The behaviour of copper(II) dithiocarbamates at the mercury electrode

1976 ◽  
Vol 29 (1) ◽  
pp. 85 ◽  
Author(s):  
TH Randle ◽  
TJ Cardwell ◽  
RJ Magee
Keyword(s):  
Propylene Carbonate ◽  
Electrochemical Techniques ◽  
Mercury Electrode ◽  
Alkyl Substituent ◽  
Reduction Step ◽  
Electron Diffusion ◽  
Reduction Potentials ◽  
Diffusion Controlled

The reduction at the mercury electrode of a series of copper(11) dithiocarbamates [CU(S2CNR2)2] in propylene carbonate has been investigated by a variety of electrochemical techniques. Thecomplexes undergo reduction in two successive one-electron diffusion-controlled steps, with associated adsorption of the complexes and the reduction products. Exhaustive reduction at a mercury-pool electrode shows the completely reduced species [CU(S2CNR2)2]2- to undergo slowdissociation. The alkyl substituent influences the strength of adsorption of the reduction products, the reduction potentials of the complexes and the reversibility of the first reduction step, thesecond step being quasi-reversible in all cases. The electroactive centre appears to be the metal.

The reduction of gold(III) dithiocarbamates at the mercury electrode

1981 ◽  
Vol 34 (9) ◽  
pp. 1861 ◽  
Author(s):  
M Ahmed ◽  
RJ Magee
Keyword(s):  
Cyclic Voltammetry ◽  
Propylene Carbonate ◽  
Chemical Reaction ◽  
Mercury Electrode ◽  
Carbonate Solution ◽  
Reduction Step ◽  
Diffusion Controlled ◽  
Electron Reduction

The reduction at the mercury electrode of a series of gold(III) dithiocarbamates [Au(S2CNR2)3] in propylene carbonate solution has been investigated by d.c. polarography, cyclic voltammetry and chronoamperometry. ��� Under polarographic conditions, the complexes undergo reduction in a single, diffusion-controlled step. Exhaustive reduction of the complexes at the mercury pool electrode gave non-integral values (3 > n > 2), suggesting the presence of a coupled chemical reaction involving dissociation of the product of the first reduction step. ��� At short electrolysis times (t < 2 s), the slopes of the chronoamperometric i against t-½ plots were typical of two-electron reductions. At longer electrolysis times (t > 4 s), the slopes approached a three-electron reduction. ��� Cyclic voltammetry confirmed that the products resulting from the first reduction are susceptible to dissociation, releasing free dialkyldithiocarbamate anion.

Electrochemical studies of Schiff base compounds derived from antipyrine nucleus in ethanolic buffer solutions

2000 ◽  
Vol 78 (9) ◽  
pp. 1170-1177 ◽  
Author(s):  
Ibrahim S El-Hallag ◽  
Gad B El-Hefnawy ◽  
Youssef I Moharram ◽  
Enass M Ghoneim
Keyword(s):  
Schiff Base ◽  
Electrochemical Behaviour ◽  
Electrochemical Techniques ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Limiting Current ◽  
Electron Transfer Process ◽  
Buffer Solutions ◽  
Mechanistic Pathway ◽  
Electrochemical Parameters

The electrochemical behaviour of Schiff base compounds derived from an antipyrine nucleus was investigated in 30% (v/v) ethanolic buffer solutions (pH 3-11) using various electrochemical techniques at mercury electrode. The results showed that, the total limiting current of each of the studied compounds corresponds to 2-electron transfer process. The mechanistic pathway of the electrode reaction of the investigated compounds at mercury electrode, the effect of the medium, and the evaluation of the electrode reaction parameters were illustrated and discussed.Key words: Schiff base, antipyrine nucleus, electrode reaction, electrochemical parameters, cyclic voltammetry.

Behaviour of disubstituted dithiocarbamates at the mercury electrode

1975 ◽  
Vol 28 (1) ◽  
pp. 21 ◽  
Author(s):  
TH Randle ◽  
TJ Cardwell ◽  
RJ Magee
Keyword(s):  
Surface Film ◽  
Electrochemical Behaviour ◽  
Mercury Electrode ◽  
Alkyl Substituent ◽  
Electrode Reaction ◽  
Anodic Wave ◽  
Alkyl Groups ◽  
Product Film ◽  
Triton X ◽  
General Method

The electrochemical behaviour at the mercury electrode of a series of sodium dithiocarbamates in aqueous solution has been investigated. Although the overall electrode reaction mechanism is the same as that for sodium diethyldithiocarbamate in each case, the current flowing in the main anodic wave is determined by the nature of the film of the particular insoluble mercury(II) dithiocarbamate deposited on the electrode and varies with the alkyl substituent group in the dithiocarbamate. A porous, loosely bound film which periodically bursts, causing localized stirring and large irregular currents, was indicated for large bulky alkyl groups (e.g. butyl) while for small or planar alkyl groups (e.g. methyl, tetramethylene) current inhibition was observed, suggesting a compact surface film. The influence of the surfactant Triton X-100 on the product film has also been examined. Linear sweep chronoamperometry is recommended as a general method of analysis for dithiocarbamates as the electrolysis time (and therefore the film thickness) can be selected to avoid the above interferences.

