Thermodynamics of protonation and complexation of EDTA derivatives and metal cations in water
作者:Angela F. Danil de Namor、David Alfredo Pacheco Tanaka
DOI:10.1039/a805435e
日期:——
derived Gibbs energies, enthalpy (derived from calorimetry) and entropy data for these ligands and metal cations in water are reported. These data show that, unlike EDTA, there is hardly any variation in the Gibbs energies of complexation (or stability constants) of EDTAMBA and EDTAPA with metal cations in water, as a result of an almost complete compensation between enthalpy and entropy.
两个EDTA衍生物,ethylenedinitrilo- Ñ,Ñ '-diacetic- Ñ,Ñ ' -双(1- phenylethylacetamido)酸(EDTAMBA)和ethylenedinitrilo- Ñ,Ñ '-diacetic- Ñ,Ñ ' -双(2- pyridylacetamido)酸(EDTAPA)已经通过IR和1H NMR光谱合成并表征。在P ķ一相对于EDTA,叔氨基的解离值降低约三个单位。EDTAMBA和EDTAPA在水中的质子化焓已通过滴定量热法测定。质子化的热力学参数表明,在水中这些衍生物的第一质子化常数之间观察到的差异是熵产生的。对于EDTAPA,焓项在该配体的第一和第二质子化常数之间的差异中占主导地位。报告了这些配体和水中金属阳离子的稳定性常数(由电位法确定)和衍生的吉布斯能量,焓(由量热法得出)和熵数据。这些数据表明,与EDTA不同,