DIELECTRIC STUDIES OF HYDROGEN BONDED COMPLEXES OF C=O COMPOUNDS WITH SUBSTITUTED PHENOLS USING FREQUENCY DOMAIN TECHNIQUE

Abstract

Dielectric studies of H-bonded complexes of acetamide and formamide with 4-aminophenol, 4-bromophenol, 4-
chlorophenol and 4-nitrophenol in benzene have been made at 308 K using 9.37 GHz dielectric relaxation set up.
Various dielectric parameters like dielectric constant (ε׳ ,(dielectric loss factor (ε״ (at Microwave frequency, static
dielectric constant (ε0
) and dielectric constant at infinite dilution (ε∞) at optical frequency have been determined. The
validity of the single frequency equation of Higasi et al. for multiple relaxation time (1) is found to be function of the
hydrogen bonding strength of the phenolic hydrogen, whereas the group rotation relaxation time (2) is a function of the
steric interactions of the proton donor. The relaxation time and molar free energy activation of 1:1 molar ratio is greater
than other higher molar ratios (i.e. 3:1, 2:1, 1:2, 1:3) confirm that the existence of most likely 1:1 complex formation
between the studied systems and also complex formation formed between free hydroxyl group of phenols and carbonyl
group of amide.