Kinetics and mechanism of oxidation of tris-(1,10-phenanthroline)iron(II) by chlorine and bromine and of the reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions

1979 ◽  
Vol 57 (15) ◽  
pp. 2065-2070 ◽  
Author(s):  
Jide Ige ◽  
J. Folorunso Ojo ◽  
Olusegun Olubuyide
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Activation Parameters ◽  
Chloride Ions ◽  
Reaction Intermediates ◽  
Rate Law ◽  
Iodide Ions ◽  
Good Linear ◽  
Linear Free Energy ◽  
Mechanism Of Oxidation

The rates of the oxidation of tris-(1,10-phenanthroline)iron(II) by chlorine and bromine, and of the reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions have been measured at ionic strength I = 1.0 mol dm−3 (LiClO4). All the reactions obey second-order rate law:[Formula: see text]The activation parameters for the reactions are: Fe(Phen)32+/Br2: ΔH≠ = (64.2 ± 3.2) kJ mol−1, ΔS≠ = −(24.9 ± 1.5) J mol−1 K−1. Fe(Phen)33+/I−:ΔH≠ = (39.8 ± 2.1) kJ mol−1, ΔS≠ = −(19.7 ± 0.8) J mol−1 K−1.The reactions of tris-(1,10-phenanthroline)iron(II) with chlorine and bromine are unaffected by chloride, bromide, and acid. The proposed mechanism for these reactions involves a series of one-electron changes, with the species X2− (X = Cl, Br) as reaction intermediates, since good linear free energy correlations for the primary step, resulting in the formation of X2−, are obtained. The reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions is catalysed by bromide and chloride ions, whereas the reduction of aquoiron(III) by iodide ions is known to be inhibited by bromide and chloride ions. A mechanistic interpretation of this observation is suggested.

scholarly journals Kinetics and Mechanism of Oxidation of Sucrose by N-Bromonicotinamide NBN

2015 ◽  
Vol 57 ◽  
pp. 95-101
Author(s):  
L. Pushpalatha
Keyword(s):  
Ionic Strength ◽  
Glycolic Acid ◽  
Activation Parameters ◽  
Zero Order ◽  
Effect Of Temperature ◽  
Kinetics Study ◽  
Reactive Intermediate ◽  
Aqueous Alkaline Solution ◽  
First Order ◽  
Mechanism Of Oxidation

Kinetics study of oxidation of sucrose, by aqueous alkaline solution of N-Bromonicotinamide (NBN) has been carried out in the temperature range 308-323K.The reaction exhibits first order in [NaOH] and [Sucrose] and zero order about oxidant. Addition of nicotinamide (NA) has no effect. Increase in ionic strength of the medium does not change the rate. Effect of temperature on the rate of oxidation has been followed to show the validity of Arrehenius equation and various activation parameters have been computed. The stoichiometry of the reaction was found to be 1:1. 1,2-enediol is found to be the reactive intermediate. Arabinonic acid, glycolic acid and formic acid are the products of oxidation.

Mécanisme des réactions du chlorite et du dioxyde de chlore. 2. Cinétique des réactions du chlorite en présence d'ortho-tolidine

1984 ◽  
Vol 62 (11) ◽  
pp. 2231-2234 ◽  
Author(s):  
Guy Schmitz ◽  
Henri Rooze
Keyword(s):  
Ionic Strength ◽  
Chloride Ions ◽  
Elementary Reaction ◽  
Side Reactions ◽  
Rate Law ◽  
Intermediate Products

With added ortho-tolidine (NH2RNH2) in order to eliminate complicating side reactions of the intermediate products of the disproportionation of chlorite, the stoichiometry is HClO2 + 2NH2RNH2 → Cl− + H+ + 2NHRNH + 2H2O. No chlorate is formed. The rate law, in the absence of chloride ions, is[Formula: see text]k = 269 M−1 s−1 at 25 °C and 1 M ionic strength. Without added iron, the observed rate is only due to the small amount of iron always present as an impurity in the reactants. Thus the reaction [Formula: see text] is not an elementary reaction.

