scholarly journals Oxidation of some catecholamines by sodium N-chloro-p-toluenesulfonamide in acid medium: A kinetic and mechanistic approach

2005 ◽  
Vol 3 (2) ◽  
pp. 326-346 ◽  
Author(s):  
◽  
R. Jagadeesh ◽  
Nirmala Vaz
Keyword(s):  
Fractional Order ◽  
Reaction Rate ◽  
Oxidation Products ◽  
Solvent Isotope Effect ◽  
Experimental Conditions ◽  
Isokinetic Relationship ◽  
Mechanistic Approach ◽  
Chloramine T ◽  
Solvent Isotope ◽  
Kinetics Of

AbstractThe kinetics of the oxidation of five catecholamines viz., dopamine (A), L-dopa (B), methyldopa (C), epinephrine (D) and norepinephrine (E) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in presence of HClO4 was studied at 30±0.1 °C. The five reactions followed identical kinetics with a first-order dependence on [CAT]o, fractional-order in [substrate]o, and inverse fractional-order in [H+]. Under comparable experimental conditions, the rate of oxidation of catecholamines increases in the order D>E>A>B>C. The variation of ionic strength of the medium and the addition of p-toluenesulfonamide or halide ions had no significant effect on the reaction rate. The rate increased with decreasing dielectric constant of the medium. The solvent isotope effect was studied using D2O. A Michaelis-Menten type mechanism has been suggested to explain the results. Equilibrium and decomposition constants for CAT-catecholamine complexes have been evaluated. CH3C6H4SO2NHCl of the oxidant has been postulated as the reactive oxidizing species and oxidation products were identified. An isokinetic relationship is observed with β=361 K, indicating that enthalpy factors control the reaction rate. The mechanism proposed and the derived rate law are consistent with the observed kinetics.

Kinetics and Mechanism of Oxidation of Coumarin and Substituted Coumarins by Chloramine-b in Hydrochloric Acid Medium

2008 ◽  
Vol 33 (4) ◽  
pp. 313-330 ◽  
Author(s):  
J.P. Shubha ◽  
Puttaswamy
Keyword(s):  
Reaction Rate ◽  
Activation Parameters ◽  
Hydroxycinnamic Acids ◽  
Oxidation Products ◽  
Experimental Conditions ◽  
Isokinetic Relationship ◽  
Order Dependence ◽  
Rate Determining Step ◽  
Solvent Isotope ◽  
Substituted Coumarins

The kinetics of oxidation of coumarin (see Equation (1)) and four substituted coumarins, viz. 7-methoxycoumarin, 7-ethoxycoumarin, 7-hydroxycoumarin and 7-nitrocoumarin, to the corresponding o-hydroxycinnamic acids by chloramine-B (CAB) have been studied at 298 K. Under comparable experimental conditions, the reaction rate shows a first-order dependence each upon [CAB]o and [coumarin]o, and individually less than unit order dependence on [H+] and [Cl-]. Addition of benzenesulfonamide retards the reaction rate and the dielectric effect is positive. Variation of ionic strength of the medium does not influence the rate but the rate increases with increase in dielectric constant of the medium. The solvent isotope effect was studied using D2O. The reaction was studied at different temperatures and activation parameters have been evaluated. The stoichiometry of the reaction was found to be 1:1 and the oxidation products of coumarins were identified as their corresponding o-hydroxycinnamic acids. The rate of oxidation of coumarins increases in the order: 7-hydroxycoumarin > 7-ethoxycoumarin > 7-methoxycoumarin > coumarin > 7-nitrocoumarin. The rates satisfactorily correlate with the Hammett γ relationship and the reaction constant ρ is -0.04, which signifies that electron-donating groups enhance the rate and the electron-withdrawing group retards the rate. An isokinetic relationship was observed with β = 348 K, which showed the reaction to be enthalpy controlled. A mechanism consistent with the experimental results is proposed in which the rate-determining step is the formation of an intermediate complex between the substrate and molecular chlorine. The related rate law has been deduced and the decomposition constants were evaluated.

