Permittivity and dielectric relaxation of aqueous solutions of hydrocarbons

Abstract

AbstractThe solutes are hydrogen bond forming, mostly non‐polar non‐electrolytes (heterocyclic hydrocarbons). ‐ From the permittivities measured in dependence of frequency between 1.5 and 38 GHz at 25 °C are derived values of the static permittivity, of the dielectric principal relaxation time, and of the relaxation time distribution parameter of the solutions. For evaluating these data simple models of the solutions are introduced.An analysis of the static permittivities of the solutions shows that the orientational polarizability of the hydration water does not markedly differ from that of pure water.From the changes of the relaxation times and of the relaxation time distribution parameters with the solute concentrations are estimated the increased reorientation times and the numbers of the dynamically disturbed water molecules around the solute particles. The reorientation times are discussed with respect to the hydration of the second kind and are compared with viscosity data.In all considerations are also included solutions of tetra‐alkyl ammonium ions. The hydrogen bond forming in the series of the neutral solute molecules and the electric field in the series of the large ionic solute particles appear as distinguishable effects counteracting the tendency to the hydration of the second kind.