Polarographic reduction of p–substituted 1-phenyl-3-aminocarbonylpyridinium salts

1987 ◽  
Vol 52 (6) ◽  
pp. 1550-1560
Author(s):  
Jiří Krechl ◽  
Daniela Mižaninová ◽  
Jiří Volke ◽  
Josef Kuthan
Keyword(s):  
Supporting Electrolyte ◽  
Substitution Effect ◽  
Heterocyclic Ring ◽  
Reduction Wave ◽  
Polarographic Reduction ◽  
Benzene Nucleus ◽  
Half Wave ◽  
The One ◽  
Low Sensitivity ◽  
Substituted 1

The substitution effect of different groups (H, NO2, COOH, Br, Cl, NHCOCH3, CH3, OCH3, OH, and N(C2H5)2) on the polarographic behaviour of p–substituted 1-phenyl-3-aminocarbonylpyridinium cations has been investigated, in particular on their half-wave potentials in aqueous phosphate buffers pH 6·65 (10% DMF) and in anhydrous solutions of dimethylformamide with 0·05 mol l-1 (n-C4H9)4N+BF4- as supporting electrolyte. The half-wave potentials of the reduction wave which corresponds to the uptake of a single electron (wave B) and to the formation of the primary radical, obey a Hammett correlation in a similar way as it is in the case of 1-benzyl-3-aminocarbonylpyridinium cations. The slope ρπ,R in the Hammett plot equals 0·093 V for 10% DMF and 0·179 V for anhydrous DMF and compares thus with this slope obtained with the 1-benzyl derivatives where 0·095 V was found for water and 0·127 V for anhydrous acetonitrile. The transfer of the substitution effect from the substituent in the para position on the benzene nucleus to the heterocyclic ring in thus equally active in both substances and depends more strongly on the solvent than on the structure of cations of both types. The low sensitivity in both series towards a change in the substituent is explained by the fact that during the uptake of the electron the benzene and the pyridine nucleus are not even approximately coplanar. This is why the π-overlap between the two nuclei is considerably restricted. The analysis of sampled dc-polarographic waves has confirmed that the one-electron uptake is followed by a chemical reaction, most probably a dimer formation or a reaction of the primary product with the starting substance.

Polarographic reduction of 1-benzyl-N-(p-X-phenyl)-3-aminocarbonylpyridinium salts

1990 ◽  
Vol 55 (8) ◽  
pp. 2008-2018 ◽  
Author(s):  
Jiří Krechl ◽  
Šárka Beranová ◽  
Věra Volkeová ◽  
Jiří Volke ◽  
Josef Kuthan
Keyword(s):  
Supporting Electrolyte ◽  
Substitution Effect ◽  
Reduction Wave ◽  
Polarographic Reduction ◽  
Electron Wave ◽  
Benzene Nucleus ◽  
Primary Radical ◽  
Polarographic Behaviour ◽  
Half Wave ◽  
Hammett Correlation

The substitution effect of different groups X (N(CH2CH3)2, OH, OCH3, CH3, NHCOCH3, H, Cl, COOCH2CH3 and NO2) on the polarographic behaviour of 3-(N-p-X-phenylaminocarbonyl)pyridines (I), 1-benzyl-N-(p-X-phenyl)-3-aminocarbonylpyridinium cations (II) and their respective 1,4-dihydroderivatives (III) has been investigated in anhydrous solutions of dimethylformamide with 0.1 mol l-1 (n-C4H9)4N+PF6- as supporting electrolyte. The half-wave potentials of the reduction wave of I and II, which correspond to the uptake of a single electron (wave B) and to the formation of a primary radical, obey a Hammett correlation in a similar way as it is in the case of 1-benzyl- and 1-phenyl-3-amino-carbonylpyridinium cations substituted at carbon 4 on the benzene nucleus. The slope ρπ,R in the Hammett plot equals 0.192 V (I) and 0.104 V (II) for anhydrous DMF and compares thus with this slope obtained with the 1-benzyl- and 1-phenyl derivatives in our previous communications.

Polarography of some coordination compounds of platinum. I. Hexammineplatinum (IV) and Tris(ethylenediamine)platinum(IV) ions

1955 ◽  
Vol 8 (2) ◽  
pp. 158 ◽  
Author(s):  
JR Hall ◽  
RA Plowman
Keyword(s):  
Potassium Chloride ◽  
Supporting Electrolyte ◽  
Platinum Metal ◽  
Potassium Nitrate ◽  
Diffusion Current ◽  
Polarographic Reduction ◽  
Wave Potential ◽  
Half Wave Potential ◽  
Half Wave ◽  
Continuous Discharge

The polarographic reduction of tris(ethylenediamine)platinum(IV) and the hexammineplatinum(IV) ions has been studied in potassium chloride, potassium nitrate, and potassium nitrate plus ammonia solutions. Both ions were reduced irreversibly producing similarly shaped waves, showing well-defined diffusion current regions corresponding to two-electron reductions of the complexes. A linear relationship existed between diffusion current and concentration within the range examined. In aqueous potassium chloride and potassium nitrate media, the waves contained slight inflexions at positions corresponding to one-electron additions. The phenomenon suggested the transient presence of platinum(III) ions, and indicated that the half-wave potential of the reduction of the complexes to the trivalent state was very close to the half-wave potential of the reduction from platinum(IV) to platinum(II). The values were so close together as to indicate the improbability of isolating the trivalent complexes. Gelatin enhanced the inflexion in the wave but shifted the wave in a more negative direction. An increased concentration of supporting electrolyte also shifted the wave to a more negative position. In all cases a continuous discharge began at about -1.3 V (v. S.C.E.). This discharge was so far removed from that of the potassium ions of the supporting electrolyte that it was attributed to the discharge of hydrogen. Since the initial reduction of the platinum complexes corresponded to a two-electron change, it can be represented by reduction to a tetrammine ion. It is postulated that at higher applied potentials (namely, -1.3 V v. S.C.E.) the reduction proceeded further, producing platinum metal. This platinum metal would be in an active state, insoluble in mercury, and being on the surface, would lower the overvoltage of hydrogen leading to its discharge at a more positive potential than on a pure mercury surface. This view was supported by the fact that gas bubbles were observed at the dropping electrode when a voltage greater than -1.3 V was applied to the electrode for some time. When ammonia was added to the supporting electrolyte, a wave, without an inflexion, and corresponding to an irreversible two-electron reduction, was obtained at more negative potentials. The bivalent tetrammineplatinum(II) and bis(ethylenediamine)platinum(II) ions also gave polarograms showing the continuous discharge of hydrogen.

