Dissociation Constant of N-(2-Acetamido)-Iminodiacetic Acid Monosodium (ADA) from (278.15 to 328.15) K

物理化学期刊(英文) Pub Date : 2014-04-21 DOI:10.4236/OJPC.2014.42011

R. Roy, L. N. Roy, J. Dinga, Mathew R. Medcalf, Katherine E. Hundley, E. Hines, Clark B. Summers, Lucas S. Tebbe, Jamie Veliz

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引用次数: 1

Abstract

The acidic dissociation constant of N-(2-acetamido)-iminodiacetic acid monosodium (ADA) has been determined at 12 temperatures from 278.15 to 328.15 K by electromotive-force (emf) measurements of hydrogen-silver chloride cells without liquid junction. At 298.15 K, the value of the dissociation constant (pK2) is 6.8416 ± 0.0004. In response to the need for new physiological pH standards, buffer solutions of NaADA and its disodium salt, Na2ADA would be useful for pH control in the biological region of pH 6.5 to 7.5. The pK2 values over the experimental temperature range are given as a function of the thermodynamic temperature (T) by the equation pK2 = 2943.784/T - 47.05762 + 7.72703 ln T. At 298.15 K, standard thermodynamic quantities for the dissociation process have been derived from the temperature coefficients; ΔH° = 12,252 J·mol-1, ΔS° = -89.9 J·K-1·mol-1 and = -148 J·K-1·mol-1. The results are interpreted and compared with those of structurally related derivatives of GLYCINE.

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N-(2-乙酰氨基)-亚氨基二乙酸钠(ADA)从(278.15 ~ 328.15)K的解离常数

用无液结的氯化氢银电池电动势(emf)测定了N-(2-乙酰氨基)-亚氨基二乙酸钠(ADA)在278.15 ~ 328.15 K 12个温度下的酸性解离常数。298.15 K时，解离常数pK2为6.8416±0.0004。为了满足对新的生理pH标准、Na2ADA及其二钠盐缓冲溶液的需求，Na2ADA可用于控制pH在6.5 ~ 7.5的生物区域。在实验温度范围内的pK2值作为热力学温度(T)的函数为:pK2 = 2943.784/T - 47.05762 + 7.72703 ln T。在298.15 K时，解离过程的标准热力学量由温度系数导出;ΔH°= 12252 J·mol-1ΔS°= -89.9 J·k·mol-1 = -148 J·k·mol-1。对结果进行了解释，并与结构相关的甘氨酸衍生物的结果进行了比较。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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物理化学期刊(英文)

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