Polarographic and Cyclic Voltammetric Behaviour of Some Azo Compounds Derived from Sulfonamide in DMF-Aqueous Solutions

1992 ◽  
Vol 57 (2) ◽  
pp. 268-275 ◽  
Author(s):  
El-Sayed M. Mabrouk ◽  
Hamada M. Killa ◽  
Abdel Fattah A. Abdel Fattah ◽  
Shalaby A. Yasen
Keyword(s):  
Reaction Mechanism ◽  
Aqueous Solutions ◽  
Kinetic Parameters ◽  
Alkaline Solution ◽  
Electrode Reaction ◽  
Azo Compounds ◽  
Cyclic Voltammetric ◽  
Ph Range

The polarographic and cyclic voltammetric behaviour of (2-hydroxyphenylazo)-4-benzenesulfonamide and some of its derivatives have been studied in Britton-Robinson buffer series containing 30 vol.% of DMF. Over the entire pH range (2-12), the reduction pathway occurs through an irreversible 4-electron step corresponding to the reduction of N=N center to the amine stage. The voltammograms recorded in acidic and alkaline solution at different scan rates exhibit one or two cathodic peaks depending on the substituent and the pH of the medium. The electrode reaction mechanism was suggested, also the kinetic parameters were calculated.

Nitroso-R-Salt in Aqueous Solutions for Redox Flow Battery Application

2011 ◽  
Vol 239-242 ◽  
pp. 2813-2816 ◽  
Author(s):  
Zhi Peng Xie ◽  
Feng Jiao Xiong ◽  
De Bi Zhou
Keyword(s):  
Aqueous Solutions ◽  
Alkaline Solution ◽  
Electrochemical Behavior ◽  
Electrode Reaction ◽  
Active Species ◽  
Electrode Kinetics ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Diffusion Controlled ◽  
Battery Application

The electrochemical behavior of Nitroso-R-salt (NRS) in aqueous solutions and the influence of pH are investigated. In alkaline solution, the electrode reaction of NRS exhibits stagnant electrode kinetics. With rising acid concentration, it exhibits more and more fast electrode kinetics and a diffusion-controlled process. Thus, acidic aqueous solutions are favorable for the NRS as active species of a redox flow battery (RFB). Average coulombic and energy efficiencies of the NRS/Zn RFB are 93.2 and 80.6%, respectively, showing that self-discharge is small. The preliminary exploration shows that the NRS is electrochemically promising for RFB application.

Temperature-dependence of electrochemical kinetic parameters: Electrode reaction of the Zn(Hg)/Zn(II) system

1982 ◽  
Vol 47 (5) ◽  
pp. 1433-1443 ◽  
Author(s):  
S. Kang ◽  
K. Matsuda ◽  
R. Tamamushi
Keyword(s):  
Aqueous Solutions ◽  
Temperature Dependence ◽  
Kinetic Parameters ◽  
Rate Constant ◽  
Activation Parameters ◽  
Electrode Reaction ◽  
Thermodynamic Quantities ◽  
Empirical Correlations ◽  
Square Wave ◽  
Different Temperatures

The electrochemical kinetic parameters of the D.M.E./Zn(II) electrode reaction in aqueous solutions containing perchlorate, nitrate, chloride and bromide ions were measured at different temperatures (5-50 °C) by the modified square-wave polarographic technique. The Arrhenius activation parameters and thermodynamic quantities of the electrode reaction were determined from the temperature dependence of the rate constant and conditional potential, respectively. Empirical correlations were observed between some pairs of kinetic and thermodynamic quantities.

scholarly journals Kinetik und Mechanismus der Substitutionsreaktionen von Komplexverbindungen, XLVIII / Kinetics and Mechanism of the Substitution Reactions of Complexes, XLVIII

1975 ◽  
Vol 30 (5-6) ◽  
pp. 393-398 ◽  
Author(s):  
J. Zsakó ◽  
Cs. Várhelyi ◽  
Z. Finta ◽  
J. Kiss-Jakab
Keyword(s):  
Activation Energy ◽  
Aqueous Solutions ◽  
Kinetic Parameters ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Ionic Species ◽  
Protolytic Equilibrium ◽  
Substitution Reactions ◽  
Basic Solutions ◽  
Ph Range

In aqueous solutions the nonelectrolyte [Co(DH)2(NO2)(H2O)] participates in protolytic eqilibria and thus it exists in 7 different forms. Rate constants of the aquation, which leads to the substitution of the nitro group, have been measured in the pH-range between 3.72 and 8 at various temperatures. From these data rate constants, activation energies and entropy values of the aquation of 2 ionic species have been derived, as well as equilibrium constants for the protolytic equilibrium between these species. The kinetic parameters obtained have been compared to those of the aquation of the ionic species which exist in acid and basic solutions and the correlation between structure and activation energy of the aquation has been discussed.

The Electroreduction of Periodate Anion in Alkaline Media

1971 ◽  
Vol 49 (16) ◽  
pp. 2657-2663 ◽  
Author(s):  
W. R. Fawcett ◽  
Y. C. Kuo Lee
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Double Layer ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Alkaline Media ◽  
Dropping Mercury Electrode ◽  
Ph Range ◽  
Theoretical Developments

The electroreduction of periodate anion was studied at a dropping mercury electrode in aqueous solutions in the pH range 11–13.3 where the process is markedly affected by the double layer. The electrode reaction was found to be complex, its mechanism depending on both pH and ionic strength. The effects of the double layer on the component reactions are discussed with respect to current theoretical developments.

