Effect of temperature and solvents on thermo-physical properties of 1,3,4-oxadiazole derivative at atmospheric pressure

The density (rho), viscosity (eta) and ultrasonic velocity (U) of pure solvents: chloroform (CF), N,N-dimethylformamide (DMF), solutions of 2-((4-acetyl-5-(4-bromophenyl)-5-methyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)methylthio)-3-o-tolylquinazolin-4(3H)-one (PDI-D) in CF and DMF were investigated at 303,308 and 313 K and at atmospheric pressure. Using rho,eta, and U data various acoustical and thermodynamic parameters such as acoustical impendence (Z), isentropic compressibility (kappa(S)), intermolecular free path length (L-f)(,) Rao's molar sound function (R-m), Van der Waals constant (b), internal pressure (pi), relaxation time (tau), free volume (V-f) and solvation number (S-n) were calculated and fairly good co-relationship between calculated parameters were obtained. A fairly good to excellent correlation between a given parameter and concentration is observed at all temperatures and solvent systems studied. Linear or non-linear increases or decreases of acoustical parameters with concentration and temperature indicated the existence of strong molecular interactions between studied systems. Moreover, the experimental results for the pure solvents and solutions of compound PDI-D studied has been carried out to analyze carefully how the structural modifications affect the values of Gibbs energy of activation (Delta G*), enthalpy of activation (Delta H*) and entropy of activation (Delta S*) in CF and DMF. (C) 2013 Elsevier B.V. All rights reserved.