scholarly journals Anodic oxidation of bisamides from diaminoalkanes by constant current electrolysis

2018 ◽  
Vol 14 ◽  
pp. 861-868 ◽  
Author(s):  
Tatiana Golub ◽  
James Y Becker
Keyword(s):  
Anodic Oxidation ◽  
Bond Cleavage ◽  
Constant Current ◽  
Anodic Process ◽  
Methylene Groups ◽  
Fragmentation Type

In general, bisamides derived from diamines and involving 3 and 4 methylene groups as spacers between the two amide functionalities behave similar to monoamides upon anodic oxidation in methanol/LiClO4 because both types undergo majorly mono- and dimethoxylations at the α-position to the N atom. However, in cases where the spacer contains two methylene groups only the anodic process leads mostly to CH2–CH2 bond cleavage to afford products of type RCONHCH2OCH3. Moreover, upon replacing LiClO4 with Et4NBF4 an additional fragmentation type of product was generated from the latter amides, namely RCONHCHO. Also, the anodic process was found to be more efficient with C felt as the anode, and in a mixture of 1:1 methanol/acetonitrile co-solvents.

Anodic oxidation of mercury in the presence of thioether acids: Methane-1,1-bis-mercaptoacetic acid

1987 ◽  
Vol 52 (3) ◽  
pp. 616-625 ◽  
Author(s):  
E. Casassas ◽  
M. Esteban ◽  
C. Ariño
Keyword(s):  
Cyclic Voltammetry ◽  
Anodic Oxidation ◽  
Stripping Voltammetry ◽  
Electrode Process ◽  
Mercaptoacetic Acid ◽  
Anodic Process ◽  
Hanging Mercury Drop Electrode ◽  
No Adsorption ◽  
Cathodic Stripping Voltammetry ◽  
Mercury Drop Electrode

The anodic oxidation of mercury in the presence of methane-1,1-bis-mercaptoacetic acid (MBMA) has been studied by DCr, DP, AC1, and AC2 polarography, cyclic voltammetry, and coulometry. The electrode process is controlled by the adsorption of the product formed according to: Hg + 2 H(2-n)Ln- → H(2-n)HgL2n- + (2-n) H+ + 2e with n = 0 at pH < pK1, n = 1 at pK1 < pH < pK2, and n = 2 at pH > pK2. No adsorption of MBMA is observed. The behaviour of MBMA at a hanging mercury drop electrode (HMDE) by cathodic stripping voltammetry (CSV) has been also studied. At MBMA concentrations above 1 10-6 mol l-1, the stripping voltammograms showed two well defined peaks, at c. -0.140 V and at c. -0.300 V. The anodic process occurring during the pre-electrolysis in CSV is described by the formation of a Hg(I) compound: 2 Hg + 2 H(2-n)Ln- → H(2-n)Hg2L2(2-2n)+ + 2e followed by its disproportionation: H(2-n)Hg2L2(2-2n)+ →c H(2-n)HgL2(2-2n)+ + Hg,where n has the above-mentioned values.

Nanomechanical Properties of Bioactive Ti Surfaces Obtained by NaOH-Based Anodic Oxidation and Alkali Treatment

2011 ◽  
Vol 493-494 ◽  
pp. 524-529 ◽  
Author(s):  
Eduardo Mioduski Szesz ◽  
G.B. de Souza ◽  
Emanuel Santos ◽  
Neide K. Kuromoto
Keyword(s):  
Mechanical Properties ◽  
Anodic Oxidation ◽  
Alkali Treatment ◽  
Pure Titanium ◽  
Sodium Titanate ◽  
Scratch Test ◽  
Alkaline Treatment ◽  
Constant Current ◽  
Commercially Pure Titanium ◽  
Constant Current Density

