Electroréduction de dérivés dinitrés aromatiques. III. Rôle du sulfate de titanyle comme médiateur redox

1993 ◽  
Vol 71 (8) ◽  
pp. 1136-1146 ◽  
Author(s):  
Anne-Marie Martre ◽  
Virginia Danciu ◽  
Guy Mousset
Keyword(s):  
Electrochemical Behavior ◽  
Chemical Reduction ◽  
Organic Substrate ◽  
Redox Mediator ◽  
Reduction Product ◽  
Dinitro Derivative ◽  
Constant Potential ◽  
Homogeneous Chemical

The electrochemical behavior of titanium oxysulfate, used as a redox mediator in the reduction of 4,4′-dinitrodibenzyl, is studied in a 5 N H2SO4/EtOH 50:50 medium. The role played by electrogenerated Ti3+ ions in the chemical reduction of nitro groups is also defined. The results obtained allow the determination of the most suitable conditions leading to selective syntheses. Macroscale electrolyses at a constant potential in the presence of TiOSO4 give 4,4′-diaminodibenzyl with a great purity and a higher yield (93%) than without mediator (75%). The homogeneous chemical reduction of 4,4′-dinitrodibenzyl by first electrogenerating the Ti3+ ions, then adding the organic substrate, is particularly selective. The nature of the reduction products depends on the [Ti3+]/[dinitro derivative] ratio. The 4-amino-4′-nitrodibenzyl is synthesized in a 70% yield for a 6:1 ratio whereas the amount of diamino derivative increases and can constitute the sole reduction product for higher ratios. A comparison is made with 1,5- and 1,8-dinitronaphthalenes and 2,2′-dinitrodiphenyl. Using a 6:1 ratio, 1-amino-8-nitronaphthalene is not obtained while 45% of 1-amino-5-nitronaphthalene and 25% of 2-amino-2′-nitrodiphenyl are formed by reduction of the corresponding dinitro derivatives.

scholarly journals Graphite Studded with Facile-Synthesized Cu2O Nanoparticle-Based Cubes as a Novel Electrochemical Sensor for Highly Sensitive Voltametric Determination of Mebeverine Hydrochloride

Chemosensors ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 35
Author(s):  
Ahmed H. Naggar ◽  
Ahmed Kotb ◽  
Ahmed A. Gahlan ◽  
Mahmoud H. Mahross ◽  
Abd El-Aziz Y. El-Sayed ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Lower Limit ◽  
Electrochemical Behavior ◽  
Cuprous Oxide ◽  
Density Functional ◽  
Limit Of Detection ◽  
Biological Fluids ◽  
Chemical Reduction ◽  
Anodic Stripping Voltammetry ◽  
Mebeverine Hydrochloride

Herein, a feasible chemical reduction method followed by intensive mixing was applied for the preparation of an attractive material based on graphite studded with cuprous oxide nanoparticle-based cubes (Cu2ONPs–C@G). Transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV) were utilized for characterization. Cuprous oxide nanoparticles (Cu2ONPs), with a diameter range mainly distributed from 4 to 20 nm, aggregate to form microcubes (Cu2ONPs–C) with an average diameter of about 367 nm. Paste electrode was prepared using Cu2ONPs–C@G (Cu2ONPs–C@G/PE) for voltametric quantification of the musculotropic antispasmodic drug: mebeverine hydrochloride (MEB). The electrochemical behavior of MEB was studied using CV, and the optimum analytical parameters were investigated using square wave adsorptive anodic stripping voltammetry (SWAdASV). Moreover, density functional theory (DFT) was used to emphasize the ability of MEB to form a complex with Cu2+, confirming the suggested electrochemical behavior of MEB at Cu2ONPs–C@G/PE. With good stability and high reproducibility, SWAdASV of Cu2ONPs–C@G/PE shows successful quantification of MEB over the concentration range of 5.00 × 10−11–1.10 × 10−9 M with lower limit of detection (LOD) and lower limit of quantification (LOQ) values of 2.41 × 10−11 M and 8.05 × 10−11 M, respectively. Finally, accurate quantification of MEB in dosage forms (tablets) and biological fluids (spiked human urine and plasma samples) was achieved using Cu2ONPs-C@G/PE.

scholarly journals Quantitative Determination of Paraquat in a Fatal Intoxication by HPLC-DAD following Chemical Reduction with Sodium Borohydride

2000 ◽  
Vol 24 (2) ◽  
pp. 116-121 ◽  
Author(s):  
K. Arys ◽  
J. Van Bocxlaer ◽  
K. Clauwaert ◽  
W. Lambert ◽  
M. Piette ◽  
...  
Keyword(s):  
Quantitative Determination ◽  
Sodium Borohydride ◽  
Chemical Reduction ◽  
Fatal Intoxication

scholarly journals Comparative Study of Ag Nanostructures: Molecular Simulations, Electrochemical Behavior, and Antibacterial Effect

