Enthalpic pairwise self-interactions of urea and its four derivatives in (dimethylformamide + water) mixtures rich in water at T = 298.15 K

Thermodynamic Difference between Protocatechualdehyde and p-Hydroxybenzaldehyde in Aqueous Sodium Chloride Solutions

“…From Figure , we can see that the values of h 2 for both PHBA and PAL in pure water and aqueous sodium chloride solutions of different molalities are all negative. These results indicate that the electrostatic and hydrogen bond interactions (negative contribution to h 2 ) are stronger than the hydrophobic–hydrophobic and hydrophobic–hydrophilic interactions (positive contribution to h 2 ) as well as partial desolvation of solvation shells of solute and solvent molecules (positive contribution to h 2 ) . In the above interactions, the electrostatic and hydrogen bond interactions are present between solvent-mediated solute (PAL or PHBA) molecules.…”

“…These results indicate that the electrostatic and hydrogen bond interactions (negative contribution to h 2 ) are stronger than the hydrophobic−hydrophobic and hydrophobic−hydrophilic interactions (positive contribution to h 2 ) 40 as well as partial desolvation of solvation shells of solute and solvent molecules (positive contribution to h 2 ). 41 In the above interactions, the electrostatic and hydrogen bond interactions are present between solvent-mediated solute (PAL or PHBA) molecules. The hydrophobic−hydrophobic interactions occur between the benzene ring of PHBA or PAL molecules.…”

A Water–Urea–Ammonium Sulfamate system: Experimental investigation and thermodynamic modelling

“…(10)): u ¼ 2 for SLE data except solubility data obtained by Speyers [72] (u ¼ 1) due to their disagreement with the rest of data, especially at T > 300 K. Coordinates of the WeUr eutectic point reported by Frèjacques et al [73] was excluded due to the phase boundaries of the system were obtained from review of literature data but not experimentally. The enthalpy of dilution (D dil H) were taken into account with weight u ¼ 2$10 À3 for data [48] and [51]; u ¼ 10 À3 was used with data obtained by Gucker and Pickard [49], by Hamilton and Stokes [50] (such low values are due to usage of Y norm ij ¼ 1, see Table 6). All experimental values of D sol H ∞ were input in target function with u ¼ 2 though data investigated by Abrosimov et al [60] were excluded due to strong disagreement (about 10e15%) with the rest of measured values.…”

The Interplay of Methyl-Group Distribution and Hydration Pattern of Isomeric Amphiphilic Osmolytes

“…The data on aqueous solutions of methylated ureas (MUs) found in the literature concern properties such as enthalpies of dilution, − enthalpies of solution and transfer, − density, ,− speed of sound, , heat capacity, ,, viscosity and surface tension, and osmotic , and diffusion coefficients . Applied spectroscopic techniques were infrared spectroscopy, ultrasonic and dielectric relaxation, − as well as NMR. ,, Despite this impressive amount of work, an overall picture of MU hydration is still lacking and peculiarities of solute–solute interactions in such systems are far from being understood.…”

“…For example, although aqueous solutions of 1,3-dimethylurea (1,3-DMU) and tetramethylurea (TMU) have been studied by a plethora of methods, almost no attention has been paid to the systems containing 1,1-dimethylurea (1,1-DMU) or trimethylurea (1,1,3-TMU). Moreover, the scarce experimental data available on these systems mainly deal with thermodynamic properties − that do not provide any atomistic details on MU hydration and MU–MU interactions.…”