Titanium has been used in the production of dental implants and orthopedic prostheses due to the low tendency to corrosion and good biocompatibility. Meanwhile, the surface of titanium is not bioactive. Several surface treatments have been developed to make the surface of such metals bioactive. The aim of this work was to evaluate two of these modification processes in commercially pure titanium grade 2, both of them using NaOH solutions: the anodic oxidation and the alkali treatment. The surface morphology was evaluated by SEM/EDS, the crystal structure by XRD, and the mechanical properties and scratch resistance by instrumented indentation. The anodic oxidation (AO) was carried out using NaOH electrolyte 0.1 mol/L and constant current density of 150 mA/cm² for one minute. The alkaline treatment (AT) was performed by soaking the Ti sample in NaOH 5 mol/L solution at 60 °C for 24 hours; after this, the sample was heat treated at 600 °C for one hour in atmospheric air. The AO produced a TiO2 layer on Ti, whereas a thin sodium titanate layer was obtained by AT. Each surface modification resulted in a specific morphology, but both of them presented the increase in roughness as a common characteristic. The alkali treated Ti surfaces showed the lowest elastic modulus and hardness values. The largest increase in hardness between the treated surfaces was obtained for Ti after anodic oxidation. Scratch test indicates that the TiO2 film from AO has higher strength to tangential loading than the Ti substrate. In addition, for the Ti submitted to AT, the scratch test indicates that the modified surface layer has a poor adhesion with the substrate. Based on these results it is possible to conclude that, using NaOH solutions, Ti surfaces treated by anodic oxidation present improved mechanical properties than the alkali-treated ones.

scholarly journals Anodic Oxidation of Anthracenes and Related Compounds. Part II. Applications of Constant Current Coulometry.

1970 ◽  
Vol 24 ◽  
pp. 2768-2774 ◽  
Author(s):  
Vernon D. Parker ◽  
Ann-Margret Nilsson ◽  
Göran Wikander ◽  
P. Karrer ◽  
Akira Shimizu
Keyword(s):  
Anodic Oxidation ◽  
Constant Current ◽  
Related Compounds

A convenient approach for the electrochemical bromination and iodination of pyrazoles

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sara Zandi ◽  
Farzad Nikpour
Keyword(s):  
Anodic Oxidation ◽  
Electrophilic Substitution ◽  
Electrochemical Cell ◽  
Coupling Reaction ◽  
Constant Current ◽  
Substitution Reactions ◽  
Reaction Conditions ◽  
Convenient Approach ◽  
Electrophilic Substitution Reactions

Abstract Electrochemical bromination and iodination of some pyrazoles were investigated under constant-current (CC) electrolysis in an undivided electrochemical cell. Anodic oxidation of KX salt produces X2 in-situ which can be consumed as an expedient electrophile in pyrazoles aromatic electrophilic substitution reactions or may participate in an X–N coupling reaction with electrochemically catalyzed pyrazolesox to form the halogenated pyrazoles. All reactions proceeded without the need to use any hazardous reagents or catalysts. The reaction conditions are mild and environmentally compatible.

Anodic Oxidation of Active Methylene Groups in the Presence of Excess Carboxylic Acid

1993 ◽  
Vol 66 (9) ◽  
pp. 2767-2769 ◽  
Author(s):  
Jugo Koketsu ◽  
Masasi Kurita ◽  
Michiko Tamano ◽  
Yoshikazu Fujimura ◽  
Fumio Ando
Keyword(s):  
Carboxylic Acid ◽  
Anodic Oxidation ◽  
Methylene Groups ◽  
Active Methylene

Fabrication of Antibacterial Titanium Implant Using Anodic Oxidation Technique

2014 ◽  
Vol 783-786 ◽  
pp. 1326-1331 ◽  
Author(s):  
Naofumi Ohtsu ◽  
Shinji Komiya ◽  
Kouta Sakamoto ◽  
Taisuke Kuji ◽  
Futoshi Sumisa
Keyword(s):  
Anodic Oxidation ◽  
Uv Light ◽  
Titanium Implant ◽  
Antibacterial Activities ◽  
Constant Current ◽  
Light Illumination ◽  
Xrd Pattern ◽  
Blue Solution ◽  
Human Use ◽  
Anodic Oxidation Technique

