ranging from 288.15 K to 328.15 K, 4-nitropyrazole in methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol, 1-pentanol, isoamyl alcohol, acetonitrile, acetone, methyl acetate, ethyl acetate, tetrahydrofuran and water exhibited the mole fraction solubility values of 0.109034–0.365964, 0.101321–0.310165, 0.087146–0.312564, 0.048152–0.238024, 0.079024–0.282653, 0.054890–0.247235, 0.071382–0.275687, 0.062864–0.21521, 0.039062–0.135087, 0.038140–0.058187, 0.007271–0.027222, 0.004829–026068, 0.004126–0.021975 and 0.002174–0.015095, respectively. The acquired solubility data of 4-nitropyrazole in the selected solvents was correlated with the modified Apelblat equation, λh equation, the ideal equation, as well as the polynomial empirical equation. Next, the correlated values of the four equations were significantly consistent with the experiment values, and the polynomial empirical equation yielded more effective correlated results than other equations. In addition, the solvent effect on 4-nitropyrazole solubility was investigated with Kamlet-Taft parameters. Moreover, to clarify the sequence of solubility in a range of solvents, the molecular modeling studies were conducted. Activity coefficient was to access the solute–solvent molecular interactions. Furthermore, the thermodynamic properties exhibited by 4-nitropyrazole (i.e., standard dissolution enthalpy (ΔdisHo), standard dissolution entropy (ΔdisSo) and standard dissolution Gibbs free energy (ΔdisGo)) in the selected solvents were characterized and then discussed from the experiment data. Besides, ΔdisHo, ΔdisSo and ΔdisGo at mean temperature in different pure solvents reached 22.40 kJ̣·mol−1-38.07 kJ̣·mol−1, 58.21 J̣·K-1̣·mol−1-81.10 J̣·K-1̣·mol−1 and 4.20 kJ̣·mol−1-13.13 kJ̣·mol−1, respectively. As revealed from the result, 4-nitropyrazole in solvents selected showed a non-spontaneous and entropy-driven dissolution. The present study could present the fundamental data to separate 4-nitropyrazole.

Effect of Temperature and Concentration on the Physical Properties of Cholesteryl Pelargonate Near Transition Temperatures

Thermodynamic and acoustical study of cholesteric liquid crystal (CLC) was carried out near phase transition temperatures using an ultrasonic interferometer. The study of ultrasonic waves and related thermo-acoustical parameters provides information in understanding the nature of molecular interactions associated with liquid crystals. A statistical mechanical approach is used to calculate the viscosity of samples. The characteristic textures and phase transition temperatures are obtained with Polarizing Microscopy (POM). Fabry Perot scattering studies (FPSS) are used to ascertain the phase transition temperatures of CLC. The thermo-acoustical parameters have been calculated using experimental data with well-known formulae. The acoustical parameters show variation with temperature as well as with concentration of CLC. Anomalous behavior of these parameters is noticed at the clearing temperature of CLC. The variation of the parameters is explained in terms of solute-solvent molecular interactions in the solution. The molecular behavior, structural changes, and intermolecular interactions between CLC and solvent are discussed in detail.

Solubility Data and Computational Modeling of Baricitinib in Various (DMSO + Water) Mixtures.

The solubility and thermodynamic analysis of baricitinib (BNB) in various dimethyl sulfoxide (DMSO) + water mixtures were performed. The “mole fraction solubilities (xe)” of BNB in DMSO and water mixtures were determined at “T = 298.2–323.2 K” and “p = 0.1 MPa” using an isothermal saturation technique. “Hansen solubility parameters (HSPs)” of BNB, pure DMSO, pure water and “DMSO + water” mixtures free of BNB were also estimated. The xe data of BNB was regressed well by five different thermodynamics-based co-solvency models, which included “Apelblat, Van’t Hoff, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van’t Hoff models” with overall deviations of <5.0%. The highest and lowest xe value of BNB was computed in pure DMSO (1.69 × 10−1 at T = 323.2 K) and pure water (2.23 × 10−5 at T = 298.2 K), respectively. The HSP of BNB was found to be closer to that of pure DMSO. Based on activity coefficient data, maximum solute–solvent molecular interactions were observed in BNB-DMSO compared to BNB-water. The results of “apparent thermodynamic analysis” indicated endothermic and entropy-drive dissolution of BNB in all “DMSO + water” combinations including mono-solvents (water and DMSO). “Enthalpy-entropy compensation analysis” showed enthalpy-driven to be the main mechanism of solvation of BNB.

