Journal of Solution Chemistry最新文献

An efficient, one-pot quantitative procedure for the preparation of benzo[a]pyrano[2,3-c]phenazine derivatives from four-component condensation reaction of 2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamine, aromatic aldehydes, and malononitrile in the presence of [(EtO)₃Si(CH₂)₃N⁺H₃][CH₃COO⁻] as basic ionic liquid as catalyst in homogenous solution under solvent-free conditions at 90 °C is described. Simple procedure, high yields, short reaction times, and an environmentally benign method are advantages of this protocol. The [(EtO)₃Si(CH₂)₃N⁺H₃][CH₃COO⁻] can be recovered and reused several times without loss of its activity.

The chemical speciation of binary and ternary VO²⁺-picolinic acid (HPic) complexes with the amino acids: Leucine (Leu, HL), Isoleucine (Ile, HL), Valine (Val, HL), Tryptophan (Thr, HL), Glutamine (Gln, HL), Lysine (Lys, HL), Arginine (Arg, HL) and Tyrosine (Tyr, H₂L) were obtained. This study was performed by potentiometric titrations at 25 °C using 1.0 mol·dm⁻³ NaCl as the ionic medium. The experimental data were analyzed with the least squares program LETAGROP, and the respective distribution diagrams were obtained with the HYSS program. The relative stability parameters Δlog₁₀ K, log₁₀ X and %R.S were determined.

Density and dielectric spectra have been measured in the liquid phase of dimethyl ether (DME)–ethanol by an oscillating U-tube densimeter and a complex dielectric spectrometer under 1.00 MPa. The density was measured at 303.15 and 313.15 K and converted to the excess molar volume. The excess molar volumes were no smaller than − 0.880 and − 0.909 cm³·mol^–1 at 303.15 and 313.15 K, respectively. The mole fraction dependence can be correlated with the Redlich–Kister equation, whose minimum was found to be around 0.58 for the mole fraction of DME. The dielectric constant and the dielectric relaxation time were evaluated from the complex dielectric spectra in the frequency range from 0.5 to 18 GHz at (293.2–313.2) K and 1.00 MPa. The dielectric constants and the relaxation time were decreased with the mole fraction of DME, and the latter tended to be around 25 ps in the mole fraction range higher than 0.6. The logarithmic dielectric constants can be correlated with a similar function to the Hildebrand equation with the volume fraction. The effective Kirkwood g-factor was evaluated at 293.2–313.2 K and 1.00 MPa. The g-factors were given by two linear functions crossed around 0.6 for the mole fraction of DME. Considering an atomic composition (C₂H₆O), the molecular sizes are not so different for DME and ethanol. Then, the solution structure was thought to be microscopically changed around 0.6 for the mole fraction of DME. The mole fraction will be utilized to switch the solubility to extract amphipathic compounds.

Carbonate esters are used as additives in biodiesel to improve its thermophysical properties for better applicability. In this work, the experimental densities, dynamic viscosities and refractive indices for binary mixtures of dimethyl carbonate and four fatty acid esters (methyl decanoate, ethyl decanoate, methyl laurate, ethyl laurate) have been measured and presented over the complete concentration range at temperatures range from 293.15 to 323.15 K under normal pressure. The excess molar volumes and the viscosity deviations of the four binary mixtures were calculated with the measured data and correlated with the Redlich-Kister equation. The excess Gibbs energy of activation was also calculated. From the values of excess properties of the binary mixtures and its deviations indicate that the changes of molecular interactions in the mixtures. The experimental results could be useful for the study of biodiesel-carbonate blended fuels.

l-Aspartic acid (ASP) and l-glutamic acid (GLU) in aqueous solution of a food additive, sodium acetate (SA) have been taken for acoustic and conductometric studies. The experimental results are analysed to predict and assess the solvation behaviour and types of interactions occurring in these ternary solutions [ASP/GLU + SA + water]. Compressibility parameters like isentropic compressibility and apparent molar isentropic compressibility along with their values at infinite dilution have been computed. Transfer values and ion pair and triplet interactions have been determined. Other thermodynamic parameters like internal pressure, molar free volume, relative association and acoustic impedance, have also been derived from the acoustic data. Specific conductance values measured experimentally led to the calculation of molar conduction of electric charge. Walden product sheds light on structure building or breaking properties of the amino acids. Gibbs thermodynamic functions predict the spontaneity of ion association process. Arrhenius equation is used to calculate activation energy which is indicative of the formation of high-energy transition state required for migration of ions. Analysis of these results establishes the amino acids as water-structure forming agents and predominance of ion–solvent, ion–ion and ion–hydrophilic interactions in the studied systems.

Fourier transform infrared spectral studies have been carried out on pure 1-propanol (PrOH), pure ethyl acetate (AcOEt), and 1:1 (ethyl acetate: 1-propanol), 1:2, 1:3, 2:1 and 3:1 binary solutions at room temperature. The broad hydroxyl stretching band of pure PrOH has been deconvoluted into six Gaussian profiles which have been assigned to the O–H stretching bands of monomer, open dimer (free and bonded O–H), closed trimer, closed tetramer and closed pentamer units with the aid of density functional theory frequency calculations. The carbonyl stretching bands of monomer and closed dimer of ethyl acetate have also been discussed. The classical and non-classical H-bond interactions of n-mers of 1-propanol with ethyl acetate monomer and dimer in the solutions have been investigated using the frequency shift of the hydrogen bond donor and acceptor bond stretching bands of PrOH and AcOEt. The concentration of PrOH/AcOEt-dependent PrOH n-mer-AcOEt complexation order has been analysed.

May and Filella (J Solution Chem 52:754–761, 2023) concluded that they had verified the data in Gamsjäger et al. (Chemical thermodynamics of tin OECD, Nuclear Energy Agency Data Bank, Leoben, 2012). However, they used exactly the same primary data and not surprisingly came up with essentially the same values. They (1) provided no new data; (2) did not comment on/re-evaluate the existing experimental data (e.g., Sn–Cl complexes) that determine the accuracy of the E⁰ value for the (Sn⁴⁺/Sn²⁺) couple, but instead relied on a calculated value that is precise but of questionable accuracy; (3) disregarded extensive cassiterite (SnO₂(cass)) solubility data that is critical to (a) ascertaining the accuracy of the E⁰ value based on ({mathrm{Sn}(mathrm{Cl})}_{y}^{4-mathrm{y}}) complexes presented in Gamsjäger et al. (2012) and May and Filella (2023), (b) determining the solubility product of SnO₂(cass), and (c) determining reliable overall K⁰ values for SnO₂(s) solubility reactions involving ({mathrm{Sn}(mathrm{OH})}_{n}^{4-n}) instead of Sn⁴⁺; and (4) in no way help resolve the many orders of magnitude differences in reported K⁰ values for various Sn(IV)–OH system reactions. These issues were extensively addressed in Rai (J Solution Chem.51:1169–1186, 2022) and are briefly discussed herein, and they help to determine that, contrary to May and Filella’s (2023) conclusions, the Sn(IV)–OH system thermodynamic constants presented in Rai (2022) are indeed reliable.