Carboxylate Complexing of Iron(III). I. The Formation of Monoacetatoiron(III) in Aqueous Solution: Equilibria and Kinetics

The kinetics and equilibria involved in the formation of monoacetatoiron(III) from iron(III) in aqueous solution has been investigated at ionic strength 0.50 M and temperatures ranging from 5.2 to 25 °C for kinetic studies and 5.2 to 41 °C for equilibria. The results support the view that the mechanism of the acid independent reaction involves the reactants FeOH2+ and CH3COOH in an interchange dissociative (Id) mechanism with ΔH≠ = 11.1 ± 2.2 kcal mol−1. The nature of the acid dependent reactions remains unresolved.

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Equilibrium and kinetic studies of the aggregation of porphyrins in aqueous solution

Biochemical Journal ◽

10.1042/bj1530279 ◽

1976 ◽

Vol 153 (2) ◽

pp. 279-285 ◽

Cited By ~ 175

Author(s):

S B Brown ◽

M Shillcock ◽

P Jones

Keyword(s):

Aqueous Solution ◽

Ionic Strength ◽

Temperature Jump ◽

Critical Concentration ◽

Protoporphyrin Ix ◽

Kinetic Studies ◽

Aggregation Processes ◽

Micellization Process ◽

Increasing Temperature ◽

Dimerization Process

An investigation of the behavior of protoporphyrin IX, deuteroporphyrin IX, haematoporphyrin IX and coproporphyrin III in aqueous solution revealed extensive and complex aggregation processes. Protoporphyrin appears to be highly aggregated under all conditions studied. At concentrations below 4 μM, aggregation of deutero-, haemato- and coproporphyrin is probably restricted to dimerization. At approx. 4muM each of these three porphyrins exhibits sharp changes in spectra consistent with a “micellization” process to form large aggregates of unknown size. This critical concentration increases with increasing temperature and pH, but is not very sensitive to variation in ionic strength. Temperature-jump kinetic studies on deuteroporphyrin also imply an initial dimerization process, the rate constants for which are comparable with those for various synthetic porphyrins, followed by a further extensive aggragation. The ability of a particular porphyrin to dimerize appears to parallel that of the corresponding iron(III) complexes (ferrihaems), although it is thought that ferrihaems do not exhibit further aggregation under these conditions.

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Uptake of chloride ion from aqueous solution by calcined layered double hydroxides: Equilibrium and kinetic studies

Water Research ◽

10.1016/j.watres.2005.11.043 ◽

2006 ◽

Vol 40 (4) ◽

pp. 735-743 ◽

Cited By ~ 145

Author(s):

Liang Lv ◽

Jing He ◽

Min Wei ◽

D.G. Evans ◽

Xue Duan

Keyword(s):

Aqueous Solution ◽

Layered Double Hydroxides ◽

Chloride Ion ◽

Kinetic Studies ◽

Double Hydroxides

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Meso tetrakis ortho-, meta-, and para-N-alkylpyridiniopor-phyrins: kinetics of copper(II) and zinc(II) incorporation and zinc porphyrin demetalation

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424603000197 ◽

2003 ◽

Vol 07 (03) ◽

pp. 139-146 ◽

Cited By ~ 6

Author(s):

Peter Hambright ◽

Ines Batinić-Haberle ◽

Ivan Spasojević

Keyword(s):

Aqueous Solution ◽

Ionic Strength ◽

Effective Charge ◽

Methyl Ethyl ◽

Ionic Strength Dependence ◽

Zinc Porphyrin ◽

Cationic Porphyrin ◽

Strength Dependence ◽

Acid Catalyzed ◽

Kinetics Of

The relative reactivities of the tetrakis( N -alkylpyridinium- X - yl )-porphyrins where X = 4 (alkyl = methyl, ethyl, n -propyl) , X = 3 (methyl) , and X = 2 (methyl, ethyl, n -propyl, n -butyl, n -hexyl, n -octyl) were studied in aqueous solution. From the ionic strength dependence of the metalation rate constants, the effective charge of a particular cationic porphyrin was usually larger when copper(II) rather than zinc(II) was the reactant. The kinetics of ZnOH + incorporation and the acid catalyzed removal of zinc from the porphyrins in 1.0 M HCl were also studied. In general, the more basic 4- (para-) and 3- (meta-) isomers were the most reactive, followed by the less basic 2- (ortho-) methyl to n -butyl derivatives, with the lipophilic ortho n -hexyl and n -octyl porphyrins the least reactive.

