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1報)

水溶液中のパラアミノサリチル酸の脱炭酸反応におよぼすpHとPropylene Glycol, Polyvinylpyrrolidone, および界面活性剤の影響

抄録

Kinetic studies were made on the decarboxylation reaction of p-aminosalicylic acid in a wide range of pH up to 11.6. The relationship between the logarithm of the reaction rate constant, k, and pH is shown in Fig. 2 where the curve is indicated by the solid line, having the minimum value of k in the range of pH 9.2-9.5. This curve is represented by equation (5) which gives a curve indicated by the dotted line in Fig. 2. The same experiments were carried out on aqueous solution of p-aminosalicylic acid of pH 1.90, 2.90, and 3.90, with the addition of propylene glycol, polyvinylpyrrolidone, or a surface-active agent as a stabilizer. As indicated in Table I, propylene glycol has no such stabilizing effect (lowering of k/k₀) but such effect was found in polyvinylpyrrolidone. Experiments carried out with polyoxyethylene monolauryl ether of the polymerization degree of 9 and 25, and polyoxyethylene monoöleate ester of the polymerization degree of 22, and their results are given in Figs, 4, 5, and 6. It was found from these experiments that, at the same pH and same molar concentration, the greater was the stabilization effect, the higher the HLB.