scholarly journals Mechanism of Oxidation of (p-Substituted Phenylthio)acetic Acids withN-Bromophthalimide

2011 ◽  
Vol 8 (1) ◽  
pp. 1-8 ◽  
Author(s):  
N. M. I. Alhaji ◽  
A. M. Uduman Mohideen ◽  
K. Kalaimathi
Keyword(s):  
Reaction Rate ◽  
Reaction Medium ◽  
Solvent Mixture ◽  
Kinetics Of Oxidation ◽  
Rate Determining Step ◽  
Water Solvent ◽  
Rate Of Reaction ◽  
Species Effect ◽  
Kinetics Of ◽  
Acetic Acids

The kinetics of oxidation of (phenylthio)acetic acid (PTAA) byN-Bromophthalimide (NBP) in acetonitrile-water solvent mixture at 298 K in the presence of perchloric acid has been followed potentiometrically. The reaction is first-order each in NBP and PTAA and inverse fractional-order in H+. Also, it has been found that the reaction rate is not affected by changes in ionic strength of the reaction medium or by the addition of chemicals such as phthalimide, acrylonitrile and potassium bromide. However, an increase in the water content of the solvent mixture causes an increase in the rate of reaction. These observations have been well analyzed in favour of a SN2-type mechanism, involving NBP itself as the reactive species. Effect of substituents on the reaction rate has been analysed by employing various (p-sustituted phenylthio)acetic acids. The electron-releasing substituent in the phenyl ring of PTAA accelerates the reaction rate while the electron-withdrawing substituent retards the rate. The excellently linear Hammett plot yields a large negative ρ value, supporting the involvement a bromosulphonium ion intermediate in the rate-determining step.

scholarly journals Mechanism of Oxidation of (p-Substituted Phenylthio)acetic Acids withN-Chlorosaccharin

2011 ◽  
Vol 8 (1) ◽  
pp. 159-166 ◽  
Author(s):  
N. M. I. Alhaj ◽  
A. M. Uduman Mohideen ◽  
S. Sofia Lawrence Mary
Keyword(s):  
Phenyl Ring ◽  
Reaction Rate ◽  
Water Medium ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Rate Determining Step ◽  
Composition Variation ◽  
Mechanism Of Oxidation ◽  
Kinetics Of ◽  
Acetic Acids

The kinetics of oxidation of (phenylthio)acetic acid (PTAA) withN-chlorosaccharin (NCSA) have been studied potentiometrically in 80:20 (v/v) acetonitrile-water medium at 298 K. The reaction is first-order each with respect to PTAA and NCSA and shows a negative dependence on [H+]. NCSA itself is shown to be the active oxidizing species. Effects of ionic strength variation, added saccharin, added acrylonitrile, added NaCl and solvent composition variation have been studied. Effect of substituents on the reaction rate has been analysed by employing various (p-sustituted phenylthio)acetic acids. The electron-releasing substituent in the phenyl ring of PTAA accelerates the reaction rate while the electron-withdrawing substituent retards the rate. The excellently linear Hammett plot yields a large negative ρ value, supporting the involvement a chlorosulphonium ion intermediate in the rate-determining step.

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.

Kinetics of carbon monoxide methanation on a Ni/SiO2 catalyst

1990 ◽  
Vol 55 (7) ◽  
pp. 1678-1685
Author(s):  
Vladimír Stuchlý ◽  
Karel Klusáček
Keyword(s):  
Carbon Monoxide ◽  
Reaction Rate ◽  
Catalyst Activity ◽  
Adsorbed Hydrogen ◽  
Reaction Products ◽  
Co Methanation ◽  
Molar Ratios ◽  
Rate Determining Step ◽  
Higher Temperature ◽  
Kinetics Of

Kinetics of CO methanation on a commercial Ni/SiO2 catalyst was evaluated at atmospheric pressure, between 528 and 550 K and for hydrogen to carbon monoxide molar ratios ranging from 3 : 1 to 200 : 1. The effect of reaction products on the reaction rate was also examined. Below 550 K, only methane was selectively formed. Above this temperature, the formation of carbon dioxide was also observed. The experimental data could be described by two modified Langmuir-Hinshelwood kinetic models, based on hydrogenation of surface CO by molecularly or by dissociatively adsorbed hydrogen in the rate-determining step. Water reversibly lowered catalyst activity and its effect was more pronounced at higher temperature.

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.

scholarly journals PERIODATE OXIDATION OF PEG–600, AN ESSENTIAL PHARMACEUTICAL POLYMER

2019 ◽  
pp. 251-256
Author(s):  
K. V. S. KOTESWARA RAO ◽  
R. VENKATA NADH ◽  
K. VENKATA RATNAM
Keyword(s):  
Polyethylene Glycol ◽  
Oxygen Atom ◽  
Temperature Dependence ◽  
Reaction Rate ◽  
Periodate Oxidation ◽  
Alkali Concentration ◽  
Rate Of Reaction ◽  
Atom Loss ◽  
Kinetics Of ◽  
Peg 600

Objective: To study the kinetics of periodate oxidation of polyethylene glycol-600 (PEG-600), a familiar non-toxic polymer used in pharmaceutical and other fields of industry. Methods: Reactions were carried out in alkaline medium and measured the kinetics by iodometry. One oxygen atom loss or two electrons transfer was observed per each molecule of periodate i.e., the rate of reaction was measured periodate converts to iodate because the formed iodate species is unable to oxidize the substrate molecules. Results: Based on log (a-x) versus t plots, order w. r. t. oxidant (periodate) is unity. Reactions were found to be independent of substrate (PEG-600) concentration. A decrease in rate with an increase in alkali concentration [OH–] was found and order was inverse fractional. Temperature dependence of reaction rate was studied and then calculated the corresponding Arrhenius parameters. Conclusion: An appropriate rate law was proposed by considering the above experimental results.

