Aluminum-Tannin Equilibria: A Potentiometric Study

1987 ◽  
Vol 40 (12) ◽  
pp. 2015 ◽  
Author(s):  
H Kipton ◽  
J Powell ◽  
AW Rate
Keyword(s):  
Potentiometric Titration ◽  
Stability Constants ◽  
Potentiometric Study ◽  
Chelate Effect ◽  
Aluminium Ion ◽  
Equilibrium Reactions

The equilibrium reactions between aluminium(III) and an epicatechin polymer or tannin (T) have been studied by potentiometric titration at 25�C, I = 0.001 M. The tannin, which has on average ten 1,2-dihydroxybenzene units per molecule, encapsulates the aluminium ion to form a bis(l,2-diphenolato) complex at pH 5-7. Stability constants are reported for Al(TH-2) (logK11-2, -3.95 � 0.05), Al(TH-3) (logK11-3, -4.5 � 0.1) and Al(TH-4) (logKl1-4, -5.7 � 0.2). A small chelate effect arising from coordination of remote pairs of 1,2-diphenolato groups was observed.

Aluminium(III) and Iron(III) 1,2-Diphenolato Complexes: a Potentiometric Study

1985 ◽  
Vol 38 (5) ◽  
pp. 659 ◽  
Author(s):  
JA Kennedy ◽  
HKJ Powell
Keyword(s):  
Aqueous Solution ◽  
Potentiometric Titration ◽  
Protocatechuic Acid ◽  
Acid System ◽  
Experimental Conditions ◽  
Potentiometric Study ◽  
Hydroxo Complexes ◽  
Equilibrium Reactions ◽  
Ternary Metal ◽  
Metal Ligand

The equilibrium reactions between aluminium(III) and the phenols catechol (LH2), protocatechuic acid (LH3) and catechin (LH4), and between iron(III) and protocatechuic acid have been studied by potentiometric titration in aqueous solution, I 0.10M ( KCl ), 25°C. Stability constants are reported for the mononuclear diphenolato complexes AlLHn-2, Al(LHn-2)2and Al(LHn-2)3, and the hydroxo complexes Al(OH)LHn-2 and Al(OH)(LHn-2)2, n = 2 ( catechol ) or 4 ( catechin ). For protocatechuic acid, the carboxylate -coordinated species lLH22+ and the species AlLH + (carboxyl- protonated ) are also postulated. Analogous species were characterized for the iron(III)- protocatechuic acid system. Stoichiometric end-points were obtained only if an excess of ligand was used (L/M > 4). Monomeric and polymeric aluminium- hydroxo species and ternary metal- ligand - hydroxo species were found to be unimportant under the experimental conditions employed.

Aluminum(III)-Isocitrate Solution Chemistry. A Potentiometric Study

1995 ◽  
Vol 48 (5) ◽  
pp. 1039
Author(s):  
KJ Powell ◽  
RM Town
Keyword(s):  
Potentiometric Titration ◽  
Thermodynamic Stability ◽  
Protonation Constants ◽  
Solution Chemistry ◽  
Potentiometric Study ◽  
Equilibrium Reactions

The equilibrium reactions of isocitrate with protons and Al3+ have been studied by potentiometric titration in aqueous 0.10 M KCl at 25°C. The protonation constants, corrected for K+-isocitrate complexing , were logβ0,1,1 = 5.838, logβ0,2,1 = 10.126 and logβ0,3,1 = 13.219. The stabilities and stoichiometries of the complexes, AlpHqLr, were defined by the constants logβ1,1,1 = 9.55(05), logβ1,0,1 = 6.90(02), logβ1,-1,1 = 3.06(04) and logβ2,-3,2 = 4.08(04) or logβ3,-4,3 = 10.36(06). Compared with the Al3+-citrate system, complexes are of lower thermodynamic stability, but equilibrate more rapidly.

Complexation of Iron with the Orally Active Decorporation Drug L1 (3-Hydroxy-1,2-Dimethyl-4-Pyridinone)

1992 ◽  
Vol 38 (4) ◽  
pp. 562-565 ◽  
Author(s):  
M A Kline ◽  
C Orvig
Keyword(s):  
Blood Plasma ◽  
Potentiometric Titration ◽  
Stability Constants ◽  
Computer Model ◽  
Chelating Agent ◽  
Glass Electrode ◽  
Simple Computer ◽  
Active Iron ◽  
The Stability ◽  
Orally Active

Abstract The stability constants for the Fe(III) complexes of the orally active iron decorporation drug L1 (3-hydroxy-1,2-dimethyl-4-pyridinone) have been determined by potentiometric titration [glass electrode, 25.0 degrees C, mu = 0.15 mol/L (isotonic) NaCl]. A simple computer model of blood plasma (citrate 100 mumol/L, transferrin 37 mumol/L) has been used to compare the Fe(III) binding efficacies in blood of L1 and the clinically used intravenously administered chelating agent deferoxamine.

