The kinetics of isomerization of allylbenzene homogeneously catalysed by palladium(II) in acetic acid

1973 ◽  
Vol 26 (12) ◽  
pp. 2635 ◽  
Author(s):  
BI Cruikshank ◽  
NR Davies
Keyword(s):  
Acetic Acid ◽  
Catalytic Activity ◽  
Experimental Evidence ◽  
Active Catalyst ◽  
Bimolecular Reaction ◽  
Equilibrium System ◽  
Constant Concentration ◽  
First Order ◽  
Rate Determining Step ◽  
Kinetics Of

The changes in the kinetics observed during the isomerization of allylbenzene catalysed by palladium(II) are interpreted in terms of the slow formation of a hydrido complex of palladium(II) which subsequently attains a constant concentration in an equilibrium system. The kinetics during these phases are shown to be consistent with first-order dependence on the concentration of an active catalyst formed in a bimolecular reaction from a mononuclear palladium(II) complex and with a regenerative hydrido-π-alkene-σ-alkyl mechanism of isomerization. The hypothesis that a further stage in the kinetics reflects a change in the rate determining step to one involving alkene displacement from the catalyst is supported by the experimental evidence. The concentration of active catalyst is shown not to fall appreciably until all the allylbenzene has undergone isomerization, but thereafter there is a slow reduction of catalytic activity which is not completely restored by the addition of further allylbenzene. It is suggested that the slow formation of a π-allylic complex is responsible.

Kinetics of the Oxidation of Aliphatic Aldehydes by Chromic Acid

1971 ◽  
Vol 26 (5) ◽  
pp. 383-385 ◽  
Author(s):  
C. Goswami ◽  
K. K. Banerji
Keyword(s):  
Acetic Acid ◽  
Chromic Acid ◽  
Activation Parameters ◽  
Acid Oxidation ◽  
First Order ◽  
Chromic Acid Oxidation ◽  
Rate Determining Step ◽  
Reversible Formation ◽  
Kinetics Of ◽  
Chromate Ion

The kinetics of chromic acid oxidation of propanaldehyde, butyraldehyde and isobutyraldehyde in aq. acetic acid have been studied. The product of the oxidation is the corresponding carboxylic acid. The reaction is of first order with respect to each the acid chromate ion, HCrO4⊖, and the aldehyde but of second order to hydrogen ion. The rate increases with proportion of acetic acid in the solution. The activation parameters for the oxidation and enolisation reactions have been evaluated. The rate of enolisation under similar condition is less than that of oxidation. A mechanism in which the first step is the rapid reversible formation of a chromate ester followed by a hydrideion transfer in the rate determining step has been suggested.

Kinetics and Mechanism of Oxidation of Dimethyl Sulphoxide by Mono- and Di-Substituted N,N-Dichlorobenzenesulphonamides in Aqueous Acetic Acid

2003 ◽  
Vol 58 (8) ◽  
pp. 787-794 ◽  
Author(s):  
B.Thimme Gowda ◽  
K. L. Jayalakshmi ◽  
K. Jyothi
Keyword(s):  
Acetic Acid ◽  
Benzene Ring ◽  
Dimethyl Sulphoxide ◽  
Aqueous Acetic Acid ◽  
Isokinetic Temperature ◽  
Free Energies ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of

