Consecutive electrochemical processes in controlled potential electrolysis

1966 ◽  
Vol 11 (6) ◽  
pp. 462-466 ◽  
Author(s):  
John G. Mason
Keyword(s):  
Electrochemical Processes ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential

scholarly journals Ligand-Centered Electrochemical Processes Enable CO2 Reduction with a Nickel Bis(triazapentadienyl) Complex

2018 ◽  
Author(s):  
Zachary Dubrawski ◽  
Joshua E. Heidebrecht ◽  
Braulio M. Puerta Lombardi ◽  
Alexander Hyla ◽  
Janina Willkomm ◽  
...  
Keyword(s):  
Transition Metal Complexes ◽  
Radical Anion ◽  
Co2 Reduction ◽  
Redox Activity ◽  
Decomposition Products ◽  
Electrochemical Processes ◽  
Reducing Conditions ◽  
Controlled Potential Electrolysis ◽  
Computational Data ◽  
Controlled Potential

We report the synthesis of Ni(TAPPy)<sub>2</sub> (TAPPy = 1,3,5-triazapentadienyl-2,4-bis(2-pyridyl)) and its reactivity with CO<sub>2</sub> under reducing conditions. Electrochemical reduction of Ni(TAPPy)<sub>2 </sub>under inert gas reveals that the complex accommodates up to two additional electrons, with DFT calculations indicating that electron density is delocalized almost exclusively onto the TAPPy ligand framework. The singly reduced product [K(crypt)][Ni(TAPPy)<sub>2</sub>] (crypt = 2.2.2-cryptand) has been synthesized, and its EPR data is consistent with having ligand-based radical anion character. Controlled potential electrolysis experiments reveal that reduced Ni(TAPPy)<sub>2</sub> converts CO<sub>2</sub> to form CO; however, spectroscopic and computational data indicate that deactivation readily occurs to form Ni(L)(CO)<i><sub>n</sub></i> compounds, CO<sub>3</sub><sup>2-</sup>, and carboxylated (RCOO<sup>-</sup>) ligand decomposition products. This study highlights that redox activity at the ligand can play an important role during the reduction of CO<sub>2</sub> using transition metal complexes.

scholarly journals Ligand-Centered Electrochemical Processes Enable CO2 Reduction with a Nickel Bis(triazapentadienyl) Complex

2018 ◽  
Author(s):  
Zachary Dubrawski ◽  
Joshua E. Heidebrecht ◽  
Braulio M. Puerta Lombardi ◽  
Alexander Hyla ◽  
Janina Willkomm ◽  
...  
Keyword(s):  
Transition Metal Complexes ◽  
Radical Anion ◽  
Co2 Reduction ◽  
Redox Activity ◽  
Decomposition Products ◽  
Electrochemical Processes ◽  
Reducing Conditions ◽  
Controlled Potential Electrolysis ◽  
Computational Data ◽  
Controlled Potential

We report the synthesis of Ni(TAPPy)<sub>2</sub> (TAPPy = 1,3,5-triazapentadienyl-2,4-bis(2-pyridyl)) and its reactivity with CO<sub>2</sub> under reducing conditions. Electrochemical reduction of Ni(TAPPy)<sub>2 </sub>under inert gas reveals that the complex accommodates up to two additional electrons, with DFT calculations indicating that electron density is delocalized almost exclusively onto the TAPPy ligand framework. The singly reduced product [K(crypt)][Ni(TAPPy)<sub>2</sub>] (crypt = 2.2.2-cryptand) has been synthesized, and its EPR data is consistent with having ligand-based radical anion character. Controlled potential electrolysis experiments reveal that reduced Ni(TAPPy)<sub>2</sub> converts CO<sub>2</sub> to form CO; however, spectroscopic and computational data indicate that deactivation readily occurs to form Ni(L)(CO)<i><sub>n</sub></i> compounds, CO<sub>3</sub><sup>2-</sup>, and carboxylated (RCOO<sup>-</sup>) ligand decomposition products. This study highlights that redox activity at the ligand can play an important role during the reduction of CO<sub>2</sub> using transition metal complexes.

