Influence of the distance between ionizable groups on the protonation behavior of various hexaamines
作者:Rene´ C. van Duijvenbode、Anton Rajanayagam、Ger J. M. Koper,、Michal Borkovec、Wolfgang Paulus、Ulrich Steuerle、Lukas Häu
DOI:10.1039/a907397c
日期:——
A synthesis route for N,N,N′,N′-tetraaminoethyl-1,2-ethylenediamine, N,N,N′,N′-tetraaminopropyl-1,2-ethylenediamine, N,N,N′,N′-tetraaminopropyl-1,3-propylenediamine and N,N,N′,N′-tetraaminopropyl-1,4-butylenediamine is presented. These molecules differ from each other in the number of carbon atoms between the six amino groups. This results in different protonation behavior. Potentiometric titrations are performed in 0.1 M and 1.0 M KCl, and the six macroscopic protonation constants are obtained from these curves. An Ising model with a limited number of microscopic protonation constants and short-ranged pair interactions describes the protonation behavior quantitatively. The results are compared to those of other, similar molecules. The advantage of the Ising model over empirical relations such as the Taft equations is the more systematic approach with which the titration curves of more complex molecules can be described. The values for the Ising model parameters obtained here can be used to predict the protonation behavior of more complex, in particular larger, polyamines.
本文介绍了一种合成N,N,N′,N′-四氨基乙基-1,2-乙二胺、N,N,N′,N′-四氨基丙基-1,2-乙二胺、N,N,N′,N′-四氨基丙基-1,3-丙二胺和N,N,N′,N′-四氨基丙基-1,4-丁二胺的合成路线。这些分子中六个氨基之间的碳原子数不同,导致它们具有不同的质子化行为。在0.1 M和1.0 M KCl中进行电位滴定,从这些曲线中获得了六个宏观质子化常数。采用有限数量的微观质子化常数和短程配对相互作用的Ising模型,可以定量描述质子化行为。将结果与其他类似分子的结果进行了比较。与Taft方程等经验关系式相比,Ising模型在描述更复杂分子的滴定曲线时采用了更系统的方法。这里获得的Ising模型参数值可以用于预测更复杂、特别是更大的多胺分子的质子化行为。