Solubility Determination, Correlation, and Solute–Solvent Molecular Interactions of 5-Aminotetrazole in Various Pure Solvents

The purpose was to evaluate solubility data and solute–solvent molecular interactions of 5-aminotetrazole in various pure solvents including methanol, ethanol, n-propanol, isopropanol, 1-butanol, t...

Solubility determination of raloxifene hydrochloride in ten pure solvents at various temperatures: Thermodynamics-based analysis and solute–solvent interactions

The purpose of the present study was to determine the solubility of raloxifene hydrochloride (RHCl) in ten solvents: water, ethanol, isopropyl alcohol (IPA), ethylene glycol (EG), propylene glycol (PG), polyethylene glycol-400 (PEG-400), Transcutol, 1-butanol, dimethyl sulfoxide (DMSO), and ethyl acetate (EA) at temperatures of 298.2–323.2 K and a pressure of 0.1 MPa. The solubility data obtained was fitted upon “Apelblat and Van't Hoff” equations. The maximum mole fraction solubility of RHCl was obtained in DMSO (5.02 × 10−2 at 323.2 K), followed by PEG-400 (5.92 × 10−3 at 323.2 K), EA (3.11 × 10−3 at 323.2 K), Transcutol (1.22 × 10−3 at 323.2 K), PG (2.19 × 10−4 at 323.2 K), 1-butanol (1.96 × 10−4 at 323.2 K), IPA (1.47 × 10−4 at 323.2 K), ethanol (7.90 × 10−5 at 323.2 K), EG (6.65 × 10−5 at 323.2 K), and water (3.60 × 10−5 at 323.2 K). Similar fashions were noticed at each studied temperature. The higher solubility of RHCl in DMSO, PEG-400, EA, and Transcutol was possibly referable to their lower polarity in comparison with water. The molecular interactions between the solute and solvent molecules were estimated by calculating parameters like activity coefficients, and more prominent solute–solvent molecular interactions were noted for RHCl–DMSO, RHCl–EA, and RHCl–PEG-400 in comparison with the other solute–solvent combinations. The outcomes of the “apparent thermodynamic analysis” showed that the dissolution of RHCl was “endothermic, spontaneous and entropy-driven” in all investigated solvents. The obtained solubility data of RHCl in commonly used solvents could be useful in the purification, recrystallization, and dosage form design of the drug.

Carbon dioxide solubility in 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium tetrachloroferrate over an extended range of temperature and pressure

Solubility data of carbon dioxide (CO2) in the two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] and 1-butyl-3-methylimidazolium tetrachloroferrate [BMIM][FeCl4] at T = (273.15–413.15) K and pressures up to p = 4.5 MPa are presented. In addition to the experiments, a literature review was done to compare the new results with published solubility data. The measurements were carried out using an isochoric method which operates in decrements of ΔT = 20 K within the investigated temperature range and at selected four different pressure steps ranging from a pressure p of around 4.5 MPa to around 0.5 MPa. The solubility of CO2 decreases in both ionic liquids with increasing temperatures. Within the p,T-range investigated, CO2 displayed a solubility in [BMIM][BF4] from a mole fraction x = 0.0117 and a corresponding molality m = 0.0526 mol·kg−1 at T = 413.15 K and p = 0.417 MPa up to x = 0.4876 and m = 4.2094 mol kg−1 at T = 293.15 K and p = 4.349 MPa. The corresponding values for the solubility in [BMIM][FeCl4] start at a mole fraction x = 0.0268 and a corresponding molality m = 0.0818 mol·kg−1 at T = 413.15 K and p = 0.443 MPa and end at x = 0.5126 and m = 3.1216 mol·kg−1 at T = 293.15 K and p = 4.478 MPa. At a constant temperature, CO2 is better soluble in [BMIM][FeCl4] than in [BMIM][BF4] and the mean value of the solubility difference related to mole fraction x over the pressure range investigated amounts to about 4% at T = 273.15 K and monotonously increases to about 92% at T = 413.15 K. Henry's law constant as well as derived thermodynamic properties, such as the Gibbs energy of solvation, the enthalpy of solvation, the entropy of solvation, and the heat capacity of solvation, were calculated and discussed regarding the solute–solvent molecular interactions.

