Journal of Solution Chemistry最新文献

Palladium-107 is one of the selected radionuclides in the safety assessment of geological disposal of radioactive waste. Although isosaccharinic acid (ISA) forms strong complexes with many elements and enhances element solubility, the thermodynamic evaluation of the complex of Pd with ISA has not been conducted. In this study, the solubility of Pd(OH)₂ at pH 8.5–12.5 in the presence of ISA was investigated under inert gas (N₂) atmosphere. Furthermore, the coordination state of aqueous Pd and ISA was investigated by X-ray absorption and Fourier transform infrared spectroscopy, respectively. According to experimental results, the number of OH ligands in the mixed complex depends on pH. The thermodynamic model and conditional equilibrium constants of the Pd-ISA complex were estimated by slope analyses of solubility experiments at different pH levels and ionic strengths based on the specific ion interaction theory. Hence, the impact of complexation with ISA on Pd(II) solubility under disposal conditions could be quantified using the proposed thermodynamic models in this study.

Molar conductances for sodium chloride have been measured in the solvent system mannitol-water covering the solvent composition range from pure water to saturated aqueous mannitol at temperature from 293.15 to 313.15 K at 5 K intervals. According to the Fuoss–Justice conductance equation, limiting molar conductance (Lambda^{infty }), association constants (K_text{A}), and the Walden products were obtained and their variations were in conformity with the thermodynamics study of solvent effect. The Eyring’s activation enthalpy of charge transport (Delta H^{dag }) was derived and the results have stipulated that this kinetic procedure depends only on the solvent properties. Ion association thermodynamic quantities, Gibbs energy ((Delta G^{ circ })), enthalpy ((Delta H^{ circ })), and entropy ((Delta S^{ circ })) were also calculated and their interpretation were further supported by other methods. Besides, by appropriate splitting of Gibbs’ energy of association into electrostatic and non-electrostatic contributions.

The structure, hydrogen bonding, and hydrogen transfer of 1-butyl-3-methylimidazolium hydroxide ([Bmim]OH) aggregations, including dimer and trimer of carbene(α) and covalent(β) conformation, have been investigated using density functional theory B3LYP together with D3 dispersion correction. The geometrical parameters, Gibbs free energy of formation in gas and solution phases were calculated for aggregates of the complex [Bmim]OH conformation. The strengths and binding energies of different types of H-bonds were predicted by quantum theory of atoms-in-molecules descriptors. The results show that O–H···C hydrogen bonds were formed between most hydroxyl protons and the carbon atom of the carbene ring (C2) in [Bmim]OH aggregations. Furthermore, we examine the proton transfer in dimer and trimer conformation of [Bmim]OH, the reaction pathway for proton transfer from hydroxyl of β-conformer to carbene ring was investigated, and the proton transfer process is energetically favorable.

The negative logarithm of the acid dissociation constant values (pK_a1 and pK_a2) of 4,4′-trimethylenedipiperidine (TMDP) was determined by a pH metric titration at 298 K. The experimentally determined pK_a values were compared with the predicted pK_a values by chem-bioinformatics software like ACD/Labs and ChemAxon. This experiment gave an excellent opportunity to deepen engagement with the Henderson–Hasselbalch equation, acid/base dissociation constant (K_a/K_b), and half equivalence point.

Graphical Abstract

Knowing about the dissolution kinetics and solubility is necessary for controlling crystallization separation process of lysozyme. In this study, the impact of four ionic liquids (ILs), namely, 1-butyl-3-methylimidazolium tetrafluoroborate [C₄mim]BF₄, 1-butyl-3-methylimidazole chloride [C₄mim]Cl, 1-butyl-3-methylimidazole bromide [C₄mim]Br, and 1,3-dimethylimidazolium iodide [dmim]I, on the dissolution rate of lysozyme was determined in an aqueous solution at 20 ℃, pH 5.01, under 101.3 kPa. The results revealed that the dissolution rate of lysozyme increased with increasing concentrations of [C₄mim]BF₄ and [C₄mim]Cl, while it remained stable with increasing concentrations of [C₄mim]Br. In contrast, the dissolution rate gradually decreased with increasing concentrations of [dmim]I. This suggests that the interaction between lysozyme molecules is influenced by the ILs, leading to variations in the dissolution rates. Additionally, the effect of anions and cations on the equilibrium solubility was analyzed. The results indicated that the order of anionic and cationic effects on equilibrium solubility is as follows: BF⁴⁻ < Cl⁻ < Br⁻ = [C₄mim]⁺  < [dmim]⁺  < I⁻. Furthermore, dissolution kinetic models were established, which could be used to predict the dissolution behavior of large molecules like lysozyme in ILs aqueous solution. These findings have significant implications for the design of crystallization process and optimization of parameters during lysozyme recovery.

