Early stages of the hydrolysis of chromium(III) in aqueous solution. 4. The stability constants of the hydrolytic dimer, trimer, and tetramer at 25.degree.C and I = 1.0 M

1989 ◽  
Vol 28 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Hans Stuenzi ◽  
Leone Spiccia ◽  
Francois P. Rotzinger ◽  
Werner Marty
Keyword(s):  
Aqueous Solution ◽  
Stability Constants ◽  
Early Stages ◽  
The Stability ◽  
Hydrolysis Of

Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be2+ ion

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.

scholarly journals Copper(II)-complexation by non enzymatically glycated peptides

2004 ◽  
Vol 22 (SI - Chem. Reactions in Foods V) ◽  
pp. S106-S108
Author(s):  
S. T Seifert ◽  
R. Krause ◽  
K. Gloe ◽  
T. Henle
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
Stability Constants ◽  
Maillard Reaction ◽  
Metal Binding ◽  
Maillard Reaction Products ◽  
Reaction Products ◽  
Nonenzymatic Glycation ◽  
The Stability

The purpose of our work was to examine the metal binding abilities of selected peptide bound Maillard reaction products (MRPs). The N<sup>α</sup>-hippuryl-protected MRPs N<sup>ε</sup>-fructoselysine and N<sup>ε</sup>-carboxymethyllysine were synthesised and measurement of stability constants for complexes formed with the physiologically important metal ions copper(II) and zinc(II) was carried out in aqueous solution (T = 298.1 K; I = 0.1M KNO<sub>3</sub>) using pH-potentiometry. The stability constants of N<sup>ε</sup>-fructoselysine and N<sup>ε</sup>-carboxymethyllysine with Cu(II) proved that new coordination centres are formed by the nonenzymatic glycation of proteins. With zinc(II) no complexation was observed. Physiological consequences are discussed, but further studies are necessary in order to clarify the effects of this phenomenon.

scholarly journals Interaction of Ampicillin and Amoxicillin with Mn2+: A Speciation Study in Aqueous Solution

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3110
Author(s):  
Claudia Foti ◽  
Ottavia Giuffrè
Keyword(s):  
Aqueous Solution ◽  
Stability Constants ◽  
Metal Ion ◽  
Formation Constants ◽  
Enthalpy Change ◽  
Ligand Concentration ◽  
Empirical Parameter ◽  
Speciation Study ◽  
Potentiometric Measurements ◽  
The Stability

A potentiometric and UV spectrophotometric investigation on Mn2+-ampicillin and Mn2+-amoxicillin systems in NaCl aqueous solution is reported. The potentiometric measurements were carried out under different conditions of temperature (15 ≤ t/°C ≤ 37). The obtained speciation pattern includes two species for both the investigated systems. More in detail, for system containing ampicillin MLH and ML species, for that containing amoxicillin, MLH2 and MLH ones. The spectrophotometric findings have fully confirmed the results obtained by potentiometry for both the systems, in terms of speciation models as well as the stability constants of the formed species. Enthalpy change values were calculated via the dependence of formation constants of the species on temperature. The sequestering ability of ampicillin and amoxicillin towards Mn2+ was also evaluated under different conditions of pH and temperature via pL0.5 empirical parameter (i.e., cologarithm of the ligand concentration required to sequester 50% of the metal ion present in traces).

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