scholarly journals Mechanistic investigations of oxidation of isatins by sodium N-chlorobenzenesulfonamide in alkaline medium: A kinetic study

2005 ◽  
Vol 3 (3) ◽  
pp. 482-501 ◽  
Author(s):  
◽  
R. Jagadeesh
Keyword(s):  
Alkaline Medium ◽  
Reaction Times ◽  
Activation Parameters ◽  
Cost Effective ◽  
Oxidation Products ◽  
High Yield ◽  
Rate Variation ◽  
Isokinetic Relationship ◽  
Anthranilic Acids ◽  
Solvent Isotope

AbstractOxidation of isatins (isatin, 5-methylisatin, 5-bromoisatin and 5-nitroisatin) to their anthranilic acids was performed efficiently with sodium N-chlorobenzenesulfonamide or chloramine-B (CAB) in alkaline medium at 35±0.1°C. The reactions follow identical kinetics for all the isatins, being first-order dependence each in [CAB]o and [Isatin]o and inverse fractional-order on [NaOH]. Addition of halide ions and benzenesulfonamide, reduction product of CAB, do not significantly affect the rate. Variation of ionic strength of the medium had no effect on the rate, while the dielectric effect is negative. The solvent isotope effect was studied using D2O. Activation parameters for the overall reaction have been computed. The rates satisfactorily correlate with the Hammett σ relationship and the reaction constant ρ is −0.31 signifies that electron releasing groups accelerate the reaction while the electron withdrawing groups retard the rate. Values of ΔH≠ and ΔS≠ are linearly related and an isokinetic relationship is observed with β=376 K, indicating the reaction is controlled by enthalpy. The stoichiometry of the title reaction is found to be 1∶1. Oxidation products of isatins were identified as their corresponding anthranilic acids and the yields were found to be around 90 %. The observed results have been explained by a plausible mechanism and the related rate law deduced. This method offers several advantages including high yield of the products, short reaction times, easier isolation of products, and stable, cost effective and relatively non-toxic reagents, which make the reaction process simple and smooth.

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.

scholarly journals Oxidative Cleavage of β-Lactam Ring of Cephalosporins with Chloramine-T in Alkaline Medium: A Kinetic, Mechanistic, and Reactivity Study

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Anu Sukhdev ◽  
A. S. Manjunatha ◽  
Puttaswamy Puttaswamy
Keyword(s):  
Alkaline Medium ◽  
Activation Parameters ◽  
Oxidation Products ◽  
Oxidation Reactions ◽  
Mass Spectral ◽  
Dielectric Effect ◽  
Lactam Ring ◽  
Chloramine T ◽  
Reactivity Study ◽  
Reaction Constants

Cephalosporins are β-lactam antibiotics, and the important drugs of this group are cephalexin, cefadroxil and cephradine. In the present research, the kinetics and mechanism of oxidation of cephalexin (CEX), cefadroxil (CFL), and cephradine (CPD) with chloramine-T (CAT) in alkaline medium were investigated at 301 K. All the three oxidation reactions follow identical kinetics with a first-order dependence each on [CAT]o and [substrate]o. The reaction is catalyzed by hydroxide ions, and the order is found to be fractional. The dielectric effect is negative. Proton inventory studies in H2O-D2O mixtures with CEX as a probe have been made. Activation parameters and reaction constants have been evaluated. Oxidation products were identified by mass spectral analysis. An isokinetic relation was observed with β = 378 K, indicating that enthalpy factors control the rate. The rate increases in the following order: CPD > CFL > CEX. The proposed mechanism and the derived rate law are consistent with the observed kinetics.

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.

Kinetic and Mechanistic Aspects of Osmium(VIII) Catalyzed Oxidation of DL-ornithine by Copper(III) Periodate Complex in Aqueous Alkaline Medium

2010 ◽  
Vol 224 (06) ◽  
pp. 865-882 ◽  
Author(s):  
Jyothi C. Abbar ◽  
Shweta J. Malode ◽  
Sharanappa T. Nandibewoor
Keyword(s):  
Alkaline Medium ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Oxidation Products ◽  
Slow Step ◽  
Thermodynamic Quantities ◽  
Aqueous Alkaline Medium ◽  
Uncatalyzed Reaction ◽  
Different Temperatures ◽  
Reaction Constants

