Abstract |
Studies have been carried out to evaluate parameters affecting solute-solvent interactions in amide-water systems. A kinetic study, accomplished conductimetrically, has shown that the degradation of urea in aqueous solutions up to 8 M, and at temperatures between 25 and 45C, is a relatively slow, first-second order reversible reaction. A second study, involving a determination of the relative solubilities of methyl salicylate and methyl benzoate in aqueous solutions of various urea and hydrochloric acid concentrations, suggests the formation of a proton-urea complex. A salting-in constant was found which was in accord with the model for the proposed complex salt. Finally, dilatometric studies were made of the aqueous solutions of 17 amides. Apparent molar volume data were obtained for each amide in solutions ranging from the infinitely dilute up to the pure amide. The partial molar volumes of methyl, ethyl and propyl groups were found to vary according to the site and type of substitution on the carbonyl-nitrogen moiety. It is suggested that the location and the depth of the minima reflect the degree of solute-solvent and solute-solute interaction. (Author) |