Polarographic Behaviour of Some Arylazotheophyllines

1993 ◽  
Vol 58 (9) ◽  
pp. 1978-1988
Author(s):  
Mohamed I. Ismail ◽  
Madlene L. Iskander
Keyword(s):  
Diffusion Coefficient ◽  
Model Compound ◽  
Aqueous Media ◽  
Chemical Characteristics ◽  
Polarographic Behaviour ◽  
Physico Chemical ◽  
Controlled Potential Electrolysis ◽  
Azo Group ◽  
Controlled Potential ◽  
Electrolysis Products

The polarographic behaviour of a series of arylazotheophyllines was studied in aqueous alcoholic buffer media and in DMF-0.1 M LiClO4 solution. The redox study gave evidence that the azo group is electroactive in aqueous as well as non-aqueous media. A mechanism interpreting the electrode process is proposed and confirmed through the identification of the controlled potential electrolysis products, the use of a model compound and the application of Hamett's σ-E relationship. The physico-chemical characteristics of these compounds, viz. the diffusion coefficient, dissociation constant, ionization potential and electron affinity, are also included.

scholarly journals Electrochemical Behaviour of N′-(p-toluenesulphonyl)-3-methyl-4-(4′-substituted arylhydrazono) pyrazolin-5-ones

2012 ◽  
Vol 9 (4) ◽  
pp. 1864-1874
Author(s):  
V. Nagaraju ◽  
R. Sreenivasulu ◽  
P. Venkata Ramana
Keyword(s):  
Electrochemical Behaviour ◽  
Reduction Process ◽  
Effect Of Solvent ◽  
Buffer Solutions ◽  
Diffusion Controlled ◽  
Controlled Potential Electrolysis ◽  
Dc Polarography ◽  
Controlled Potential ◽  
Ph Range ◽  
And Diffusion

The electrochemical behaviour of N′-(p-toluenesulphonyl)-3-methyl-4-(4′-substituted arylhydrazono) pyrazolin-5-ones has been investigated at dme and gc electrodes in buffer solutions of pH 2.0, 4.0, 6.0, 8.0 and 10.0 using dc polarography and cyclic voltammetry and coulometry. The compounds exhibit one well defined wave in the entire pH range of study. The process is irreversible and diffusion controlled. Controlled potential electrolysis indicates the involvement of four electrons in the reduction process. The effect of solvent, cations and anions, temperature and substitutents on the mechanism of reduction has been studied. Based on the results obtained the mechanism of reduction has been suggested.

Substituent effects on polarographic reduction of some photographic color intermediates

1976 ◽  
Vol 54 (8) ◽  
pp. 1205-1210 ◽  
Author(s):  
Ahmad S. Shawali ◽  
Bahgat E. El-Anadouli
Keyword(s):  
Dissociation Constants ◽  
Substituent Effects ◽  
Protonated Form ◽  
Acid Dissociation ◽  
Polarographic Reduction ◽  
Substituent Constant ◽  
Acid Dissociation Constants ◽  
Controlled Potential Electrolysis ◽  
Half Wave ◽  
Controlled Potential

Polarographic reduction of two series of benzoylacetanilides has been investigated in 40% (by volume) ethanolic Britton–Robinson buffers. One series (A) contains substituents on the anilide moiety, and the second (B) has substituents on both the anilide and benzoyl moieties. Polarographic controlled-potential electrolysis data indicate that the electroactive species in both series is the protonated form (ArCOCH2CONHAr′)H+. The reduction half-wave potentials of anilides of series A were found to be independent of the nature of the substituent, whereas those of series B show a good linear relationship when plotted vs. the σ substituent constant of the substituent on the benzoyl moiety (ρ = 0.284, r = 0.995). Values of the acid dissociation constants of the keto (K1) and enol (K2) tautomers of the anilides of series A were calculated; unlike their E1/2 values, the pK1 data show a linear correlation with the Hammett substituent constant, σ. The pK2 values show, however, little variation with σ.

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