scholarly journals Electroreduction of cefetamet on mercury platinum and gold electrodes

2000 ◽  
Vol 65 (1) ◽  
pp. 47-53 ◽  
Author(s):  
M. Avramov-Ivic ◽  
V. Kapetanovic ◽  
M. Aleksic ◽  
P. Zuman
Keyword(s):  
Alkaline Medium ◽  
Mercury Electrode ◽  
Reduction Process ◽  
Gold Electrodes ◽  
Platinum Electrodes ◽  
Medium Ph ◽  
Solid Electrodes

The electroreduction of cefetamet (CEF) using gold and platinum electrodes has been investigated in slightly alkaline medium (pH 8.40) where adsorption, previously observed at mercury electrode, was pronounced. This investigation was performed in order to determine whether the adsorption interfers with the reduction process even at solid electrodes and to compare with a mercury electrode.

Characterization of Tris(Diselenocarbamato)Cobalt(III) and Pentakis(Diselenocarbamato)Dicobalt(III) Complexes by Electrochemical, Cobalt-59 N.M.R. and Mass-Spectrometric Techniques. Comparisons With Dithiocarbamate Analogs

1986 ◽  
Vol 39 (9) ◽  
pp. 1385 ◽  
Author(s):  
AM Bond ◽  
R Colton ◽  
DR Mann ◽  
JE Moir
Keyword(s):  
Electrochemical Oxidation ◽  
Chemical Shifts ◽  
Chemical Reactivity ◽  
Mercury Electrode ◽  
Substituent Effects ◽  
Reduction Process ◽  
Reduced Form ◽  
Platinum Electrodes ◽  
Redox Potentials ◽  
Mercury Electrodes

A series of Co(RR′dsc)3 and [Co2(RR′dsc)5]+ complexes (R, R′ = two alkyl groups or one heterocyclic group; dsc = NCSe2) have been synthesized and their redox behaviour, chemical reactivity and spectroscopic properties compared with the corresponding dithiocarbamate (RR′dtc) complexes. Electrochemical oxidation of Co(RR′dsc)3 in dichloromethane at platinum electrodes occurs at potentials about 0.34 V less positive than for Co(RR′dsc)3. The formally cobalt(IV) complexes [Co(RR′dsc)3]+ can be identified as a product which is then converted into [Co2(RR′dsc)5]+ via dimerization and an internal redox reaction. Despite the enhanced thermodynamic stability implied by the redox potentials, [Co(RR′dsc)3]+ has similar kinetic stability to the analogous dithiocarbamate complexes. Co(RR′dsc)3 is reduced at fairly negative potentials on both platinum and mercury electrodes with extremely rapid loss of [RR′dsc]-. [Co(RR′dsc)3]- is therefore thermodynamically and kinetically more unstable than [Co(RR′dtc)3]- . The [Co2(RR′dsc)5]+ complexes are also more readily oxidized and harder to reduce than the sulfur analogues. Oxidation of [Co2(RR′dsc)5]+ produces [Co2(RR′dsc)5]2+ at low temperatures and fast scan rates, but no stable reduced form of the dimer is accessible on the voltammetric time scale examined. The reduction process for the dimer is consistent with the reaction [Co2(RR′dsc)5]+ +e- → Co(RR′dsc)3+ Co(RR dsc)2. Electrochemical oxidation data obtained at mercury electrodes for the diselenocarbamate complexes are complicated by adsorption but are similar to that found at platinum electrodes. This contrasts with the dithiocarbamates where a mercury electrode specific pathway is observed. Cobalt-59 n.m.r. spectroscopy in dichloromethane shows the non- equivalence of the two cobalt atoms in [Co2(RR′dsc)5]+. The chemical shifts for Co(RR′dsc)3 complexes exhibit similar substituent effects to the dithiocarbamates in cobalt-59 n.m.r. measurements as was the case in oxidative electrochemistry. Cobalt-59 n.m.r. spectroscopy and mass spectrometry demonstrate that exchange, substitution and redox reactions can lead to the formation of mixed ligand diselenocarbamate complexes and mixed dithiocarbamate/diselenocarbamate complexes for both the cobalt(III) monomers and dimers.

