Electrochemical investigation of reduction of mercury complexes of 2-aminocyclopentene-1-dithiocarboxylic acid and some of its derivatives at mercury electrodes

1996 ◽  
Vol 74 (1) ◽  
pp. 95-102 ◽  
Author(s):  
A. Safavi ◽  
M. B. Gholivand
Keyword(s):  
Electrochemical Techniques ◽  
Mercury Electrode ◽  
Elemental Mercury ◽  
Redox Processes ◽  
Electrochemical Investigation ◽  
Controlled Potential Electrolysis ◽  
Mercury Complexes ◽  
Controlled Potential ◽  
Mercury Electrodes ◽  
Complementary Study

Electrochemical techniques of polarography, cyclic voltammetry, and controlled potential electrolysis at mercury electrodes have permitted a detailed investigation of the reduction reactions associated with mercury 2-aminocyclopentene dithiocarboxylate complexes, Hg(ACD)2, in dimethyl sulphoxide (DMSO). As a complementary study, the electrochemistry of the ligands themselves was investigated in DMSO solutions and at mercury electrodes. The lability of mercury(II) complexes and their rapid interaction with elemental mercury strongly influence the nature of the redox processes observed at mercury electrodes. Reduction of Hg(ACD)2 at a mercury electrode occurs in an overall two-electron step as:[Formula: see text]although mercury(I) is implicated as an intermediate. Key words: reduction, electrochemical techniques, mercury complexes.

Polarography of aromatic azo compounds. II. Kinetic study of the disproportionation of 4-Aminohydrazobenzene-4'-sulphonic acid

1965 ◽  
Vol 18 (5) ◽  
pp. 619 ◽  
Author(s):  
TM Florence
Keyword(s):  
Mercury Electrode ◽  
Sulphonic Acid ◽  
Azo Compounds ◽  
Rate Determining Step ◽  
A Value ◽  
Controlled Potential Electrolysis ◽  
Mercury Cathode ◽  
Dropping Mercury Electrode ◽  
Controlled Potential ◽  
Aromatic Azo Compounds

Solutions of 4-aminoazobenzene-4'-sulphonic acid were reduced by controlled potential electrolysis at a mercury cathode, and the disproportionation rate of the hydrazo derivative determined by spectrophotometry and polarography. The kinetics of the reaction were found to be first-order with respect to both hydrazo and hydrogen ion concentrations, although the overall reaction involved two molecules of the hydrazo compound. In the rate law, -d[hydrazo]/dt = k[H+][hydrazo], k was calculated to be (5.0�0.3) x 106 l. mole-1 sec-1 from spectrophotometric measurements, and (4.5�0.5) x 106 l. mole-1 sec-1 by polarography (25�). A reaction mechanism based on a rate determining step involving a quinonediimine intermediate has been proposed. Another value of the disproportionation rate constant was obtained from the effect of drop time on the limiting currents of 4-aminoazobenzene-4'-sulphonic acid at the dropping mercury electrode. A value of k of (22�5) x 106 l. mole-1 sec-1 was determined by this method. Reasons for the discrepancy between this result, and those found by direct measurement, are discussed.

The electrochemical oxidation of 2,5-dihydroxybenzoic acid on a mercury electrode in aqueous solutions

1986 ◽  
Vol 64 (1) ◽  
pp. 11-14 ◽  
Author(s):  
D. Sazou ◽  
N. Papadopoulos
Keyword(s):  
Oxidation Process ◽  
Electrochemical Behaviour ◽  
Mercury Electrode ◽  
The Other ◽  
Hanging Mercury Drop Electrode ◽  
Dihydroxybenzoic Acid ◽  
Current Function ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential ◽  
Ph Range

The electrochemical behaviour of 2,5-dihydroxybenzoic acid (2,5-DHBA) has been studied in the pH range 5.5–12.7 at a hanging mercury drop electrode (HMDE). Voltammograms show the existence of one reversible wave of 2,5-DHBA governed by diffusion conditions. In the oxidation process a two-electron transfer takes place, as shown by the controlled potential electrolysis. From the calculation of the voltammetric parameters (peak width Ep − Ep/2, peak current function [Formula: see text]and from the other experimental data, a mechanism for the overall reaction in two different pH ranges, 5.5–9.5 and 9.5–12, is proposed.

Polarography and coulometry of Rh(III) in a pyridine – pyridinium chloride electrolyte

1969 ◽  
Vol 47 (12) ◽  
pp. 2123-2135 ◽  
Author(s):  
Leslie E. Johnston ◽  
John A. Page
Keyword(s):  
Mercury Electrode ◽  
Normal Wave ◽  
Bulk Solution ◽  
Pyridinium Chloride ◽  
Chloride Electrolyte ◽  
Catalytic Wave ◽  
Controlled Potential Electrolysis ◽  
Dropping Mercury Electrode ◽  
Controlled Potential ◽  
Electron Reduction

The polarography and coulometry of Rh(III) has been studied in an aqueous pyridine–pyridinium chloride–sodium chloride electrolyte at pH 5.30 and ionic strength 0.30 M at 25.0 °C. Two distinct types of polarographic behavior were noted as the total Py concentration was varied between 0.05 and 0.45 M, a "normal" wave with E1/2 of −0.43 V vs. a standard calomel electrode, and a second catalytic wave which under some conditions masked the normal wave.For both types of behavior, controlled potential electrolysis gave a well-defined two electron reduction but there was a definite H+ consumption in the electrolyses. It is postulated that hydride species are involved in the reduction according to the scheme[Formula: see text]surface reaction at dropping mercury electrode[Formula: see text]slow, bulk solution in controlled potential electrolysis

