Hammett-Streitwieser Reaction Constants for the Electroreduction of Diaryl Ketones in Aprotic Media

1996 ◽  
Vol 49 (8) ◽  
pp. 901 ◽  
Author(s):  
E Wagnerczauderna ◽  
MK Kalinowski
Keyword(s):  
Cyclic Voltammetry ◽  
Dimethyl Sulfoxide ◽  
Propylene Carbonate ◽  
Radical Anion ◽  
Electrode Reaction ◽  
Hexamethylphosphoric Triamide ◽  
Ketyl Radical ◽  
Donor Numbers ◽  
Reaction Constants ◽  
Solvent Acidity

Cyclic voltammetry has been used to measure formal potentials of seven aromatic ketone/ketyl radical anion systems in benzonitrile, acetonitrile , propylene carbonate, acetone, N,N- dimethylformamide, N-methylpyrrolidin-2-one, dimethyl sulfoxide and hexamethylphosphoric triamide. The values measured in each solvent obey the Hammett- Streitwieser equation; the reaction constants were found to depend on the solvent acidity and basicity expressed by acceptor and donor numbers, respectively. The results are discussed in terms of the solvation of the products and reactants of the electrode reaction.

Solvent Effect on the Hammett Reaction Constant of Substituted Benzoic Acids

1993 ◽  
Vol 46 (1) ◽  
pp. 31 ◽  
Author(s):  
H Bartnicka ◽  
I Bojanowska ◽  
MK Kalinowski
Keyword(s):  
Solvent Effect ◽  
Dimethyl Sulfoxide ◽  
Dissociation Constants ◽  
Benzoic Acids ◽  
Hammett Equation ◽  
P Values ◽  
Reaction Constant ◽  
Substituted Benzoic Acids ◽  
Reaction Constants ◽  
Solvent Acidity

Potentiometric titration has been used to measure dissociation constants of 13 monosubstituted benzoic acids in nitromethane, benzonitrile , acetonitrile , propylene carbonate, acetone, N,N-dimethylformamide, dimethyl sulfoxide, methanol and formamide. The reaction constants of the Hammett equation were found to depend on the solvent acidity and basicity expressed by the α and β parameters of Kamlet and Taft. The p values determined earlier in water and ethanol also obey this rule.

Electrochemical Properties of 4-[(Anthracen -9-ylmethylene)-amino]-1, 5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one at a Platinum Electrode in Acetonitrile Solvent

2011 ◽  
Vol 15 (2) ◽  
pp. 113-121
Author(s):  
Abdullah M. Asiri ◽  
Ibrahim S. El-Hallag ◽  
Ibrahim S. El-Hallag ◽  
A.O. Al-Youbi ◽  
Khalid A. Alamry ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Properties ◽  
Radical Anion ◽  
Platinum Electrode ◽  
Reaction Pathway ◽  
Electrochemical Behaviour ◽  
Digital Simulation ◽  
Electrode Reaction ◽  
Simulation Technique ◽  
Fast Chemical

The electrochemical properties of 4-[(anthracen -9-ylmethylene)-amino]-1, 5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one have been carried out using cyclic voltammetry and convolution - deconvolution voltammetry combined with digital simulation technique at a platinum electrode in 0.1 mol/L tetraethyl ammonium chloride (TEACl) in solvent acetonitrile (CH3CN). In switching the potential to positive scan, the compound was oxidized by loss of one electron forming radical cataion followed by fast chemical step and the radical cation loss another two electrons producing trication which followed by chemical reaction (ECEEC). The investigated compound was reduced via consumption of two consecutive electrons to form radical anion followed by fast chemical step and the radical anion gain another electron to form dianion followed by chemical step (ECEC mechanism). The electrode reaction pathway and the chemical and electrochemical parameters of the investigated compound were determined using cyclic voltammetry, convolutive voltammetry and chronoamperometry. The Electrochemical data such as a, ks, Eo , D, and kc of the investigated pyrazole derivative were evaluated expeimentally and verified via digital simulation technique Electrochemical behaviour of the pyrazole compound under consideration was presented and discussed.

