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.

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.

EPR Studies on Carboxylic Esters, 22 [1, 2]. Preparation of New Alkyl Azulenecarboxylates and EPR-spectroscopic Study of Their Radical Anions

2014 ◽  
Vol 69 (4) ◽  
pp. 466-480 ◽  
Author(s):  
Jürgen Voss ◽  
Thomas Pesel ◽  
Dirk Buddensiek ◽  
Juuso Lehtivarjo
Keyword(s):  
Differential Pulse ◽  
Coupling Constants ◽  
Epr Spectra ◽  
Differential Pulse Polarography ◽  
Radical Anions ◽  
Mo Calculations ◽  
Pulse Polarography ◽  
Carboxylic Esters ◽  
Influence Of Substituents

Five regio-isomeric alkyl azulenecarboxylates were prepared. Additional substituents such as tertbutyl groups or deuterium were introduced in certain positions of the azulene skeleton in order to facilitate the assignment of the proton hyperfine structure (hfs) coupling constants of the EPR spectra. The electrochemical behavior of the esters was studied by means of differential pulse polarography and cyclovoltammetry. In-situ electroreduction of the azulenecarboxylic esters led to the corresponding radical anions, the EPR spectra of which were recorded. The spin density distribution in these non-alternant systems as determined from hfs coupling constants was compared with the results of MO calculations and discussed with respect to the influence of substituents.

EPR studies on carboxylic esters, 23 [1]. Preparation of new dialkyl azulenedicarboxylates and EPR-spectroscopic study of their radical anions

2015 ◽  
Vol 70 (7) ◽  
pp. 441-454
Author(s):  
Jürgen Voss ◽  
Thomas Pesel ◽  
Dirk Buddensiek ◽  
Juuso Lehtivarjo
Keyword(s):  
Functional Group ◽  
Differential Pulse ◽  
Coupling Constants ◽  
Differential Pulse Polarography ◽  
Radical Anions ◽  
Electron Systems ◽  
Pulse Polarography ◽  
Carboxylic Esters ◽  
Influence Of Substituents

AbstractSelected dialkyl azulenedicarboxylates were prepared by carbo-bromination of alkyl azulenemonocarboxylates and subsequent alcoholysis or by alkoxycarbonylcarbene insertion of ethyl indane-2-carboxylate. The electrochemical behavior of the diesters was studied by means of differential pulse polarography and cyclovoltammetry. In-situ electroreduction of the azulenedicarboxylic esters led to the corresponding radical anions, the EPR spectra of which were recorded. For certain radical anions a rearrangement under migration of the functional group from the 5- into the 6-position was observed. The spin density distribution in these non-alternant π-electron systems as determined from the proton hyperfine structure (hfs) coupling constants was compared with the results of MO calculations and discussed with respect to the influence of substituents.

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.

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.

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