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2報)

水溶液中のパラアミノサリチル酸ナトリウムの濃度と脱炭酸反応

抄録

Following the previous report on the reaction velocity constant k to changes in pH in aqueous solution with constant ionic strength, in the decarboxylation reaction of p-aminosalicylic acid, experiments were carried out on variation in the concentration of sodium p-aminosalicylate and the minimum rate of decomposition was obtained in 0.5M concentration, as shown in Fig. 1. Various amounts of acetic acid-sodium acetate buffer were tested at a constant pH, as indicated in Table III, and the value of b=1.098 of equation (1) was obtained. The effect of the concentration of p-aminosalicylate was tested and the values of k_obs. listed in Table I were obtained. From k_obs. of 0.3M solutions at various temperatures, functions of temperature and H₃O⁺ concentration were calculated and the values were interpolated in equation (2), from which equation (2′) was obtained. From this equation, k_calc. was calculated. The values of E_obs^≠., ΔH^≠, ΔS^≠, and ΔR^≠ at various temperatures were calculated from Eyring's absolute reaction rate theory and the values became the lowest at 0.5M concentration, as indicated in Table II.