Synthesis and Electrochemical Reduction of Methyl 3-Halo-1-benzothiophene-2-carboxylates

2004 ◽  
Vol 69 (1) ◽  
pp. 242-260 ◽  
Author(s):  
Michal Rejňák ◽  
Jiří Klíma ◽  
Jiří Svoboda ◽  
Jiří Ludvík
Keyword(s):  
Cyclic Voltammetry ◽  
Radical Anion ◽  
Preparative Method ◽  
Platinum Electrodes ◽  
Disk Electrode ◽  
Dimer Formation ◽  
Halide Anion ◽  
Primary Radical ◽  
Heterocyclic Radical ◽  
Ece Mechanism

A preparative method of synthesis of the new methyl 3-iodo-1-benzothiophene-2-carboxylate was elaborated. Electrochemical behavior of methyl 3-chloro-, bromo- and iodo-1-benzothiophene-2-carboxylates 1-3, and of their reduction and dimer products 4, 5 in anhydrous dimethylformamide has been investigated at mercury and platinum electrodes using polarography, cyclic voltammetry and voltammetry on a rotating platinum disk electrode. The reduction in divided cells follows the ECE mechanism (electron - chemical step - electron), where the primary radical anion is split into a halide anion and neutral heterocyclic radical, which is immediately reduced by the second electron and protonated. The only reduction product is the methyl 1-benzothiophene-2-carboxylate (5); whereas the EDim mechanism (electron - dimer formation) leading to the dimeric species 4 was not observed under the above conditions. Reduction of 1-3 on platinum causes formation of a blocking film on the electrode. Sonication during electrolysis successfully reactivates the electrode.

On the electroreduction mechanism of halobenzenes: Detection of intermediates in reduction of monohalobenzenes

1989 ◽  
Vol 54 (4) ◽  
pp. 900-910 ◽  
Author(s):  
Juan Casado ◽  
Iluminada Gallardo
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behaviour ◽  
Experimental Results ◽  
Disk Electrode ◽  
Rotating Ring Disk Electrode ◽  
Mercury Cathode

Experimental results from electrochemical behaviour of halobenzenes in DMF at a mercury cathode are used to discuss alternative mechanisms of reduction. Intermediates of these mechanisms, such as phenyl anion, phenylmercury radical and phenylmercury cation have been detected at the electrode by using cyclic voltammetry and a rotating ring-disk electrode.

Facile Fabrication of Silver Dendrites by Different Electrodeposition Methods

2012 ◽  
Vol 550-553 ◽  
pp. 1976-1979 ◽  
Author(s):  
Zong Mu Li
Keyword(s):  
Cyclic Voltammetry ◽  
Formation Mechanism ◽  
Glassy Carbon ◽  
Efficient Method ◽  
Electrochemical Techniques ◽  
Disk Electrode ◽  
Fractal Structures ◽  
Galvanostatic Method ◽  
Facile Fabrication ◽  
Silver Dendrites

Three classical electrochemical techniques such as the pulsed potentiostatic method, cyclic voltammetry, and galvanostatic method were used to study the Ag morphology on glassy carbon disk electrode. The results of the three electrochemical methods were compared and the possible formation mechanism of fractal phenomena was discussed. It was found that cyclic voltammetry, and galvanostatic method are mild, convenient, fast and efficient method to prepare silver fractal structures.

Hammett-Streitwieser Reaction Constants for the Electroreduction of Diaryl Ketones in Aprotic Media

1996 ◽  
Vol 49 (8) ◽  
pp. 901 ◽  
Author(s):  
E Wagnerczauderna ◽  
MK Kalinowski
Keyword(s):  
Cyclic Voltammetry ◽  
Dimethyl Sulfoxide ◽  
Propylene Carbonate ◽  
Radical Anion ◽  
Electrode Reaction ◽  
Hexamethylphosphoric Triamide ◽  
Ketyl Radical ◽  
Donor Numbers ◽  
Reaction Constants ◽  
Solvent Acidity

Cyclic voltammetry has been used to measure formal potentials of seven aromatic ketone/ketyl radical anion systems in benzonitrile, acetonitrile , propylene carbonate, acetone, N,N- dimethylformamide, N-methylpyrrolidin-2-one, dimethyl sulfoxide and hexamethylphosphoric triamide. The values measured in each solvent obey the Hammett- Streitwieser equation; the reaction constants were found to depend on the solvent acidity and basicity expressed by acceptor and donor numbers, respectively. The results are discussed in terms of the solvation of the products and reactants of the electrode reaction.

