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

1976 ◽  
Vol 29 (6) ◽  
pp. 1191 ◽  
Author(s):  
TH Randle ◽  
TJ Cardwell ◽  
RJ Magee
Keyword(s):  
Electron Transfer ◽  
Chemical Reaction ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Reduction Mechanism ◽  
Ece Mechanism ◽  
Controlled Potential ◽  
Nickel Species ◽  
Electron Transfers ◽  
Potential Conditions

The reduction mechanism of a series of nickel(11) dithiocarbamates has been investigated in dimethyl sulphoxide at the mercury electrode. Under controlled-potential conditions, the reduction proceeds initially by an ECE mechanism (electron transfer-chemical reaction-electron transfer) with n = 1 for both electron transfers. The chemical reaction involves a dissociation to produce a nickel species more easily reduced than the nickel(11) dithiocarbamate. However, for some derivatives, rate constants for the chemical step show a time dependence, at electrolysis times above 5 s, consistent with an ECCE mechanism of the type where the product of the first chemical reaction reacts further to produce a nickel species more difficult to reduce than nickel(11) dithiocarbamate. Exhaustive reduction of nickel(11) diethyldithiocarbamate at the mercury-pool electrode gave non-integral n-values (2 > n > 1) consistent with the ECCE mechanism, and demonstrated that the product of the second chemical reaction is reoxidized to nickel(11) diethyldithiocarbamate by oxygen. The nature of the complete electrode reaction suggests a metal-centred reduction.

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.

Faradaic Impedance Study of Mn(II) Reduction Mechanism in NaClO4 and NaCl Solutions on Mercury Electrode

2002 ◽  
Vol 67 (11) ◽  
pp. 1589-1595
Author(s):  
Barbara Marczewska ◽  
Andrzej Persona ◽  
Marek Przegaliński
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Electrochemical Reaction ◽  
Mercury Electrode ◽  
Reduction Mechanism ◽  
True Rate ◽  
Faradaic Impedance ◽  
Impedance Measurements ◽  
Order Of Magnitude ◽  
Adsorptive Properties

The electrochemical reaction of the Mn(II)/Mn(Hg) system on mercury electrode was studied in 1 M NaClO4 and 1 M NaCl as supporting electrolytes of different complexing and adsorptive properties. The impedance measurements confirmed the two-stage electroreduction of the Mn(II) in investigated solutions. Both the apparent and the true rate constants of the second electron transfer in both supporting electrolytes are lower by one order of magnitude than the rate constant of the first electron transfer. Similar values of corrected rate constants in both electrolytes suggest the similarity in mechanism of the Mn(II) electroreduction.

scholarly journals Electrochemical reduction mechanism of several oxides of refractory metals in FClNaKmelts

2020 ◽  
Vol 39 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Hui Li ◽  
Lei Jia ◽  
Jing Wang ◽  
Jing-long Liang ◽  
Hong-yan Yan ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electrochemical Reduction ◽  
Chemical Reaction ◽  
Transfer Process ◽  
Reduction Process ◽  
Refractory Metals ◽  
Reduction Mechanism ◽  
Reversible Process ◽  
Electron Transfer Process ◽  
One Step

AbstractThe dissolution characteristics and electrochemical reduction mechanism of oxides of refractory metals ZrO2, HfO2 and MoO3 in NaCl-KCl-NaF melts are studied. The results shows that there are no chemical reaction of ZrO2 and HfO2 in NaCl-KCl-NaF melts, the dissolution of MoO3 is chemically dissolved, and MoO3 reactwith melts to form Na2Mo2O7. The reduction process of zirconium in the NaCl-KCl-NaF-ZrO2 melts is a reversible process of one-step electron transfer controlled by diffusion. The electrochemical reduction process of ruthenium is a one-step reversible process and the product is insoluble; Electrochemical reduction of metallic molybdenum in melts is controlled by the diffusion and electron transfer process of active ion Mo2O27− . The electrochemical reduction process of the metal molybdenum in the melts is carried out in two steps.

Mechanism of L-ascorbic acid oxidation and dehydro-L-ascorbic acid reduction on a mercury electrode. I. Acid medium

1977 ◽  
Vol 55 (15) ◽  
pp. 2799-2806 ◽  
Author(s):  
Juan José Ruiz ◽  
Antonio Aldaz ◽  
Manuel Dominguez
Keyword(s):  
Electron Transfer ◽  
Ascorbic Acid ◽  
Oxidation Process ◽  
Mercury Electrode ◽  
Oxidation Mechanism ◽  
Limiting Current ◽  
Acid Oxidation ◽  
Rate Determining Step ◽  
Reaction Orders ◽  
Electron Transfers