In an effort to introduce N,N-dichloroarylsulphonamides of different oxidising strengths, four mono- and five di-substituted N,N-dichlorobenzenesulphonamides are prepared, characterised and employed as oxidants for studying the kinetics of oxidation of dimethyl sulphoxide (DMSO) in 50% aqueous acetic acid. The reactions show first order kinetics in [oxidant], fractional to first order in [DMSO] and nearly zero order in [H+]. Increase in ionic strength of the medium slightly increases the rates, while decrease in dielectric constant of the medium decreases the rates. The results along with those of the oxidation of DMSO by N,N-dichlorobenzenesulphonamide and N,N-dichloro-4- methylbenzenesulphonamide have been analysed. Effective oxidising species of the oxidants employed in the present oxidations is Cl+ in different forms, released from the oxidants. Therefore the introduction of different substituent groups into the benzene ring of the oxidant is expected to affect the ability of the reagent to release Cl+ and hence its capacity to oxidise the substrate. Significant changes in the kinetic and thermodynamic data are observed in the present investigations with change of substituent in the benzene ring. The electron releasing groups such as CH3 inhibit the ease with which Cl+ is released from the oxidant, while electron-withdrawing groups such as Cl enhance this ability. The Hammett equation, log kobs = −3.19 + 1.05 σ , is found to be valid for oxidations by all the p-substituted N,N-dichlorobenzenesulphonamides. The substituent effect on the energy of activation, Ea and log A for the oxidations is also analysed. The enthalpies and free energies of activation correlate with an isokinetic temperature of 320 K.

Studies on the oxidative degradation of paracetamol by a μ-oxo-diiron(III) complex

2020 ◽  
Vol 98 (2) ◽  
pp. 98-105
Author(s):  
Bula Singh ◽  
Ranendu Sekhar Das
Keyword(s):  
Acetic Acid ◽  
Oxidative Degradation ◽  
Active Role ◽  
Order Reaction ◽  
Proton Abstraction ◽  
First Order ◽  
Initial Activation ◽  
Reaction Media ◽  
Kinetics Of ◽  
Reactivity Order

In higher organisms, metalloenzymes like cytochrome P450, containing a Fe(III) metal center, play an active role in metabolism of paracetamol (APAP). Here, we have chosen a mimicking μ-oxo-diiron complex, [Fe(III)2(μ-O)(phen)4(H2O)2]4+ (1, phen = 1,10-phenanthroline), to study spectrophotometrically the kinetics of the redox interactions with APAP. In acidic buffer media (pH = 3.4–5.1), APAP quantitatively reduces 1 following first-order reaction kinetics. Each molecule of 1 accepts two electrons from APAP and is reduced to ferroin [Fe(phen)3]2+. On oxidation, APAP produces N-acetyl-p-benzoquinone imine (NAPQI), which on hydrolysis results in a mixture of benzoquinone, quinone oxime, acetamide, and acetic acid. In reaction media due to successive deprotonations, 1 exists in equilibrium with the species [Fe(III)2(μ-O)(phen)4(H2O)(OH)]3+ (1a) and [Fe(III)2(μ-O)(phen)4(OH)2]2+ (1b) (pKa = 3.71 and 5.28, respectively). The kinetic analyses suggest for an unusual reactivity order as 1 < 1a ≫ 1b. The mechanistic possibilities suggest that although 1 is reduced by concerted electron transfer (ET) – proton transfer (PT) mechanism, 1a and 1b may be reduced by a concerted PT–ET mechanism where a slow proton-abstraction step is followed by a rapid ET process. It seems that the initial activation of the bridging μ-oxo group by a proton-abstraction results in the higher reactivity of 1a.

scholarly journals The thermal decomposition of acetaldehyde and the existence of different activated states

1933 ◽  
Vol 141 (843) ◽  
pp. 41-55 ◽  
Keyword(s):  
High Pressures ◽  
Initial Pressure ◽  
Bimolecular Reaction ◽  
Bimolecular Reactions ◽  
First Order ◽  
Straight Line ◽  
Gas Reactions ◽  
Pass Through ◽  
Low Pressures ◽  
Kinetics Of

Homogeneous thermal gas reactions were at one time tacitly assumed to possess a definite order, unimolecular and bimolecular reactions, for example, being sharply distinguished. The kinetics of the decomposition of acetalde­ hyde, CH 3 CHO = CH 4 + CO, over the pressure range of 100 to 400 mm. were found to satisfy the criterion of a bimolecular reaction, namely, that the reciprocal of the time for half change (1/ t 1/2 ) )plotted against the initial pressure ( p 0 ) gave a straight line inclined to the axes. The line, however, did not pass through the origin, as may be seen in fig. 1 of the present paper. This indicated the presence of some first order reaction, the nature of which was not determined. Subsequently, in accordance with the collision theory of activation and deactivation, it was shown that certain reactions, sometimes called quasiummolecular, change their order from the second at low pressures to the first at high pressures. This apparently was the reverse of the behaviour shown by acetaldehyde.

