Kinetics and mechanism of oxidation of V(II) ions with trichloroacetic acid

1980 ◽  
Vol 45 (12) ◽  
pp. 3287-3292 ◽  
Author(s):  
Ľubica Adamčíková
Keyword(s):  
Exchange Rate ◽  
Redox Reaction ◽  
Trichloroacetic Acid ◽  
Outer Sphere ◽  
Kinetics And Mechanism ◽  
Kinetic Measurements ◽  
Exchange Rate Constant ◽  
Marcus Equation ◽  
Mechanism Of Oxidation ◽  
Sphere Mechanism

The kinetics and mechanism of the redox reaction of V(II) ions with trichloroacetic acid were studied in the medium of 0.04-2.0M-HClO. The results of kinetic measurements were compared with the analogous oxidation of U(III) ions with trichloroacetic acid, and the exchange rate constant for the reaction U3+ + *U4+ → U4+ + *U3+ was calculated. The influence of binary mixtures on the kinetic parameters of the reaction and the application of the Marcus' equation show that the oxidation of V2+ions with trichloroacetic acid proceeds by an outer-sphere mechanism.

Kinetics and mechanism of redox reaction of U(III) ions with trichloroacetic acid

1980 ◽  
Vol 45 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Ľudovít Treindl
Keyword(s):  
Electron Transfer ◽  
Redox Reaction ◽  
Trichloroacetic Acid ◽  
Outer Sphere ◽  
Elementary Step ◽  
Kinetics And Mechanism ◽  
Kinetic Measurements ◽  
Chloroacetic Acids ◽  
Acetic Acids ◽  
Sphere Mechanism

The kinetics and mechanism of redox reaction of U3+ ions with trichloroacetic acid in the medium of perchloric acid were studied. The form of the dependence of the rate constant on the concentration of H3O+ ions suggests that the U3+ion reacts in the first elementary step with the CCL3.COO- anion under formation of an intermediary radical which reacts rapidly in the second step.The results of kinetic measurements of all three chloro substituted acetic acids are compared. A detailed study of the influence of binary mixtures on kinetic parameters of the studied reaction (especially of water-tert-butanol mixtures) shows that the reduction of chloroacetic acids with U3+ ions proceeds by the outer sphere mechanism of the electron transfer.

scholarly journals Kinetics and mechanism of oxidation of mandelic acid with Bi(V) in phosphoric acid medium

2020 ◽  
Vol 16 (5) ◽  
pp. 50-57
Author(s):  
MUKESH KUMAR JHA ◽  
◽  
AVINASH KUMAR ◽  
Keyword(s):  
Electron Transfer ◽  
Phosphoric Acid ◽  
Acid Medium ◽  
Mandelic Acid ◽  
Reaction Rate ◽  
Outer Sphere ◽  
Kinetics And Mechanism ◽  
Opposite Charge ◽  
Mechanism Of Oxidation ◽  
Sphere Mechanism

The kinetics and mechanism of oxidation of Mandelic acid with Bi(V) has been investigated in phosphoric acid medium. The order with respect to substrate and oxidant each is one. The reaction rate is independent of [H+] ion as well as [Bi(III)]. The reaction rate decreases with increasing ionic strength indicating reactive species of opposite charge. The simple rate law explained all the experimental observations. The mode of electron transfer from the substrate to Bi(V) has been indicated is a bridged outer sphere mechanism.

Kinetics and mechanism of redox reactions of U(III) ions with monochloroacetic and dichloroacetic acids

1979 ◽  
Vol 44 (2) ◽  
pp. 401-405 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Ľudovít Treindl
Keyword(s):  
Redox Reactions ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Outer Sphere ◽  
Alcohol Concentration ◽  
Kinetics And Mechanism ◽  
Solvent Structure ◽  
Influence Of Ph ◽  
Sphere Mechanism

The kinetics and mechanism of the redox reactions of U3+ ions with mono- and dichloroacetic acids were studied. The influence of pH was observed mainly in the second case and led to the determination of the rate constants and activation parameters corresponding to two parallel steps, namely oxidation of U3+ with CHCl2COO- ions and oxidation of U3+ with CHCl2.COOH molecules. The influence of binary mixtures of water with methanol, ethanol, isopropanol, or tert-butenol on the reaction rate was followed. Increasing alcohol concentration influences the rate constant not only through changing dielectric constant and solvation of the reactants but also through a change of the solvent structure which plays a role in reactions with an outer sphere mechanism of the electron transfer.

scholarly journals Synthesis and Oxidation ofCobalt(II) Pheophytin-α Complex

2011 ◽  
Vol 8 (s1) ◽  
pp. S297-S303 ◽  
Author(s):  
Ezekiel D. Dikio ◽  
David A. Isabirye
Keyword(s):  
Metal Ion ◽  
Oxidation Reaction ◽  
Dilute Hydrochloric Acid ◽  
Outer Sphere ◽  
Central Metal ◽  
First Order ◽  
First Order Kinetics ◽  
Mechanism Of Oxidation ◽  
Absorption Transitions ◽  
Sphere Mechanism

