M. Abdel Azzem

Electro-oxidative oligomerization of 1,5-diaminonaphthalene in acetonitrile medium

Abstract New electroactive oligomer films of 1,5-diaminonaphthalene have been prepared on platinum and carbon graphite electrodes in acetonitrile solution by potential sweep electrolysis and controlled potential electrolysis. The films were electroactive in aqueous acidic solutions with a formal redox potential of ca. 0.33 V vs. SCE in 1 M HCl solution. Cyclic voltammetry, controlled potential electrolysis, SEM, FT-IR spectroscopy, 1 H NMR, conductivity measurements and gel permeation chromatography were used to characterize the oligomeric film.

Polarographic behaviour of dimedone-2-arylazo derivatives in alcoholic aqueous media

Abstract The polarographic behaviour of a series of the title compounds was studied in alcoholic buffered media. These molecules predominate in the azo form and are reduced in a 4 e − irreversible process. The results were confirmed through spectrophotometric p K a determination, CPE, the use of models, and Hammetts linear relationships. The kinetic parameter k ° f,h was also determined.

Electroreduction of a series of arylazo thiohydantoin derivatives at the DME

Abstract The polarographic reduction data of a series of 5-arylazo-1-phenyl-2-thiohydantoin derivatives in 40% by volume ethanolic aqueous buffers covering a wide range of pH are reported and discussed. A mechanism interpreting the electrode process, in both acid and alkaline media, is proposed and confirmed via the identification of CPE products, Hammetts -E1/2 relations and pKa determinations

Electrochemical polymerization of a new heterocyclic monomer using a sacrificial nickel anode

Abstract The electropolymerization of a new heterocyclic monomer, viz. N -antipyryl acrylamide, has been carried out in dimethylformamide using a Ni electrode. Better yields and higher degrees of polymerization are obtained in the presence of tetrabutylammonium perchlorate as a supporting electrolyte. A study has been made of the effects of various parameters such as duration of electrolysis, current strength, concentrations of monomer and electrolyte, type of electrolyte and the temperature of the reaction on the yield of the polymer and the rate of polymerization. An electropolymerization mechanism is suggested and confirmed by i.r. spectra, differential thermal analysis and thermogravimetric analysis.

Electrocatalytic reduction of some imino compounds on a glassy carbon electrode electrochemically modified with a new copper-salen complex

Abstract A copper complex of the half-unit 2,6-diacetylpyridine-mono(ethylenediamine) was prepared and characterized using analytical, spectral and magnetic measurements. The electropolymerization of this complex on glassy carbon electrode was performed. A new electroactive polymeric film was prepared by potential sweep electrolysis. Electroanalytical studies were carried out using the cyclic voltammetric technique to examine the indirect electroreduction of 2-aryl-4-cyano-6-mercapto-5-phenyl-3-(2H)-pyridiazinimine derivatives (compounds IIa-IId) modified with the Cu complex. In the absence of compounds IIa-IId the film showed a single pair of peaks corresponding to the Cu(II) Cu(I redox system. However, in the presence of the imino compounds, a catalytic effect was observed and the anodic peak for Cu(I) oxidation disappeared at low scan rates. The imino group was reduced to give the corresponding amino compounds. Direct electrochemical reduction of compounds IIa-IId was performed for comparison. The proposed mechanism has been confirmed by cyclic voltammetry and the product of controlled-potential electrolysis was identified via elemental analysis, IR spectroscopy and 1H NMR spectroscopy.

Ionization and electroreduction of some benzthiazin-4-one azodyes

AbstractpKa values of a series of the titled compounds (2 a–g) together with a model compound3 have been determined spectrophotometrically in alcoholic buffered media. These values were correlated to different σ sets. The polarographic behaviour of the parent2 a and its nitro derivative2 g was studied in detail. The obtained data showed that2 a is reduced via a 2-electron process to the corresponding hydrazo from which was stabilized through hydrogen bonding.ZusammenfassungEs wurden diepKa-Werte einer Serie der Titelverbindungen (2 a–g) zusammen mit einer Modellverbindung3 spektrophotometrisch in alkoholischer gepufferter Lösung bestimmt. Diese Werte wurden mit verschiedenen Sets von σ-Werten korreliert. Das polarographische Verhalten der Stammverbindung2 a und deren Nitroderivat2 g wurde im Detail untersucht. Die Daten zeigen, daß2 a über einen Zweielektronenprozeß zur entsprechenden Hydrazo-Verbindung reduziert wird, die durch Wasserstoffbrücken stabilisiert ist.

Electroactive film of polyaniline substituted with heterocyclic benzothiazole ring

Abstract Voltammetric studies of substituted ring aniline with a heterocyclic ring namely 2-(4-aminophenyl)-6-methylbenzothiazole (ABT) were carried out in acetonitrile and acidic aqueous solutions. Potential sweep electrolysis of 0.05 M ABT at a glassy carbon electrode in CH 3 CN containing 0.1 M LiClO 4 and 0.05 M pyridine produced a polymeric film. The film coated electrode showed an electrochemical response in acidic aqueous solution. The electrical conductivity measurement on pressed pellets of PABT prepared by constant current electrolysis was 3.8 × 10 −5 S/cm. Based on i.r. spectroscopic characterization and electrical conductivity measurement, a polymerization mechanism was proposed.

Electropolymerization of N-methacryloyloxy phthalimide monomer using sacrificial nickel anode and characterization of the resulting polymer

Abstract The electropolymerization of N-methylacryloyloxy phthalimide has been studied in DMF using a sacrificial nickel anode in the presence of tetrabutylammonium perchlorate as supporting electrolyte. The effect of different reaction parameters such as the type of electrolyte, concentration of monomer and electrolyte, current strength, the duration of electrolysis and the temperature of the reaction on the yield of the polymer and the rate of polymerization were studied. It was found that the nickel content in the obtained polymer depends on the concentration of the monomer. A mechanism of electropolymerization is suggested and confirmed by i.r., 1 H-NMR, thermal analysis and electrical conductivity measurements.

The electrochemical reduction of some fused ring systems

Abstract The electrochemical reduction of some fused ring systems containing four carbonyl moieties has been studied in alcoholic aqueous media. A mechanism has been proposed and clarified in which one carbonyl is reduced to a methylene group via an uptake of four electrons.

Electroreduction of the activated olefinic double bond in some 2-aryl-1(2-acetylamino-1,3,4-thiadiazol-5-yl)-propionitrile derivatives

The electrochemical reduction of a series of the title compounds has been investigated in alcoholic buffered media at the DME. A mechanism for the reduction process has been proposed and confirmed through spectrophotometric and potentiometricpKa determinations and identification of CPE products. A trial to calculate the kinetic parameterkf,ho by different methods is included.ZusammenfassungEs wurde die elektrochemische Reduktion einer Serie der Titelverbindungen in alkoholischer, gepufferter Lösung an der tropfenden Quecksilberelektrode untersucht. Ein Mechanismus für den Reduktionsprozeß wird vorgeschlagen, der auf Befunde spektrophotometrischer und potentiometrischerpKa-Messungen und die Identifizierung von Produkten der kontrollierten Potentialelektrolyse (CPE) gestützt ist. Ein Versuch zur Ermittlung der kinetischen Parameterkf,ho mit verschiedenen Methoden wurde unternommen.