Dielectric relaxation studies of alkyl acrylates with phenol derivatives in carbon tetrachloride using microwave absorption techniques

The dielectric relaxation of alkyl acrylates (methyl acrylate, ethyl acrylate and butyl acrylate) with phenol derivatives (p-cresol, p-chlorophenol. 2,4-dichlorophenol and p-bromophenol) has been measured at microwave frequency 9.37 GHz in dilute solution of carbon tetrachloride at 308K. Different dielectric parameters like dielectric constant epsilon' and dielectric loss epsilon '' at microwave frequency, static dielectric constant c. and dielectric constant epsilon(infinity) at optical frequency have been determined. The relaxation time and activation energy have been determined using the measured dielectric data. The results show a linear dependence or relaxation time on alkyl chain length of acrylic esters and acidity of phenol derivatives. Comparative study of free energy of activation for the dielectric relaxation and viscous flow suggests that the process of viscous flow involves greater interference by neighbours than does dielectric relaxation, as the latter takes place by rotation only whereas the viscous flow involves both rotational and translational motion. The validity of the single frequency equation of Higasi et al. Bull Chem Soc Japan, 44(1971)988. For multiple relaxation time tau(1) is found to be function of the hydrogen bonding strength of phenolic hydrogen whereas the group rotation relaxation time tau(2) is a function of the steric interaction of proton donor. The relaxation time is maximum at 50:50 mol% ratio.