The Polarity of Solutions of Electrolytes

The polarity of solutions of LiCIO 4 in acetic acid has been investigated. However, polarity scal4s based on light absorption, e.g. the ~-scale, are interfered by aggregation phenomena of the used ~olvatochromic dyes, whereas solvatochromic fluorescent dyes give proper results. Salt containing solvents are used in mechanistic studies of solvolytic displacement reactions. The special salt effect of LiCIO 4 in acetic acid, for example, is 1) the experimental basis for the formulation of a solvent separated ion pair Although these reactions are strongly influenced by the solvent polarity, little is known about the effect of salts on the polarity of a medium 2). The applied polarity scale mustn't be interfered by the formation of ion pairs. The well-known and widely applicated ET(30) polarity scale 3) as an independent scale cannot be applied in the case of acetic acid, for the corresponding pyridiniumphenolatebetaine is protonated under these conditions. Therefore we tested the~-scale 4) which is based on the solvatochromism of dye ! having a lower basicity. In acetic acid lmax of the absorption of dye ! is only little shifted