Molecular relaxation mechanism in substituted benzotrifluorides and their ternary mixtures

Abstract

Three substituted benzotrifluorides, namely ortho-aminobenzotrifluoride, metaaminobenzotrifluoride and ortho-chlorobenzotrifluoride and four ternary systems of different compositions are subjected to microwave absorption studies at 9.408 GHz over a temperature range from 300K to 330K. These polar compounds and their ternary mixture compositions have been used in pure liquid state as dielectric samples. Various dielectric parameters are experimentally measured at MW frequency. The measured dielectric data of these substituted benzotrifluorides are discussed in terms of relaxation time for single molecular rotation and relaxation time for group rotation i.e. for intramolecular orientation. The processes of dipole orientation and viscous flow in these liquid samples are discussed on the basis of rate theory. Dependence of relaxation time on temperature is used to calculate various thermodynamical parameters viz. entropy, enthalpy and free energy of activation. These calculated thermodynamical parameters for relaxation processes and viscous flow processes confirm existence of both intermolecular and intramolecular orientations in these substituted benzotrifluorides.