パラアミノサリチル酸とその塩の分解に関する物理化学的研究 (第4報)

パラアミノサリチル酸ナトリウム水溶液の電導度

抄録

Electric conductivity of aqueous solution of sodium p-aminosalicylate was measured and physicochemical properties of the salt was examined. Electric conductivity was measured at 25° with a diluted aqueous solution of 0.1M to 0.005M, and Λ₀ in equation (3) was calculated by the method of Shedlovsky. Relationship between Λ₀ and C, as indicated in Fig. 2, gave a straight line and Λ₀′ increased below 0.01M concentration, which is thought to be due to hydrolysis of sodium p-aminosalicylate. The value of Λ₀=81.7 was obtained. Ionic electroconductivity of p-aminosalicylic acid ion was calculated as 31.6, which was used to obtain ionic radius, γ_s, of 2.9 Å. This value is smaller than the ionic volume calculated from the specific gravity. Measurement of Λ in a concentrated solution of from 0.1M to near saturation gave the values shown in Fig. 3, from which Λ was calculated and indicated by a graph in Fig. 4. Equation (9) was calculated for ηΛ by the use of absolute reaction rate theory of Eyring and proportionation to one-third power of the volume of moving unit (V) gave the lowest value at 0.5M concentration, at every temperature, as indicated in Table I. This concentration is the same as the concentration at which the reaction rate shows the lowest value and at which viscosity shows abnormality. It is therefore considered that some change occurs in the dissolved state in the aqueous solution of sodium p-aminosalicylate at this concentration and this may be somewhat related to the reaction rate.