Solubility determination and thermodynamic data of apigenin in binary {Transcutol® + water} mixtures

Solubility and thermodynamic data of apigenin (APG) in binary {2-(2-ethoxyethoxy)ethanol (Transcutol®) + water} mixtures were obtained in this work. The mole fraction solubilities (xe) of APG in binary {Transcutol® + water} mixtures were measured at temperature T = 298.15 K to318.15 K and atmospheric pressure p = 0.1 MPa. Solubility values of APG determined in this study were fitted well with four different computational models namely “van’t Hoff, Apelblat, Yalkowsky and Jouyban-Acree” models with root mean square deviations of <4.0%. The maximum xe value of APG was recorded in neat Transcutol® (0.382 at T = 318.15 K). However, the minimum xe value of APG was recorded in neat water (1.01 × 10−6 at T = 298.15 K). The values of activity coefficients were also determined for the evaluation of solute-solvent molecular interactions and results suggested higher solute-solvent molecular interaction in APG-Transcutol in comparison with other combinations studied. Apparent thermodynamic analysis suggested endothermic and entropy-driven dissolution of APG in all binary {Transcutol® + water} mixtures studied. Enthalpy-entropy compensation analysis suggested enthalpy-driven mechanism as the main mechanism for solvation behavior of APG.

Solubility, thermodynamic properties and solute-solvent molecular interactions of luteolin in various pure solvents

The objective of this study was to evaluate solubility, thermodynamic properties and solute-solvent molecular interactions of poorly water-soluble bioactive compound luteolin (LUT) in various pure solvents namely water (H2O), ethylene glycol (EG), propylene glycol (PG), polyethylene glycol-400 (PEG-400), methanol (MeOH), ethanol (EtOH), isopropanol (IPA), 1-butanol (1-BuOH), 2-butanol (2-BuOH), ethyl acetate (EA), dimethyl sulfoxide (DMSO) and Transcutol® (THP) at temperatures “T = 298.2 K to 318.2 K” and pressure “p = 0.1 MPa”. The solubility values of LUT at equilibrium were determined using a shake flask technique with the help of ultra-performance liquid chromatography technique at 348 nm. The solid state of LUT in pure and equilibrated form was characterized using differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) techniques. The solubilities of LUT measured by shake flask method were correlated with “van't Hoff and Apelblat models”. The DSC and PXRD spectra of pure and equilibrated LUT were similar, suggesting no transformation of LUT during equilibrium. Good correlation was recorded between experimental and calculated solubilities of LUT. The solubility values of LUT (mole fraction) were obtained maximum in PEG-400 (1.27 × 10−1) followed by DMSO (7.15 × 10−2), THP (4.01 × 10−2), 2-BuOH (5.53 × 10−3), 1-BuOH (5.36 × 10−3), EA (5.11 × 10−3), IPA (4.14 × 10−3), PG (3.89 × 10−3), EtOH (3.08 × 10−3), EG (2.38 × 10−3), MeOH (8.16 × 10−4) and H2O (4.17 × 10−6) at “T = 318.2 K” and similar trend was obtained at each temperature studied. The physical values of activity coefficients were determined with the help of ideal solubilities of LUT. Based on the physical values of activity coefficients, maximum solute-solvent interactions were observed in LUT-PEG-400, LUT-DMSO and LUT-THP. Apparent thermodynamic analysis suggested endothermic and entropy-driven dissolution of LUT in each pure solvent studied.