AbstractThe oxidation of DL-ornithine monohydrochloride (OMH) by diperiodatocuprate(III) (DPC) has been investigated in the presence of osmium(VIII) catalyst in aqueous alkaline medium at a constant ionic strength of 0.20 mol dm−3 spectrophotometrically. The reaction exhibits 1:4 stoichiometry i.e., [OMH]: [DPC]. The order of the reaction with respect to [DPC] was unity while the order with respect to [OMH] was less than unity over the concentration range studied. The rate increased with an increase in [OH –] and decreased with an increase in [IO4−]. The order with respect to [Os(VIII)] was unity. The reaction rates revealed that Os(VIII) catalyzed reaction was about nine-fold faster than the uncatalyzed reaction. The oxidation products were identified by spectral analysis. Suitable mechanism has been proposed. The reaction constants involved in the different steps of the reaction mechanism were calculated. The catalytic constant (KC) was also calculated at different temperatures. The activation parameters with respect to slow step of the mechanism and also the thermodynamic quantities were determined. Kinetic experiments suggest that [OsO4(OH)2]2− is the reactive Os(VIII) species and [Cu(H2IO6)(H2O)2] is the reactive copper(III) species.

scholarly journals Sodium Periodate as a Selective Oxidant for Diclofenac Sodium in Alkaline Medium: A Quantum Chemical Approach

2020 ◽  
Vol 15 (2) ◽  
pp. 545-560
Author(s):  
Madhu Gupta ◽  
Amrita Srivastava ◽  
Sheila Srivastava
Keyword(s):  
Alkaline Medium ◽  
Quantum Chemical ◽  
Density Functional ◽  
Sodium Periodate ◽  
Diclofenac Sodium ◽  
Waste Water Treatment ◽  
Activation Parameters ◽  
Active Species ◽  
Oxidation Products ◽  
Spectral Studies

Diclofenac sodium is a well known anti-inflammatory drug. It has also been proclaimed to exhibit adverse effects on aquatic animals through sewage and waste water treatment plants. Kinetic and mechanistic studies of the novel oxidation of diclofenac sodium (DFS) by sodium periodate were discussed with an emphasis on structure and reactivity by using kinetic and computational approach. The proposed work had been studied in alkaline medium at 303 K and at a constant ionic strength of 0.60 mol.dm−3. Formation of [2-(2,6-dicloro-phynylamino)-phenyl]-methanol as the oxidation product of DFS is confirmed with the help of structure elucidation. The active species of catalyst, oxidant and oxidation products were recognized by UV and IR spectral studies. Proton inventory studies in H2O−D2O mixtures had been shown the involvement of a single exchangeable proton of OH− ion in the transition state. All quantum chemical calculations were executed at level of density functional theory (DFT) with B3LYP function using 6-31G (d,p) basis atomic set for the validation of structure, reaction and mechanism. Molecular orbital energies, nonlinear optical properties, bond length, bond angles, reactivity, electrophilic and nucleophilic regions were delineated. Influence of various reactants on rate of chemical reaction were also ascertained and elucidated spectro-photometrically. Activation parameters have been assessed using Arrhenius-Eyring plots. A suitable mechanism consistent with observed kinetic results had been implicated and rate law deduced. Copyright © 2020 BCREC Group. All rights reserved 

scholarly journals Oxidation of Tetracaine Hydrochloride by Chloramine-B in Acid Medium: Kinetic Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Jayachamarajapura Pranesh Shubha ◽  
Puttaswamy
Keyword(s):  
Dielectric Constant ◽  
Free Acid ◽  
Activation Parameters ◽  
Local Anaesthetics ◽  
Oxidation Products ◽  
Rate Variation ◽  
First Order ◽  
Order Dependence ◽  
Different Temperatures ◽  
Plausible Mechanism

Tetracaine hydrochloride (TCH) is one of the potent local anaesthetics. A kinetic study of oxidation of tetracaine hydrochloride by sodium N-chlorobenzenesulfonamide (chloramine-B or CAB) has been carried in HClO4 medium at 303 K. The rate shows first-order dependence on [CAB]o, shows fractional–order dependence on [substrate]o, and is self-governing on acid concentration. Decrease of dielectric constant of the medium, by adding methanol, increased the rate. Variation of ionic strength and addition of benzenesulfonamide or NaCl have no significant effect on the rate. The reaction was studied at different temperatures and the activation parameters have been evaluated. The stoichiometry of the reaction was found to be 1 : 5 and the oxidation products were identified by spectral analysis. The conjugate free acid C6H5SO2NHCl of CAB is postulated as the reactive oxidizing species. The observed results have been explained by plausible mechanism and the related rate law has been deduced.