Effect of Ultrasound on Voltammetric Measurements on a Miniaturized Mercury Electrode; Sonovoltammetry and Sonopolarography

1996 ◽  
Vol 61 (12) ◽  
pp. 1703-1708 ◽  
Author(s):  
Ladislav Novotný
Keyword(s):  
Mercury Electrode ◽  
Solid Electrodes ◽  
Voltammetric Measurements

The influence of ultrasound on voltammetric measurements at a mechanically stable renewed mercury electrode was described. The measurements were carried out in a solution of 4,4'-bipyridyl in 0.1 M KCl + 0.01 M NaOH, in 1 . 10-4 M CdSO4 + 5 . 10-6 M tribenzylamine in 0.1 M H2SO4 and in 3 . 10-3 M CdSO4 + 1 . 10-4 M tribenzylamine hydrochloride. Possible development and applications of related electroanalytical techniques by using mercury and solid electrodes were discussed. A pronounced influence of ultrasound was observed mainly in cases where the kinetics and irreversibility of the electrochemical and related processes played an important role.

In Situ ATR-FTIR Studies of Ethanol Electro-oxidation in Alkaline Medium on PtRh/C Electrocatalyst Prepared by an Alcohol Reduction Process

2016 ◽  
Vol 7 (4) ◽  
pp. 297-304 ◽  
Author(s):  
E. H. Fontes ◽  
Sirlane G. da Silva ◽  
E. V. Spinace´ ◽  
A. O. Neto ◽  
R. F. B. de Souza
Keyword(s):  
Alkaline Medium ◽  
Reduction Process ◽  
Ftir Studies ◽  
Electro Oxidation ◽  
Alcohol Reduction

Polarography as an Analytical Tool

1964 ◽  
Vol 47 (1) ◽  
pp. 21-27
Author(s):  
John K Taylor
Keyword(s):  
Mercury Electrode ◽  
Selective Extraction ◽  
Analytical Tool ◽  
Diffusion Control ◽  
Oscillographic Polarography ◽  
Dropping Mercury Electrode ◽  
Anodic Stripping ◽  
Controlled Potential ◽  
Solid Electrodes ◽  
Practice Methods

Abstract Polarography is a useful analytical tool for determining many substances in solutions at small concentrations, and is frequently applied to analysis of minor constituents. Conventional polarography employs a dropping mercury electrode, can measure solutions in concentrations ranging from 10-2 to 10-5M, and requires only a few tenths of ml for analysis. Because of the difficulty of obtaining diffusion control in practice, methods are comparative and involve empirical calibrations with standard solutions. Practical tolerances have been worked out to insure that results are reliable to 2 relative per cent. Interferences have been lessened by several means, e.g., complexing, separation by electrolysis at controlled potential, selective extraction, and improvements in circuitry to permit use of relatively dilute supporting electrolytes. Modified polarographic methods include solid electrodes, derivative polarography, differential polarography, cathode ray polarography, anodic stripping polarography, and oscillographic polarography.

Surface poisoning during electrocatalytic monosaccharide oxidation reactions at gold electrodes in alkaline medium

2007 ◽  
Vol 9 (8) ◽  
pp. 1892-1898 ◽  
Author(s):  
Masato Tominaga ◽  
Makoto Nagashima ◽  
Katsuhiko Nishiyama ◽  
Isao Taniguchi
Keyword(s):  
Alkaline Medium ◽  
Gold Electrodes ◽  
Oxidation Reactions ◽  
Surface Poisoning

Determination of Sucralose by Controlled UV Photodegradation Followed by UV Spectrophotometry

2013 ◽  
Vol 96 (3) ◽  
pp. 603-606
Author(s):  
Mohd Idris ◽  
V Jayathirtha Rao ◽  
Deepak Middha ◽  
Sudhir Kumar Shukla ◽  
Tulsidas Ramachandra Rao Baggi
Keyword(s):  
Correlation Coefficient ◽  
Alkaline Medium ◽  
Spectrophotometric Method ◽  
Calibration Curve ◽  
Artificial Sweeteners ◽  
Uv Spectrophotometry ◽  
Medium Ph ◽  
Accuracy And Precision ◽  
Uv Photodegradation

