scholarly journals Kinetic and Mechanistic Study of the Reduction of Chromium(VI) by Lactic Acid

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Jinhuan Shan ◽  
Fang Wang ◽  
Changying Song ◽  
Heye Wang
Keyword(s):  
Lactic Acid ◽  
Rate Constant ◽  
Activation Parameters ◽  
Mechanistic Study ◽  
First Order ◽  
Chromium Vi ◽  
Rate Determining Step ◽  
Probable Reaction Mechanism ◽  
Probable Reaction ◽  
Aqueous Acidic Medium

The kinetics and mechanism of the reduction of chromium(VI) by lactic acid (Lac) in aqueous acidic medium was studied with spectrophotometry in a temperature range of 298.15 K~313.15 K. Under the conditions of the pseudo-first order , the observed rate constant increased with the increase in [Lac] and . There is no salt effect. Based on the experimental results, a probable reaction mechanism of oxidation was proposed. The rate equation derived from the mechanism could explain all the experimental phenomena. Activation parameters along with rate constant of the rate-determining step have been evaluated.

scholarly journals Mechanistic Study on the Oxidation of 4-Hydroxycoumarin by Diperiodatonickelate(IV) in Aqueous Alkaline Medium

2009 ◽  
Vol 6 (3) ◽  
pp. 601-610 ◽  
Author(s):  
Ramesh S. Shettar ◽  
Nagaraj P. Shetti ◽  
Sharanappa T. Nandibewoor
Keyword(s):  
Alkaline Medium ◽  
Activation Parameters ◽  
Spot Test ◽  
Mechanistic Study ◽  
Slow Step ◽  
Thermodynamic Quantities ◽  
Aqueous Alkaline Medium ◽  
First Order ◽  
Rate Determining Step ◽  
Reaction Constants

The oxidation of 4-hydroxycoumarin (HDC) by diperiodato- nickelate(IV) (DPN) in aqueous alkaline medium at a constant ionic strength of 1.0 mol dm-3was studied spectrophotometrically at 298 K. The reaction between DPN and 4-hydroxycoumarin in alkaline medium exhibits 1:3 stoichiometry (HDC: DPN). The reaction is of first order in [DPN] and has less than unit order in [HDC] and fractional order in [alkali]. The oxidation reaction in alkaline medium has been shown to proceed via a DPN- 4-hydroxycoumarin complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main products were identified by spot test, IR,1HNMR studies. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed and thermodynamic quantities were also determined.

scholarly journals Kinetics and Mechanistic Study of Cetyltrimethylammonium Bromide Catalyzed Oxidation of Tetraethylene Glycol byN-Chlorosaccharin in Acidic Medium

2008 ◽  
Vol 5 (3) ◽  
pp. 598-606
Author(s):  
Vandana Sharma ◽  
K. V. Sharma ◽  
V. W. Bhagwat
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Mechanistic Study ◽  
Tetraethylene Glycol ◽  
Aqueous Acetic Acid ◽  
Acetic Acid Medium ◽  
First Order ◽  
Dielectric Effect ◽  
Catalyzed Oxidation

The kinetics and mechanism of cetyltrimethylammonium bromide catalyzed oxidation of tetraethylene glycol [2,2'-(oxibis(ethylenoxy)diethanol)] byN-chlorosaccharin in aqueous acetic acid medium in presence of perchloric acid have been investigated at 323K. The reaction is first order dependence on Nchlorosaccharin. The reaction rate follows first order kinetics with respect to [tetraethylene glycol] with excess concentration of other reactants. The miceller effect due to cetyltrimethylammonium bromide, a cationic surfactant has been studied. The change in ionic strength shows negligible salt effect. The dielectric effect is found to be positive. Addition of one of the products (saccharin) retards the reaction rate. Activation parameters are calculated from the Arrhenious plot. A possible mechanism consistent with the experimental results has been proposed.

