Oxidation of Tyrosine by Hexacyanoferrate(III) in Aqueous Ethanoic Acid Medium–A Kinetic and Mechanistic Study

2008 ◽  
Vol 33 (4) ◽  
pp. 331-348 ◽  
Author(s):  
K.A. Thabaj ◽  
S.A. Chimatadar ◽  
S.T. Nandibewoor
Keyword(s):  
Acid Concentration ◽  
Chloride Concentration ◽  
Activation Parameters ◽  
Mechanistic Study ◽  
Slow Step ◽  
Ethanoic Acid ◽  
The Difference ◽  
Formed Product ◽  
Reaction Constants ◽  
Kinetics Of

The kinetics of oxidation of tyrosine by Fe(CN)63- have been studied in 40% AcOH-H2O containing 4.0 mol dm-3 HCl. The oxidation is made possible by varying the difference in redox potential by adding HCl and AcOH to the reaction mixture. The reaction is first order with respect to [Fe(CN)63- and fractional (0.72) order with respect to [tyrosine]. Increasing the acid concentration at constant chloride concentration accelerates the reaction. The order with respect to acid concentration is nearly two and H2Fe(CN)6- is regarded as the active oxidant. The initially formed product, Fe(CN)64- retards the reaction. A suitable mechanism is proposed and the reaction constants of the different steps involved have been evaluated. Activation parameters have also been calculated with respect to the slow step of the mechanism and discussed.

Mechanistic Study of the Oxidation of Isonicotinate ion by Diperiodatocuprate(III) in Aqueous Alkaline Medium

2005 ◽  
Vol 2005 (3) ◽  
pp. 197-201 ◽  
Author(s):  
G.C Hiremath ◽  
R.M Mulla ◽  
S.T Nandibewoor
Keyword(s):  
Ionic Strength ◽  
Alkaline Medium ◽  
Activation Parameters ◽  
Mechanistic Study ◽  
Slow Step ◽  
Thermodynamic Quantities ◽  
Aqueous Alkaline Medium ◽  
Kinetics Of Oxidation ◽  
Reaction Constants ◽  
Kinetics Of

The kinetics of oxidation of isonicotinate ion by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.60 mol dm−3 was studied spectrophotometrically. A mechanism involving the formation of an intermediate complex between the diperiodatocuprate(III) as the oxidant species and isonicotinate ion is proposed. The reaction constants involved in the different steps of mechanism have been calculated. The activation parameters with respect to the slow step of the mechanism have been computed and discussed and thermodynamic quantities were also determined.

scholarly journals Kinetics and Mechanism of Oxidation of L-proline by Trivalent Copper: A free radical intervention and decarboxylation

2004 ◽  
Vol 1 (5) ◽  
pp. 216-227 ◽  
Author(s):  
M. I. Hiremath ◽  
R. S. Shettar ◽  
S. T. Nandibewoor
Keyword(s):  
Ionic Strength ◽  
Alkaline Medium ◽  
Reaction Medium ◽  
Activation Parameters ◽  
Solvent Polarity ◽  
Medium Effect ◽  
Slow Step ◽  
Thermodynamic Quantities ◽  
Reaction Constants ◽  
Kinetics Of

The kinetics of oxidation of L-proline by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm-3was studied spectrophotometrically. The reaction between DPC and L-proline in alkaline medium exhibits 2:1 stoichiometry (DPC: L-Proline). The reaction is of first order in [DPC], less than unit order in [L-proline] and [alkali]. Periodate has no effect on the rate of reaction. The reaction rate increases with increase in ionic strength and decrease in solvent polarity of the medium. Effect of added products and ionic strength of the reaction medium have been investigated. The main products were identified by spot test and I.R spectra. A mechanism involving the DPC as the reactive species of the oxidant and a complex formation with L-proline has been proposed. The reaction constants involved in the different steps of mechanism are calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also calculated.

scholarly journals Mechanism of Oxidation of L-Histidine by Heptavalent Manganese in Alkaline Medium