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Determination of the complexation properties of a crosslinked poly(acrylic acid) gel with copper(II), nickel(II), and lead(II) in dilute aqueous solution

Canadian Journal of Chemistry ◽

10.1139/v01-059 ◽

2001 ◽

Vol 79 (4) ◽

pp. 370-376 ◽

Cited By ~ 5

Author(s):

Catherine Morlay ◽

Yolande Mouginot ◽

Monique Cromer ◽

Olivier Vittori

Keyword(s):

Aqueous Solution ◽

Ionic Strength ◽

Acrylic Acid ◽

Metal Ion ◽

Conditional Stability ◽

Binding Properties ◽

Complex Species ◽

Complexing Capacity ◽

Dilute Aqueous Solution ◽

Poly Acrylic Acid

The possible removal of copper(II), nickel(II), or lead(II) by an insoluble crosslinked poly(acrylic acid) was investigated in dilute aqueous solution. The binding properties of the polymer were examined at pH = 6.0 or 4.0 with an ionic strength of the medium µ = 0.1 or 1.0 M (NaNO3) using differential pulse polarography as an investigation means. The highest complexing capacity of the polyacid was obtained with lead(II) at pH = 6.0 with µ = 0.1 M, 4.8 mmol Pb(II)/g polymer. The conditional stability constants of the complex species formed were determined using the method proposed by Ruzic assuming that only the 1:1 complex species was formed; for lead(II) at pH = 6.0 and µ = 0.1 M, log K' = 5.3 ± 0.2. It appeared that the binding properties of the polymer increased, depending on the metal ion, in the following order: Ni(II) < Cu(II) < Pb(II). The complexing capacity and log K' values decreased with the pH or with an increase of the ionic strength. These results were in agreement with the conclusions of our previous studies of the hydrosoluble linear analogues. Finally, with the insoluble polymer, the log K' values were comparable to those previously obtained with the linear analogue whereas the complexing capacity values expressed in mmol g-1 were slightly lower.Key words: insoluble crosslinked poly(acrylic acid), copper(II), nickel(II), and lead(II) complexation.

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Inerte Amminkomplexe als mehrwertige Kationsäuren in wäßriger Lösung / Inert Ammine Complexes as Multivalent Cationic Acids in Aqueous Solution

Zeitschrift für Naturforschung B ◽

10.1515/znb-1980-0907 ◽

1980 ◽

Vol 35 (9) ◽

pp. 1096-1103 ◽

Cited By ~ 3

Author(s):

Matthias Kretschmer ◽

Lutwin Labouvie ◽

Karl-W. Quirin ◽

Helmut Wiehn ◽

Ludwig Heck

Keyword(s):

Aqueous Solution ◽

Ionic Strength ◽

Spectrophotometric Method ◽

Complex Cation ◽

Aqua Ligand ◽

Second Step ◽

Acidity Constants ◽

Ammine Complexes ◽

Temperature Variations ◽

Enthalpy Changes

Acidity constants of ammine complexes of tetravalent platinum in aqueous solutions have been determined by a spectrophotometric method at very low ionic strengths and extrapolated to zero ionic strength. Temperature variations of pK-values (25 °C and 50 °C) yield thermodynamic parameters for two successive deprotonation steps of hexaammineplatinum(IV), pentaamminechloroplatinum(IV), and tris(ethylenediamine)pla- tinum(IV) complexes and for the deprotonation of pentaammineaquacobalt(III) ion.The enthalpy changes for the first and second steps are similar and range from 50 to 75 kJ/mole while for the aqua ligand of Co(III) 33 kJ/mole are found. The very large difference in the entropy changes (about 70 to 80 J/K mole for the first step and -10 to + 20 J/K mole for the second step) is interpreted by a model of solvation change. The primary hydration sphere of strongly oriented and immobilized water dipoles around the highly charged complex cation is transformed to a hydrogen-bonded solvation sheath when the electric field of the complex is weakened upon release of the first proton.

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Micellar catalysis of organic reactions. VIII. Kinetic studies of the hydrolysis of 2-acetyloxybenzoic acid (aspirin) in the presence of micelles

Australian Journal of Chemistry ◽

10.1071/ch9821357 ◽

1982 ◽

Vol 35 (7) ◽

pp. 1357 ◽

Cited By ~ 19

Author(s):

TJ Broxton

Keyword(s):

Aqueous Solution ◽

Cetyltrimethylammonium Bromide ◽

Cetylpyridinium Chloride ◽

Kinetic Studies ◽

Base Catalysis ◽

Plateau Region ◽

General Base ◽

Mechanism Of Hydrolysis ◽

Ph Range ◽

Hydrolysis Of

The hydrolysis of 2-acetyloxybenzoic acid in the pH range 6-12 has been studied in the presence of micelles of cetyltrimethylammonium bromide (ctab) and cetylpyridinium chloride (cpc). In the plateau region (pH 6-8) the hydrolysis is inhibited by the presence of micelles, while in the region where the normal BAC2 hydrolysis (pH > 9) occurs the reaction is catalysed by micelles of ctab and cpc. The mechanism of hydrolysis in the plateau region is shown to involve general base catalysis by the adjacent ionized carboxy group both in the presence and absence of micelles. This reaction is inhibited in the presence of micelles because the substrate molecules are solubilized into the micelle and water is less available in this environment than in normal aqueous solution.

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