Salt effects on the protonation of imidazole in aqueous solution at different ionic strengths: A tentative explanation by a complex formation model |
| |
Authors: | Pier G. Daniele Alessandro De Robertis Concetta De Stefano Silvio Sammartano |
| |
Affiliation: | (1) Dipartimento di Chimica Analitica dell'Università, via Giuria 5, I-10125 Torino, Italy;(2) Istituto di Chimica Analitica dell'Università, Salita Sperone 31, I-98166 Messina S. Agata, Italy |
| |
Abstract: | Imidazole protonation constants were determined potentiometrically, using a (H+)-glass electrode, in LiCl, NaCl, KCl, CaCl2, MgCl2, tetramethylammonium (Me4N-) iodide and chloride, Et4N-, Pr4N- and Bu4N-iodides. Salt effects were tentatively explained by assuming that complexes [H(Im)X]o (Im = imidazole, X–=Cl– or I–), [M(Im)]2+ (M2+=Mg2+ or Ca2+) and [A(Im)]+ (A+ = tetraalkylammonium cation) were formed in solution. Calcium(II)-selective electrode measurements confirmed our hypothesis about the formation of the Ca2+-imidazole complex. The reliability of the complex formation model is discussed on the basis of its self consistency and in light of previous results. |
| |
Keywords: | Protonation of imidazole imidazole complexes complex formation model salt effects on protonation |
本文献已被 SpringerLink 等数据库收录! |
|