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.

Synthesis of Highly Functionalized Quinazoline-2,4(1H,3H)-diones from Isocyanides, Aniline and Isocyanate via Cu-Catalyzed Intermolecular C-H Activation Reactions

2020 ◽  
Vol 17 (11) ◽  
pp. 832-836
Author(s):  
Manijeh Nematpour ◽  
Hossein Fasihi Dastjerdi ◽  
Mehdi Jahani ◽  
Sayyed Abbas Tabatabai
Keyword(s):  
13C Nmr ◽  
Reaction Times ◽  
High Yield ◽  
One Pot ◽  
1H And 13C Nmr ◽  
Activation Reaction ◽  
Elemental Analyses

A simple and appropriate procedure for the synthesis of quinazoline-2,4(1H,3H)-dione derivatives from isocyanides, aniline and isocyanate via the Cu-catalyzed intramolecular C-H activation reaction is reported. The advantages of this method are one-pot conditions, accessible starting materials- catalyst, high yield of products, and short reaction times. The structures are confirmed spectroscopically (1H- and 13C-NMR, IR and EI-MS) and by elemental analyses.

Quality Improvement of the DNA extracted by boiling method in Gram negative bacteria

2017 ◽  
Vol 6 (04) ◽  
pp. 5347 ◽  
Author(s):  
Omar B. Ahmed* ◽  
Anas S. Dablool
Keyword(s):  
Dna Extraction ◽  
Control Method ◽  
Extraction Procedure ◽  
Cost Effective ◽  
High Yield ◽  
Gram Negative Bacteria ◽  
Bacterial Dna ◽  
Gram Negative ◽  
E Coli

Several methods of Deoxyribonucleic acid (DNA) extraction have been applied to extract bacterial DNA. The amount and the quality of the DNA obtained for each one of those methods are variable. The study aimed to evaluate bacterial DNA extraction using conventional boiling method followed by alcohol precipitation. DNA extraction from Gram negative bacilli was extracted and precipitated using boiling method with further precipitation by ethanol. The extraction procedure performed using the boiling method resulted in high DNA yields for both E. coli and K. pneumoniae bacteria in (199.7 and 285.7μg/ml, respectively) which was close to control method (229.3 and 440.3μg/ml). It was concluded that after alcohol precipitation boiling procedure was easy, cost-effective, and applicable for high-yield quality of DNA in Gram-negative bacteria.

scholarly journals Cost Effectiveness of Transbronchial Needle Aspiration

1999 ◽  
Vol 6 (4) ◽  
pp. 332-335 ◽  
Author(s):  
Jennifer A Crocket ◽  
Eric YL Wong ◽  
Dale C Lien ◽  
Khanh Gia Nguyen ◽  
Michelle R Chaput ◽  
...  
Keyword(s):  
Cost Effectiveness ◽  
Cost Effective ◽  
Diagnostic Procedures ◽  
Needle Aspiration ◽  
Benign Disease ◽  
University Hospital ◽  
High Yield ◽  
Transbronchial Needle Aspiration ◽  
Computed Tomographic ◽  
The Cost

OBJECTIVE: To evaluate the yield and cost effectiveness of transbronchial needle aspiration (TBNA) in the assessment of mediastinal and/or hilar lymphadenopathy.DESIGN: Retrospective study.SETTING: A university hospital.POPULATION STUDIED: Ninety-six patients referred for bronchoscopy with computed tomographic evidence of significant mediastinal or hilar adenopathy.RESULTS: Ninety-nine patient records were reviewed. Three patients had two separate bronchoscopy procedures. TBNA was positive in 42 patients (44%) and negative in 54 patients. Of the 42 patients with a positive aspirate, 40 had malignant cytology and two had cells consistent with benign disease. The positive TBNA result altered management in 22 of 40 patients with malignant disease and one of two patients with benign disease, thereby avoiding further diagnostic procedures. The cost of these subsequent procedures was estimated at $27,335. No complications related to TBNA were documented.CONCLUSIONS: TBNA is a high-yield, safe and cost effective procedure for the diagnosis and staging of bronchogenic cancer.

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