Kinetics and mechanism of the oxidation of the sulphite ion by the Mn(III)–cydta complex ion

1995 ◽  
Vol 73 (9) ◽  
pp. 1531-1537 ◽  
Author(s):  
Uttra Chandrawat ◽  
Aditya Prakash ◽  
Raj N. Mehrotra
Keyword(s):  
Outer Sphere ◽  
Kinetics And Mechanism ◽  
The Other ◽  
Rapid Scan ◽  
Complex Ion ◽  
Sphere Mechanism

The reinvestigated oxidation of S(IV), HSO3−/SO32−ions, by [Mn(cydta)(OH)]− confirmed that S(IV) is oxidized in two parallel paths; the order with respect to [S(IV)] is one in one of the paths and two in the other. The nature of the dependence of the rate on [H+] is also confirmed. However, the rapid scan of the reaction mixture and measurement of the initial absorbance of the reaction mixture at different wavelengths at the beginning of the reaction suggest an outer-sphere mechanism. The rate parameters are of the same order as obtained in known reactions of an outer-sphere mechanism and this mechanism is further supported by the Marcus cross relation. Keywords: kinetics, outer-sphere mechanism, [Mn(cydta)]−, SO32−.

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 Kinetics and mechanism of the reduction of n-(2-hydroxyethyl)ethylenediaminetriacetatoiron(III) complex by thioglycol in bicarbonate buffer medium

2018 ◽  
Vol 6 (1) ◽  
pp. 102 ◽  
Author(s):  
I U. Nkole ◽  
C R. Osunkwo ◽  
A D. Onu ◽  
O D. Onu
Keyword(s):  
Salt Effect ◽  
Reaction Medium ◽  
Outer Sphere ◽  
Reaction Rates ◽  
Kinetics And Mechanism ◽  
Bicarbonate Buffer ◽  
First Order ◽  
Buffer Medium ◽  
Activated Complex ◽  
Sphere Mechanism

The kinetics and mechanism of reduction of N-(2-hydroxyethyl) ethylenediaminetriacetatoiron (III) complex (hereafter [Fe(III)HEDTAOH2]) by thioglycol (hereafter RSH) has been studied spectrophotometrically in a bicarbonate buffer medium. The study was carried out under pseudo-first order conditions of an excess of thioglycol concentration at 28 ± 1℃, I = 0.44 mol dm-3 (KNO3) and λmax = 490 nm. The reaction is first order in [Fe(III)HEDTAOH2] and half order in [RSH] and a stoichiometric mole ratio of [Fe(III)HEDTAOH2]: RSH is 2:1. Reaction rates increased with increase in ionic strength (I) and dielectric constant (D) of the reaction medium of the reaction. The reaction displayed positive primary salt effect, which suggests the composition of activated complex are likely charged reactants ions. Test for possibility of an intermediate complex formation shows negative as Michaelis-Menten plot was linear with very negligible intercept. Based on the findings, outer-sphere mechanism is proposed for the reaction. The experimental rate law obtained is; - = k2 [Fe(III)HEDTAOH2][RSH]½   

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.

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.

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.

scholarly journals RuIII(edta) complexes as molecular redox catalysts in chemical and electrochemical reduction of dioxygen and hydrogen peroxide: inner-sphere versus outer-sphere mechanism

RSC Advances ◽  
2021 ◽  
Vol 11 (35) ◽  
pp. 21359-21366
Author(s):  
Debabrata Chatterjee ◽  
Marta Chrzanowska ◽  
Anna Katafias ◽  
Maria Oszajca ◽  
Rudi van Eldik
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transfer ◽  
Electrochemical Reduction ◽  
Molecular Oxygen ◽  
Outer Sphere ◽  
Transfer Processes ◽  
Edta Complexes ◽  
Inner Sphere ◽  
Electron Transfer Processes ◽  
Sphere Mechanism

[RuII(edta)(L)]2–, where edta4– =ethylenediaminetetraacetate; L = pyrazine (pz) and H2O, can reduce molecular oxygen sequentially to hydrogen peroxide and further to water by involving both outer-sphere and inner-sphere electron transfer processes.

