scholarly journals KINETICS OF OXIDATION WITH HYDROGEN PEROXIDE AND IRON(II) COMPLEX WITH A MACROCYCLIC BINUCLEATING LIGAND

1995 ◽  
Vol 3 (3) ◽  
pp. 55-62
Author(s):  
Lourdes T. Kist ◽  
Bruno Szpoganicz ◽  
Manuel G. Basallote ◽  
Maria J. F. Trujillo ◽  
Maria A. Mariez
Keyword(s):  
Hydrogen Peroxide ◽  
Macrocyclic Ligand ◽  
Kinetic Studies ◽  
Organic Substrates ◽  
Kinetics Of Oxidation ◽  
Oxidation Processes ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
Catalyzed Oxidation

In the present study solutions of a complex of Fe(II) with a macrocyclic ligand were prepared and their oxidation kinetics with hydrogen peroxide examined. The kinetic studies of the oxidation processes lead to values of rate constant of two-step which occur via first-order kinetics. The results are expected to result in a better knowledge of the mechanism of H202 activation in catalyzed oxidation of organic substrates.

scholarly journals Kinetics of Oxidation of Cobalt(III) Complexes ofaAcids by Hydrogen Peroxide in the Presence of Surfactants

2008 ◽  
Vol 5 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Mansur Ahmed ◽  
K. Subramani
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transfer ◽  
Bond Cleavage ◽  
Micellar Medium ◽  
Hydroxy Acids ◽  
Peroxide Oxidation ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of

Hydrogen peroxide oxidation of pentaamminecobalt(III) complexes ofα-hydroxy acids at 35°C in micellar medium has been attempted. In this reaction the rate of oxidation shows first order kinetics each in [cobalt(III)] and [H2O2]. Hydrogen peroxide induced electron transfer in [(NH3)5CoIII-L]2+complexes ofα-hydroxy acids readily yields 100% of cobalt(II) with nearly 100% of C-C bond cleavage products suggesting that it behaves mainly as one equivalent oxidant in micellar medium. With unbound ligand also it behaves only as C-C cleavage agent rather than C-H cleavage agent. With increasing micellar concentration an increase in the rate is observed.

Kinetics of oxidation of hydrogen peroxide and ascorbic acid by a tribridged manganese(IV,IV) dimer in feebly acidic media

1999 ◽  
Vol 77 (4) ◽  
pp. 451-458 ◽  
Author(s):  
Anup Kumar Bhattacharya ◽  
Anath Bondhu Mondal ◽  
Anadi C Dash ◽  
G S Brahma ◽  
Rupendranath Banerjee
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Dehydroascorbic Acid ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetic Activity ◽  
First Order Kinetics ◽  
Oxidation Of Hydrogen ◽  
Kinetics Of ◽  
Complex Ion

In weakly acidic, aqueous buffer (MeCO2-+ bipy), the complex ion [Mn2IV(μ-O)2(μ-MeCO2)(bipy)2(H2O)2]3+, 1 (bipy = 2,2prime-bipyridine), coexists in rapid equilibrium with its hydrolytic derivatives, [Mn2IV(μ-O)2(bipy)2(H2O)4]4+, 2, and [Mn2IV(μ-O)2(μ-MeCO2)(bipy)(H2O)4]3+, 3. The solution quantitatively oxidizes hydrogen peroxide to oxygen and ascorbic acid to dehydroascorbic acid, itself being reduced to MnII. In the presence of excess reductant, the reactions follow simple first-order kinetics with no evidence for the accumulation of a significant amount of any intermediate manganese complex. The ascorbate anion shows overwhelming kinetic dominance over ascorbic acid, but no evidence is available for deprotonation of hydrogen peroxide. The preferred intimate mechanism for hydrogen peroxide is inner sphere but that for ascorbic acid is uncertain. For both reductants, increased extent of aquation leads to increased kinetic activity in the order: 1 < 2 < 3.Key words: kinetics, manganese, ascorbic acid, hydrogen peroxide, 2,2prime-bipyridine.