3D Supramolecular Chiral Crystal Structures of Radical Anion Salts of (−)-NDI-Δ and Possible Magnetic Phase Diagrams

CrystEngComm ◽  
2021 ◽  
Author(s):  
Asato Mizuno ◽  
Yoshiaki Shuku ◽  
Rie Suizu ◽  
Masahisa Tsuchiizu ◽  
Kunio Awaga
Keyword(s):  
Phase Diagrams ◽  
Crystal Structures ◽  
Propylene Carbonate ◽  
Electron Acceptor ◽  
Radical Anion ◽  
Magnetic Phase ◽  
Naphthalene Diimide ◽  
Solutions Of Electrolytes ◽  
Chiral Crystals ◽  
Magnetic Phase Diagrams

Supramolecular chiral crystals of radical anion salts of a rigid triangular chiral electron acceptor, (−)-naphthalene diimide (NDI)-Δ, were electrochemically grown in propylene carbonate (PC) solutions of electrolytes (M·ClO4, M =...

Synthesis and Electrochemical Reduction of Methyl 3-Halo-1-benzothiophene-2-carboxylates

2004 ◽  
Vol 69 (1) ◽  
pp. 242-260 ◽  
Author(s):  
Michal Rejňák ◽  
Jiří Klíma ◽  
Jiří Svoboda ◽  
Jiří Ludvík
Keyword(s):  
Cyclic Voltammetry ◽  
Radical Anion ◽  
Preparative Method ◽  
Platinum Electrodes ◽  
Disk Electrode ◽  
Dimer Formation ◽  
Halide Anion ◽  
Primary Radical ◽  
Heterocyclic Radical ◽  
Ece Mechanism

A preparative method of synthesis of the new methyl 3-iodo-1-benzothiophene-2-carboxylate was elaborated. Electrochemical behavior of methyl 3-chloro-, bromo- and iodo-1-benzothiophene-2-carboxylates 1-3, and of their reduction and dimer products 4, 5 in anhydrous dimethylformamide has been investigated at mercury and platinum electrodes using polarography, cyclic voltammetry and voltammetry on a rotating platinum disk electrode. The reduction in divided cells follows the ECE mechanism (electron - chemical step - electron), where the primary radical anion is split into a halide anion and neutral heterocyclic radical, which is immediately reduced by the second electron and protonated. The only reduction product is the methyl 1-benzothiophene-2-carboxylate (5); whereas the EDim mechanism (electron - dimer formation) leading to the dimeric species 4 was not observed under the above conditions. Reduction of 1-3 on platinum causes formation of a blocking film on the electrode. Sonication during electrolysis successfully reactivates the electrode.

Voltammetric investigation of the kinetics of alkali metal cation reduction in N,N-dimethylformamide

1975 ◽  
Vol 28 (2) ◽  
pp. 237 ◽  
Author(s):  
JW Diggle ◽  
AJ Parker ◽  
DA Owensby
Keyword(s):  
Electron Transfer ◽  
Alkali Metal ◽  
Propylene Carbonate ◽  
Rate Constant ◽  
Alkali Metal Cation ◽  
Electrode Reaction ◽  
Amalgam Electrode ◽  
Kinetics Of ◽  
Dipolar Aprotic Solvents

The standard electron-transfer heterogeneous rate constant of lithium, potassium, sodium and caesium amalgams in N,N-dimethylformamide was ascertained employing cyclic voltammetry in an effort to relate the presence of a non-equilibrium electrode reaction at the dropping lithium amalgam electrode to the variation of the lithium amalgam electrode potential with amalgam electrode con- figuration, i.e. whether streaming, dropping or stationary. Such variations are not observed at other alkali metal amalgam electrodes. ��� In the dipolar aprotic solvents the standard electron-transfer heterogeneous rate constant for the Li(Hg) electrode increases as the solvating power for Li+ decreases, i.e. dimethyl sulphoxide < di- methylformamide < propylene carbonate. Water is a much stronger solvator of Li+ than is propylene carbonate, but the electron transfer is faster in water than in propylene carbonate; the important role of entropic contributions in ion solvation is discussed as an explanation.

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