Kinetics of Isoprenepolymerization Initiated with TiCl4—Trialkyl Aluminum

1960 ◽  
Vol 33 (3) ◽  
pp. 696-698
Author(s):  
S. E. Bresler ◽  
M. I. Mosevitskiĭ
Keyword(s):  
Active Sites ◽  
Reaction Medium ◽  
Heat Evolution ◽  
Polymerization Reaction ◽  
Reaction Conditions ◽  
Low Viscosity ◽  
Rate Of Polymerization ◽  
Rate Of Reaction ◽  
Entire Experiment ◽  
Kinetics Of

Abstract For the study of the mechanism of polymerization by means of complexes of aluminum organic compounds with titanium chlorides, data on the kinetics of polymerization is of great interest. Up to the present time, the rate of polymerization of propylene has been studied but the interpretation of the kinetic data is difficult because the polymer, which is practically insoluble in the reaction medium, entraps the catalyst resulting in a rate of reaction which is dependent on the diffusion of monomer through the polymer to the active sites. In this work the polymerization of isoprene, which yields polymers soluble in the monomer, in saturated hydrocarbons and in benzene, was studied. The rate of the polymerization reaction was measured by the thermal effect in a calorimeter consisting of a 3.5 1. Dewar flask, with a lid, immersed in a thermostated air bath maintained at approximately the temperature of the reaction. Low viscosity spindle oil, heated to the temperature of the reaction (about 32°), served as the calorimeter fluid. The ampoule holder extended outside of the calorimeter and was connected to a shaking apparatus. The ampoule was divided by a thin partition into two sections each holding 45–50 cc. Into one section previously purified monomers and solvent were distilled. The other section was filled with catalyst components from a Shlenk container. The change in temperature of the calorimeter was determined with a Beckman thermometer with an accuracy of 0.01 °. When the temperature of the calorimeter containing the ampoule remained constant to within 0.01–0.02° for 30–40 minutes, the shaking apparatus was connected and the partition was broken with a striker. Intensive shaking was continued during the entire experiment resulting in mixing of the reaction mixture and of the calorimeter fluid. The rate of reaction was determined by the rate of heat evolution ; in other words, by the temperature rise in the calorimeter. For a rise of 0.1–0.5° the reaction conditions remained practically isothermal. This rise permits the kinetics of the reaction to be observed with sufficient accuracy. Adiabaticity of the calorimeter and the effect of mechanical heat were controlled in separate experiments.

The Oxidation of Dithiocarbamate Anion by Substitution Inert Metal Complexes

1989 ◽  
Vol 42 (7) ◽  
pp. 1085 ◽  
Author(s):  
PJ Nichols ◽  
MW Grant
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Metal Complexes ◽  
Radical Anion ◽  
Outer Sphere ◽  
Aqueous Acetone ◽  
Kinetics Of Oxidation ◽  
Rate Determining Step ◽  
Exchange Rate Constant ◽  
Kinetics Of

The kinetics of oxidation of dithiocarbamate anions to thiuram disulfides in aqueous acetone by {Fe(CN)6}3- and 11 other substitution inert metal complexes have been investigated. Outer-sphere electron transfer, resulting in the formation of dithiocarbamate thio radicals, is the rate determining step. A Marcus cross reaction treatment allows an estimate for the redox potential for the dithiocarbamate radical/anion couple. For diethyldithiocarbamate, E �(edtc/edtc-) = 425 � 33 mV v.s.c.e. and the outer-sphere electron self-exchange rate constant is log kex = 7.0 � 0.3. A comparison with thiophenolate oxidation is also given.

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.

Kinetics and mechanism of oxidation of iodide ion by the molybdenum (VI) – hydrogen peroxide system

1990 ◽  
Vol 68 (9) ◽  
pp. 1499-1503 ◽  
Author(s):  
Conchita Arias ◽  
Fernando Mata ◽  
Joaquin F. Perez-Benito
Keyword(s):  
Hydrogen Peroxide ◽  
Rate Constants ◽  
Reaction Rate ◽  
Sodium Molybdate ◽  
Initial Reaction Rate ◽  
Initial Reaction ◽  
Kinetics Of Oxidation ◽  
Iodide Ion ◽  
Aqueous Perchloric Acid ◽  
Kinetics Of

The kinetics of oxidation of potassium iodide by hydrogen peroxide in aqueous perchloric acid has been studied both in the absence and in the presence of sodium molybdate by means of the initial-rates method. The law found for the total initial reaction rate is[Formula: see text]The activation energies associated with rate constants k1, k2, and k3 are 52 ± 1, 49 ± 1, and 42 ± 3 kJ mol−1, respectively. A mechanism in agreement with the experimental kinetic data is proposed, according to which rate constants k1, k2, and k3 correspond to the oxidations of iodide ion by H2O2, H3O2+ and H2MoO5, respectively. Keywords: catalysis, hydrogen peroxide, iodide ion, kinetics, molybdate ion.

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