1961 年 81 巻 4 号 p. 600-603
As it had been recognized that the reaction rate varied with concentration of sodium p-aminosalicylate, the state of solution was examined in the aqueous solution of the salt, especially on the density and viscosity. Specific gravity was measured in the range of temperatures at 20-40° and equations (5), (6), (7), (8), and (9) were obtained. Calculations were made on the apparent molal and ionic volumes and the values approximately agreed with those of p-aminosalicylic acid calculated from X-ray diffraction. Viscosity of sodium p-aminosalicylate solution was measured and relationship between ηred. and concentration was plotted in a graph. As indicated in Fig. 2, a specificity was found in the curve at around 0.5M concentration. Using the absolute reaction rate theory of Eyring, ΔFV≠, ΔHV≠, and ΔSV≠ at 20° were calculated and, as shown in Table II, ΔHV≠ and ΔSV≠ were found to increase suddenly at 0.5M concentration. From these results, sodium p-aminosalicylate is considered to take a pseudomicelle structure in the solution at a concentration above 0.5M and this is thought to be related to the reaction rate.