Kinetics and mechanism of the osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(III) ion

1968 ◽  
Vol 21 (12) ◽  
pp. 2913 ◽  
Author(s):  
NP Singh ◽  
VN Singh ◽  
MP Singh
Keyword(s):  
Benzoic Acid ◽  
Oxidation Product ◽  
Osmium Tetroxide ◽  
Reaction Rate ◽  
Zero Order ◽  
Ion Concentration ◽  
First Order ◽  
First Order Kinetics ◽  
Catalysed Oxidation ◽  
Hydroxyl Ion

The osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(111) ion has been studied kinetically. The reaction rate has been found to be independent of hexacyanoferrate(111) ion while the order with respect to both osmium tetroxide and mandelate ion comes out to be unity. The reaction rate follows first-order kinetics at low hydroxyl ion concentration and becomes zero order at higher concentrations. The course of the reaction has been considered to proceed through the formation of an activated mandelate-OsO4, complex which decomposes in alkaline medium giving reduced osmium(V1) followed by a fast oxidation by hexacyanoferrate(111) ion. The probable course of the reactions is also described with the help of its oxidation product, benzoic acid.

Mechanism of Hg(II) Oxidation of D-Galactose in Alkaline Medium

1978 ◽  
Vol 33 (6) ◽  
pp. 657-659 ◽  
Author(s):  
M. P. Singh ◽  
A. K. Singh ◽  
Mandhir Kumar
Keyword(s):  
Alkaline Medium ◽  
Reaction Rate ◽  
Reducing Sugar ◽  
Zero Order ◽  
Ion Concentration ◽  
Kinetics Of Oxidation ◽  
Ion Concentrations ◽  
First Order ◽  
Kinetics Of ◽  
Direct Proportionality

Abstract The present paper deals with the kinetics of oxidation of D-galactose by Nessler's reagent in alkaline medium. The reaction is zero order with respect to Hg(II) and first order with respect to reducing sugar. The direct proportionality of the reaction rate at low hydroxide ion concentrations shows retarding trend at higher concentrations. The reaction rate is inversely proportional to iodide ion concentration. A mechanism has been proposed taking HgI3- as the reacting species

scholarly journals Kinetics and Mechanism of Oxidation of Malic Acid by N-Bromonicotinamide (NBN) in the Presence of a Micellar System

2015 ◽  
Vol 52 ◽  
pp. 111-119
Author(s):  
L. Pushpalatha
Keyword(s):  
Malic Acid ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Zero Order ◽  
Micellar System ◽  
First Order ◽  
First Order Kinetics ◽  
Rate Of Reaction ◽  
Different Temperatures ◽  
Experimental Findings

The oxidation of malic acid by N-bromonicotinamide in the presence of micellar system is studied. First order kinetics with respect to NBN is observed. The kinetics results indicate that the first order kinetics in hydroxy acid at lower concentrations tends towards a zero order at its higher concentrations. Inverse fractional order in [H+] and [nicotinamide] are noted throughout its tenfold variation. Variation of [Hg (OAc)2] and ionic strength of the medium do not bring about any significant change in the rate of reaction. Rate of the reaction increases with a decrease in the percentage of acetic acid. Decrease in the rate constant was observed with the increase in [SDS]. The values of rate constants observed at four different temperatures were utilized to calculate the activation parameters. A suitable mechanism consistent with the experimental findings has been proposed.

Ag nanoparticles stabilized on cubic polyhedral oligomeric silsesquioxane cross-linked poly(N-isopropyl acrylamide-co-itaconic acid): An efficient catalyst for 4-nitrophenol reduction

2020 ◽  
Vol 13 (07) ◽  
pp. 2051040
Author(s):  
Vahid Rahimkhoei ◽  
Ali Akbari ◽  
Maryam Zirak ◽  
Bagher Eftekhari-Sis
Keyword(s):  
Itaconic Acid ◽  
Ag Nanoparticles ◽  
Zero Order ◽  
Polymeric Support ◽  
Efficient Catalyst ◽  
First Order ◽  
First Order Kinetics ◽  
Isopropyl Acrylamide ◽  
Nitrophenol Reduction ◽  
Oligomeric Silsesquioxane

Ag nanoparticles were synthesized and stabilized on a polymeric support, poly([Formula: see text]-isopropyl acrylamide-co-itaconic acid)/POSS, by simply reducing Ag[Formula: see text] ions adsorbed in the interior of the polymeric network. The prepared Ag@p(NIPAM-IA)/POSS was used as an efficient and recyclable catalyst for removal of the 4-nitrophenol (4-NP) contaminant by NaBH4-induced reduction to 4-aminophenol (4-AP) in aqueous solution. Different conditions including Ag content and amount of the nanocomposite, and also temperature of the 4-NP reduction were investigated. Also, two kinetic models, zero-order and first-order kinetics, were studied for the reduction of 4-NP to 4-AP.