Catalytic Activity of 4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl in Homogeneous Electrooxidation of Hydroxylamine

1998 ◽  
Vol 63 (12) ◽  
pp. 1994-2000 ◽  
Author(s):  
He Xia ◽  
Hu Lin Li
Keyword(s):  
Catalytic Activity ◽  
Reaction Mechanism ◽  
Kinetic Parameters ◽  
Glassy Carbon ◽  
Catalytic Reaction ◽  
Electrocatalytic Activity ◽  
Electrode Reaction ◽  
Carbon Electrode ◽  
Homogeneous Oxidation ◽  
Catalytic Reaction Mechanism

4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (1) shows catalytic electroactivity in homogeneous oxidation of hydroxylamine on a glassy carbon electrode. Kinetic parameters of the electrode reaction were measured and an catalytic reaction mechanism for the electrooxidation was proposed. Possible application of electrocatalytic activity of 1 in determination hydroxylamine was also discussed.

scholarly journals Reduction of dicarbonyl compounds on a mercury electrode. II. Reduction mechanism of acetylbenzoyl

1985 ◽  
Vol 63 (4) ◽  
pp. 891-895 ◽  
Author(s):  
J. M. Rodriguez-Mellado ◽  
J. L. Avila ◽  
J. J. Ruiz
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Aqueous Solutions ◽  
Mercury Electrode ◽  
Reduction Mechanism ◽  
Tafel Slopes ◽  
Reaction Orders ◽  
Drop Time ◽  
Ph Range ◽  
Adsorption Phenomena

A study on the electrochemical reduction of acetylbenzoyl on a mercury electrode has been carried out in the pH range 0–9 in buffered aqueous solutions. The effect of pH, drop time, temperature, and acetylbenzoyl concentration on polarographic and kinetic parameters has been studied. The occurrence of adsorption phenomena is inferred from the recordings of C–E curves. Tafel slopes and reaction orders have been obtained at potentials corresponding to the foot of the wave. On the basis of these experimental data, a reaction mechanism is proposed for the zone of potentials where Tafel's law is satisfied.

scholarly journals Investigations of ternary complexes of Co(II) and Ni(II) with thiodiacetate anion and 1,10-phenanthroline or 2,2’-bipyridine in aqueous solutions

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Dariusz Wyrzykowski ◽  
Joanna Pranczk ◽  
Dagmara Jacewicz ◽  
Aleksandra Tesmar ◽  
Bogusław Pilarski ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Substitution Reactions ◽  
Experimental Conditions ◽  
Kinetic Measurements ◽  
Hydroxo Complexes ◽  
Binary Complexes ◽  
Vis Spectroscopy ◽  
Potentiometric Titration Method ◽  
The Stability ◽  
Ph Range

AbstractA potentiometric titration method (PT) and a stopped-flow kinetic technique monitored by a UV−Vis spectroscopy have been used to characterize the stability of series of Co(II)- and Ni(II)-thiodiacetato complexes, M(TDA), in the presence of 1,10-phenanthroline (phen) or 2,2’-bipyridine (bipy) in aqueous solutions. The stability constants of the binary (1:1), ternary (1:1:1) as well as the resulting hydroxo complexes were evaluated and compared to the corresponding oxydiacetate complexes. Based on the species distribution as a function of pH the relative predominance of the species in the system over a pH range was discussed. Furthermore, the kinetic measurements of the substitution reactions of the aqua ligands to phen or bipy in the coordination sphere of the binary complexes M(TDA) were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (0.2–0.5 mM). The kinetic stability of the M(TDA) complexes was discussed in relation to the experimental conditions and the kind of the auxiliary ligands (phen/bipy). Moreover, the influence of the type of primary ligand (thiodiacetate/oxydiacetate) on the substitution rate of the auxiliary ligands was also compared.

Chemilumineszenz der SO2-Oxidation / Chemiluminescence of SO2-Oxidation

1978 ◽  
Vol 33 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Joachim Stauff ◽  
Wolfgang Jaeschke
Keyword(s):  
Aqueous Solutions ◽  
Spectral Region ◽  
Time Course ◽  
Light Emission ◽  
Analog Computer ◽  
Reaction Scheme ◽  
So2 Oxidation ◽  
Recombination Product ◽  
Electronically Excited ◽  
Ph Range

Abstract The reactions of diluted aqueous solutions of SO2 resp. HSO3-ions with MnO4-or Ce4+ ions in the pH range 1-4 produce chemiluminescence in the spectral region of 450-600 nm. Measurements of the time course of the light emission and their simulation on an analog computer led to a reaction scheme in which a recombination product of primarily formed HSO3 radicals -of a lifetime of about 1 second -appears as precursor of electronically excited SO2 molecules. The participation of singlet oxygen can be excluded because at least the reaction with Ce4+ ions proceeds also in the absence of oxygen.

Construction of a pH-sensitive self-assembly in aqueous solutions based on a dansyl-modified β-cyclodextrin

Soft Matter ◽  
2021 ◽  
Author(s):  
Bing Jiang ◽  
Yu Liu ◽  
Linlin Zhao ◽  
Li Zhao ◽  
Ce Wang ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Self Assembly ◽  
Ph Sensitive ◽  
Ph Responsive ◽  
Ph Range

Here we present a pH-responsive self-assembly based on a β-cyclodextrin (β-CD) derivative bearing a dansyl terminus (βCD-C6-Dns). Vesicular structures were formed over the entire studied pH range (8.5-0.7); however, the...

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