Fast disproportionation of hexacyanomanganate(III) in acidic solution. Formation of hexacyanomanganate(IV) and kinetics of its decomposition

1986 ◽  
Vol 64 (12) ◽  
pp. 2301-2304 ◽  
Author(s):  
Guillermo López-Cueto ◽  
Carlos Ubide
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Solution ◽  
Activation Parameters ◽  
Rate Law ◽  
First Order ◽  
Experimental Rate ◽  
Parallel Pathways ◽  
Solution Formation ◽  
Kinetics Of

When potassium hexacyanomanganate(III) dissolves in acidic solution it rapidly disproportionates into hexacyanomanganate(IV) and Mn(II). Hexacyanomanganate(IV) then slowly decomposes to yield Mn(II) and (CN)2. Kinetics of the latter reaction has been studied. The reaction is found to be first order with respect to [Formula: see text], H+, and Mn(II) concentrations and the experimental rate law has the form v = kobs[Mn(IV)] = (ka + kb[H+] + kc[Mn(II)])[Mn(IV)]. At 40 °C and ionic strength 2.0, ka, kb, and kc values are (1.78 ± 0.01) × 10−4 s−1, (5.97 ± 0.05) × 10−5 s−1 M−1, and (3.40 ± 0.18) × 10−3 s−1 M−1, respectively. A mechanism with three parallel pathways is proposed, the deduced rate law being similar to the experimental one. Activation parameters, ΔH≠and ΔS≠ for the rate constants ka, kb, and kc are also reported.

Palladium(II)-Catalyzed Oxidation of α-Hydroxy Acids with Sodium N-Chlorobenzenesulfonamide in Perchloric Acid Solution: A Kinetic and Mechanistic Study

2004 ◽  
Vol 69 (8) ◽  
pp. 1577-1589 ◽  
Author(s):  
Somanalli K. Revathi ◽  
Sannaiah Ananda ◽  
Kikkeri N. Mohana ◽  
Rangaswamy
Keyword(s):  
Reaction Rate ◽  
Activation Parameters ◽  
Chloride Ions ◽  
Mechanistic Study ◽  
Linear Free Energy Relationship ◽  
Isokinetic Relationship ◽  
Perchloric Acid Solution ◽  
Order Dependence ◽  
Linear Free Energy ◽  
Hydroxybutanoic Acid

Kinetics of oxidation of glycolic acid (GA), lactic acid (LA) and 2-hydroxybutanoic acid (BA) with Chloramines B (CAB) catalyzed by Pd(II) in a HClO4 solution has been studied at 30 °C. The reaction rate shows first-order dependence each on [CAB], [hydroxy acid] and [Pd(II)] and a fractional-order dependence on [H+]. Additions of chloride ions, perchlorate ions and the reduction product of CAB, benzenesulfonamide (BSA), have no effect on the reaction rate. Variations of ionic strength and dielectric permittivity of the medium have no effect on the rate. Activation parameters have been evaluated. A mechanism consistent with kinetic data is proposed. A Taft linear free-energy relationship is observed for the reaction with ρ* = -3.593, indicating an increase in the rate with the presence of electron-donating substituents. An isokinetic relationship is observed with β = 376 K, indicating the effect of enthalpy factors on the rate.

Hydrogen Atom Transfer Reaction Free Energy as a Predictor of Abiotic Nitroaromatic Reduction Rate Constants: A Comprehensive Analysis

2019 ◽  
Author(s):  
Dominic Di Toro ◽  
Kevin P. Hickey ◽  
Herbert E. Allen ◽  
Richard F. Carbonaro ◽  
Pei C. Chiu
Keyword(s):  
Free Energy ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Energy Model ◽  
Second Order ◽  
Transfer Model ◽  
Atom Transfer ◽  
Order Rate ◽  
Linear Free Energy ◽  
Free Energy Model

<div>A linear free energy model is presented that predicts the second order rate constant for the abiotic reduction of nitroaromatic compounds (NACs). For this situation previously presented models use the one electron reduction potential of the NAC reaction. If such value is not available, it has been has been proposed that it could be computed directly or estimated from the electron affinity (EA). The model proposed herein uses the Gibbs free energy of the hydrogen atom transfer (HAT) as the parameter in the linear free energy model. Both models employ quantum chemical computations for the required thermodynamic parameters. The available and proposed models are compared using second order rate constants obtained from five investigations reported in the literature in which a variety of NACs were exposed to a variety of reductants. A comprehensive analysis utilizing all the NACs and reductants demonstrate that the computed hydrogen atom transfer model and the experimental one electron reduction potential model have similar root mean square errors and residual error probability distributions. In contrast, the model using the computed electron affinity has a more variable residual error distribution with a significant number of outliers. The results suggest that a linear free energy model utilizing computed hydrogen transfer reaction free energy produces a more reliable prediction of the NAC abiotic reduction second order rate constant than previously available methods. The advantages of the proposed hydrogen atom transfer model and its mechanistic implications are discussed as well.</div>

Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA

1994 ◽  
Vol 59 (6) ◽  
pp. 1311-1318 ◽  
Author(s):  
Ladislav Svoboda ◽  
Petr Vořechovský
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sodium Perchlorate ◽  
Exchange Capacity ◽  
Chloride Ions ◽  
Point Of View ◽  
Alkaline Media ◽  
Ion Exchangers ◽  
Acidic Media ◽  
Cadmium And Lead

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

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