Kinetics of Photochemical Oxidation of Glucose by Chloramine-T in Acidic Medium: A Mechanistic Approach

2013 ◽  
Vol 816-817 ◽  
pp. 7-12
Author(s):  
Meena Wadhwani ◽  
Shubha Jain
Keyword(s):  
Acidic Medium ◽  
Reaction Rate ◽  
Accurate Method ◽  
Photochemical Oxidation ◽  
First Order ◽  
Mechanistic Approach ◽  
Excess Concentration ◽  
Chloramine T ◽  
Kinetics Of ◽  
Oxidation Of Glucose

A simple, convenient and accurate method for the kinetic study of photochemical oxidation of glucose by chloramine-T in acidic medium is described. The kinetic investigation shows the first order dependence of reaction rate on chloramine-T. With excess concentration of other reactants the reaction rate follows fractional order kinetics with respect to substrate. The reaction is catalyzed by H+ ions as well. A small salt effect and increase in reaction rate with increasing the intensity of light source is also observed. Addition of p-toluene sulphonamide retards the reaction rate. A suitable mechanism in agreement with observed kinetics has been proposed

scholarly journals Kinetics of Oxidation of Metochlopramide withChloramine-T in HClO4 Medium

2009 ◽  
Vol 6 (2) ◽  
pp. 545-552 ◽  
Author(s):  
K. M. Meenakshi ◽  
K. Vasant Kumar Pai
Keyword(s):  
Thermodynamic Parameters ◽  
Fractional Order ◽  
Reaction Rate ◽  
Oxidation Products ◽  
Perchloric Acid Solution ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Different Temperatures ◽  
Negative Effect ◽  
Kinetics Of

The kinetics of oxidation of metochlopramide hydrochloride (MCP) with sodiumN-chlorop-toluenesulfonamide (CAT) in perchloric acid solution has been studied at 313K. The reaction rate shows a first order dependence on [CAT], fractional order on [MCP] and inverse fractional order on [H+]. There is a negative effect of dielectric constant of the solvent. The addition of the reduction product of CAT has no significant effect on the rate. The rate remained unchanged with the variation in the ionic strength of the medium. The reaction fails to induce the polymerization of acrylonitrile. Thermodynamic parameters have been computed by Arrhenius plot. The stoichiometry of the reaction was found to be 1:2 and oxidation products were identified. The Michaelis-Menten type of kinetics has been proposed. CH3C6H4SO2NHCl have been assumed to be the reactive oxidizing species. Thermodynamic parameters were computed by studying reactions at different temperatures. A mechanism consistent with observed kinetics is proposed.

scholarly journals Kinetics and Mechanism of Oxidation of Diethyl Ether by Chloramine-T in Acidic Medium

2012 ◽  
Vol 9 (2) ◽  
pp. 642-649 ◽  
Author(s):  
Y. I. Hassan ◽  
N. H. M. Saeed
Keyword(s):  
Diethyl Ether ◽  
Reaction Rate ◽  
Oxidation Products ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Order Dependence ◽  
Rate Limiting Step ◽  
Chloramine T ◽  
Rate Limiting ◽  
Kinetics Of

The kinetics of oxidation of diethyl ether (DE) with sodium N-chloro-p-toluenesulphonamide (CAT) in hydrochloric acid solution has been studied at (313°K).The reaction rate show a first order dependence on [CAT] and fractional order dependence on each [DE] and [H+] .The variation of ionic strength of the medium has no significant effect on the reaction rate , addition of p-toluenesulphonamide (p-TSA) affects the reaction rate marginally the rate increased with decreasing dielectric constant of the medium , the stochiometry of the reaction was found to be 1:2 and oxidation products were identified , A Michaelis – Menten type mechanism has been suggested to explain the results.The equilibrium and the decomposition constants of CAT – diethyl ether complex have been evaluated. Thermodynamic parameters were computed by studying reaction at temperatures range ( 308 – 323°K) for the rate limiting step and for the observed first order constants by the linear Arrhenius plot. The mechanism proposed and the derived rate law are consistent with observed kinetics.

scholarly journals Exploration of Ruthenium (III) Chloride catalysis on oxidative conversion of aryloximes to arylaldehydes with bromamine-B: A kinetic and mechanistic approach

