正烷基亚氨二乙酸与二价过渡金属离子络合平衡的研究——正烷基亚氨二乙酸根离子的加质子常数

来源期刊：中南大学学报(自然科学版)1983年第2期

论文作者：殷群生 张祥麟 陈超球

文章页码：135 - 142

关键词：亚氨二乙酸； 加质子常数； 混合溶剂； 过渡金属离子； 十四烷基； 络合平衡； 酸根离子； 线性回归法； 离子强度； 氧己环

摘    要：本文介绍五种长碳链的正烷基亚氨二乙酸(Cn H_2n+1 N(CH₂COOH)₂,其中n=6,8,10,12,14)的合成。在25±0.1℃,表观离子强度0.1(KNO₃)的条件下,用pH电位法测定了上述各酸根离子的三级加质子常数。用HClO₁4标定pH计求取了混合溶剂中H⁺的浓度;推导了线性回归法计算K₂H和K₃H的公式。

Abstract: Five n-alkyl iminodiacetic acids CnH_2n+1 N (CH₂COOH)₂, in whichn=6, 8, 10, 12 or 14, were synthesized from chloroacetic acid and thecorresponding amines according to A.Stein′s method. The protonation constants of the five n-alkyl iminodiacetate ions havebeen determined at 25±0.1℃ and the apparent ionic strength 0.1 (KNO₃)with the pH-potentiometric method in the mixed solvent water-dioxane(75% dioxane by volume). The protonation constant of n-hexyl iminodiac-etate ion has also been determined in the aqueous solution at the sametemperature and the same apparent ionic strength with the same method. For these ligands, K₁^H>>K₂^H, but K₂^H and K₃^H differ not much from eachother. Therefore, Bjerrum′s half n (formation function) method was appliedto evaluating the first protonation constants of these ligands while thesecond and third protonaton constants were evaluated with both thelinear regression method and the formulas derived by ourselves. The protonation constants determined are listed in the following table.