The hygrometric method is used to determine new thermodynamic data on water activity and saturated aqueous solution of the water/d-sucrose/ammonium dihydrogen phosphate (ADP) system in a wide range of NH₄H₂PO₄ molality, ranging from 0.1 to 3 mol⋅kg⁻¹, and for various d-sucrose contents from 0 to 4 mol⋅kg⁻¹. Powder X-ray diffraction (XRD) and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy were used to characterize the solid state. The Pitzer–Simonson–Clegg model (PSC) is used to fit the experimental data of osmotic coefficient obtained from water activities data. The predicted saturated aqueous solutions, with the PSC model, are in good agreement with experimental data. For the concentration inferior to 1 mol⋅kg⁻¹, the negative deviation from ideality was shown with increasing the ADP concentrations. The estimated values of the activity coefficient of d-sucrose, activity coefficient of ADP, and the Gibbs energy of transfer of ADP from water to mixture (water/d-sucrose) show that both ADP and d-sucrose exert significant salting-out effects on the aqueous solution.

The intermolecular interactions and solution properties of the antihistamine drug chlorpheniramine (CP) in aqueous, aqueous solutions of electrolyte and non-electrolyte have been examined in the current work using volumetric and spectroscopic approaches to investigate how the drug is affected by co-solutes. Also, a drug’s behavior in water and other aqueous systems can be studied to learn more about the chemistry of biological systems. Using an Anton Paar density and sound velocity meter, densities and sound velocities for CP (0–0.10 mol⋅kg⁻¹) at various temperatures (298.15, 308.15, and 318.15 K) in water and in aqueous 0.05 mol⋅kg⁻¹ urea, glucose, and sodium chloride have been measured to determine apparent molar properties: apparent molar volume ((V_{phi} )) and apparent molar compressibility ((K_{phi, {mathrm{S}}})). A number of derived parameters, including limiting apparent molar volume (left( {V_{phi }^{0} } right)), limiting apparent molar compressibility ((K_{phi, {mathrm{S}}}^{0})), limiting apparent molar expansibility ((phi_{mathrm{E}}^{0} )), and isobaric thermal expansion coefficient (ɑ) were obtained using the data on apparent molar properties. While analyzing the data, solute–solvent interactions are taken into account, as well as their considerable effects on CP hydration when co-solutes, are introduced to the combination. The negative transfer properties suggest the predominance of ion-hydrophobic and hydrophobic-hydrophobic interactions in all the studied systems. Positive and small negative values of Hepler’s constant revealed the structure-making capability of CP in aqueous urea, glucose, and sodium chloride. Also, an IR study has been done to verify the results obtained from volumetric and compressibility data. Understanding how drugs behave in various solvent systems during drug development is made easier by understanding drug interactions.

The main purpose of this research was to evaluate the mass/volume percentage (%m/v) solubility of acetaminophen (ACP) in {ethanol (EtOH) (1) + propylene glycol (PG) (2) + water (3)} mixtures from 20.0 to 40.0 °C to expand the solubility database of this drug in mixed pharmaceutical solvents useful for designing high concentrated liquid products including injectable solutions. This is because ACP is an analgesic drug widely used available for oral administration as tablets or solutions. Besides, as injectable products, it is only available for perfusion in as 1 g in 100 mL (1.0%m/v). However, it is not available as 5 mL ampules for supplying doses of 500 mg. As demonstrated in this research some cosolvent mixtures allow ACP concentrations higher than 10.0%m/v, for instance the aqueous ternary mixture with 20% w/w of ethanol and 30% w/w of PG, among other possible mixtures. Flask shake method and UV–vis spectrophotometry were used for ACP solubility determinations at different temperatures. ACP solubility results are presented as Cartesian and triangular solubility profiles. ACP solubility increases with temperature arising and the cosolvent proportion in the mixtures. Maximum %m/v ACP solubility value is observed in the aqueous ethanol binary mixture of w₁ = 0.80 at all temperatures being 21.18% at 25.0 °C. All the solubility values were well correlated using the Jouyban-Acree model obtaining mean percentage deviations of 3.8% (N = 330). In this way, %m/v equilibrium solubility of ACP in {EtOH + PG + water} mixtures has been studied and correlated at several temperatures as contribution to preformulation studies of injectable homogeneous liquid pharmaceutical dosage forms.

The dynamic behaviour of a chemical system made of two coupled reactions is compared with that of a mechanical system consisting of two oscillating bodies connected by springs. First, the principle of energy departure from equilibrium is employed to derive the motion equations of both systems. Subsequently, the relevant characteristic frequencies and the amplitude parameters are obtained and analysed in terms of “Normal Modes”. The results show that systems belonging to different branches of science can be analysed using the same methodologies. To elucidate the application of Normal Modes to chemistry, the dynamic analysis of a system consisting of a proton transfer reaction coupled to a complex formation reaction is described in the Supporting Information: the procedure enables the evaluation of rate constants, equilibrium constants and reaction enthalpies of a reacting chemical system made of two coupled reactions. The method is then extended to a cycle of three reactions.