Substituent effects on electroreduction of the carbon-halogen bond

1981 ◽  
Vol 34 (11) ◽  
pp. 2331 ◽  
Author(s):  
RS Abeywickrema ◽  
EW Della
Keyword(s):  
Reduction Potential ◽  
Halogen Bond ◽  
Substituent Effects ◽  
High Yield ◽  
Polarographic Reduction ◽  
Electric Field Effects ◽  
Controlled Potential Electrolysis ◽  
Half Wave ◽  
Controlled Potential ◽  
Substituted 1

Polarographic reduction of a series of 4-substituted 1-iodobicyclo[2,2,2]octanes has been examined in an attempt to assess the effect of substituents on the half-wave reduction potential. It is found that the values of E� do not show a linear correlation with the relevant σ1 constants; the deviations are discussed in terms of the relative importance of the steric and electric field effects of the substituent. Controlled-potential electrolysis of a number of the substrates reveals that the hydrocarbon corresponding to fission of the carbon-iodine bond is formed in high yield.

scholarly journals The antibacterial action of lactoperidoxase. The nature of the bacterial inhibitor

1970 ◽  
Vol 117 (4) ◽  
pp. 779-790 ◽  
Author(s):  
D. McC. Hogg ◽  
G. R. Jago
Keyword(s):  
Hydrogen Peroxide ◽  
Reduction Wave ◽  
Polarographic Reduction ◽  
Basic Form ◽  
Acid Base ◽  
Wave Potential ◽  
Half Wave Potential ◽  
Half Wave ◽  
Acid Base Equilibrium ◽  
Dilute Aqueous Solution

Lactoperoxidase (EC 1.11.1.7), an enzyme present in various mammalian glands and in their secretions, catalyses the oxidation of thiocyanate by hydrogen peroxide to form a compound that inhibits the growth, oxygen uptake and acid production of certain bacteria. This compound was found to be too unstable to isolate in pure form, but its properties in dilute aqueous solution were studied with a view to establishing its identity. At thiocyanate concentrations of approximately 1mm, formation of the inhibitor, which took place by a nonstoicheiometric reaction, was maximal when an approximately equimolar amount of hydrogen peroxide was added. Excess of hydrogen peroxide oxidized the inhibitor to sulphate and cyanate. The inhibitor displayed a polarographic reduction wave of which the half-wave potential was pH-dependent. Studies of the variation of the polarographic half-wave potential and of the u.v. extinction with pH indicated that the inhibitor existed in an acid–base equilibrium (pKa 5.1±0.1). The inhibitor decomposed by a mechanism involving H+ ions and thiocyanate, the kinetics varying according to whether the inhibitor was in its acidic or basic form. From these studies it was concluded that the inhibitor was either cyanosulphurous acid (HO2SCN) or cyanosulphuric acid (HO3SCN).

scholarly journals Annuity Markets and Capital Accumulation

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Shantanu Bagchi ◽  
James A. Feigenbaum
Keyword(s):  
Old Age ◽  
Capital Stock ◽  
Early Life ◽  
Capital Accumulation ◽  
Substitution Effect ◽  
Income Effect ◽  
Substitution Effects ◽  
Income Effects ◽  
Annuity Markets ◽  
The One

AbstractWe examine how the absence of annuities in financial markets affects capital accumulation in a two-period overlapping generations model. Our findings indicate that the effect on capital is ambiguous in general equilibrium, because there are two competing mechanisms at work. On the one hand, the absence of annuities increases the price of old-age consumption relative to the price of early-life consumption. This induces a substitution effect that reduces saving and capital, and an income effect that has the opposite effect as households want to consume less when young, causing them to save more. On the other hand, accidental bequests originate from the assets of the deceased under missing annuity markets. The bequest received in early life always has a positive income effect on saving, but the bequest received in old age, conditional on survival, is effectively a partial annuity with both substitution and income effects. We find that when the desire to smooth consumption is high, the income effects dominate, so the capital stock always increases when annuity markets are missing. However, when the desire to smooth consumption is low, the substitution effects dominate, and the capital stock decreases with missing annuity markets.

A novel inorganic–organic nanohybrid material H4SiW12O40/pyridino-MCM-41 as efficient catalyst for the preparation of 1-amidoalkyl-2-naphthols under solvent-free conditions

2015 ◽  
Vol 44 (20) ◽  
pp. 9596-9609 ◽  
Author(s):  
R. Tayebee ◽  
M. M. Amini ◽  
M. Akbari ◽  
A. Aliakbari
Keyword(s):  
Solvent Free ◽  
One Pot ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
The One ◽  
Substituted 1 ◽  
Nanohybrid Material ◽  
Mcm 41

A new inorganic–organic nanohybrid material was prepared and performed as an efficient catalyst for the one-pot multi-component synthesis of different substituted 1-amidoalkyl-2-naphthols under solvent-free conditions.

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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