Electrochemical reduction of benzenediazonium salts in aprotic medium

1989 ◽  
Vol 54 (6) ◽  
pp. 1496-1507
Author(s):  
Pavel Janderka ◽  
Igor Cejpek
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Reduction ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Reduction Mechanism ◽  
Aprotic Medium ◽  
Pulse Polarography ◽  
Dc Polarography ◽  
Donor Numbers

DC polarography, TAST polarography, differential pulse polarography, polarography with superimposed alternating current, slow cyclic voltammetry with a hanging Hg drop electrode and a Pt electrode, rapid cyclic voltammetry with a hanging Hg drop, and coulometry were used to study the electrochemical reduction of p-methoxy- and p-nitrobenzenediazonium cations in aprotic medium. A reduction mechanism involving two separate one-electron steps is proposed, the first of which being complicated by adsorption and follow-up chemical reaction leading to evolution of nitrogen. The basicity of the aprotic solvents, expressed by donor numbers according to Gutman, influences the reduction mechanism of these cations.

Electrochemical Behaviour of 3-Pyridyl-N,N-bis[(8-quinolyl)amino]methane

1993 ◽  
Vol 58 (6) ◽  
pp. 1279-1284
Author(s):  
Angeles Loeches ◽  
Carmen Teijeiro ◽  
Dolores Marín
Keyword(s):  
Cyclic Voltammetry ◽  
Limit Of Detection ◽  
Electrochemical Behaviour ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Reduction Mechanism ◽  
Pulse Polarography ◽  
Dc Polarography ◽  
The Waves

3-Pyridyl-N,N-bis[(8-quinolyl)amino]methane was studied by DC polarography, coulometry, cyclic voltammetry and differential pulse polarography in a system comprising Britton-Robinson buffer and 15 vol.% ethanol at pH 7.0. The nature of the waves was investigated, and the reduction mechanism is suggested. DPP was also used for a quantitative determination of the substance, and a limit of detection of 3 μmol l-1 was obtained.

Influence of substituents on electrochemical reduction potentials of benzenediazonium salts

1989 ◽  
Vol 54 (12) ◽  
pp. 3135-3143 ◽  
Author(s):  
Pavel Janderka ◽  
Igor Cejpek
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Reduction ◽  
Linear Correlation ◽  
Structural Parameters ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Reduction Potentials ◽  
Pulse Polarography ◽  
Substituent Constants ◽  
Influence Of Substituents

TAST polarography, differential pulse polarography, and cyclic voltammetry on a hanging mercury drop and on a platinum disc were employed to measure the electrochemical reduction potentials of nine para substituted benzenediazonium salts in dimethylformamide. A satisfactory linear correlation was obtained between the potentials of the adsorption prewave and the substituent constants σ+p. The influence of substituents on some structural parameters was studied by using the CNDO/2 method for both a closed and a opened shell.

Polarography of N,N-dimethyl-4-amino-4'-hydroxyazobenzene in water-methanol mixtures

1985 ◽  
Vol 50 (3) ◽  
pp. 712-725 ◽  
Author(s):  
Jiří Barek ◽  
Lubomír Kelnar
Keyword(s):  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Polarographic Reduction ◽  
Reduction Mechanism ◽  
Pulse Polarography ◽  
Methanol Medium

The polarographic reduction of N,N-dimethyl-4-amino-4'-hydroxyazobenzene in water-methanol medium was investigated. Evidence is presented for adsorption of the depolarizer on the electrode, and a reduction mechanism is proposed. Conditions are indicated for the determination of this compound in the concentration range 10-4-10-6 mol/l by d.c. polarography, 10-5 to 3 . 10-7 mol/l by Tast polarography, and 10-5-3 . 10-8 mol/l by differential pulse polarography.

Polarographic and voltammetric determination of 6-nitrobenzimidazole and mechanism of its electrochemical reduction

2009 ◽  
Vol 74 (10) ◽  
pp. 1443-1454 ◽  
Author(s):  
Dana Deýlová ◽  
Jiří Barek ◽  
Vlastimil Vyskočil
Keyword(s):  
Electrochemical Reduction ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Optimal Conditions ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Constant Potential ◽  
Pulse Voltammetry

Optimal conditions were found for the determination of 6-nitrobenzimidazole by tast polarography (at 1 × 10–4–1 × 10–6 mol l–1), by differential pulse polarography at dropping mercury electrode (at 1 × 10–4–1 × 10–7 mol l–1), and by differential pulse voltammetry at hanging mercury drop electrode (at 1 × 10–4–1 × 10–8 mol l–1). Practical applicability of the developed methods was verified on the determination of 6-nitrobenzimidazole in drinking water (at 10–8 mol l–1). Coulometry at constant potential and cyclic voltammetry were used for elucidation of the mechanism of electrochemical reduction.

Polarographic Determination of 4'-Substituted Derivatives of 3-Carboxy-4-hydroxy-6-acetylaminoazobenzene

1994 ◽  
Vol 59 (11) ◽  
pp. 2397-2414 ◽  
Author(s):  
Jiří Barek ◽  
Piero Savarino ◽  
Lucie Stuchlíková ◽  
Jiří Zima
Keyword(s):  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Reduction Mechanism ◽  
Optimum Conditions ◽  
Entire Series ◽  
Pulse Polarography ◽  
Half Wave ◽  
Hammett Σ Constants ◽  
Derivatives Of

Tast polarography, differential pulse polarography and cyclic voltammetry were applied to the examination of 7 derivatives of 3-carboxy-4-hydroxy-6-acetylaminoazobenzene with H, CH3, OCH3, Cl, COCH3, NO2 and NHCOCH3 substituents in position 4'. A general reduction mechanism was suggested for the substances. The half-wave potentials obtained from tast polarographic measurements were correlated with the Hammett σ constants of the substituents in the para-position. The plot of this dependence is linear, which suggests that the reduction mechanism is identical within the entire series. The optimum conditions for quantitation of the substances were found within the concentration regions of 1 .10-4 to 1 .10-6 mol l-1 for tast polarography and 1 .10-4 to 1 .10-7 mol l-1 for differential pulse polarography.

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