Dielectric relaxation studies of molecular association: complexing of methyl acrylate and butyl acrylate with phenols in the MW region

摘要

Dielectric relaxation measurements oil alkyl acrylates (methyl acrylate and butyl acrylate) with phenols (p-cresol, p-chlorophenol and 2,4-dichlorophenol) have been studied at microwave frequency 9.37 G Hz in dilute solution of carbon tetrachloride at 308 K. The relaxation time and activation energy have been determined using the measured dielectric data. The results show a linear dependence of relaxation time on alkyl chain length of acrylic esters and acidity of phenols and also oil the nature of the solvent. Comparative study of free energy of activation for the dielectric relaxation and viscous flow suggest the fact that the process of viscous flow involves greater inference by neighbouring than does dielectric relaxation, as the latter takes place by rotation only, whereas the viscous flow involves both the rotational and translational forms of motion. The validity of the single frequency equation of Higasi et al. (Bull. Client. Soc. Jpn, 44, 988 (1971)) for multiple relaxation time tau((1)) is found to be a 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 the maximum at 50: 50 (molar ratio).