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.

scholarly journals Kinetics and Mechanism of Oxidation oft-Butylbenzylamine by Diperiodatoargentate(III) in Aqueous Alkali

2012 ◽  
Vol 9 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Mahantesh A. Angadi ◽  
Suresh M. Tuwar
Keyword(s):  
Kinetic Studies ◽  
Active Species ◽  
Alkali Concentration ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Middle Range ◽  
Wide Range ◽  
Rate Of Reaction ◽  
Mechanism Of Oxidation ◽  
Kinetics Of

t-Butylbenzylamine (t-BA) is used as a free base in the synthesis of salbutamol drug. Its mechanism of oxidation was proposed from kinetic studies. The kinetics of oxidation oft-butylbenzylamine by diperiodatoargentate(III) (DPA) was studied spectrophotometrically by monitoring decrease in absorbance of DPA. The reaction was found to be first order each in [DPA] and [t-BA]. The effect of alkali concentration in a wide range on rate of reaction was studied. The rate of reaction was found to be increased with increase in [OH–] in the lower range of [OH–], decreasing effect in the middle range and at higher range again increasing effect on rate of reaction was observed. The added periodate retarded the rate of reaction. The polymerization test revealed that oxidation was occurred with the intervention free radical. A suitable mechanism was proposed for a middle range of [OH–]. The active species of silver(III) periodate for all the three different stages of [OH–] are assayed. Rate law was derived and verified. The oxidative product oft-BA was characterized by LC-ESI-MS spectra.

Investigations into the kinetics and stoichiometry of bacterial oxidation of covellite (CuS) using a polarographic oxygen probe

1978 ◽  
Vol 24 (8) ◽  
pp. 998-1003 ◽  
Author(s):  
Pamela A. D. Rickard ◽  
Donald G. Vanselow
Keyword(s):  
Oxygen Uptake Rate ◽  
Zero Order ◽  
Bacterial Oxidation ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Cupric Ion ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Cupric Sulphate ◽  
Kinetics Of

"Oxygraph" apparatus was used to measure quantitatively the kinetics of oxidation of synthetic covellite (CuS) in the presence and absence of Thiobacillus species. The expected stoichiometric relationship between oxygen consumed and cupric sulphate produced was verified by atomic absorption assays of cupric ion and sulphate ion. Thiobacillus cultures markedly increased the oxidation rate.The dependence of each oxygen-uptake rate on oxygen concentration was also measured. Sterile controls and some bacterial cultures showed first-order kinetics while other cultures showed zero-order kinetics.Addition of biological inhibitors to reacting slurries revealed that cultures showing first-order kinetics did not oxidize CuS itself but merely oxidized elemental sulphur formed by non-enzymic oxidation of CuS. Cultures showing zero-order kinetics oxidized CuS in a way that resulted in all oxygen reduction being enzymic. This mechanism possibly involves the cyclic oxidation and reduction of soluble iron.

scholarly journals Kinetics and Mechanism of Catalyzed Oxidation of L-Cysteine by Salen Schiff Base Complexes of Co(III), Fe (III) and Cr(III)

2021 ◽  
Vol 13 (2) ◽  
pp. 25
Author(s):  
Hamzeh M. Abdel-Halim ◽  
Hutaf M. Baker ◽  
Akef I. Alhmaideen ◽  
Adnan S. Abu-Surrah
Keyword(s):  
Schiff Base ◽  
Metal Ion ◽  
Reduction Potential ◽  
Order Conditions ◽  
Schiff Base Complexes ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Constant Ph ◽  
Kinetics Of ◽  
Catalyzed Oxidation

Kinetics of oxidation of L-cysteine by new series of substituted ONNO-donor salen-type Schiff base complexes of general formula [MIII(L)Cl] (M = Co, Fe, Cr; L = Schiff base ligand) have been studied in aqueous solutions. Measurements were run at constant temperature (25&ordm; C), constant ionic strength (0.20 M), and constant pH (7.0) under pseudo-first order conditions, in which the concentration of cysteine is around two orders of magnitude greater than that of metal complex. The observed rate constant was determined by following the change in absorbance of reaction mixture at a predetermined wavelength with time. Results show that the rate of oxidation depends on the type of metal center, with Co(III) complexes were found to have the highest rates due to higher reduction potential of Co(III). The oxidation rate was also found to depend on steric factor and the electron withdrawing / releasing ability of the ligand bound to the metal ion.