A polarographic study of the oxidation mechanism of L-ascorbic acid and of the reduction mechanism of dehydro-L-ascorbic acid was carried out in an acid medium.For L-ascorbic acid, the oxidation process involves a two electron transfer and obeys the overall reaction[Formula: see text]The polarographic curve shows that the limiting current is governed by diffusion. On the rising portion of the wave, the two electron oxidation process consists of two consecutive one electron transfers, the second being the rate determining step (rds). The reaction orders, together with the Tafel slopes, were calculated.The reduction of dehydro-L-ascorbic acid at the limiting current is kinetically controlled and involves a two electron transfer. The reaction kinetic pathways were studied and the reaction orders and Tafel slope were calculated. It is deduced that, for low overvoltages, the second one electron transfer is the rate determining step.

scholarly journals Voltammetric and potentiometric studies of some sulpha drug-Schiff base compounds and their metal complexes

2007 ◽  
Vol 5 (3) ◽  
pp. 898-911 ◽  
Author(s):  
M. Ghoneim ◽  
E. Mabrouk ◽  
A. Hassanein ◽  
M. El-Attar ◽  
E. Hesham
Keyword(s):  
Schiff Bases ◽  
Reaction Pathway ◽  
Mercury Electrode ◽  
Transition Metal Ions ◽  
Electrode Reaction ◽  
Cyclic Voltammograms ◽  
Azomethine Group ◽  
Sulpha Drug ◽  
Controlled Potential ◽  
The Stability

AbstractThe electrochemical behavior of some sulpha drug-Schiff bases at a mercury electrode was examined in the Britton-Robinson universal buffer of various pH values (2.5–11.7) containing 20% v/v) of ethanol using DC-polarography, cyclic voltammetry and controlled-potential electrolysis. The DC-polarograms and cyclic voltammograms of the examined compounds exhibited a single, 2-electron, irreversible, diffusion-controlled cathodic step within the entire pH range which is attributed to the reduction of the azomethine group-CH=N- to -CH2-NH-. The symmetry transfer coefficient (α) of the electrode reaction and the diffusion coefficient (D 0) of the reactant species were determined. The electrode reaction pathway of the compounds at the mercury electrode was suggested to follow the sequence: H+, e−, e−, H+. The dissociation constant of the sulpha drug-Schiff bases, the stability constant and stoichiometry of their complexes with various divalent transition metal ions (Mn2+, Co2+, Ni2+, Cu2+ and Zn2+) were determined potentiometrically at room temperature.

Electroanalytical chemistry of vanadium complexes. Comparison of the voltammetric features of amavadine with those of the vanadium complexes with iminodiacetic acid and methyliminodiacetic acid

1989 ◽  
Vol 54 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Roland Meier ◽  
Harald Frank ◽  
Reinhard Kirmse ◽  
Reiner Salzer ◽  
Joachim Stach ◽  
...  
Keyword(s):  
Iminodiacetic Acid ◽  
Vanadium Complexes ◽  
Reduction Mechanism ◽  
Reversible Process ◽  
Electroanalytical Chemistry ◽  
Probable Explanation ◽  
Chemical Sense ◽  
Ece Mechanism ◽  
Methyliminodiacetic Acid

The voltammetric behaviour of amavadine (AV) was found to be considerably different from that of the complexes of VO2+ with methyliminodiacetic acid (MIDA) and iminodiacetic acid (IDA). To get an insight in the rather complicated reduction mechanism of the latter complexes the reductions of V(III) (MIDA) and V(III) (IDA) have been studied for comparison. The species V(III) (MIDA)2 and V(III) (IDA)2 are reduced to the appropriate V(II) complexes in a chemically reversible process. VO(MIDA)2 and VO(IDA)2 are reduced to the same complexes via an ECE mechanism. The investigation of the electroreduction of AV shows that this process is not reversible in the chemical sense. As a probable explanation, the conclusion was drawn that AV and the usual V(IV)O-iminocarboxylato complexes differ in their structures.

The Effect of p-Toluidine on the Two-Step Electroreduction of Zn(II) in Water-Methanol and Water-Dimethylformamide

1999 ◽  
Vol 64 (4) ◽  
pp. 585-594 ◽  
Author(s):  
Barbara Marczewska
Keyword(s):  
Electron Transfer ◽  
Binary Mixtures ◽  
Rate Constant ◽  
Rate Constants ◽  
Electrode Surface ◽  
Mercury Electrode ◽  
Forward Rate ◽  
Solvent Molecules ◽  
Activated Complex

The acceleration effect of p-toluidine on the electroreduction of Zn(II) on the mercury electrode surface in binary mixtures water-methanol and water-dimethylformamide is discussed. The obtained apparent and true forward rate constants of Zn(II) reduction indicate that the rate constant of the first electron transfer increases in the presence of p-toluidine. The acceleration effect may probably be accounted for by the concept of the formation on the mercury electrode an activated complex, presumably composed of p-toluidine and solvent molecules.

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