2021 ◽  
Vol 23 (05) ◽  
pp. 240-261
Author(s):  
Manjunatha A S ◽  
◽  
Anu Sukhdev ◽  
Putta Swamy ◽  
Shashi Dhara T S ◽  
...  
Keyword(s):  
Fractional Order ◽  
Reaction Times ◽  
Activation Parameters ◽  
Oxidation Products ◽  
Isokinetic Temperature ◽  
Experimental Conditions ◽  
Mechanistic Approach ◽  
Different Temperatures ◽  
Plausible Mechanism ◽  
Catalyzed Reactions

Conversion of aryloximes to corresponding arylaldehydes is an important oxidative transformation in synthetic chemistry. In the course of this research, optimum conditions for the facile oxidation of benzaldehyde oxime and p-substituted benzaldehyde oximes viz., p-hydroxybenzaldehyde oxime, p-methoxy benzaldehyde oxime, p-bromobenzaldehyde oxime and p-nitrobenzaldehyde oxime (aryloximes) with bromamine–B (BAB) catalyzed by ruthenium (III) chloride (RuCl3) in perchloric acid (HClO4) medium have been kinetically investigated at 303 K. All the five aryloximes follow identical kinetics with a first-order dependence of rate on [BAB]o, fractional-order each on [aryloximes]o and [RuCl3], and an inverse fractional-order on [H+]. Activation parameters have been evaluated. Oxidation products were characterized by spectral analysis. Under the identical set of experimental conditions, the kinetics of catalyzed reactions has been compared with uncatalyzed reactions and found that the catalyzed reactions are 4–6 folds faster. Isokinetic temperature is found to be 338 K. The catalytic constants (Kc) have been calculated at different temperatures and the values of activation parameters with respect to the catalyst have been evaluated. Spectroscopic evidence for the formation of 1:1 complex between BAB and RuCl3 has been obtained. The observed results have been explained by a plausible mechanism and the related rate law has been deduced. The present method offers many advantages including high conversion, short reaction times and the involvement of non-toxic reagents.

scholarly journals Carbon Dioxide Gasification Kinetics of Char from Rapeseed Oil Press Cake

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2318 ◽  
Author(s):  
Lech Nowicki ◽  
Dorota Siuta ◽  
Maciej Markowski
Keyword(s):  
Carbon Dioxide ◽  
Rapeseed Oil ◽  
Reaction Rate ◽  
Press Cake ◽  
Agricultural Waste ◽  
Estimation Procedure ◽  
Experimental Conditions ◽  
Two Step Estimation ◽  
Kinetics Of ◽  
Carbon Dioxide Gasification

Rapeseed oil press cake (RPC) is an abundantly available and renewable agricultural waste material for the production of fuels or chemicals. In this study, the rates of carbon dioxide gasification of rapeseed oil press cake char were measured by thermogravimetric analysis measurements performed at various temperatures (800–900 °C) and CO2 mole fractions (0.10–1.00). The char was obtained by slow pyrolysis, where the dried RPC was decomposed at a temperature range of 1000 °C to obtain char free of impurities that can affect the measurements. The random pore model appeared to be suitable for describing the effect of conversion on the reaction rate. The temperature, CO2, and concentration dependence of the reaction rate were given by the Arrhenius equation and a power law (nth order) correlation. The kinetic parameters based on the experimental data were determined by a two-step estimation procedure. For the experimental conditions employed in this study, the parameters E and n were 222.1 kJ/mol and 0.57, respectively.

Kinetics of the reaction between Manganese Dioxide and Ferrous Ion

1957 ◽  
Vol 10 (2) ◽  
pp. 150 ◽  
Author(s):  
DFA Koch
Keyword(s):  
Manganese Dioxide ◽  
Surface Area ◽  
Active Sites ◽  
Reaction Rate ◽  
Ferrous Sulphate ◽  
Zero Order ◽  
Ferrous Ion ◽  
Active Surface Area ◽  
Experimental Conditions ◽  
Kinetics Of

