Several authors determined dissociation constants of acids such as benzoic, succinic and azelaic acids in mixed solvents and reported that the dissociation constants determined in aqueous dioxane were higher than those determined in aqueous alcohols having the same dielectric constants. However, if the variation of the amount of water in mixed solvents is taken into consideration in calculating the dissociation constant, an acid has almost the same dissociation constant in various mixed solvents with the same dielectric constant.

The apparent molal volumes (φV), apparent molal adiabatic compressibilities (φKS), and relative viscosities (nr) at 25 °C have been obtained for the following amino acids in aqueous alkali-chloride solutions from measurements of the density, the ultrasonic velocity, and the flow time: glycine, l-alanine, β-alanine, α-aminoisobutyric acid, l-serine, and l-threonine. Viscosity measurements were also carried out in water for reference. The alkali chlorides used were lithium, sodium, and potassium chlorides. The limiting values φVo, φKSo and the extended Jones-Dole viscosity coefficients, B and D, were calculated by a linear extrapolation using the least-squares method. All the φVo, φKSo, and B values obtained in the mixed solvents were larger than the corresponding ones in water, except in a few cases of the B coefficient. The results are discussed in terms of the dehydration effect of the electrolytes upon the amino acids.

Stability constants of the bivalent metal complexes formed with several mono- and dicarboxylic acids were determined at 25°C and ionic strength of 0.1. For monocarboxylic acids and several dicarboxylic acids having no double bond or forming larger chelate rings than six membered rings the following stability order held: Pb>Cu>Cd>Zn>Ni. It is very remarkable that lead showed the highest stability among bivalent metals.

Apparent molal volumes (φV) and apparent molal adiabatic compressibilities (φKS) at 25 °C have been obtained for the following amino acids in water and in urea-water mixtures (up to 8 mol kg−1 urea for φV and at 3 mol kg−1 for φKS) from measurements of density and ultrasonic velocity: glycine, l-alanine, β-alanine, α-aminoisobutyric acid, l-valine, l-serine, and l-threonine. The limiting values φVo and φKSo were calculated by a linear extrapolation using the least-squares method. These data were used to derive the volumes of transfer and the adiabatic compressibilities of transfer of the amino acids from water to aqueous urea solutions. Both of these transfer functions were positive. The results were interpreted in terms of structure-breaking interaction of urea upon water.

No abstract