Solvent properties of polyaromatic hydrocarbons

Abstract

The solubility of inorganic and organic salts at 150 °C in polyaromatic hydrocarbons has been studied, and the results analysed using an electrostatic model. It is shown that only significant solubilities can be obtained with quaternary ammonium salts with C₃ or longer carbon chains. The π^* solvatochromic parameter has been calculated for the different solvents from the absorption spectra of o-nitroaniline. It has been found that the Hildebrand solubility parameter and the work of cavity formation calculated from the scaled particle theory cannot account for the large solubility differences observed in the various solvents studied. It is proposed that the Gibbs energy of solvation is determined by the local polarisability, as shown by its linear dependence on π^*. It is shown that these results rationalise previous observations on the solubilisation of transition-metal ions in aromatic solvents using hydrophobic ligands.