The kinetics of the reaction between manganese dioxide and ferrous ion in acid solution have been investigated by using the potential of the ferrous-ferric couple as a measure of the extent of reaction. The experimental conditions were such that the reaction rate was independent of ferrous, ferric, manganous ions, and acid concentrations and the agitation was sufficient to prevent bulk diffusion in the solution from being a rate-determining factor. The reaction rate of sized samples of pyrolusite and γ-MnO2 in ferrous sulphate solution was proportional to the surface area of the solid and was constant (i.e. " zero-order ") until 50 per cent. of the solid was consumed. γ-MnO2 reacted about twice as rapidly as the pyrolusite. The reaction occurred most readily at certain active sites on the particles and appeared to proceed along crystal boundaries in such a manner that the active surface area was not significantly changed during the first half of the reaction. In ferrous perchlorate the reaction rate of 10 μ diameter pyrolusite was about one-hundredth of that in sulphate and the reaction appeared to occur at a more even rate over the whole surface of the particle so that the zero-order law was no longer obeyed. Activation energies of 7.4 and 5 kcal in sulphate and perchlorate respectively, for the temperature range 18 to 40 �C, suggest that the difference in rate is a result of a change in the entropy factor of the Arrhenius equation. It is suggested that this difference in rate may result from the activation, by sulphate ions, of a less reactive lower oxide of manganese which is formed on the surface.

scholarly journals Kinetics of Micellar Effect of Non-Ionic Surfactant on Oxidative Degradation of Ciprofloxacin

2019 ◽  
Vol 32 (2) ◽  
pp. 359-368
Author(s):  
Ajaya Kumar Singh ◽  
Alpa Shrivastava ◽  
Dilip R. Shrivastava ◽  
Rajmani Patel ◽  
Neerja Sachdev
Keyword(s):  
Degradation Kinetics ◽  
Oxidative Degradation ◽  
Activation Parameters ◽  
Solvent Polarity ◽  
Degradation Process ◽  
Oxidation Products ◽  
Ionic Surfactant ◽  
Reaction Conditions ◽  
Chloramine T ◽  
Kinetics Of

Oxidative degradation kinetics of leading fluoroquinolone family drug ciprofloxacin (CIP) by chloramine-T (CAT) in TX-100 micelle media was studied spectrophotometrically at 275 nm and 298 K. In pseudo-first-order conditions the rate constant (kobs) decreased regularly with increasing [TX-100]. To understand the self-organizing activities of TX-100, CMC values in varying reaction conditions had been evaluated. The role of non-ionic surfactant in the oxidative degradation process of ciprofloxacin by chlorinating agent chloramine-T is explained in terms of mathematical model explained by Menger-Portnoy. The reaction showed first to zero order dependence on [CAT] and fractional order on [CIP]. Increasing [H+] decreased the rate of reaction. The effect of ionic strength and solvent polarity of the medium in reaction conditions were studied. The effects of added salts [HSO4Na], [KCl], [KNO3] and [K2SO4] had also been studied. The stoichiometry of the reaction determined was 1:2 and the oxidation products were identified by LC-EI-MS. The analysis of degradation product of ciprofloxacin evidently reveals that the piperazine moiety is active site for oxidation in the reaction. Activation parameters were studied to propose appropriate mechanism for the reaction.

Kinetics and Mechanism of Oxidation of Thiocyanate Ion by Sodium N-Chloro-4-methyl Benzene Sulphonamide in Alkaline Medium

1979 ◽  
Vol 34 (1) ◽  
pp. 52-57 ◽  
Author(s):  
D. S. Mahadevappa ◽  
B. T. Gowda ◽  
N. M. M. Gowda
Keyword(s):  
Activation Parameters ◽  
Potassium Thiocyanate ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
Thiocyanate Ion ◽  
Different Temperatures ◽  
Chloramine T ◽  
Solvent Isotope ◽  
Kinetics Of ◽  
Substrate Concentrations

Abstract Kinetics of oxidation of potassium thiocyanate by the oxidant chloramine-T (CAT) in presence of NaOH has been studied at 30 °C. At low substrate concentrations, the approximate rate law is, - d[CAT]/dt = k[CAT][KNCS]/[NaOH]2 . At higher substrate concentrations, the rate law simplifies to, -d[CAT]/dt = k[CAT]/[NaOH]. Ionic strength and addition of p-toluene sulphonamide have negligible influence on the rate. The rate of reaction decreases in D2O medium and the value of the inverse solvent isotope effect, kH2O/kD2O is 0.46. The reaction has been studied at different temperatures and the activation parameters have been calculated.

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