Determination of Co(II) and Ni(II)-humate stability constants at high ionic strength NaCl solutions

2000 ◽  
Vol 88 (9-11) ◽  
Author(s):  
D.N. Kurk ◽  
Gregory R. Choppin
Keyword(s):  
Humic Acid ◽  
Ionic Strength ◽  
Solvent Extraction ◽  
Potentiometric Titration ◽  
Stability Constants ◽  
Dissociation Constants ◽  
High Ionic Strength ◽  
Extraction Technique ◽  
Solvent Extraction Technique

Complexation of Ni(II) and Co(II) by unfractionated humic acid (HA) was measured in 0.3 to 5.0 m NaCl solutions at pH 6 and 20 °C, using a solvent extraction technique. The dissociation constants and capacities of the humic acid were investigated in 0.1 to 5.0 m NaCl solutions at 25 °C using potentiometric titration methods.

Thermodynamics for complex formation between palladium(ii) and oxalate

2014 ◽  
Vol 43 (32) ◽  
pp. 12243-12250 ◽  
Author(s):  
Radomír Pilný ◽  
Přemysl Lubal ◽  
Lars I. Elding
Keyword(s):  
Complex Formation ◽  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Chelate Effect ◽  
Overall Stability ◽  
Oxalato Complexes

Overall stability constants and thermodynamic parameters for formation of palladium(ii) oxalato complexes have been determined. The chelate effect is discussed.

scholarly journals COMPLEXATION OF GOLD (III) WITH 1-FURFURYLIDENE AMINO-1,3,4-TRIAZOLE AT 288 – 318 K

2017 ◽  
Vol 60 (5) ◽  
pp. 37
Author(s):  
Safarmamad M. Safarmamadov ◽  
Davron A. Muborakkadamov ◽  
Kimyo S. Mabatkadamova
Keyword(s):  
Potentiometric Titration ◽  
Stability Constants ◽  
Least Squares Method ◽  
Slope Angle ◽  
Organic Ligand ◽  
General Stability ◽  
Wide Ph Range ◽  
Titration Data ◽  
Ph Range ◽  
Number Of Particles

The potentiometric titration method was used to determine the ionization constant of 1-furfurylideneamino-1,3,4-triazole (pKk = 11.83 log.). The dominating region of 1-furfurylideneamino-1,3,4-triazoles (FF) was identified in a wide pH range. It was shown that 1-furfurylideneamino-1,3,4-triazole ion (HL+) predominates in the pH range up to 0.5-2.0. At pH of 5.0 to 10.5, the neutral molecule (L) predominates, and at pH>13.0 1-furfurylideneamino-1,3,4-triazolate ion (L-) predominates in a solution. To determine the number of a particles formed during the interaction of Au (III) with FF from the potentiometric titration data the dependence of ΔE on -lg [FF] was used for 1-furfurylideneamino-1,3,4-triazole gold (III) complexes at 288-318 K. The slope of the curves of the ΔE-lg [FF] with the excess of 1-furfurylideneamino-1,3,4-triazole at temperatures of 288, 298 and 308 K is 0.059, 0.060 and 0.061 V/mol/l-1, which corresponds to the sequential addition of three molecules of 1-furfurylideneamino-1,3,4-triazole to gold (III). At the temperature of 318 K it is not possible to find the slope angle corresponding to the tris complex due to a quick change in the potential with an excess of FF in a solution. General stability constants of 1-furfuryldenoamino-1,3,4-triazole complexes of Au (III) according to potentiometric titration data was determined by the Friedman method and non-linear least squares method. It was shown that as the temperature increases, the general stability constants of gold (III) complexes are reduced. It was shown that the introduction of substituents into the 1,2,4-triazole molecule affects both the number of particles formed in a solution and the stability of the complexes. Thus, in the system Au (III) -1,2,4-triazole-H2O at 298 K four complex particles are formed, and in the Au (III) system, 1-furfurylideneamino-1,3,4-triazole-H2O only three are formed. The general stability constants of 1,2,4-triazole complexes equal to lgβ1 = 6.56, lgβ2 = 11.13, lgβ3 = 14.94 and lg4 = 18.78 log units, and for 1-furfurylideneamino-1,3,4-triazole complexes Igβ1 = 5.92, lgβ2 = 10.14, lgβ3 = 13.80 log units. The thermodynamic functions of complexe formation were calculated by the temperature coefficient method. It was shown that all complex particles are enthalpy-stabilized. The greatest increase in the exothermicity of the reactions is observed when a complex of three organic-ligand molecules is formed. The value of ΔS at all steps of complexation is negative, which is most likely due to the decrease in the number of particles in a system under study. The spontaneous reaction of complexation is determined by the enthalpy factorFor citation:Safarmamadov S.M., Muborakkadamov D.A., Mabatkadamova K.S. Complexation of gold (III) with 1-furfurylidene amino-1,3,4-triazole at 288 – 318 K. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 5. P. 37-43.

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