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 of the Substitution of Norbornadiene in Tetracarbonyl(norbomadiene)molybdenum(0) by 2,2'-Bipyridine

2001 ◽  
Vol 56 (3) ◽  
pp. 281-286 ◽  
Author(s):  
Ceyhan Kayran ◽  
Eser Okan
Keyword(s):  
Reaction Rate ◽  
Activation Parameters ◽  
Bipy Ligand ◽  
First Order ◽  
Rate Determining Step ◽  
Vis Spectroscopy ◽  
Different Temperatures ◽  
Ft Ir ◽  
Thermal Substitution ◽  
Kinetics Of

Abstract The kinetics of the thermal substitution of norbornadiene (nbd) by 2,2'-bipyridine (2,2'-bipy) in (CO)4Mo(C7H9) was studied by quantitative FT-IR and UV-VIS spectroscopy. The reaction rate exhibits first-order dependence on the concentration of the starting complex, and the observed rate constant depends on the concentration of both leaving nbd and entering 2,2'-bipy ligand. The mechanism was found to be consistent with the previously proposed one, where the rate determining step is the cleavage of one of the two Mo-olefin bonds. The reaction was performed at four different temperatures (35 -50 °C) and the evaluation of the kinetic data gives the activation parameters which now support states.

scholarly journals KINETICS OF REACTION BETWEEN MALACHITE GREEN AND HYDROXYL ION IN THE PRESENCE OF REDUCING SUGARS

2015 ◽  
Vol 23 (23) ◽  
pp. 61-72
Author(s):  
Dayo Felix Latona ◽  
Adewumi Oluwasogo Dada
Keyword(s):  
Malachite Green ◽  
Activation Parameters ◽  
Cell Compartment ◽  
First Order ◽  
Rate Determining Step ◽  
First Order Kinetics ◽  
Hydroxyl Ion ◽  
Kinetics Of Reaction ◽  
Kinetics Of ◽  
Sphere Mechanism

The reaction was studied via pseudo-first-order kinetics using a UV-1800 Shimadzu spectrophotometer with a thermostated cell compartment and interfaced with a computer. The reaction showed first order with respect to malachite green and sugar and hydroxyl ion concentrations. However, the reaction was independent of ionic strength and showed no dependence on the salt effect, indicating an inner sphere mechanism for the reaction. There was no polymerization of the reaction mixture with acrylonitrile, indicating the absence of radicals in the course of the reaction. Michaelis-Menten plot indicated the presence of a reaction intermediate in the rate-determining step. The activation parameters of the reaction have been calculated and products were elucidated by FTIR spectroscopy. The stoichiometry of the reaction is 1:1. A mechanism consistent with the above facts has been suggested.

scholarly journals Degradation of chlorinated benzaldehydes in aqueous solutions by UV-irradiation

2002 ◽  
Vol 4 (4) ◽  
pp. 133-139 ◽  
Author(s):  
Miray Bekbölet ◽  
Nikola Getoff
Keyword(s):  
Aqueous Solutions ◽  
Hplc Analysis ◽  
Degradation Rate ◽  
Uv Light ◽  
Order Reaction ◽  
Quantum Yields ◽  
Homolytic Cleavage ◽  
First Order ◽  
Probable Reaction Mechanism ◽  
Probable Reaction

Photoinduced degradation of chlorinated benzaldehydes was investigated using UV light with λ = 253.7 nm in aerated aqueous solutions. Substrate degradation rate as expressed by first order reaction kinetics revealed rate constants, k;7.45×10−3min-1,3.90×10−3min-1and3.90×11−2min-1for 2- chlorobenzaldehyde, 3-chlorobenzaldehyde and 4-chlorobenzaldehyde respectively. The decomposition of the substrates was related to the formation of chloride and formaldehyde by homolytic cleavage processes. initial quantum yields and photochemical “GiPH-values” are reported for the degradation of the substrates. Based on the qualitative HPLC analysis, a probable reaction mechanism for the photoinduced degradation of chlorinated benzaldehydes is also presented.

Kinetics and mechanism of oxidation of lactic acid by KMnO4 in H2SO4 medium

1985 ◽  
Vol 63 (12) ◽  
pp. 3317-3321 ◽  
Author(s):  
M. M. Girgis ◽  
S. A. El-Shatoury ◽  
Z. H. Khalil
Keyword(s):  
Lactic Acid ◽  
Oxidation Rate ◽  
Arrhenius Equation ◽  
Activation Parameters ◽  
Initial Oxidation ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Acid Catalyzed ◽  
Mechanism Of Oxidation ◽  
Kinetics Of

The initial oxidation stages of lactic acid by acid permanganate were investigated. The rate of the induction period was slow and then gradually increased. The kinetics of oxidation were second order, first order with respect to both lactic acid and Mn(VII). The reaction was acid catalyzed. Addition of Mn(II) ions largely increased the rate of the initial stages and decreased the rate of the following stages. The oxidation rate was decreased by the addition of F− or [Formula: see text] ions. The Arrhenius equation was valid for the reaction between 16.5 and 34 °C. Activation parameters were evaluated and a mechanism consistent with the results obtained was proposed.