2005 ◽  
Vol 2 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Timy P. Jose ◽  
Sharanappa T. Nandibewoor ◽  
Suresh M. Tuwar
Keyword(s):  
Ionic Strength ◽  
Alkaline Medium ◽  
Reaction Medium ◽  
Activation Parameters ◽  
Slow Step ◽  
Thermodynamic Quantities ◽  
Kinetics Of Oxidation ◽  
Reaction Constants ◽  
Kinetics Of ◽  
Equilibrium Step

The kinetics of oxidation of L-histidine by manganese(VII) in aqueous alkaline medium at a constant ionic strength of 0.05 mol dm-3was studied spectrophotometrically. The reaction between permanganate and L-histidine in alkaline medium exhibits 2:1 stoichiometry (KMnO4: L-histidine). The reaction is of first order in [KMnO4], less than unit order in [L-histidine] and [alkali]. Decrease in the dielectric constant of the medium decreases the rate of reaction. Effect of added products and ionic strength of the reaction medium have been investigated. The main products were identified by spot test and I.R. A mechanism involving the free radical has been proposed. In composite equilibrium step L-histidine binds to MnO4-species to form a complex(C). The reaction constants involved in the different steps of mechanism are evaluated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined.

scholarly journals Oxidation of Paracetamol Drug by a New Oxidant Diperiodatoargentate (III) in Aqueous Alkaline Medium

2006 ◽  
Vol 3 (1) ◽  
pp. 13-24 ◽  
Author(s):  
D. C. Hiremath ◽  
C. V. Hiremath ◽  
S. T. Nandibewoor
Keyword(s):  
Ionic Strength ◽  
Alkaline Medium ◽  
Reaction Medium ◽  
Activation Parameters ◽  
Slow Step ◽  
Thermodynamic Quantities ◽  
Kinetics Of Oxidation ◽  
Rate Determining Step ◽  
Reaction Constants ◽  
Kinetics Of

The kinetics of oxidation of anti-pyretic drug, paracetamol by diperiodatoargentate (III) (DPA) in alkaline medium at a constant ionic strength of 0.01 mol dm-3was studied spectrophotometrically. The reaction between DPA and paracetamol in alkaline medium exhibits 1:2 stoichiometry (paracetamol: DPA). The reaction is of first order in [DPA] and has less than unit order in both [PAM] and [alkali]. A decrease in the dielectric constant of the medium increases the rate of the reaction. The effect of added products and ionic strength of the reaction medium have been investigated. The oxidation reaction in alkaline medium has been shown to proceed via a DPA- paracetamol complex, which decomposes slowly in a rate determining step followed by other fast step to give the products. The main products were identified by spot test, IR, NMR and GC-MS. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined.

Kinetic and Mechanistic Study of Oxidative Degradation of Paracetamol by Diperiodatonickelate (IV) in Aqueous Alkaline Medium

2002 ◽  
Vol 2002 (4) ◽  
pp. 147-148 ◽  
Author(s):  
R.M. Kulkarni ◽  
D.C. Bilehal ◽  
S.T. Nandibewoor
Keyword(s):  
Alkaline Medium ◽  
Oxidative Degradation ◽  
Activation Parameters ◽  
Reactive Species ◽  
Mechanistic Study ◽  
Slow Step ◽  
Aqueous Alkaline Medium ◽  
Reaction Constants

A mechanism involving the monoperiodatonickelate (IV) (MPN) as the reactive species of the oxidant has been proposed. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to the slow step of the mechanism are computed and discussed.

Kinetics and Mechanism of Oxidation of L-Proline by Heptavalent Manganese: A Free Radical Intervention and Decarboxylation

2005 ◽  
Vol 2005 (1) ◽  
pp. 13-17 ◽  
Author(s):  
R.T. Mahesh ◽  
M.B. Bellakki ◽  
S.T. Nandibewoor
Keyword(s):  
Reaction Rate ◽  
Activation Parameters ◽  
Solvent Polarity ◽  
Reaction Scheme ◽  
Slow Step ◽  
Reaction Products ◽  
Experimental Conditions ◽  
Kinetics Of Oxidation ◽  
Reaction Constants ◽  
Kinetics Of

The kinetics of oxidation of L-proline by permanganate in alkaline medium was studied spectrophotometrically. The reaction is first order with respect to[MnO4-] and is an apparent less than unit order, each in [L-proline] and [alkali] under the experimental conditions. The reaction rate increases with increase in ionic strength and decrease in solvent polarity of the medium. Addition of reaction products has no effect on the reaction rate. A mechanism involving the formation of a complex between the oxidant and substrate has been proposed. The reaction constants involved in the mechanism were evaluated. There is a good agreement between the observed and calculated rate constants under varying experimental conditions. The activation parameters with respect to the slow step of the proposed reaction scheme were evaluated and discussed.