Parameters Effect on Photocatalytic Reduction Kinetics of Bromate in Aqueous Dispersion of TiO2

2013 ◽  
Vol 779-780 ◽  
pp. 1658-1665
Author(s):  
Rong Shu Zhu ◽  
Fei Tian ◽  
Ling Ling Zhang ◽  
Ling Min Yu
Keyword(s):  
Aqueous Dispersion ◽  
Zero Order ◽  
Photocatalytic Reduction ◽  
Reduction Kinetics ◽  
First Order ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Experimental Parameters ◽  
Pseudo First Order ◽  
Kinetics Of

This paper studied the photocatalytic reduction kinetics of bromate in aqueous dispersion of TiO2 and investigated the effects of experimental parameters, including initial concentration of BrO3-, pH, TiO2 dosage, anion and cation. The results indicate that the process of photocatalytic reduction of bromate follows a zero-order kinetics. In all the investigated experimental parameters, the initial bromate concentration, pH and anion have great effect on the photocatalytic reduction kinetics. The processes of photocatalytic reduction of bromate show the pseudo first-order kinetics at initial bromate concentration of 0.39 μmolL-1, pH=5.0, or in presence of HCO3-/CO32-, NO3-, SO42-, respectively.

scholarly journals Occurrence and Some Characterization Studies of Invertase in the Green Plantain Fruit (Musa parasidiaca)

1969 ◽  
Vol 46 (2) ◽  
pp. 120-126
Author(s):  
Betty G. García
Keyword(s):  
Crude Protein ◽  
Reaction Rate ◽  
Order Reaction ◽  
Zero Order ◽  
Optimum Temperature ◽  
First Order ◽  
Sucrose Solutions ◽  
Optimum Ph ◽  
Characterization Studies ◽  
Substrate Concentrations

The crude-protein fraction of green plantains was isolated and found to cause an inversion of sucrose solutions. The rate of inversion of sucrose by the invertase of the green plantain is proportional to the concentration of enzyme. The inversion of sucrose, when catalyzed by green-plantain invertase, appears to follow a first-order reaction rate at low substrate concentrations (below 6 percent). As the concentration of sucrose exceeds 6 percent the rate of the reaction changes to zero order. An optimum pH of 4.15 and an optimum temperature of 44.4° C. were obtained for the activity of green-plantain invertase.

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.

Use of purified lyophilized human lactate dehydrogenase isoenzymes in a study of the measurement of lactate dehydrogenase activity.

1986 ◽  
Vol 32 (5) ◽  
pp. 758-762 ◽  
Author(s):  
D A Smith ◽  
G C Moses ◽  
A R Henderson
Keyword(s):  
Lactate Dehydrogenase ◽  
Zero Order ◽  
Lactate Dehydrogenase Activity ◽  
First Order ◽  
First Order Kinetics ◽  
Activity Concentrations ◽  
Zero Order Kinetics ◽  
Specific Activities ◽  
The Stability ◽  
Lactate Dehydrogenase Isoenzymes

Abstract We examined the stability of human lactate dehydrogenase (EC 1.1.1.27; LD) isoenzymes 1, 2, and 3--purified to specific activities of about 200 kU/g--when lyophilized in a buffered stabilized matrix of bovine albumin. Each isoenzyme was prepared at two activity concentrations and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. LD-1 activity decayed with zero-order kinetics, LD-2 and LD-3 with first-order kinetics. The extrapolated half-lives of these preparations at -20 degrees C varied between 80 and 530 years. Stability of reconstituted samples stored at 4 degrees C was excellent for LD-1 but poor for LD-2 and LD-3. We suggest that preparations of human LD-1 be further investigated as a possible reference material.

The 4,4'-dimethoxytrityl carbenium ion by ionization of 4,4'-dimethoxytrityl alcohol in acetonitrile - aqueous perchloric and nitric acids containing electrolytes: kinetics, equilibria, and ion-pair formation

1999 ◽  
Vol 77 (5-6) ◽  
pp. 530-536 ◽  
Author(s):  
Juan Crugeiras ◽  
Howard Maskill
Keyword(s):  
Rate Constant ◽  
Perchloric Acid ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Ion Pair ◽  
Ion Concentration ◽  
Forward Rate ◽  
First Order ◽  
Hydronium Ion ◽  
Carbenium Ion

We have studied the equilibration shown in eq. [3] of 4,4prime-dimethoxytrityl alcohol in aqueous perchloric and nitric acids containing low proportions of acetonitrile using stopped-flow kinetics techniques. The rate constants for the overall progress to equilibrium, kobs, have been resolved into forward and reverse components using the equilibrium UV absorbance and a value for the molar absorptivity of the 4,4prime-dimethoxytrityl carbenium ion determined in concentrated aqueous perchloric acid. The forward reaction (rate constant kf) is first order in both the alcohol and the acid concentrations; the reverse reaction (rate constant kr) is pseudo first order with respect to the carbocation. At constant hydronium ion concentration, the forward rate constant increases linearly with the concentration of electrolyte, whereas the reverse rate constant decreases. These effects depend upon the nature of the anion, but not the cation, and are not ionic strength effects. At constant anion concentrations, kf in both acids, and kr in perchloric acid, are independent of hydronium ion concentration; however, kr decreases with increasing hydronium ion concentration at constant nitrate concentration. At nonconstant ionic strength, changes in kf and kr observed in increasing concentrations of perchloric acid are attributable wholly to changes in perchlorate concentration. A mechanism is proposed which involves pre-equilibrium protonation of the alcohol, heterolysis of the protonated alcohol to give a 4,4prime-dimethoxytrityl carbenium ion - water ion-molecule pair, then conversion of this into a dissociated carbenium ion in equilibrium with ion pairs. To account for the strong effects of perchlorate and nitrate upon the forward rate constants, it is proposed that these anions provide additional reaction channels from the ion-molecule pair. However, we find no evidence of acid catalysis in the reaction of the ion-molecule pair (in contrast to our finding for the reaction of the corresponding ion-molecule pair formed from dimethoxytritylamine in acidic media). Some of the elementary rate and equilibrium constants of the proposed mechanism have been evaluated.Key words: trityl, carbenium ion, stopped-flow, ion pair, ion-molecule pair.

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