Effect of temperature on volumetric and viscometric properties of some non-steroidal anti-inflammatory drugs in aprotic solvents

Densities and viscosities of salicyl amide, salicylic acid, and acetyl salicylic acid (non-steroidal anti-inflammatory drugs) in two aprotic solvents namely, dimethyl sulfoxide and acetonitrile at T = (293.15, 298.15, 303.15, 308.15, 310.15, and 313.15) K have been determined in a molality range of (9.7 · 10−3 to 33.3 · 10−3) mol · kg−1. The data have been used to calculate apparent molar volumes (Vϕ,), and viscosity B  -coefficients. The partial molar volumes and hydration numbers have been determined at different temperatures. The effect of temperature on the thermodynamic properties has been studied by determining partial molar expansibilities ∂Vm0/∂T and Hepler’s constant ∂2Vm0/∂T2. Free energies of activation for viscous flow of the solution were obtained by application of the transition state theory of solutions to the B-coefficient data and the corresponding activation enthalpies are reported.