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The solubility of 3-nitrobenzaldehyde in mixed solvents of N,N-dimethylformamide + ethanol, N,N-dimethylformamide + n-propanol and N,N-dimethylformamide + n-butanol were determined experimentally by using the isothermal dissolution equilibrium method within the temperature range from (273.15 to 298.15) K under 101.2 kPa. The mole fraction solubility of 3-nitrobenzaldehyde increased with increasing temperature and mass fraction of the N,N-dimethylformamide (DMF). At the same temperature and mass fraction of DMF, the mole fraction solubility of 3-nitrobenzaldehyde in ethanol was greater than those in the other two systems. The obtained solubilities were correlated by employing Jouyban-Acree, van't Hoff-Jouyban-Acree and Apelblat-Jouyban-Acree models. The largest value of RAD was 0.30 × 10− 2, and of RMSD, 8.10 × 10− 4. Dissolution of 3-nitrobenzaldehyde in these mixed solvents was an endothermic process. Preferential solvation parameters of 3-nitrobenzaldehyde were also derived by means of the inverse Kirkwood-Buff integrals method. The preferential solvation parameter δx1,3 was negative in ethanol, n-propanol or n-butanol-rich mixtures but positive in DMF-rich mixtures. The solubility data presented in this work expand the physicochemical information about 3-nitrobenzaldehyde in binary solvent mixtures.

In this work, the solid-liquid phase equilibrium data for ternary system of 4-nitrobenzaldehyde + 3-nitrobenzaldehyde + ethyl acetate were determined by using an isothermal saturation method at three temperatures of 278.15 K, 288.15 K, and 298.15 K under atmosphere pressure (101.2 kPa). Three isothermal phase diagrams were built based on the measured solubility data. There were two pure solids formed in the ternary system at a certain temperature, which corresponded to pure 3-nitrobenzaldehyde and pure 4-nitrobenzaldehyde, and were confirmed by Schreinemaker's method of wet residue and X-ray powder diffraction. The crystallization region of 4-nitrobenzaldehyde was larger than that of 3-nitrobenzaldehyde at each temperature. Two thermodynamic models, NRTL and Wilson were employed to correlate and calculate the mutual solubility data for the system of 4-nitrobenzaldehyde + 3-nitrobenzaldehyde + ethyl acetate. The largest value of RMSD for the ternary system was 5.95 × 10 − 3 , and the maximum value of RAD was 3.02%. The calculated results with NRTL model agreed well than those with Wilson model. The solid-liquid equilibrium phase diagrams and the thermodynamic models for the ternary system can provide the foundation for separating high purity3-nitrobenzaldehyde or 4-nitrobenzaldehyde from its isomeric mixtures.

Semi-empirical (PM3, AM1) and ab initio (B3LYP/6-31G(d,p)) calculations of the structure and energies of isolated 3-nitrobenzaldehyde (3-NBA) reveal that the planar trans and cis isomers are in equilibrium, with the trans being more stable by about 2.2 kJ/mol. The experimental dipole moments of 3-NBA in solvents of dielectric permittivity e ranging from 1.9 to 25 have been determined. The increase in the mean dipole moment with increasing e can be well explained in terms of the trans ⇔ cis equilibrium and dipolar isomer–solvent interaction. The heterogeneous dielectric medium model with two concentric dielectric layers proved to be the best description for this interaction. On the other hand, the intrinsic experimental Gibbs energy for the trans ⇔ cis conversion obtained from this model was higher than the quantum-chemical values. It is suggested that the quadrupolar interaction acts oppositely to the dipolar one stabilizing the more quadrupolar trans isomer.

Equilibrium dialysis and NMR spin-lattice relaxation time (T1) studies of the interaction of the trypanocidal drug 3-nitrobenzaldehyde guanyl hydrazone (3NBGH) with bovine serum albumin (BSA) were used to show that this interaction is weak and nonspecific, making 3NBGH a potential agent for the prophylaxis of Trypanosoma cruzi infected blood.