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.

scholarly journals Kinetics and Mechanism of Micellar Catalyzed Oxidation of Dextrose by N-Bromosuccinimide in H2SO4 Medium

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Minu Singh
Keyword(s):  
Fractional Order ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Kinetics And Mechanism ◽  
Stoichiometric Ratio ◽  
Product Analysis ◽  
Experimental Conditions ◽  
First Order ◽  
Order Dependence ◽  
Wide Range

Kinetics and mechanism of micellar catalyzed N-bromosuccinimide oxidation of dextrose in H2SO4 medium was investigated under pseudo-first-order condition temperature of 40°C. The results of the reactions studied over a wide range of experimental conditions show that NBS shows a first order dependence, fractional order, on dextrose and negative fractional order dependence on sulfuric acid. The determined stoichiometric ratio was 1 : 1 (dextrose : N-bromosuccinimide). The variation of Hg(OAC)2 and succinimide (reaction product) has insignificant effect on reaction rate. Effects of surfactants, added acrylonitrile, added salts, and solvent composition variation have been studied. The Arrhenius activation energy and other thermodynamic activation parameters are evaluated. The rate law has been derived on the basis of obtained data. A plausible mechanism has been proposed from the results of kinetic studies, reaction stoichiometry, and product analysis. The role of anionic and nonionic micelle was best explained by the Berezin’s model.

scholarly journals Non enzymatic NADH-dependent reduction of Cis-[Co(en)2(H2O)2]3+ in aqueous medium

2018 ◽  
Vol 6 (2) ◽  
pp. 163
Author(s):  
Bharati Behera ◽  
Jashoda Behera
Keyword(s):  
Electron Transfer ◽  
Aqueous Medium ◽  
Transfer Reaction ◽  
Activation Parameters ◽  
Electron Transfer Reaction ◽  
Transfer Reactions ◽  
Electron Transfer Reactions ◽  
First Order ◽  
Order Dependence ◽  
Kinetics Of

The kinetics of the electron transfer reaction of NADH with Cis-[Co(en)2(H2O)2]3+ has been studied over the range 1.0 ≤ 102 [NADH] ≤ 3.0 mol dm-3, 7.0 ≤ pH ≤ 8.0 and 200C ≤ t ≤ 350C in aqueous medium. The rate of electron transfer reaction was found to be first-order dependence each in [NADH]T and Cis-[Co(en)2(H2O)2]3+T. The products of the reaction were found to be NAD+ and Co(II). The corresponding activation parameters of the electron transfer reactions were found to be as ΔH#=27.55 kJ mol-1 and  ΔS#= -189.35 JK-1mol-1. 

scholarly journals Kinetics and mechanism of electron transfer to pyridinium chlorochromate (VI) from sulfur containing amino acid, L-cysteine in aqueous and micellar media

2011 ◽  
Vol 13 (2) ◽  
pp. 6-10 ◽  
Author(s):  
Sadhana Senapati ◽  
Smrutiprava Das ◽  
P. Mohanty ◽  
A. Patnaik
Keyword(s):  
Electron Transfer ◽  
Amino Acid ◽  
Transfer Reaction ◽  
Sodium Dodecyl ◽  
Electron Transfer Reaction ◽  
Kinetics And Mechanism ◽  
Pyridinium Chlorochromate ◽  
Activation Entropy ◽  
Micellar Media ◽  
Sulfur Containing

Kinetics and mechanism of electron transfer to pyridinium chlorochromate (VI) from sulfur containing amino acid, L-cysteine in aqueous and micellar media The electron transfer reaction of L-cysteine (RSH) with pyridinium chlorochromate (PCC) has been studied spectrophotometrically over the range 2.0 ≤ 103 [RSH] ≤ 6.0; 0.01 ≤ [H+] ≤ 0.2; 298 ≤ T ≤ 318 K and I = 0.3 mol dm-3 (NaClO4). The electron transfer reaction has also been carried out in the presence of anionic, cationic and neutral micelle. The reaction in acid medium is strongly catalyzed by changing [SDS]T (sodium dodecyl sulfate) up to 3 × 10-2 mol dm-3, beyond this concentration of SDS, the rate is retarded. The cationic and neutral micelle has a small effect on the rate. ΔH≠ (kJ mol-1) and ΔS≠ (JK-1 mol-1) values for the k1 and k2 paths are 30.20 ± 0.25, -159.65 ± 0.83 and 29.60 ± 0.62, -127.09 ± 2.17, respectively. The negative activation entropy is indicative of the ordered transition state for the electron transfer reaction. Formation of 2-amino-3-(2-amino-2-carboxy-ethyl) disulfanyl-propanoic acid as product is strongly supported by IR spectra.