In the present study, we demonstrated that antibacterial titanium can be simply fabricated by anodic oxidation technique, which involves connecting the Ti to the anode and then applying a direct current through the electrolyte. The substrate was soaked in 100−mM NH4NO3, 100−mM (NH4)2SO4, and (NH4)3PO4aqueous solutions, after which a constant current of 50 mA cm-2 was galvanostatically applied for 30 min. The substrate was thereafter annealed at 723 K in air for 5 h, in order to improve the crystallinity. The XRD pattern showed the layer comprised TiO2 with anatase and/or rutile type structures. All the anodized substrate could degrade methylene blue solution under ultraviolet (UV) and visible light illuminations. Antibacterial activities of the treated substrates were estimated using Escherichia coli (E.coli). The anodized Ti substrate showed sufficient antibacterial activity under weak UV light illumination with the intensity of 100 μW cm-2. In conclusion, anodic oxidation is expected as one of the promising surface treatments, in order to improve the safety of Ti devices in human use.

ChemInform Abstract: Anodic Oxidation of Active Methylene Groups in the Presence of Excess Carboxylic Acid.

ChemInform ◽  
2010 ◽  
Vol 25 (3) ◽  
pp. no-no
Author(s):  
J. KOKETSU ◽  
M. KURITA ◽  
M. TAMANO ◽  
Y. FUJIMURA ◽  
F. ANDO
Keyword(s):  
Carboxylic Acid ◽  
Anodic Oxidation ◽  
Methylene Groups ◽  
Active Methylene

Fabrication and Evaluation of Titanium Dioxide Nanotube Thin Films by Anodic Oxidation on Transparent Electrodes

2013 ◽  
Vol 582 ◽  
pp. 111-114
Author(s):  
Yusuke Okumoto ◽  
Ryo Kawakami ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Thin Films ◽  
Titanium Dioxide ◽  
Anodic Oxidation ◽  
Indium Tin Oxide ◽  
Dye Sensitized Solar Cells ◽  
Current Method ◽  
Oxide Glass ◽  
Constant Current ◽  
Constant Voltage ◽  
Titanium Dioxide Films

Titanium dioxide nanotube (TNT) thin films were fabricated, for application as the negative electrode of dye-sensitized solar cells (DSC), by anodic oxidation of titanium thin films deposited by RF magnetron sputtering on indium tin oxide glass substrates. Anodic oxidation was carried out by a constant voltage or constant current method in an electrolyte in order to determine the best method to increase TNT film thickness. Thick titanium dioxide films were fabricated by the constant voltage method at higher voltages. Thicker titanium dioxide films were obtained by the constant current method compared to the constant voltage method. However, the constant current method with optimal current yielded TNT films with higher quality (high transparency). The power conversion efficiency of DSC was improved using films fabricated by the constant current method.

INVESTIGATION OF THE INFLUENCE OF SPACE CHARGE ON THE ANODIC OXIDATION OF ALUMINUM, A TYPICAL VALVE METAL

1963 ◽  
Vol 41 (12) ◽  
pp. 3108-3117 ◽  
Author(s):  
M. J. Dignam ◽  
P. J. Ryan
Keyword(s):  
Field Strength ◽  
Oxide Film ◽  
Electric Field ◽  
Electric Field Strength ◽  
Anodic Oxidation ◽  
Ionic Conduction ◽  
Time Derivative ◽  
Ionic Current ◽  
Constant Current ◽  
Frenkel Defect

Measurements of the time derivative of the anodic overpotential of superpurity aluminum during anodic oxidation were made at various constant current densities. The data have been interpreted in terms of the variation of electric field strength with position in the oxide film. The analytic form of the profile of the electric field strength in the oxide film was deduced, assuming the high field Frenkel defect model. The data were found to be incompatible with the theoretical profile, providing, therefore, evidence against this model. The data are only consistent with a model for the transport process in which the concentration of ionic current carriers at a position in the oxide remote from the metal interface is independent of the field strength. A new model, proposed recently by Dignam to explain transient ionic conduction phenomena, is consistent with this conclusion.

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