Fraction and stiffness transition from the H[sbnd]O vibrational mode of ordinary water to the HI, NaI, and NaOH hydration states

Solvation of acid, base, and salt is ubiquitously important to all subject areas in chemistry, health care and life science. However, fine resolution of the solvation dynamics, solute-solvent molecular interactions, and solute capability of transforming the hydrogen bond (O:HO, or HB) and surface stress remain great challenge. Incorporating the notion of O:HO bond cooperativity with a strategy of differential phonon spectroscopy (DPS) has enabled resolution on the fraction and stiffness of the solvent HB from the mode of water to the hydration shells upon NaOH, NaI and HI solvation. Results show that Na+ and I+ ionic polarization shortens the HO bond and stiffens its phonon from 3200 to 3500cm−1 in the hydration shells. The H+ in the HI solution forms a H↔H anti-HB that disrupts the solution network and surface stress. The excessive electron lone pairs of OH– form the O:⇔:O super-HB that compresses the network, sharing the same effect of mechanical compression shifting the HO phonon from above 3100cm−1 to its below; the solute HO bond performs the same to the HO dangling bond at surface featured at 3610cm−1. The fraction coefficients or phonon abundance transition, fH=0, fHO∝C, and fx∝1-exp(−C/C0) (x=Na+ and I− and C the solute concentration) towards saturation, feature the solute capability of HB transformation. Practice not only confirms the essentiality of the H↔H anti-HB point fragilization, the O:⇔:O super-HB point compression, and the ionic polarization to the performance of the respective HI, NaOH, and NaI solutions, but also demonstrate the power of the DPS that enables fine-resolution of solvation dynamics and solute capabilities.

HCl, KCl and KOH solvation resolved solute-solvent interactions and solution surface stress

An incorporation of the hydrogen bond (O:HO or HB) cooperativity notion, contact angle detection, and the differential phonon spectrometrics (DPS) has enabled us to gain refined information on the HCl, KCl and KOH solvation resolved solute-solvent molecular interactions and the solution surface stresses. Results show that ionic polarization stiffens the solvent HO bond phonon from 3200 to 3480cm−1 in the hydration shells. The HO− in alkaline solution, however, shares not only the same HO phonon redshift of compressed water from 3200 to <3100cm−1 but also the dangling bonds of H2O surface featured at 3610cm−1. Salt and alkaline solvation enhances the solution surface stress by K+ and Cl− ionic polarization. The excessive H+ proton in acid solution forms a H↔H anti-HB that depresses the solution surface stress, instead. The solute capability of transforming the fraction of the O:HO bonds of the solvent matrix is featured by: fH=0 and fx ∝ 1-exp(-C/C0) (x=HO−,K+ and Cl−) towards saturation. Exercises not only confirm the presence of the H↔H anti-HB point fragilization, the O:⇔:O super-HB point compression, and ionic polarization dominating the performance of the respective HCl, KOH, and KCl solutions, but also demonstrate the power of the DPS that enables high resolution of solute-solute-solvent interactions and correlation between HB relaxation and solution surface stress.

Solubility measurement, thermodynamics and molecular interactions of flufenamic acid in different neat solvents

The solubility data of poorly soluble anti-inflammatory drug flufenamic acid (FFA) are scarce in literature. Therefore, in the current study, the solubility of FFA in eleven different neat solvents including “water, methanol, ethanol, isopropanol (IPA), ethylene glycol (EG), propylene glycol (PG), 1-butanol, 2-butanol, dimethyl sulfoxide (DMSO), polyethylene glycol-400 (PEG-400) and Transcutol®” was measured and correlated at temperatures “T=298.2K to 318.2K” and pressure “p=0.1MPa”. The solubilities of FFA in mole fraction were measured using a static equilibrium method and correlated with “van't Hoff and Apelblat equations”. The mole fraction solubilities of FFA were obtained maximum in DMSO (2.86×10−1), followed by Transcutol (2.78×10−1), 2-butanol (1.79×10−1), 1-butanol (1.77×10−1), IPA (1.44×10−1), ethanol (1.12×10−1), methanol (6.29×10−2), PEG-400 (6.16×10−2), EG (1.20×10−2), PG (1.81×10−2) and water (1.60×10−6) at “T=318.2K” and similar trends were also recorded at each temperature studied. Activity coefficients were also calculated in order to evaluate the molecular interactions between solute and solvent molecules and results showed higher solute-solvent molecular interactions in FFA-DMSO, FFA-Transcutol, FFA-2-butanol, FFA-1-butanol, FFA-IPA and FFA-ethanol in comparison with other solute-solvent combinations. “Apparent thermodynamic analysis” showed an “endothermic and entropy-driven dissolution” of FFA in all neat solvents studied.

