The polarography of some substituted azobenzenes in acetonitrile. II. Identification of reduction products

1973 ◽  
Vol 26 (6) ◽  
pp. 1251 ◽  
Author(s):  
KG Boto ◽  
FG Thomas
Keyword(s):  
Visible Spectrophotometry ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential ◽  
Electron Reduction

The reduction products of azobenzene and 4-nitroazobenzene in acetonitrile were investigated by polarography and ultraviolet-visible spectrophotometry after generation by controlled potential electrolysis. The results obtained indicate that azobenzene is reduced in two steps to give firstly the monoanion and secondly the monoprotonated form of the dianion, whereas 4-nitroazobenzene gives the monoanion and the dianion, respectively, as the products of the two one-electron reduction steps. The azobenzene monoanion undergoes a very slow disproportionation (k = 8.2 dm3 mol-1 min-1) to produce azobenzene and the monoprotonated dianion in equimolar amounts. The second reduction products of both compounds are stable in the absence of oxygen.

Polarography and coulometry of Rh(III) in a pyridine – pyridinium chloride electrolyte

1969 ◽  
Vol 47 (12) ◽  
pp. 2123-2135 ◽  
Author(s):  
Leslie E. Johnston ◽  
John A. Page
Keyword(s):  
Mercury Electrode ◽  
Normal Wave ◽  
Bulk Solution ◽  
Pyridinium Chloride ◽  
Chloride Electrolyte ◽  
Catalytic Wave ◽  
Controlled Potential Electrolysis ◽  
Dropping Mercury Electrode ◽  
Controlled Potential ◽  
Electron Reduction

The polarography and coulometry of Rh(III) has been studied in an aqueous pyridine–pyridinium chloride–sodium chloride electrolyte at pH 5.30 and ionic strength 0.30 M at 25.0 °C. Two distinct types of polarographic behavior were noted as the total Py concentration was varied between 0.05 and 0.45 M, a "normal" wave with E1/2 of −0.43 V vs. a standard calomel electrode, and a second catalytic wave which under some conditions masked the normal wave.For both types of behavior, controlled potential electrolysis gave a well-defined two electron reduction but there was a definite H+ consumption in the electrolyses. It is postulated that hydride species are involved in the reduction according to the scheme[Formula: see text]surface reaction at dropping mercury electrode[Formula: see text]slow, bulk solution in controlled potential electrolysis

The Reactions of Electrogenerated [Ni(sacsac)2]-: Biomimetic Chemistry Related to Nickel Enzymes

1995 ◽  
Vol 48 (4) ◽  
pp. 835 ◽  
Author(s):  
PA Lay ◽  
AF Masters ◽  
CD Wasiowych
Keyword(s):  
Cyclic Voltammetry ◽  
Lewis Base ◽  
Spectroscopic Methods ◽  
Initial Product ◽  
Light Water ◽  
Nickel Enzymes ◽  
Controlled Potential Electrolysis ◽  
Scan Rate ◽  
Controlled Potential ◽  
Electron Reduction

The electrochemical reduction of [Ni( sacsac )2] ( sacsac = C5H7S2- = pentane-2,4-dithionate) has been investigated by cyclic voltammetry and controlled-potential electrolysis in acetone/tetra- butylammonium tetrafluoroborate (0.1 M). The reactions of the reduction product(s) with CO, CO2, CH3I, C12H25SH, light and water have been surveyed. At a scan rate of 100 mV s-1, [Ni( sacsac )2] (0.5 mM ) undergoes a quasi-reversible one-electron reduction (∆ Ep = 88 mV) at -1.543 V (v. Fc+/0) and an irreversible four-electron oxidation at +0.635 V. The oxidation generates the 3,5-dimethyl-1,2-dithiolium cation, as evidenced by the observation of the (known) reduction of this cation at -0.840 V. The initial product of the reduction of [Ni( sacsac )2] is a Lewis base, and reacts with light, water, CO, CO2, CH3I and C12H25SH. These reactions have been followed by electrochemical and spectroscopic methods. They appear to be biomimetic for a number of reactions observed for nickel enzymes.

Electrochemical Studies of Organotitanium Nitrogen Fixation Systems

1973 ◽  
Vol 51 (6) ◽  
pp. 815-820 ◽  
Author(s):  
T. Chivers ◽  
E. D. Ibrahim
Keyword(s):  
Cyclic Voltammetry ◽  
Nitrogen Fixation ◽  
Electrochemical Reduction ◽  
Argon Atmosphere ◽  
Electrochemical Studies ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential ◽  
Electron Reduction ◽  
The One ◽  
Ether Solvents

The electrochemical reduction of compounds of the type (π-Cp)2Ti(R)Cl (R = Cl, CH3, C6H5, C5F5, OTiCl(π-Cp)2) in ether solvents has been studied using the techniques of polarography, controlled potential electrolysis, and cyclic voltammetry. The one-electron reduction products, presumably (π-Cp)2TiR (R = CH3, C6F5), are initially green in tetrahydrofuran but, in a dinitrogen or argon atmosphere, they form intensely blue solutions which result from the reaction of (π-Cp)2TiR with tetrahydrofuran solvent.

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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