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.

Enantioselective hydrosilylation of tert-butyl phenyl ketone by diphenylsilane catalysed by [Rh{(-)-DIOP}2]+ClO4-

1980 ◽  
Vol 45 (10) ◽  
pp. 2808-2816 ◽  
Author(s):  
Ivan Kolb ◽  
Jiří Hetflejš
Keyword(s):  
Reaction Rates ◽  
Reaction Model ◽  
Rhodium Complex ◽  
Initial Reaction ◽  
Chiral Ligand ◽  
Title Reaction ◽  
First Order ◽  
Rate Determining Step ◽  
Phenyl Ketone ◽  
Kinetics Of

Kinetics of the title reaction has been studied by the method of initial reaction rates. In the presence of free chiral ligand the hydrosilylation was found to be first order in the catalyst and in the ketone and fractional order in the organosilicon hydride. The rate data and the results of spectroscopic study of interaction of diphenylsilane with the rhodium complex have been interpreted in terms of a reaction model involving formation of the corresponding cationic silyl(hydrido)rhodium complex followed by interaction of the ketone with this complex in the rate determining step. The results are confronted with those obtained for the analogous reaction catalysed by [Rh(1,5-COD)(-)-DIOP]+ClO4-.

Kinetics of Reactions of 8-Quinolinol and Acetate with Hydroxyaluminum Species in Aqueous Solutions. 1. Polynuclear Hydroxyaluminum Cations

1971 ◽  
Vol 49 (10) ◽  
pp. 1683-1687 ◽  
Author(s):  
R. C. Turner ◽  
Wan Sulaiman
Keyword(s):  
Acetic Acid ◽  
Rate Constant ◽  
Empirical Equation ◽  
Decomposition Reaction ◽  
Order Rate Constant ◽  
Acetate Concentration ◽  
First Order ◽  
Order Rate ◽  
Pseudo First Order ◽  
Kinetics Of

The effect of varying 8-quinolinol and acetate concentration on the rate of decomposition of poly-nuclear hydroxyaluminum cations was studied. It was found that the concentration of the undissociated 8-quinolinol and acetic acid molecules determined the magnitude of the first order rate constant for the decomposition of the polynuclear hydroxyaluminum cations, except when the acetate concentrations were relatively high. With high acetate concentrations, it appeared that polynuclear acetate species were involved in the reactions. An empirical equation was developed showing the effect of 8-quinolinol and acetic acid molecule concentrations on the pseudo first order rate constant for the decomposition reaction.

scholarly journals Kinetics of the Oxidation of methyl n-propyl ketone by manganese(III) sulphate

1971 ◽  
Vol 26 (1) ◽  
pp. 30-31 ◽  
Author(s):  
K. K. Banerji ◽  
P. Nath ◽  
G. V. Bakore
Keyword(s):  
Acetic Acid ◽  
Activation Parameters ◽  
Solvent Composition ◽  
Keto Form ◽  
First Order ◽  
Propyl Ketone ◽  
Kinetics Of

The oxidation of methyl n-propyl ketone by Mn (III) sulphate in aq. acetic acid is first order with respect to the ketone and Mn (III). The rate is independent of acidity and solvent composition. The activation parameters for oxidation and enolisation were evaluated. Oxidation is faster than enolisation under similar conditions. A mechanism involving an attack on the keto-form by Mn (III) is proposed.

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