Carbon dioxide solubility in 1-hexyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide in a wide range of temperatures and pressures.

Solubility measurement data of carbon dioxide (CO2) in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [HMIM][NTf2] at T = 273.15-413.15 K and pressures up to p = 4.5 MPa using an isochoric method in decrements of ΔT = 20 K are presented. The temperature dependency of the Henry's law constant was calculated, and the average deviation of the Henry's law constant is always better than ±1%. Thermodynamic properties of solution such as the free energy of solvation, the enthalpy of solvation, the entropy of solvation, and the heat capacity of solvation were calculated to evaluate the solute-solvent molecular interactions.

Carbon dioxide solubility in 1-butyl-3-methylimidazolium-bis(trifluormethylsulfonyl)imide over a wide range of temperatures and pressures

Solubility measurement data of carbon dioxide (CO2) in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][NTf2] at T=(273.15 to 413.15)K, and pressures up to p=4.5MPa are presented. The measurements were carried out using the isochoric method as a function of temperature ranging from T=(413.15 to 273.15)K in decrements of ΔT=20K at selected four different pressure steps ranging from around P=4.5MPa to around P=0.5MPa. The temperature dependency of Henry’s law constant was calculated and the average deviation of the Henry’s law constant is always better than ±1%. Thermodynamic properties of solution such as the Gibbs free energy of solvation, the enthalpy of solvation, the entropy of solvation, and the heat capacity of solvation were calculated to evaluate the solute–solvent molecular interactions.

Evaluating coal tar–water partitioning coefficient estimation methods and solute–solvent molecular interactions in tar phase

Equilibrium partitioning coefficients between an industrial coal tar sample and water ( K CT/w) were determined for 41 polar and nonpolar solutes in batch systems. Together with literature values, 69 K CT/w data were analyzed using the following model approaches: Raoult’s law, the single parameter linear free energy relationship (SPLFER) with octanol–water partitioning coefficients ( K ow), the linear solvation energy relationships (LSERs), SPARC and COSMOtherm. Estimations by Raoult’s law and the SPLFER agreed well with the experimental log K CT/w values for the investigated coal tar, with root mean square errors (RMSE) of 0.31 and 0.33, respectively. LSER resulted in as good estimations (RMSE = 0.29) as the previous two. The LSER analysis revealed significant hydrogen (H)-bond acceptor properties of the studied coal tar phase. Using naphthalene as a surrogate solvent for the coal tar phase, SPARC and COSMOtherm provided fairly good predictions (RMSE of 0.63 and 0.65, respectively) of log K CT/w, without any additional empirical parameter. Further calculations using SPARC and COSMOtherm for partitioning between water and other tar-components (e.g., benzofuran, phenol and quinoline) suggested that minor components in coal tar do not significantly influence K CT/w of nonpolar solutes, and that Raoult’s law and the SPLFER thus may be generally applied to these types of solutes, e.g., polycyclic aromatic hydrocarbons and alkylbenzenes, regardless of coal tar compositions. In contrast, partitioning of H-bonding solutes (e.g., phenols) can significantly vary depending on the amount of polar tar-components such as N-heterocyclic aromatic compounds. Therefore, the presented successful applications of Raoult’s law and SPLFER to the studied coal tar could be a special case, and these simple approaches may not provide reasonable estimations for partitioning of H-bonding solutes from compositionally different coal tars.