Electrochemical Studies of Organotitanium Nitrogen Fixation Systems

1973 ◽  
Vol 51 (6) ◽  
pp. 815-820 ◽  
Author(s):  
T. Chivers ◽  
E. D. Ibrahim
Keyword(s):  
Cyclic Voltammetry ◽  
Nitrogen Fixation ◽  
Electrochemical Reduction ◽  
Argon Atmosphere ◽  
Electrochemical Studies ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential ◽  
Electron Reduction ◽  
The One ◽  
Ether Solvents

The electrochemical reduction of compounds of the type (π-Cp)2Ti(R)Cl (R = Cl, CH3, C6H5, C5F5, OTiCl(π-Cp)2) in ether solvents has been studied using the techniques of polarography, controlled potential electrolysis, and cyclic voltammetry. The one-electron reduction products, presumably (π-Cp)2TiR (R = CH3, C6F5), are initially green in tetrahydrofuran but, in a dinitrogen or argon atmosphere, they form intensely blue solutions which result from the reaction of (π-Cp)2TiR with tetrahydrofuran solvent.

Clam-shaped cyclam-functionalized porphyrin for electrochemical reduction of carbon dioxide

2019 ◽  
Vol 23 (04n05) ◽  
pp. 453-461
Author(s):  
Sumana Tawil ◽  
Hathaichanok Seelajaroen ◽  
Amorn Petsom ◽  
Niyazi Serdar Sariciftci ◽  
Patchanita Thamyongkit
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Cyclic Voltammetry ◽  
Catalytic Activity ◽  
Electrochemical Reduction ◽  
Target Compound ◽  
Faradaic Efficiency ◽  
Controlled Potential Electrolysis ◽  
Improved Stability ◽  
Controlled Potential

A clam-shaped molecule comprising a Zn(II)-porphyrin and a Zn(II)-cyclam is synthesized and characterized. Its electrochemical behavior and catalytic activity for homogeneous electrochemical reduction of carbon dioxide (CO[Formula: see text] are investigated by cyclic voltammetry and compared with those of Zn(II)-meso-tetraphenylporphyrin and Zn(II)-cyclam. Under N2-saturated conditions, cyclic voltammetry of the featured complex has characteristics of its two constituents, but under CO2-saturated conditions, the target compound exhibits significant current enhancement. Iterative reduction under electrochemical conditions indicated the target compound has improved stability relative to Zn(II)-cyclam. Controlled potential electrolysis demonstrates that, without addition of water, methane (CH[Formula: see text] is the only detectable product with 1% Faradaic efficiency (FE). The formation of CH4 is not observed under the catalysis of the Zn(II)-porphyrin benchmark compound, indicating that the CO2-capturing function of the Zn(II)-cyclam unit contributes to the catalysis. Upon addition of 3% v/v water, the electrochemical reduction of CO2 in the presence of the target compound gives carbon monoxide (CO) with 28% FE. Dominance of CO formation under these conditions suggests enhancement of proton-coupled reduction. Integrated action of these Zn(II)-porphyrin and Zn(II)-cyclam units offers a notable example of a molecular catalytic system where the cyclam ring captures and brings CO2 into the proximity of the porphyrin catalysis center.

On the One and Two-Electron Oxidations of Water-Soluble Zinc Porphyrins in Aqueous Media

1981 ◽  
Vol 36 (5) ◽  
pp. 596-600 ◽  
Author(s):  
Michael Neumann-Spallart ◽  
K. Kalyanasundaram
Keyword(s):  
Cyclic Voltammetry ◽  
Aqueous Media ◽  
Water Soluble ◽  
Chemical Methods ◽  
Controlled Potential Electrolysis ◽  
Half Wave ◽  
Controlled Potential ◽  
Zinc Porphyrins ◽  
The One ◽  
Soluble Zinc

The one and two-electron oxidations of water soluble ionic zinc porphyrins (Zinctetra-methylpyridylporphyrin, ZnTMPyP, Zinc-tetra-p-sulfonato-phenyl-porphyrin, ZnTPPS, and Zinc-tetra-p-carboxy-phenylporphyrin, ZnTPPC) leading to the porphyrin Π-cations and Π-dications have been investigated in water by electrochemical (cyclic voltammetry and controlled potential electrolysis) and chemical methods. The half-wave potentials for the oxidation are shown to be markedly dependent on the charge on the β-substituents. While the one-electron oxidations for all these porphyrins are reversible, the dication formation leads to labile isoporphyrins as intermediates