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.

Substituent Effects in Electron Transfer Reactions: The Preparation and Chromium(II) Reduction of 3-Formylpentane-2,4-dionatobis(ethylenediamine)cobalt(III). Preparation of the Linkage Isomer 2-Acetylbutane-1,3-dionatobis(ethylenediamine)cobalt(III)

1975 ◽  
Vol 53 (8) ◽  
pp. 1154-1164 ◽  
Author(s):  
Robert J. Balahura ◽  
N. A. Lewis
Keyword(s):  
Electron Transfer ◽  
Acidic Solution ◽  
Substituent Effects ◽  
Activation Parameters ◽  
Transfer Reactions ◽  
Linkage Isomers ◽  
A Value ◽  
Parent Complex ◽  
Kinetics Of ◽  
Sphere Mechanism

The preparation of the linkage isomers, 3-formylpentane-2,4-dionatobis(ethylenediamine)cobalt(III), (1), and 2-acetylbutane-1,3-dionatobis(ethylenediamine)cobalt(III), (2), are described. The kinetics of the reaction of Cr(OH2)62+ with 1 and the parent complex, 2,4-pentanedionatobis(ethylenediamine)cobalt(III), (3), have been studied spectrophotometrically in acidic solution. For 1, the reduction is described by the rate law −d ln [Co(III)complex]/dt = k[Cr2+], and k = 0.0863 M−1 s−1 at 25 °C, μ = 1.0 M (LiClO4). The activation parameters for this reaction were found to be ΔH≠ = 9.9 ± 0.5 kcal mol−1 and ΔS≠ = −30 ± 3 e.u. The reaction proceeded by an inner-sphere mechanism and the product of this reaction was isolated and characterized as 2-acetylbutane-1,3-dionatotetraaquochromium(III). The linkage isomer of this complex was also prepared. The parent complex (3) was not reduced by Cr(OH2)62+ at an observable rate and an upper limit for the rate constant of this reaction was assigned a value of 10−4–10−6M−1s−1 at 25 °C. The ability of the formyl group to enhance the rate of electron transfer is discussed, and the chromium(II) reduction studies of related chelated systems are compared with the results obtained in this investigation.

Electron-Transfer Reactions in Non-Aqueous Media. V. Solvent Effects in the Reduction of CoN3(NH3)52+ by Iron(II)

1979 ◽  
Vol 32 (10) ◽  
pp. 2139 ◽  
Author(s):  
TJ Westcott ◽  
DW Watts
Keyword(s):  
Electron Transfer ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Transfer Reactions ◽  
Tetrahedral Coordination ◽  
First Order ◽  
Precursor Complex ◽  
Stage Process ◽  
Pseudo First Order ◽  
Reversible Formation

The reduction of CoN3(NH3)52+ by iron(II) is rate-determined by a two-stage process involving the reversible formation of an azide-bridged precursor complex prior to electron transfer in each of the solvents water, Me2SO, aqueous Me2SO and HCONMe2. The activation parameters in H2O and Me2SO, and the trends shown with increasing Me2SO concentrations in aqueous Me2SO, are similar to the properties of the previously studied CoCl(NH3)52+ and CoBr(NH3)52+ systems and contrast with the reduction of COF(NH3)52+. The results are consistent with a bridged precursor complex octahedral at both the iron and cobalt atoms in water but with tetrahedral coordination about the iron in Me2SO. In HCONMe2, as in the reduction of COF(NH3)52+, COCl(NH3)52+ and COBr(NH3)52+, the precursor complex is a significant part of the reacting solutions, and as a result the experimental pseudo-first-order rate constants for the loss of CoIII are not linearly dependent on the concentration of FeII. The initial spectra of the reacting solutions in this system also indicate significant concentrations of the precursor complex.