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 Mechanistic aspects of oxidation on L-tyrosine by diperiodatocuprate(III) complex in alkali media: a kinetic model

2009 ◽  
Vol 7 (4) ◽  
pp. 929-937 ◽  
Author(s):  
Nagaraj Shetti ◽  
Rajesh Hegde ◽  
Sharanappa. Nandibewoor
Keyword(s):  
Alkaline Medium ◽  
Activation Parameters ◽  
Spectral Studies ◽  
Slow Step ◽  
Isokinetic Temperature ◽  
Thermodynamic Quantities ◽  
Radical Intermediate ◽  
Different Temperatures ◽  
Reactive Oxidant ◽  
Reaction Constants

AbstractOxidation of an amino acid, L-tyrosine (L-Tyr) by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of 0.1 mol dm−3 was studied spectrophotometrically at different temperatures (288.1–313.1 K). The reaction between DPC and L-Tyr in alkaline medium exhibits 1:4 stoichiometry (L-Tyr:DPC). Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidence, a mechanism involving monoperiodatocuprate(III) (MPC) as the reactive oxidant species has been proposed. A suitable mechanism is proposed through the formation of a complex and free radical intermediate. The products were identified by spot test and characterized by spectral 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 are discussed. The thermodynamic quantities were determined for different equilibrium steps. Isokinetic temperature was also calculated and found to be 252.3 K.

A KINETICS AND MECHANISTIC STUDY OF THE OXIDATION OF L-ARGININE BY QDC IN DMF-WATER MEDIUM

2021 ◽  
pp. 11-12
Author(s):  
Deepika Jain ◽  
Shilpa Rathor
Keyword(s):  
Perchloric Acid ◽  
Reaction Rate ◽  
Main Product ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Mechanistic Study ◽  
Water Medium ◽  
Volume Percentage ◽  
Kinetics Of Oxidation ◽  
Kinetics Of

The present paper describes the kinetics of oxidation of l-Arginine by QDC in the presence of perchloric acid in 30% DMF-H O(v/v) medium at 2 + 40⁰C spectrophotometrically at λ =354nm. The reaction is rst order with respect to [QDC], [H ], and [substrate]. The reaction rate increased with max increasing volume percentage of DMF in reaction mixture. Michaelis- Menten type kinetic was observed with l-Arginine. The reaction rates were studied at different temperature and the activation parameters has been computed. The main product was identied as Cr (III) and 4-Guanidino buteraldehyde.

The kinetics and the mechanism of oxidative decarboxylation of benzilic acid by acidic permanganate (stopped-flow technique) — An autocatalytic study

2004 ◽  
Vol 82 (9) ◽  
pp. 1372-1380 ◽  
Author(s):  
Sairabanu A Farokhi ◽  
Sharanappa T Nandibewoor
Keyword(s):  
Activation Parameters ◽  
Oxidative Decarboxylation ◽  
Two Stage ◽  
First Order ◽  
First Order Kinetics ◽  
Stage Process ◽  
Benzilic Acid ◽  
Reaction Constants ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of the oxidation of benzilic acid by potassium permanganate in an acidic medium were studied spectrophotometrically. The reaction followed a two-stage process, wherein both stages of the reaction followed first-order kinetics with respect to permanganate ion and benzilic acid. The rate of the reaction increased with an increase in acid concentration. Autocatalysis was observed by one of the products, i.e., manganese(II). A composite mechanism involving autocatalysis has been proposed. The activation parameters of the reaction were calculated and discussed and the reaction constants involved in the mechanisms were calculated. There is a good agreement between the observed and calculated rate constants under different experimental conditions.Key words: oxidation, autocatalysis, benzilic acid, two-stage kinetics.

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