The mechanism of oxidation of natural pheophytin-aincorporated with cobalt as the central metal ion has been investigated. Natural pheophytin-aextracted from spinach was metallated with cobalt(II) to form the complex, cobalt(II) pheophytin-α[Cophe]. The complex was characterized by Ultraviolet and Visible, Fourier Transform Infrared and Electrospray ion Mass Spectroscopy. The synthesis of cobalt(II) pheophytin-awas carried out and the effect of the substitution on the chlorophyll macrocycle was studied by the reaction of hexaaquachromium(III) cation. The presence of cobalt as the central metal ion increases the energies of the chlorophyll main absorption transitions. The oxidation of the cobalt(II) pheophytin-α, [Cophe] by hexaaquachromium(III) cation in dilute hydrochloric acid has been studied and found to follow first-order kinetics. Rate constants for the oxidation reaction at 313, 322.8 and 332.9 K were found to be 5.4×10-5, 1.8×10-4and 5.9×10-4/s respectively. An outer-sphere mechanism has been proposed for the oxidation of cobalt(II) pheophytin-α.

Reduction of hexaammineruthenium(III) ions by a series of tris(polypyridyl)chromium(II) ions – Revisiting the Cr(NN)33+/2+ self-exchange rate

2001 ◽  
Vol 79 (7) ◽  
pp. 1124-1127 ◽  
Author(s):  
K Omar Zahir
Keyword(s):  
Exchange Rate ◽  
Excited States ◽  
Rate Constants ◽  
Driving Force ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Outer Sphere ◽  
Laser Flash ◽  
Exchange Rate Constant ◽  
Kinetics Of

The kinetics of the outer-sphere oxidation of Cr(NN)32+ ions (NN = 2,2'-bipyridine, 1,10-phenanthroline, and their substituted analogs) by hexaammineruthenium(III) was studied using laser flash photolysis. The Cr(NN)32+ ions were generated via the reductive quenching of the *Cr(NN)33+ excited states by oxalate ions or by H2edta2–. The second-order rate constants were found to vary with the driving force of the reaction. The rate constants increase from (7.1 ± 0.5) × 106 M–1 s–1 for Cr(5-Clphen)32+ to (2.6 ± 0.2) × 108 M–1 s–1 for Cr(4,7-Me2phen)32+. The self-exchange rate constant for the couple (Cr(NN)33+/2+) was calculated by applying Marcus cross relation to present and other known reactions of Cr(NN)3n+ ions, where n = 3 or 2 with various reactants and is estimated to be (6 ± 4) × 107 M–1 s–1.Key words: tris(polypyridyl)chromium(II)/(III) self-exchange rate, hexaammineruthenium(III), oxidation of Cr(NN)32+.

The Oxidation of Dithiocarbamate Anion by Substitution Inert Metal Complexes

1989 ◽  
Vol 42 (7) ◽  
pp. 1085 ◽  
Author(s):  
PJ Nichols ◽  
MW Grant
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Metal Complexes ◽  
Radical Anion ◽  
Outer Sphere ◽  
Aqueous Acetone ◽  
Kinetics Of Oxidation ◽  
Rate Determining Step ◽  
Exchange Rate Constant ◽  
Kinetics Of

The kinetics of oxidation of dithiocarbamate anions to thiuram disulfides in aqueous acetone by {Fe(CN)6}3- and 11 other substitution inert metal complexes have been investigated. Outer-sphere electron transfer, resulting in the formation of dithiocarbamate thio radicals, is the rate determining step. A Marcus cross reaction treatment allows an estimate for the redox potential for the dithiocarbamate radical/anion couple. For diethyldithiocarbamate, E �(edtc/edtc-) = 425 � 33 mV v.s.c.e. and the outer-sphere electron self-exchange rate constant is log kex = 7.0 � 0.3. A comparison with thiophenolate oxidation is also given.

Outer-sphere electron transfer reactions of aqua(5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-1-acetato) nickel(II) and (III).

2003 ◽  
Vol 81 (2) ◽  
pp. 186-192 ◽  
Author(s):  
Robert I Haines ◽  
Dean R Hutchings
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Outer Sphere ◽  
Second Order ◽  
Marcus Theory ◽  
Pendant Arm ◽  
Key Words Nickel ◽  
Kinetics Of ◽  
Kinetics Of Reduction ◽  
Sphere Mechanism

The outer-sphere oxidation of the nickel(II) complex of the deprotonated pendant-arm macrocycle, 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-1-acetate, [NiL1(OH2)]+ by bis-(1,4,7-triazacyclononane)nickel(III), [Ni(tacn)2]3+ has been studied in aqueous perchlorate media. The reaction displays reversible second-order behaviour and the kinetic study reveals the forward and reverse rate constants for the reaction: [Formula: see text] The kinetics show the forward reaction to be acid dependent, a feature that is attributed to protonation of the acetato group of the nickel(II) complex. Using Marcus theory, the self-exchange rate for the [NiL1(OH2)]+/2+ couple has been calculated. The nickel(II/III) electron transfer is a reversible one electron process with E° = 1.04 V (vs. S.H.E.). The formation of the authentic nickel(III) product has been confirmed by esr spectroscopy. The kinetics of reduction of the [NiL1(OH2)]2+ species by Fe2+(aq) exhibits a second-order rate law, the reaction being independent of acid. Using the calculated self-exchange rate for the nickel complex, its reaction with Fe2+(aq) has been examined in terms of an inner- versus outer-sphere mechanism. Key words: nickel(III), pendant-arm macrocycles, hexaaquairon(II), outer sphere, kinetics, Marcus theory.

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