Kinetics of metribuzin degradation by colloidal manganese dioxide in absence and presence of surfactants

2014 ◽  
Vol 68 (1) ◽  
Author(s):  
Qamruzzaman ◽  
Abu Nasar
Keyword(s):  
Sodium Dodecyl ◽  
Oxidative Degradation ◽  
Activation Parameters ◽  
Water Soluble ◽  
Ionic Surfactant ◽  
Ammonium Bromide ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Colloidal Mno2 ◽  
Kinetics Of

AbstractThe kinetics of the degradation of metribuzin by water-soluble colloidal MnO2 in acidic medium (HClO4) were studied spectrophotometrically in the absence and presence of surfactants. The experiments were performed under pseudo-first-order reaction conditions in respect of MnO2. The degradation was observed to be of the first order in respect of MnO2 while of fractional order for both metribuzin and HClO4. The rate constant for the degradation of metribuzin was observed to decrease as the concentration of MnO2 increased. The anionic surfactant, sodium dodecyl sulphate (SDS), was observed to be ineffective whereas the non-ionic surfactant, Triton X-100 (TX-100), accelerated the reaction rate. However, the cationic surfactant, cetyltrimethyl ammonium bromide (CTAB), caused flocculation with oppositely-charged colloidal MnO2; hence further study was not possible. The catalytic effect of TX-100 was discussed in the light of the available mathematical model. The kinetic data were exploited to generate the various activation parameters for the oxidative degradation of metribuzin by colloidal MnO2 in the absence as well as the presence of the non-ionic surfactant, TX-100.

scholarly journals Kinetics and Mechanism of Oxidation of Diethanolamine and Triethanolamine by Potassium Ferrate

2011 ◽  
Vol 8 (2) ◽  
pp. 903-909 ◽  
Author(s):  
Shan Jinhuan ◽  
Zhang Jiying
Keyword(s):  
Activation Parameters ◽  
Rate Equations ◽  
Potassium Ferrate ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Order Dependence ◽  
Rate Determining Step ◽  
Thermodynamic Activation Parameters ◽  
Plausible Mechanism ◽  
Kinetics Of

The kinetics of oxidation of diethanolamine and triethanolamine by potassium ferrate(VI)in alkaline liquids at a constant ionic strength has been studied spectrophotometrically in the temperature range of 278.2K-293.2K. The reaction shows first order dependence on potassium ferrate(VI), first order dependence on each reductant, The observed rate constant (kobs) decreases with the increase in [OH-], the reaction is negative fraction order with respect to [OH-]. A plausible mechanism is proposed and the rate equations derived from the mechanism can explain all the experimental results. The rate constants of the rate-determining step and the thermodynamic activation parameters are calculated.

Kinetics and Mechanism of the Reaction of Dichlorotetraaquaruthenium(III) and Thiols

2012 ◽  
Vol 65 (2) ◽  
pp. 113 ◽  
Author(s):  
Suprava Nayak ◽  
Gouri Sankhar Brahma ◽  
K. Venugopal Reddy
Keyword(s):  
Electron Transfer ◽  
Ionic Strength ◽  
Equilibrium Constants ◽  
Activation Parameters ◽  
Kinetics And Mechanism ◽  
Intermediate Complex ◽  
Mechanism Of Formation ◽  
Temperature Range ◽  
Temperature Reduction ◽  
Mechanism Of The Reaction

The formation of an intermediate ruthenium(iii) thiolate complex by the interaction of thiols, RSH (R = glutathione and l-cysteine) and dichlorotetraaquaruthenium(iii), [RuIIICl2(H2O)4]+, is reported in the temperature range 25–40°C. The kinetics and mechanism of formation of the intermediate complex were studied as a function of [RuIIICl2(H2O)4]+, [RSH], pH, ionic strength and temperature. Reduction of the intermediate complex takes place slowly and results in the corresponding disulfides RSSR and [RuIICl2(H2O)4]+. The results are interpreted in terms of a mechanism involving a rate-determining inner-sphere one-electron transfer from RSH to the oxidant used in the present investigation and a comparison of rate and equilibrium constants is presented with activation parameters.

Sign in / Sign up

Export Citation Format

Share Document