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.

Distinguishing between outer-sphere and inner-sphere redox mechanism on the basis of the solvent effect

1980 ◽  
Vol 45 (12) ◽  
pp. 3266-3269 ◽  
Author(s):  
Ľudovít Treindl ◽  
Ľubica Adamčíková
Keyword(s):  
Redox Reactions ◽  
Reaction Rate ◽  
Molar Fraction ◽  
Kinetic Studies ◽  
Outer Sphere ◽  
Diagnostic Value ◽  
Tert Butanol ◽  
Influence Of Water ◽  
Water Alcohol ◽  
Sphere Mechanism

During kinetic studies of redox reactions of U3+ ions, we paid special attention to the influence of water-alcohol binary mixtures on the reaction rate. Kinetic data suggest that the water-tert-butanol system is of a high diagnostic value. The dependence of log kexp on the molar fraction of tert-butanol passes through a characteristic minimum in the case of an outer-sphere mechanism, whereas in the other case it decreases monotonously.

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 Penerapan Metode Sonikasi terhadap Adsorpsi Fe(III) pada Zeolit Alam Teraktivasi

ALCHEMY ◽  
2016 ◽  
Vol 5 (2) ◽  
pp. 63
Author(s):  
Zuri Rismiarti ◽  
Yuyun Yuniati ◽  
Rokiy Alfanaar
Keyword(s):  
Heavy Metal ◽  
Reaction Rate ◽  
Operation Time ◽  
Industrial Activity ◽  
Fe Content ◽  
Short Operation Time ◽  
Potential Impact ◽  
Sonication Technique ◽  
Influence Of Ph

<p>Iron (III) (Fe (III)) is widely used in the industry such us water treatment, the sugar cane, the concrete industry and coal mining. Industrial activity using Fe(III) has potential impact to environmental pollution problems due to that industry produces Fe waste that one of hazardous waste. Fe content excess might toxic effect to human health and the environment. Zeolite as adsorbent has been evaluated extensively for Fe and other heavy metal. Sonication method has been widely developed in polymer preparation. The method is more effective in operation time because the reaction rate increased and also more efficient on the usage of chemical reagens. The optimization of reaction time, the ratio of Fe(III) with activated zeolite, the influence of pH, and temperature has been assessed for Fe(III) adsorption with an activated zeolite by sonication technique. The formation of Fe(III)-SCN complex assay was used for determination of Fe(III) adsorbed by the activated zeolite with using spectrophotometer. The results showed a relatively short operation time (15 minutes), at pH of 4, temperature of  30 °C with the ratio of 1:50 (weight/volume) for the activated zeolite and Fe(III). </p>

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 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−.

Solvolysis rates in aqueous–organic mixed solvents. IX. Solvolysis of dichloroacetate ion in water–methanol solutions

1981 ◽  
Vol 59 (8) ◽  
pp. 1208-1211 ◽  
Author(s):  
El-Hussieny M. Diefallah ◽  
Mohamed A. Ashy ◽  
Ahmed O. Baghlaf
Keyword(s):  
Mole Fraction ◽  
Reaction Rate ◽  
Mixed Solvents ◽  
Activation Parameters ◽  
Solvent Structure ◽  
Temperature Range ◽  
Methanol Solutions ◽  
Aqueous Organic Mixed Solvents ◽  
Kinetics Of ◽  
Influence Of Solvent

The kinetics of the alkaline solvolysis of dichloroacetate ion in water–methanol solutions have been studied in the temperature range of 50.0 to 65.0 °C and the influence of solvent variation on reaction rate has been examined in terms of changes in the activation parameters. The activation parameters ΔH≠ and ΔS≠ for the solvolysis reaction showed a minimum at about 0.8 water mole fraction. The significance of the results was discussed in view of the electrostatic theory and the changing of solvent structure.

scholarly journals Alcohol-assisted base-free hydrogenation of acetophenone catalyzed by OsH(NHCMe2CMe2NH2)(PPh3)2

2014 ◽  
Vol 92 (8) ◽  
pp. 731-738 ◽  
Author(s):  
Sean E. Clapham ◽  
Marco Zimmer-De Iuliis ◽  
Katharina Mack ◽  
Demyan E. Prokopchuk ◽  
Robert H. Morris
Keyword(s):  
Reaction Rate ◽  
Catalyst Concentration ◽  
Initial Conditions ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Alcohol Concentration ◽  
Transfer Hydrogenation ◽  
Kinetic Isotope ◽  
Constant Rate