Oxidation of the mercurous ion by peroxidase

1986 ◽  
Vol 64 (5) ◽  
pp. 969-972 ◽  
Author(s):  
Donald C. Wigfield ◽  
Season Tse
Keyword(s):  
Elemental Mercury ◽  
Order Rate Constant ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Order Rate ◽  
First Order Kinetics ◽  
Cold Vapour ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Mercurous Ion

The kinetics of oxidation of the mercurous ion by peroxidase have been measured by following the disappearance of mercurous ion using cold-vapour atomic absorption spectroscopy. Pseudo-first-order kinetics are observed with respect to mercurous ion, and the pseudo-first-order rate constants are linearly related to peroxidase concentration, showing first-order dependence on peroxidase. This behaviour is identical to oxidation of elemental mercury, and the second-order rate constant, 1.44 × 104 M−1 s−1 at 23 °C, is also, within experimental error, the same as that for elemental mercury oxidation. The data are interpreted in terms of peroxidase-induced disproportionation of the mercurous dimer, followed by two-electron oxidation of zero-valent mercury.

scholarly journals The Kinetics of Basic Dye Removal Using Palm-Fruit Bunch

1997 ◽  
Vol 15 (8) ◽  
pp. 609-617 ◽  
Author(s):  
Mamdouh M. Nassar
Keyword(s):  
Contact Time ◽  
Dye Removal ◽  
Kinetic Studies ◽  
Palm Fruit ◽  
Adsorption Models ◽  
First Order ◽  
First Order Kinetics ◽  
Equilibrium Data ◽  
Effect Of Particle Size ◽  
Kinetics Of

Equilibrium and kinetic studies were carried out during the adsorption of Basic Yellow dye on palm-fruit bunch adsorbent. The adsorbent is a cheap, abundant waste in tropical countries and has a monolayer equilibrium capacity of 320 mg dye/(g palm-fruit bunch). The effect of particle size, contact time and temperature were studied. The equilibrium data were analyzed using the Langmuir, Freundlich and Redlich–Peterson adsorption models. The applicability of the Lagergren kinetic model has also been investigated. The adsorption isotherm rate constants demonstrate that palm-fruit bunch is a favourable adsorbent. The removal process follows first-order kinetics. The temperature dependence indicates the endothermic nature of the process.

Kinetic Study on Delignification of Kraft-AQ Pine Pulp with Hydrogen Peroxide Catalyzed by Mn(IV)-Me4DTNE

Holzforschung ◽  
2000 ◽  
Vol 54 (4) ◽  
pp. 413-419 ◽  
Author(s):  
Yu Cui ◽  
Pratuang Puthson ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl ◽  
Adrianna G. Kirkman
Keyword(s):  
Hydrogen Peroxide ◽  
Initial Phase ◽  
Model Compound ◽  
Kinetic Studies ◽  
Kappa Number ◽  
Lignin Model Compound ◽  
First Order Kinetics ◽  
Residual Phase ◽  
Lignin Model ◽  
Kinetics Of

Summary The kinetics of delignification of a kraft-AQ southern pine pulp with hydrogen peroxide catalyzed by [LMn(IV)(μ-O)3Mn(IV)](ClO4)2 (1), where L = 1,2-bis(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)ethane was studied. The degree of delignification was significantly improved by using the catalyst. The pulp was bleached for 2 hours at 80°C, in 10% consistency with 2% NaOH, 4% H2O2 and 60 ppm catalyst charges on pulp (O.D.). Kappa number of the pulp was reduced from 31.6 to 16.8 corresponding to a degree of delignification of approximately 4%, while GE brightness was increased from 24.2 to 44.7. At the same time, viscosity of the resulting pulp was reduced from 31.1 mPa•s to 20.1 mPa•s compared to the reduction from 31.1 mPa•s to 20.1 mPa•s in the uncatalyzed bleaching under the same reaction condition. This indicates that the degradation of the carbohydrates was moderate in the catalyzed bleaching compared to the uncatalyzed bleaching. The delignification was found to follow pseudo first order kinetics with respect to kappa number, i.e., residual lignin, in the initial phase and quickly slowed down after 30 minutes (residual phase) under all the reaction temperatures investigated. The delignification rate constants in the initial phase were 0.17, 0.18, and 0.21 min−1 at 50, 60, and 80°C, respectively. Degree of delignification at the delignification time of 30 minutes is approximately 40% at 80°C. The possible delignification mechanism was discussed on the basis of the kinetic studies and lignin model compound experiments.

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