The Reactions of Electrogenerated [Ni(sacsac)2]-: Biomimetic Chemistry Related to Nickel Enzymes

1995 ◽  
Vol 48 (4) ◽  
pp. 835 ◽  
Author(s):  
PA Lay ◽  
AF Masters ◽  
CD Wasiowych
Keyword(s):  
Cyclic Voltammetry ◽  
Lewis Base ◽  
Spectroscopic Methods ◽  
Initial Product ◽  
Light Water ◽  
Nickel Enzymes ◽  
Controlled Potential Electrolysis ◽  
Scan Rate ◽  
Controlled Potential ◽  
Electron Reduction

The electrochemical reduction of [Ni( sacsac )2] ( sacsac = C5H7S2- = pentane-2,4-dithionate) has been investigated by cyclic voltammetry and controlled-potential electrolysis in acetone/tetra- butylammonium tetrafluoroborate (0.1 M). The reactions of the reduction product(s) with CO, CO2, CH3I, C12H25SH, light and water have been surveyed. At a scan rate of 100 mV s-1, [Ni( sacsac )2] (0.5 mM ) undergoes a quasi-reversible one-electron reduction (∆ Ep = 88 mV) at -1.543 V (v. Fc+/0) and an irreversible four-electron oxidation at +0.635 V. The oxidation generates the 3,5-dimethyl-1,2-dithiolium cation, as evidenced by the observation of the (known) reduction of this cation at -0.840 V. The initial product of the reduction of [Ni( sacsac )2] is a Lewis base, and reacts with light, water, CO, CO2, CH3I and C12H25SH. These reactions have been followed by electrochemical and spectroscopic methods. They appear to be biomimetic for a number of reactions observed for nickel enzymes.

On the electroreduction mechanism of halobenzenes: The special case of 1,2-dibromobenzene

1989 ◽  
Vol 54 (4) ◽  
pp. 911-921 ◽  
Author(s):  
Juan Casado ◽  
Manuel Ortega ◽  
Iluminada Gallardo
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Reduction ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Disk Electrode ◽  
Stepwise Mechanism ◽  
Rotating Ring Disk Electrode ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential ◽  
Special Case

Reinvestigation of the electrochemical reduction of 1,2-dibromobenzene by polarography, cyclic voltammetry, rotating ring-disk electrode voltammetry and controlled potential electrolysis, as well as theoretical calculations, leads to the proposal of a stepwise mechanism. Experimental results for bromobenzene and 1,3-dibromobenzene are also reported for comparison.

scholarly journals Studies on sulfenamides. III. Cyclic voltammetry and controlled potential electrolysis of 4'-substituted 2-nitrobenzenesulfenanilides.

1979 ◽  
Vol 27 (9) ◽  
pp. 2093-2098 ◽  
Author(s):  
HIROTERU SAYO ◽  
KOICHI MORI ◽  
TAKASHI MICHIDA
Keyword(s):  
Cyclic Voltammetry ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential

Reductive dechlorination of DDT electrocatalyzed by synthetic cobalt porphyrins in N,N′-dimethylformamide

2011 ◽  
Vol 15 (01) ◽  
pp. 66-74 ◽  
Author(s):  
Weihua Zhu ◽  
Yuanyuan Fang ◽  
Wei Shen ◽  
Guifen Lu ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Reaction Time ◽  
Oxidation State ◽  
Reductive Dechlorination ◽  
Reaction Products ◽  
Ms Analysis ◽  
Controlled Potential Electrolysis ◽  
Cobalt Porphyrins ◽  
Controlled Potential ◽  
Uv Visible

Two cobalt porphyrins, (OEP) CoII and (TPP) CoII , where OEP and TPP are the dianions of octaethylporphyrin and tetraphenylporphyrin, respectively, were examined as electrocatalysts for the reductive dechlorination of DDT (1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane) in N,N′-dimethylformamide (DMF) containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). No reaction is observed between DDT and the porphyrin in its Co(II) oxidation state but this is not the case for the reduced Co(I) forms of the porphyrins which electrocatalyze the dechlorination of DDT, giving initially DDD (1,1-bis(4-chlorophenyl)-2,2-dichloroethane), DDE (1,1-bis(4-chlorophenyl)-2, 2-dichloroethylene) and DDMU (1,1-bis(4-chlorophenyl)-2-chloroethylene) as determined by GC-MS analysis of the reaction products. A further dechlorination product, DDOH (2,2-bis(4-chlorophenyl)ethanol), is also formed on longer timescales when using (TPP)Co as the electroreduction catalyst. The effect of porphyrin structure and reaction time on the dechlorination products was examined by GC-MS, cyclic voltammetry, controlled potential electrolysis and UV-visible spectroelectrochemistry and a mechanism for the reductive dechlorination is proposed.