The hydrido–amido complex OsH(NHCMe2CMe2NH2)(PPh3)2 (1) catalyzes the base-free hydrogenation of ketones in benzene. Kinetic studies using acetophenone revealed that the system has an induction period, after which the rate of the reaction increases. A constant rate was observed when a critical amount of the product alcohol was added, indicating that the reaction is autocatalytic in 1-phenylethanol. Varying the initial conditions showed that the reaction rate is dependent on hydrogen and catalyst concentration and independent of ketone concentration. Above the critical concentrations of 1-phenylethanol, the reaction rate is independent of alcohol concentration. The rate law for pressures up to 5 atm was found to be rate = d[alcohol]/dt = −d[ketone]/dt = k[Os][H2], with k = 30 mol L−1 s−1 at 293 K and the temperature dependence provided energy of activation parameters. Therefore, the heterolytic splitting of dihydrogen is rate determining under these conditions. Only small kinetic isotope effects were measured in contrast with the analogous ruthenium system. Complex 1 reacts with the product alcohol 1-phenylethanol and is partially converted into the dihydride complex trans-OsH2(NH2CMe2CMe2NH2)(PPh3)2 and acetophenone; with excess alcohol, an osmium alkoxide is observed at low temperature. As expected from these results, 1 is a ketone transfer hydrogenation catalyst in isopropanol.

Kinetics and mechanism of oxidation of tartaric acid by bromate ions and an heterogeneous oscillation reaction of tartaric acid

1983 ◽  
Vol 48 (8) ◽  
pp. 2335-2342 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Olga Knappová
Keyword(s):  
Tartaric Acid ◽  
Rate Constant ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Reaction Rate Constant ◽  
Kinetics And Mechanism ◽  
Acid Solutions ◽  
Oscillation System ◽  
Oscillation Reaction ◽  
Mechanism Of Oxidation

The kinetics and mechanism of oxidation of tartaric acid by bromate ions in sulphuric acid solutions have been studied. As the relation between the concentration of H3O+ ions and the reaction rate constant indicates, the species involved in the reaction are protonized bromate ions (HBrO3) and tartaric acid molecules. Their interaction is of dipole-dipole nature, as borne out by measurements of the rate constant in dependence on the dielectric constant and on the ionic strength. The activation parameters and the stoichiometry of the reaction have been evaluated. An oscilation behaviour is observed in the presence of a Mn(II) catalyst if bromine is removed from the system constantly. The concentration ranges in which the oscillations occur have been established. Bromine is shown to play a major part in the heterogeneous oscillation system.

scholarly journals Kinetics and Mechanism of Electron Transfer to Heptavalent Manganese byDL-Aspartic Acid in Alkaline Aqueous and Micellar Media

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
M. Sanjana ◽  
A. K. Patnaik ◽  
S. K. Badamali ◽  
P. Mohanty
Keyword(s):  
Electron Transfer ◽  
Spectral Analysis ◽  
Aspartic Acid ◽  
Sodium Dodecyl ◽  
Activation Parameters ◽  
Kinetics And Mechanism ◽  
Micellar Media ◽  
First Order ◽  
Order Dependence ◽  
Sphere Mechanism

The kinetics and mechanism of the electron transfer ofdl-Aspartic acid (Asp) by Mn (VII) in alkaline medium has been studied spectrophotometrically over the range2.0≤103[Asp]≤5.0 mol dm−3;0.01≤[OH-]≤0.05 mol dm−3;298≤T≤318 K andI=0.05 mol dm−3(KNO3). The reaction exhibits first-order dependence in[MnO4-]Tbut shows fractional-order dependence in both[Asp]Tand[OH−]T. The reaction was studied in the presence of sodium dodecyl sulfate (SDS); an increase in the rate with the increase in the micellar concentration was observed. The products were characterized by spectral analysis. A mechanism involving free radicals is proposed. Asp bindsMnO4-to form a complex that subsequently decomposes to products. Activation parametersΔH° (kJ mol−1) andΔS° (JK−1 mol−1) for the reaction are5.62±0.35and−227.65±1.1, respectively. The negative value ofΔS° indicates that oxidation occurs via inner sphere mechanism.

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