Abstract A simple and time-efficient UV spectrophotometric method was developed for the determination of sucralose in artificial sweeteners. The procedure is based on the UV spectrophotometric determination of the photodegraded product at 270 nm in alkaline medium (pH 12). LOD for this method was 0.02 g/L, and the calibration curve was found to obey Beer's law in the concentration range of 0.1 to 1.2 g/L, with a correlation coefficient (R2) value of 0.9977. The proposed method was studied for accuracy and precision.

scholarly journals Electrochemical and Spectrastudies of Some Sulfa Drug Azodyes and Their Metal Complexes in Aqueous Solution

2017 ◽  
Vol 14 (1) ◽  
pp. 6021-6032 ◽  
Author(s):  
E.M. Mabrouk ◽  
Kh.A.Al Omary ◽  
A.S.Al- Omary ◽  
E.H. El-Mossalamy
Keyword(s):  
Dissociation Constants ◽  
Mercury Electrode ◽  
Reduction Process ◽  
Electrode Reaction ◽  
Formation Constants ◽  
Azo Compounds ◽  
Alkaline Solutions ◽  
Sulfa Drugs ◽  
Sulfa Drug ◽  
Buffer Solutions

The electrochemical behavior of some azo compounds derived from sulfa drugs derivatives in B.R. buffer solutions of different pH containing 20 (v/v) ethanol was investigated at the mercury  electrode using different techniques (DC,DPP,CV and Coulometry) to investigate the effect of medium on the electro reduction process and suggestion the electrode reaction mechanism. The obtained results denoted that these compounds were reduced undergo a single irreversible 4- electron polarographic wave in acid and neutral solutions which represent the cleavage of the N=N center to the amine stage, whereas in alkaline solution, two wave are obtained the second is 2-electron irreversible wave corresponding to the reduction ofCHO group to CH2OH. The DPP and CV data showed a single peak in solutions of pH< 8, whereas three peaks are in alkaline solutions. The dissociation constants of the investigated compounds were determined by using spectrophotometric and potentiometric methods. Also the metal – ligand formation constants were determined potentiometrically and found in the order Cu˃ Co˃ Ni ˃Zn.

scholarly journals Hybrid Electromagnetic Nanomaterials Based on Polydiphenylamine-2-carboxylic Acid

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1568
Author(s):  
Sveta Zhiraslanovna Ozkan ◽  
Aleksandr Ivanovich Kostev ◽  
Galina Petrovna Karpacheva ◽  
Petr Aleksandrovich Chernavskii ◽  
Andrey Aleksandrovich Vasilev ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Alkaline Medium ◽  
Acidic Medium ◽  
Oxidative Polymerization ◽  
Reaction Medium ◽  
Medium Ph ◽  
Extraction And Purification ◽  
Structure Morphology ◽  
Polymer Metal ◽  
Walled Carbon Nanotubes

Hybrid ternary nanomaterials based on conjugated polymer polydiphenylamine-2-carboxylic acid (PDPAC) (poly-N-phenylanthranilic acid), Fe3O4 nanoparticles and single-walled carbon nanotubes (SWCNT) were prepared for the first time. Polymer–metal–carbon Fe3O4/SWCNT/PDPAC nanocomposites were synthesized via in situ oxidative polymerization of diphenylamine-2-carboxylic acid (DPAC) by two different ways: in an acidic medium and in the interfacial process in an alkaline medium. In an alkaline medium (pH 11.4), the entire process of Fe3O4/SWCNT/PDPAC-1 synthesis was carried out in one reaction vessel without intermediate stages of product extraction and purification. In an acidic medium (pH 0.3), to prepare the Fe3O4/SWCNT/PDPAC-2 nanocomposites, prefabricated magnetite nanoparticles were deposited on the surface of obtained SWCNT/PDPAC-2. The phase composition of the nanocomposites does not depend on the synthesis reaction medium pH. The influence of the reaction medium pH on the structure, morphology, thermal, magnetic, and electrical properties of the obtained ternary nanocomposites was studied.

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