Electrochemical reduction of nickel(II) dithiocarboxylates at the mercury electrode

1997 ◽  
Vol 75 (7) ◽  
pp. 1023-1029 ◽  
Author(s):  
A. Safavi ◽  
L. Fotouhi
Keyword(s):  
Electron Transfer ◽  
Electrochemical Techniques ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Ece Mechanism ◽  
Reduction Mechanisms ◽  
Ec Mechanism ◽  
Controlled Potential ◽  
Electron Reduction ◽  
Derivatives Of

The reduction mechanisms of a series of nickel(II) dithiocarboxylate complexes have been investigated in dimethyl sulphoxide at the mercury electrode. Various electrochemical techniques, including polarography, cyclic voltammetry, chronoamperometry, and controlled potential coulometry, were employed. The reduction of the complexes of the acid derivatives of 2-aminocyclopentene-1-dithiocarboxylate (ACD) proceeds initially by an ECE mechanism (electron transfer – chemical reaction – electron transfer) followed by a one-electron irreversible process. The nature of the complete electrode reaction suggests a metal-centered reduction. The nickel complexes of the ester derivatives of ACD underwent a one-electron reduction that was subject to a follow-up catalytic reaction (EC′ mechanism) and the original complex is regenerated through this regeneration reaction. Keywords: reduction, nickel(II) dithiocarboxylate, mercury electrode.

Regioselective S—O vs. C—O bond cleavage in sulfenate ester radical anions

2005 ◽  
Vol 83 (9) ◽  
pp. 1473-1482 ◽  
Author(s):  
Donald LB Stringle ◽  
Mark S Workentin
Keyword(s):  
Electron Transfer ◽  
Bond Cleavage ◽  
Electrochemical Techniques ◽  
Radical Anions ◽  
Peak Potential ◽  
Dissociative Mechanism ◽  
Dissociative Electron Transfer ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential ◽  
Singly Occupied Molecular Orbitals

The electron transfer (ET) reduction of benzyl benzenesulfenate ester (1) and tert-butyl benzenesulfenate ester (2) was investigated using electrochemical techniques. Analysis of the cyclic voltammetry of each compound suggests that the ET reduction proceeds via a stepwise dissociative mechanism. The voltammograms of 1 are similar to those of diaryl disulfides and it was found through controlled potential electrolysis (CPE) product studies that ET reduction leads to S—O bond cleavage. The voltammograms of 2 are dramatically different with a sharper dissociative wave occurring at a more negative peak potential. CPE experiments indicate products that result from ET leading to C—O bond cleavage in this case. DFT calculations of the singly occupied molecular orbitals (SOMOs) of 1 and 2 were performed and offer a rationale for the different reactivity of the two radical anions.Key words: sulfenate esters, dissociative electron transfer, electrochemistry, radical anions.

Electrochemical investigation of some potential antibacterials, II

1997 ◽  
Vol 75 (5) ◽  
pp. 567-574 ◽  
Author(s):  
Rajeev Jain ◽  
P. Padmaja ◽  
Seema Gupta
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behaviour ◽  
Reduction Reaction ◽  
Carbon Electrodes ◽  
Reduction Wave ◽  
Electrochemical Investigation ◽  
Glassy Carbon Electrodes ◽  
Controlled Potential Electrolysis ◽  
Wide Range ◽  
Controlled Potential

The electrochemical behaviour of 2-(4′-sulphonamoyl)hydrazonobutyrate-1,3-diones and sulphonamoylazoaminobenzenes has been studied over a wide range of pH at dropping mercury as well as glassy carbon electrodes. Both types of compounds exhibited a 4e− reduction reaction at both electrodes. At pH > 4.5, 2-(4′-sulphonamoyl)hydrazonobutyrate-1,3-diones exhibited a 2e− reduction wave at higher potentials. Both compounds undergo a 2e− oxidation reaction. On the basis of polarography, linear and cyclic voltammetry, controlled potential electrolysis, coulometry, and spectral analysis, a detailed mechanism has been postulated for the reduction as well as the oxidation. Keywords: electrochemistry, sulphonamides, polarography, cyclic voltammetry, coulometry.

Polarographic Behaviour of Some Arylazotheophyllines

1993 ◽  
Vol 58 (9) ◽  
pp. 1978-1988
Author(s):  
Mohamed I. Ismail ◽  
Madlene L. Iskander
Keyword(s):  
Diffusion Coefficient ◽  
Model Compound ◽  
Aqueous Media ◽  
Chemical Characteristics ◽  
Polarographic Behaviour ◽  
Physico Chemical ◽  
Controlled Potential Electrolysis ◽  
Azo Group ◽  
Controlled Potential ◽  
Electrolysis Products

The polarographic behaviour of a series of arylazotheophyllines was studied in aqueous alcoholic buffer media and in DMF-0.1 M LiClO4 solution. The redox study gave evidence that the azo group is electroactive in aqueous as well as non-aqueous media. A mechanism interpreting the electrode process is proposed and confirmed through the identification of the controlled potential electrolysis products, the use of a model compound and the application of Hamett's σ-E relationship. The physico-chemical characteristics of these compounds, viz. the diffusion coefficient, dissociation constant, ionization potential and electron affinity, are also included.

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