scholarly journals Kinetic Isotope Effects in the Chromium(VI) Oxidation of Bicyclic Alcohols

1999 ◽  
Vol 23 (2) ◽  
pp. 146-147
Author(s):  
J. Hodge Markgraf ◽  
Jordan S. Dubow ◽  
Jessica A. Charland ◽  
Elliott H. Sohn
Keyword(s):  
Rate Constants ◽  
Acidic Solution ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Kinetic Isotope Effects ◽  
Secondary Alcohols ◽  
First Order ◽  
Chromium Vi ◽  
Kinetic Isotope ◽  
Pseudo First Order

Pseudo first-order rate constants are determined for the oxidation of a series of secondary alcohols and their monodeutero analogues by ammonium chromate in aqueous acidic solution at several temperatures; the relative rates and activation parameters are consistent with a cyclic, symmetrical transition state.

scholarly journals The carboxybiotin complex of chicken liver pyruvate carboxylase. A kinetic analysis of the effects of acetyl-CoA, Mg2+ ions and temperature on its stability and on its reaction with 2-oxobutyrate

1986 ◽  
Vol 235 (2) ◽  
pp. 359-364 ◽  
Author(s):  
P V Attwood ◽  
J C Wallace
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Protein Conformation ◽  
Pyruvate Carboxylase ◽  
Activation Parameters ◽  
Slow Phase ◽  
Acetyl Coa ◽  
First Order ◽  
Thermodynamic Activation Parameters ◽  
Pseudo First Order

The enzyme-[14C]carboxybiotin complex of chicken liver pyruvate carboxylase has been isolated and shown to be relatively stable, with a half-life at 0 degree C of 342 min. The kinetic properties of the decay of this complex, in both the presence and the absence of the substrate analogue, 2-oxobutyrate, have been examined. The data for the reaction with 2-oxobutyrate at 0 degree C fitted a biphasic exponential decay curve, enabling the calculation of rate constants for both the fast and slow phases of the reaction at this temperature. The effect of temperature on the observed pseudo-first-order rate constant for the slow phase of the reaction with 2-oxobutyrate, and that for the decay of the enzyme-[14C]carboxybiotin complex alone, have been examined. Arrhenius plots of these data revealed that the processes being studied in each type of experiment were single reactions represented by one rate constant in each case. For the decay of the enzyme-[14C]carboxybiotin complex in the absence of 2-oxobutyrate, the rate-determining process may be the movement of carboxybiotin from the site of the first partial reaction to the site of the second. The calculated thermodynamic activation parameters indicate that this reaction is accompanied by a large change in protein conformation. With 2-oxobutyrate present, the observed process in the slow phase of the reaction was probably the dissociation of the carboxybiotin from the first subsite. Here, the activation parameters suggest that a much smaller change in protein conformation accompanies this reaction. Both sets of experiments were also performed in the presence of acetyl-CoA, but this activator had little effect on the measured thermodynamic activation parameters. However, in both cases the observed pseudo-first-order rate constants in the presence of acetyl-CoA were about 75% of those in its absence. The effects of Mg2+ on the reaction kinetics of the enzyme-[14C]carboxybiotin complex with 2-oxobutyrate were similar to those observed with the sheep enzyme by Goodall, Baldwin, Wallace & Keech [(1981) Biochem. J. 199, 603-609].

Reduction of chromate by molybdenum hydrogen bronze

2016 ◽  
Vol 94 (4) ◽  
pp. 401-405 ◽  
Author(s):  
Kevin N. Barber ◽  
Cory K. Perkins ◽  
Allen W. Apblett
Keyword(s):  
Aqueous Solution ◽  
Rate Constant ◽  
Redox Process ◽  
Acidic Ph ◽  
Chromium Species ◽  
First Order ◽  
Chromium Vi ◽  
Equilibrium Process ◽  
Weakly Dependent ◽  
Rapid Adsorption

Molybdenum hydrogen bronze, H0.57MoO3, is capable of removing up to 80 mequiv./g chromate from aqueous solution. The redox process is accompanied by adsorption of the reduced chromium species so that the chromium is completely removed from solution. Chromate removal was only weakly dependent on pH, being slightly favored at acidic pH. The kinetics appear to involve the rapid adsorption of chromate in an equilibrium process that is followed by reduction of the chromium(VI). The rate constant was found to be first order in chromate and the amount of suspended H0.57MoO3 with a rate constant of 1.40 L g−1 min−1.

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