Abiotic Reactivity of De Novo Designed Artificial Copper Peptides (ArCuPs): The Case of C-H Activation

2022 ◽  
Author(s):  
Divyansh Prakash ◽  
Suchitra Mitra ◽  
Morgan Murphy ◽  
Saumen Chakraborty
Keyword(s):  
Steric Effect ◽  
De Novo ◽  
Outer Sphere ◽  
The Other ◽  
Easy Access ◽  
Oxygen Species ◽  
Redox Potentials ◽  
Spectroscopic Feature ◽  
Detailed Assessment ◽  
Active Variant

We report a series of de novo designed Artificial Cu Peptides (ArCuPs) that oxidize and peroxygenate C-H bonds of model abiotic substrates via electrochemically generated Cu-oxygen species using H2O2 as the terminal oxidant, akin to native Cu enzymes. Detailed assessment of kinetic parameters established the catalytic nature of the ArCuPs. Selective alteration of outer sphere steric at the d layers above and below the Cu site allows facilitated access of substrates, where a more pronounced effect on catalysis is observed when space is created at the d layer below the Cu site via Ile to Ala mutation producing a kcat of 6.2 s-1, TONmax of 14800 and catalytic proficiency (kcat/KM/kuncat) of 340 M-1 for the oxidation of benzyl alcohol. Independent spectroscopic studied revealed that the rate of formation of the Cu-oxygen species and the spectroscopic feature of the most active variant is distinct compared to the other ArCuPs. Systematic alteration of outer sphere hydrophobicity led to a correlated tuning of the T2 Cu site redox potentials by ~80 mV. The enhanced activity of the ArCuP variant is attributed to a combination of steric effect that allows easy access of substrates, the nature of Cu-oxygen species, and stability of this construct compared to others, where Ile to Ala mutation unexpectedly leads to a higher thermostability which is further augmented by Cu binding.

scholarly journals Darstellung und Charakterisierung von Tetrabutylammonium-Tetraiodooxotechnetat(V), (TBA) [TcOI4] / Preparation and Characterization of Tetrabutylammonium Tetraiodooxotechnetate(V), (TBA)[TcOI4]

1981 ◽  
Vol 36 (2) ◽  
pp. 138-140 ◽  
Author(s):  
G. Peters ◽  
W. Preetz
Keyword(s):  
Raman Spectrum ◽  
Exchange Reaction ◽  
Vibrational Spectra ◽  
Ligand Exchange ◽  
Resonance Raman ◽  
The Other ◽  
Resonance Raman Spectrum ◽  
Ligand Exchange Reaction ◽  
Complex Ion

Abstract Pure (TBA)[TcOI4] is prepared from (TBA)[TcOCl4] by ligand exchange reaction with Nal in acetone. The vibrational spectra indicate C4v symmetry for the complex ion. On excitation with the 514.5 nm line of an Ar-laser a resonance Raman spectrum is obtained showing v(TcO) = 996 cm-1 and four of its overtones, symmetrically surrounded by groups of bands arising as well from the sums as from the differences of frequencies with the other fundamentals. In contrast to the ligand exchange reaction the reduction of Tc04- with conc. HI yields products always contaminated with polyiodides. The extremely strong Raman scatterer (TBA)l3 is detected by a characteristic doublet at 111 and 116 cm-1 and even small amounts of it cover the Raman spectrum of (TBA)[TcOI4].

scholarly journals Dy-DOTA integrated mesoporous silica nanoparticles as promising ultrahigh field magnetic resonance imaging contrast agents

Nanoscale ◽  
2018 ◽  
Vol 10 (45) ◽  
pp. 21041-21045 ◽  
Author(s):  
Xiao-Yu Zheng ◽  
Juan Pellico ◽  
Alexandr A. Khrapitchev ◽  
Nicola R. Sibson ◽  
Jason J. Davis
Keyword(s):  
Magnetic Resonance Imaging ◽  
Mesoporous Silica ◽  
Mesoporous Silica Nanoparticles ◽  
Silica Nanoparticle ◽  
Outer Sphere ◽  
Resonance Imaging ◽  
Mesoporous Silica Nanoparticle ◽  
Ultrahigh Field ◽  
Magnetic Resonance Imaging Contrast ◽  
Sphere Mechanism

Integrating Dy-DOTA motifs into mesoporous silica nanoparticle scaffolds significantly amplifies the ultrahigh field T2 relaxivity via a Curie outer-sphere mechanism.

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