A chronoamperometric study of the oxidative nucleation of niazid and isoniazid on mercury electrodes in basic solutions

2011 ◽  
Vol 76 (6) ◽  
pp. 755-762
Author(s):  
Mercedes Ruiz Montoya ◽  
Sara Pintado ◽  
José Miguel Rodríguez Mellado
Keyword(s):  
Electrode Surface ◽  
Oxidation Product ◽  
Oxidation Process ◽  
Mercury Electrode ◽  
Oxidation Mechanism ◽  
Electron Process ◽  
Basic Solutions ◽  
Mercury Electrodes

Using chronoamperometric measurements at pH 12 it is shown that the oxidation mechanism of niazid adsorbed on the mercury electrode changes with respect to the mechanism reported in the literature for the electrooxidation of the molecules reaching the electrode by diffusion. A compact monolayer of niazid molecules is formed on the electrode surface, being the hydrazide oxidized through a two-electron process. The oxidation product is not able to dissociate a H+ ion, and the oxidation process does not proceeds beyond. For isoniazid the monolayer never becomes compact.

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.

Electrochemical behaviour of 2,5-dihydroxyanisole on a mercury electrode in aqueous media

1989 ◽  
Vol 54 (1) ◽  
pp. 42-52 ◽  
Author(s):  
Dimitra Sazou ◽  
Ioannis Poulios
Keyword(s):  
Oxidation Process ◽  
Electrochemical Behaviour ◽  
Aqueous Media ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Hanging Mercury Drop Electrode ◽  
Electrochemical Investigation ◽  
Basic Solutions ◽  
Ph Range ◽  
Subsequent Chemical

Electrochemical investigation of 2,5-dihydroxyanisole (2,5-DHA) has been carried out in aqueous solutions in pH range 2-11 on hanging mercury drop electrode (HMDE). The oxidation process in pH range 2-6 is a quasi-reversible electrode reaction which involves the transfer of two electrons and two protons. By use of semi-integration a dependence of the heterogeneous rate constant on the potential has been appreciated. Thus, the variation of peak current with pH changes can be explained. In more basic solutions the electrooxidation is complicated by subsequent chemical reactions as indicated from the calculated voltammetric and chronoamperometric parameters.

Oxidation mechanism of carcinogenic bis-azo dyestuff Trypan Blue

1982 ◽  
Vol 47 (10) ◽  
pp. 2746-2748 ◽  
Author(s):  
Miroslav Matrka ◽  
Jana Pípalová
Keyword(s):  
Acid Medium ◽  
Quantitative Evaluation ◽  
Oxidation Product ◽  
Trypan Blue ◽  
Oxidation Mechanism ◽  
Azo Coupling ◽  
Arenediazonium Salt

Oxidation of Trypan Blue with cerium(IV) ion in acid medium gives arenediazonium cation similar to the oxidation product of N,N-dimethyl-4-aminoazobenzene. Quantitative evaluation of the arenediazonium salt formed has been carried out spectrophotometrically after previous C-azo coupling with 2-naphthol.

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.

First principle simulation on oxidation mechanism of diethyl ether by nitrogen dioxide

2015 ◽  
Vol 14 (03) ◽  
pp. 1550020 ◽  
Author(s):  
Yuan Yuan ◽  
Wei Hu ◽  
Xuhui Chi ◽  
Cuihua Li ◽  
Dayong Gui ◽  
...  
Keyword(s):  
Diethyl Ether ◽  
Energy Barrier ◽  
Density Functional ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
High Energy ◽  
First Principle ◽  
Functional Theory ◽  
The Third ◽  
High Energy Barrier

The oxidation mechanism of diethyl ethers by NO2was carried out using density functional theory (DFT) at the B3LYP/6-31+G (d, p) level. The oxidation process of ether follows four steps. First, the diethyl ether reacts with NO2to produce HNO2and diethyl ether radical with an energy barrier of 20.62 kcal ⋅ mol-1. Then, the diethyl ether radical formed in the first step directly combines with NO2to form CH3CH ( ONO ) OCH2CH3. In the third step, the CH3CH ( ONO ) OCH2CH3was further decomposed into the CH3CH2ONO and CH3CHO with a moderately high energy barrier of 32.87 kcal ⋅ mol-1. Finally, the CH3CH2ONO continues to react with NO2to yield CH3CHO , HNO2and NO with an energy barrier of 28.13 kcal ⋅ mol-1. The calculated oxidation mechanism agrees well with Nishiguchi and Okamoto's experiment and proposal.

Temperature-Driven Oxidation Behavior of Pure Iron Surface Investigated by Time-Resolved EXAFS Measurements

1998 ◽  
Vol 524 ◽  
Author(s):  
S. J. Doh ◽  
J. M. Lee ◽  
D. Y. Noh ◽  
J. H. Je
Keyword(s):  
Heat Treatment ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Rapid Heating ◽  
Oxidation Mechanism ◽  
Front Surface ◽  
Time Resolved ◽  
Treatment Conditions ◽  
Surface Front ◽  
Prolonged Heat

ABSTRACTThe surface-front oxidation mechanism of iron was investigated by time-resolved, glancingangle Fe K-edge fluorescence EXAFS measurements at various oxidation temperatures of 200-700 C. The glancing angle was chosen according to the depth of the oxide layer, roughly 1500-2000A. The oxidation behavior under rapid heating(up to 600°C within 10 minutes) was compared with the slowly heated oxidation process using the Quick-EXAFS measurements. In the slowly heated process, Fe3O4 was the dominating phase at a relatively low temperature (300-400 C) initially. However, at a relatively high temperature (above 600°C), the Fe2O3 and FeO crystalline phases are gradually enriched as the successive oxidation process involving intrusive oxygen proceeded. Remarkably under a prolonged heat treatment above 600°C, the stable FeO phase that exists in a deep-lying interface structure and Fe2O3 phase eventually dominates the thick front-surface structure. In a quickly heated process, however, Fe3O4 phase is less dominating, which is contradictory to the commonly accepted oxidation models. The EXAFS results are discussed in conjunction with the x-ray diffraction features under the same heat treatment conditions.

Cyclic Oxidation Resistance of Co-10Cr-5Al-0.3Y Alloy at 800 oc

2014 ◽  
Vol 1015 ◽  
pp. 505-508
Author(s):  
Ling Yun Bai ◽  
Hong Hua Zhang ◽  
Huai Shu Zhang ◽  
Yun Xiang Zheng ◽  
Jun Huai Xiang
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
Local Zone

The cyclic oxidation behavior of Co-10Cr-5Al alloys with and without 0.3 at% Y doped in atmosphere at 800oC was investigated. The addition of 0.3 at.% Y increased the oxidation rate of the alloy and changed the oxidation mechanism. The scales grown the alloys with and without Y were both composed of an outer Co2O3layer and an inner complex layer of Al2O3, Co2O3and Cr2O3, except that the addition of 0.3 at% Y enhanced the adhesion of the scale. 0.3 at% Y agglomerated in local zone which accelerated the oxidation rate and was not conductive to the oxidation process of the Co-10Cr-5Al alloy.

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