Electrochemical Reaction Mechanism of Tiron in Acidic Aqueous Solution

2011 ◽  
Vol 396-398 ◽  
pp. 1730-1735 ◽  
Author(s):  
Yan Xu ◽  
Yue Hua Wen ◽  
Jie Cheng ◽  
Gao Ping Cao ◽  
Yu Sheng Yang
Keyword(s):  
Aqueous Solution ◽  
Cyclic Voltammetry ◽  
Aqueous Solutions ◽  
Electrochemical Oxidation ◽  
Electrochemical Reaction ◽  
Mass Spectrometric ◽  
Acidic Aqueous Solution ◽  
Ece Mechanism ◽  
Flow Through ◽  
Electro Oxidation

Electrochemical oxidation of tiron in the presence of H2O as a nucleophile in strongly acidic aqueous solutions was studied by cyclic voltammetry, controlled-voltage coulometry and spectrometric investigations. The mechanism of electrochemical reaction is confirmed by spectrophotometric tracing in various times of controlled-voltage coulometry. The voltammetric and spectrophotometric foundations indicate that a 1,4-Michael addition of H2O from its hydroxy moiety to the position 4 of electrochemically derived o-quinone is occurred. The electrochemical oxidation and reduction of tiron has been successfully accomplished by controlled-voltage coulometry in a redox flow-through type cell and the final electro-reduced product was characterized by spectrophotometric, 1H NMR and mass spectrometric methods. It is demonstrated that the electro-oxidation of tiron follows an ECE mechanism in acidic aqueous solutions, leading to formation of a new compound of para- benzoquinone derivative.

A novel sulfur–nitrogen π-heterocyclic radical anion, (6H-1,2,3-benzodithiazol-6-ylidene)malononitrilidyl, and its homo- and heterospin salts

Polyhedron ◽  
2014 ◽  
Vol 72 ◽  
pp. 43-49 ◽  
Author(s):  
Alexander Yu. Makarov ◽  
Elena A. Chulanova ◽  
Nikolay A. Semenov ◽  
Nikolay A. Pushkarevsky ◽  
Anton V. Lonchakov ◽  
...  
Keyword(s):  
Radical Anion ◽  
Heterocyclic Radical

Bismuth(III) Complex of the [S4]•– Radical Anion: Dimer Formation via Pancake Bonds

2017 ◽  
Vol 139 (46) ◽  
pp. 16490-16493 ◽  
Author(s):  
Ryan J. Schwamm ◽  
Matthias Lein ◽  
Martyn P. Coles ◽  
Christopher M. Fitchett
Keyword(s):  
Radical Anion ◽  
Dimer Formation

Correlation of the first reduction potential of selected radiosensitizers determined by cyclic voltammetry with theoretical calculations

2011 ◽  
Vol 76 (8) ◽  
pp. 937-946 ◽  
Author(s):  
Miroslav Gál ◽  
Viliam Kolivoška ◽  
Marta Ambrová ◽  
Ján Híveš ◽  
Romana Sokolová
Keyword(s):  
Experimental Study ◽  
Cyclic Voltammetry ◽  
Radical Anion ◽  
Reduction Potential ◽  
Theoretical Calculations ◽  
Dft Method ◽  
Basis Set ◽  
Radical Anions ◽  
Electron Affinities ◽  
Electron Reduction

Radiosensitizers are drugs that make cancer cells more sensitive to radiation therapy. The cytotoxic properties of such compounds are due to the fact that in the cell these compounds undergo one-electron reduction to generate radical anions. Therefore, their theoretical and/or experimental study is of high interest. To determine the correlation between reduction potential determined by cyclic voltammetry measurements and some physicochemical properties of selected radiosensitizers theoretical calculations of electron affinities based on the DFT method with B3LYP functional at the level of 6-311++G** basis set in vacuum were utilized. Very good correlation was found between electron affinities of radiosensitizers and their reduction potential and so called E71 potential that account for the energy necessary to transfer the first electron to an electroactive group at pH 7 in aqueous medium to form a radical anion.

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