Electrochemical evaluation of electron acceptor materials

1984 ◽  
Vol 62 (10) ◽  
pp. 1877-1885 ◽  
Author(s):  
R. O. Loutfy ◽  
C. K. Hsiao ◽  
B. S. Ong ◽  
B. Keoshkerian
Keyword(s):  
Electron Acceptor ◽  
Methylene Chloride ◽  
Energy Levels ◽  
Mercury Electrode ◽  
Transport Processes ◽  
Reduction Potentials ◽  
Half Wave ◽  
Intermediate Anion ◽  
Wave Reduction ◽  
Anion Radicals

The electrochemical half-wave reduction potential (E1/2) of 33 electron acceptor molecules in dry methylene chloride has been measured by cyclic voltammetry (CV) at a mercury electrode. The differences in E1/2 values for the reversible reduction to the corresponding anion radicals reflect the electronic influence of the substituent at different ring positions.The measurements of the half-wave reduction potentials provided a convenient method for determining the conducting energy levels of the electron relay molecules in condensed media. Repetitive potential cycle measurements provided information on the chemical stability and cyclability of the intermediate anion radicals formed during electron transport processes.

The polarography of beryllium

1964 ◽  
Vol 17 (10) ◽  
pp. 1072 ◽  
Author(s):  
PJ Shirvington ◽  
TM Florence ◽  
AJ Harle
Keyword(s):  
Aqueous Media ◽  
Electrode Reaction ◽  
Complexing Agents ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Reduction Step ◽  
Current Time ◽  
Diffusion Controlled ◽  
Coordinated Water ◽  
Potentiometric Data

The polarography of beryllium in 0.5M lithium chloride has been investigated in some detail, using several polarographic and coulometric techniques. Current-time curves, microscopic examination and cinematography of the mercury drop, and the effect of complexing agents, aided in elucidating the electrode process. The experimental data show that the polarographic step for the tetraquoberyllium ion is diffusion-controlled but irreversible, and results from the reduction of two protons liberated from the coordinated water molecules, yielding beryllium hydroxide and hydrogen. The evidence suggests that this reduction takes place in a stepwise process, with a soluble beryllium hydroxy complex as an intermediate. The polarographic results can be correlated with published potentiometric data on the composition and stabilities of hydrolysed beryllium species in aqueous media. The number of electrons involved in the electrode reaction depends on the number of hydroxyl groups per beryllium atom in the beryllium complex. Beryllium oxalate and salicylate complexes also give a reduction step, but only if the complex contains coordinated water molecules. The diffusion coefficient of the tetraquoberyllium ion was found to be 6.2 � 0.3 x 10-6 cm2 sec-1 at 30�.

Polarography of n-butylthioglycolate in aqueous media, methanol, and acetonitrile

1984 ◽  
Vol 62 (9) ◽  
pp. 1817-1821
Author(s):  
K. C. Gupta ◽  
Kalpana K. Sharma
Keyword(s):  
Aqueous Media ◽  
Mercury Electrode ◽  
Wave Characteristics ◽  
Anodic Wave ◽  
Diffusion Controlled ◽  
Dropping Mercury Electrode ◽  
Drop Time ◽  
And Diffusion ◽  
Mechanism Of The Reaction

The polarographic behaviour of n-butylthioglycolate (RSH) at the DME in aqueous media, methanol, and acetonitrile has been investigated in the presence of 0.1 M KNO3 and 0.01% thymol. The effect of pH, concentration of RSH, and drop time on the wave characteristics and the mechanism of the reaction occurring at the surface of the mercury drop have been studied. Well-defined reversible and diffusion-controlled anodic waves were obtained in aqueous media (pH 4.2), 40% methanol (pH 3.22), and 40% acetonitrile (pH 2.96). Mathematical and analytical evidence was obtained to show that the anodic wave of RSH at a dropping mercury electrode in aqueous media, 40% methanol, and 40% acetonitrile is due to the formation of the mercury complex RSHg. The dissociation constant (pK) of the mercapto group in n-butylthioglycolate is 9.6 and the diffusion coefficient in the different media are 1.17 × 10−6 cm2 s−1 (in aqueous media) 1.23 × 10−6 cm2 s−1 (in 40% methanol), and 2.43 × 10−6 cm2 s−1 (in 40% acetonitrile). The linearity of id with RSH concentration provides a rapid and precise method for the determination of RSH, down to 0.4 mM in aqueous media, methanol, and acetonitrile.

Reduction of indium(III) at dropping mercury electrode in the presence of pyridine in aqueous and ethanol–water media

2010 ◽  
Vol 75 (6) ◽  
pp. 653-663 ◽  
Author(s):  
Vinita Sharma ◽  
Krishna D. Gupta
Keyword(s):  
Mercury Electrode ◽  
Complexation Reaction ◽  
Complex Species ◽  
Diffusion Controlled ◽  
Straight Line ◽  
Half Wave ◽  
Dropping Mercury Electrode ◽  
Water Media ◽  
Single Complex ◽  
The Stability

The reduction of indium(III) at dropping mercury electrode in aqueous as well as in 25% ethanol–water media in the presence of pyridine has been studied at a constant ionic strength (0.1 M KNO3) and at 30 and 40 °C. The reduction is diffusion-controlled but the electrode process is quasi-reversible in both media. The reversible half-wave potential values,E1/2r, have been obtained by Gelling’s method. The plot ofE1/2r versus pyridine concentration is a straight line and the number of ligands,j, was determined from the slope. This shows the formation of a single complex. The stability constant has been determined by Lingane’s method. In(III) forms one complex species with composition 1:1, [In(py)]3+. The values of thermodynamic parameters ΔG, ΔHand ΔSof the complexation reaction have also been determined at 30 °C.

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.

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