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Álvaro de Jesús Ruíz-Baltazar ◽  
Simón Yobanny Reyes-López ◽  
D. Larrañaga ◽  
R. Pérez
Keyword(s):  
Cyclic Voltammetry ◽  
Ethylene Glycol ◽  
Comparative Study ◽  
Sodium Borohydride ◽  
Electrochemical Behavior ◽  
Antibacterial Effect ◽  
Chemical Reduction ◽  
Molecular Simulations ◽  
The Other ◽  
E Coli

Nanoparticles of Ag with different sizes and structures were obtained and studied. Two methods for reductions of Ag ions were employed, chemical reduction by sodium borohydride and ethylene glycol. Cuboctahedral and icosahedral structures were obtained. Molecular simulations were carried out in order to evaluate the reactivity of both structures. On the other hand, the electrochemical activity and antibacterial effect (E. coli) of the cuboctahedral and icosahedral structures were measured experimentally. The results obtained by molecular simulation, cyclic voltammetry, and antibacterial effect were compared and discussed in this work.

scholarly journals The effect of tamoxifen on the electrochemical behavior of Bi+3/Bi on the glassy carbon electrode and its determination via differential pulse anodic stripping voltammetry

2019 ◽  
Vol 63 (1) ◽  
Author(s):  
Mehdi Jalali ◽  
Zeinab Deris Falahieh ◽  
Mohammad Alimoradi ◽  
Jalal Albadi ◽  
Ali Niazi
Keyword(s):  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Peak Height ◽  
Carbon Electrode

The electrochemical behavior of Bi+3 ions on the surface of a glassy carbon electrode, in acidic media and in the presence of tamoxifen, was investigated. Cyclic voltammetry, chronoamperometry, differential pulse voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy were used to find the probable mechanism contributing to the reduction of the peak height of bismuth oxidation with an increase in the concentration of tamoxifen. The obtained results show a slight interaction between the bismuth species and tamoxifen which co-deposit on the surface of glassy carbon electrode. Therefore, the reduction in the peak height of bismuth oxidation as a function of tamoxifen concentration was used to develop a new differential pulse anodic striping voltammetry method for determination of trace amount of tamoxifen. The effects of experimental parameters on the in situ DPASV of Bi+3 ions in the presence of tamoxifen shown the optimal conditions as: 2 mol L-1 H2SO4 (1% v v-1 MeOH), a deposition potential of -0.5 V, a deposition time of 60 s, and a glassy carbon electrode rotation rate of 300 rpm. The calibration curve was plotted in the range of 0.5 to 6 µg mL-1 and the limits of detection and quantitation were calculated to be 3.1 × 10-5 µg mL-1 and 1.0 × 10-4 µg mL-1, respectively. The mean, RSD, and relative bias for 0.5 µg mL-1 (n=5) were found to be 0.49 µg mL-1, 0.3%, and 2%, respectively. Finally, the proposed method was successfully used for the determination of tamoxifen in serum and pharmaceutical samples.

scholarly journals Possibilities of Application of Modern Neurophysiological Methods in Diagnosis of Vibration Disease

2019 ◽  
Vol 3 (6) ◽  
pp. 82-87
Author(s):  
L. S. Vasileva ◽  
N. V. Slivnitsyna ◽  
O. L. Lakhman ◽  
O. I. Shevchenko
Keyword(s):  
Thermal Sensitivity ◽  
Statistical Processing ◽  
Diagnostic Value ◽  
Pathological Process ◽  
Cold Sensitivity ◽  
Control Group ◽  
Vibration Disease ◽  
Equilibrium Function ◽  
Constant Potential

Vibration disease is one of the leading in the structure of occupational diseases. A more detailed study of the pathogenesis, expanding the possibilities of diagnosis of vibration disease, is necessary. The aim of the study is to determine the diagnostic value of stabilometry, quantitative sensory testing and neuroenergocarting in vibration disease associated with the combined effects of local and general vibration. Materials and methods. Two groups of patients were examined: with the diagnosis of vibration disease associated with the combined effect of local and general vibration – 50 people (age 48.7 ± 3.1 years), not in contact with vibration – 30 people (age 49.1 ± 2.8 years). The study of the equilibrium function, the determination of the level of the constant potential of the brain by 12 standard leads and the determination of temperature and pain sensitivity. Statistical processing of the results was carried out using the software package “Statistica 6.0” (StatSoft Inc., USA). Differences were considered statistically significant at p < 0.05. Results. In vibration disease, the vertical stance of patients is more unstable than in patients with no contact with vibration. In patients with vibration disease, there is a decrease in the threshold of cold sensitivity and an increase in the threshold of thermal sensitivity and thermal pain compared to the control group. According to our data, the increased level of permanent potential in patients with vibration disease is observed in the central (22.7 (12.6; 30.7) mV) and right central (20.4 (11.5; 27.1) mV), also the average level of permanent capacity in this group is increased – 17.1 (8.4; 25.8) mV.Conclusion. The results obtained indicate the involvement of the neurosensory complex united by single thalamic and cortical centers in the pathological process and confirm the diagnostic value of the methods used.

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