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Studies on 1,2‐Bis( O ‐Aminophenoxy)Ethane‐ N,N,N′,N′ ;‐Tetraacetic Acid Chelates of the Tripositive Lanthanide Ions
Author(s) -
Hseu TongMing,
Liu KeiLee
Publication year - 1990
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.199000033
Subject(s) - chemistry , chelation , potentiometric titration , lanthanide , stability constants of complexes , inorganic chemistry , dissociation (chemistry) , enthalpy , ion , dota , ionic strength , dissociation constant , nuclear chemistry , organic chemistry , biochemistry , physics , receptor , aqueous solution , quantum mechanics
The acid dissociation constants of 1,2‐bis( cis ‐aminophenoxy)ethane‐ N,N,N′,N′ ;‐tetraacetic acid (H 4 BAPAT or H 4 Z), and the stability constants of its chelates with tripositive rare‐earth metal ions have been determined by the potentiometric titration and mercury indicator electrode methods at 15°, 25′ and 35°C and an ionic strength of 0.1 (KNO 3 ). The existence of a monohydrogen chelate species, LnHZ, and the normal chelate, LnZ − , is illustrated. Enthalpy and entropy changes characterizing the formation of the normal chelates and the dissociation of the last two protons of chelating acid have been calculated at 25°C. These functions have been compared with corresponding values for related chelating agents.