Utilisation of Silver Cryptate [222] /Silver System as a Potential Reference for the Determination of the Solvation Transfer Coefficients of Ions. Stability of Cryptates in a Solvent Medium
作者:
J. Bessiere,
M.F. Lejaille,
期刊:
Analytical Letters
(Taylor Available online 1979)
卷期:
Volume 12,
issue 7
页码: 753-763
ISSN:0003-2719
年代: 1979
DOI:10.1080/00032717908059756
出版商: Taylor & Francis Group
关键词: Non Aqueous Solvents;Cryptates;Stability Constants;Extrathermodynamic Hypothesis;Potentiometry
数据来源: Taylor
摘要:
The formal potential of Ag [222] /Ag(s) system is supposed to be independent of the solvent, taking in account the [222] ligand structure and the corresponding cryptate. This extrathermodynamic hypothesis is confronted to the one usually considered, water, methanol, D. M. S. O., acetonitrile and tetramethylurea being the used solvents. It seems possible to generalize this hypothesis to other cations and cryptands. The stability constants of cryptate [222] of the evaluation of pKAg[222]+constants, Nernst's law being respected. The argentometric titration of ligand [222] in presence of Na+, Li+, Tl+, Cd2+, Ni2+ions allows to evaluate the pKof corresponding cryptates in D. M. S. O. and methanol. Tl [222]+/Tl system follows Nernst's law in methanol and D. M. S. O. The dissociation constants have been evaluated from polarographic measurements in acetonitrile. The electrochemical systems are not rigorously fast, which does not allow an accurate determination of those constants by that method. Still it gives an order of magnitude.
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