scholarly journals One-Electron Reduction Potentials: Calibration of Theoretical Protocols for Morita–Baylis–Hillman Nitroaromatic Compounds in Aprotic Media

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2129 ◽  
Author(s):  
Amauri Francisco da Silva ◽  
Antonio João da Silva Filho ◽  
Mário Vasconcellos ◽  
Otávio Luís de Santana
Keyword(s):  
Cyclic Voltammetry ◽  
Biological Activity ◽  
Chemical Structure ◽  
Reduction Potential ◽  
Chemical Reactivity ◽  
Nitroaromatic Compounds ◽  
Reduction Potentials ◽  
Electron Reduction ◽  
The One ◽  
Antileishmanial Activities

Nitroaromatic compounds—adducts of Morita–Baylis–Hillman (MBHA) reaction—have been applied in the treatment of malaria, leishmaniasis, and Chagas disease. The biological activity of these compounds is directly related to chemical reactivity in the environment, chemical structure of the compound, and reduction of the nitro group. Because of the last aspect, electrochemical methods are used to simulate the pharmacological activity of nitroaromatic compounds. In particular, previous studies have shown a correlation between the one-electron reduction potentials in aprotic medium (estimated by cyclic voltammetry) and antileishmanial activities (measured by the IC50) for a series of twelve MBHA. In the present work, two different computational protocols were calibrated to simulate the reduction potentials for this series of molecules with the aim of supporting the molecular modeling of new pharmacological compounds from the prediction of their reduction potentials. The results showed that it was possible to predict the experimental reduction potential for the calibration set with mean absolute errors of less than 25 mV (about 0.6 kcal·mol−1).

Electrochemical behavior of C-methoxy, amino, cyano, and mercapto nitrones

1992 ◽  
Vol 70 (7) ◽  
pp. 2076-2080 ◽  
Author(s):  
Bruce J. Acken ◽  
David E. Gallis ◽  
James A. Warshaw ◽  
DeLanson R. Crist
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behavior ◽  
Spin Trapping ◽  
Redox Behavior ◽  
Electron Process ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential

The redox behavior of various C-substituted nitrones was investigated by cyclic voltammetry in acetonitrile. These included C-methoxynitrones (MeO)CR = N(O)t-Bu with R = C6H5(1a), p-MeOC6H4 (1b), p-NO2C6H4 (1c), and H (1d) and nitrones YCH = N(O)t-Bu with Y = n-BuS (2a), CN (2b), and C6H5NH (2c). All gave anodic peaks which can be identified as oxidations of the nitrone function. Controlled potential electrolysis of 1a at 1.05 V (SCE) showed that its oxidation was a one-electron process. Reduction of 1a occurs stepwise at −2.08 and at −2.47 V, the same potential for reduction of methyl N-tert-butylbenzimidate (MeO)CPh = Nt-Bu. With electrochemical windows of ca. 3 V, all of the nitrones studied appear suitable for spin-trapping experiments.

The polarography of some substituted azobenzenes in acetonitrile. II. Identification of reduction products

1973 ◽  
Vol 26 (6) ◽  
pp. 1251 ◽  
Author(s):  
KG Boto ◽  
FG Thomas
Keyword(s):  
Visible Spectrophotometry ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential ◽  
Electron Reduction

The reduction products of azobenzene and 4-nitroazobenzene in acetonitrile were investigated by polarography and ultraviolet-visible spectrophotometry after generation by controlled potential electrolysis. The results obtained indicate that azobenzene is reduced in two steps to give firstly the monoanion and secondly the monoprotonated form of the dianion, whereas 4-nitroazobenzene gives the monoanion and the dianion, respectively, as the products of the two one-electron reduction steps. The azobenzene monoanion undergoes a very slow disproportionation (k = 8.2 dm3 mol-1 min-1) to produce azobenzene and the monoprotonated dianion in equimolar amounts. The second reduction products of both compounds are stable in the absence of oxygen.

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