Thermodynamic and volumetric properties of hydroxamic acids in dimethylsulfoxide at T = (298.15 to 313.15) K

Abstract

Physical properties, such as density, (ρ) and refractive index, (n) of three hydroxamic acids (N-phenylbenzo-, N-phenyl-4-methyl-3-nitrobenzo-, and N-phenyl-4-nitrobenzo-) were measured in dimethyl sulfoxide (DMSO) as a function of concentrations at T = (298.15, 303.15, 308.15, and 313.15) K . The apparent molar volumes (Vϕ0), limiting apparent molar volumes (Vϕ0) at infinite dilution, slope (SV*) and Hepler's constant (∂2Vϕ0∂T2) are calculated from the experimental values of densities (ρ) by applying the Masson's equation. The apparent molar expansibilities at infinite dilution (ϕ0E), molar volumes (V), thermal expansion coefficient (α2) and the excess molar volumes (VE) are also computed. The precise refractive indices (n) data have been used to evaluate the steric parameters viz. molar refractions (RM), polarizability (α) and excess molar refraction (RME) of these molecules. It is inferred from these results that the above mentioned drugs act as structure-making compound due to hydrophobic hydration of the molecules in the drug.