Dielectric properties of binary and ternary mixtures of some aliphatic alcohols: analysis of H-bonded interaction in complex systems

Abstract

The formation of the heterogeneous H-bonded interactions in binary mixtures of ethyl alcohol (EA) with ethylene glycol (EG), (EA + EG), and glycerol, (Gly) (EA + Gly); EG with Gly (EG + Gly); and ternary mixtures of equimolar EA + EG, EA + Gly and EG + Gly systems with Gly, EG and EA, respectively, have been investigated at 21 concentrations by precision dielectric measurements at 25°C. The concentration-dependent values of excess dielectric parameter, , and effective Kirkwood correlation factor, g eff, were determined using the measured values of the static dielectric constant, ε o , at 1 MHz, and the high-frequency limiting dielectric constant, ϵ∞ = n D², at optical frequency. The observed values of EA + EG and EA + Gly systems were found to be negative over the entire concentration range, which indicates the decrease of the total number of same direction-aligned effective dipoles due to heterogeneous H-bond interactions. In contrast to these binary systems, the values of the EG + Gly system were found to be positive, which confirms the increase in total number of effective dipoles aligned in the same direction due to H-bond interactions. In (EA + EG) + Gly ternary mixtures, the observed positive values also indicate the increase of an effective number of dipoles aligned in the same direction due to the formation of the complex H-bonded heterogeneous structures. The (EG + Gly) + EA system shows negative values at all EG concentrations, but in case of the (EA + Gly) + EG system, the values change from positive to negative with the increase in the concentration of EG. Results also show that the heterogeneous H-bond interactions in the presence of Gly molecules in the binary and ternary mixtures of alcohols significantly increase the strength of electronic polarisation.