Anodic oxidation of amines. Part III. Cyclic voltammetry and controlled potential electrolysis of 4-dimethylaminoantipyrine (4-dimethylamino-2,3-dimethyl-1-phenyl-Δ3-pyrazolin-5-one) in acetonitrile

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.

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

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424611002957 ◽

2011 ◽

Vol 15 (01) ◽

pp. 66-74 ◽

Cited By ~ 16

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.

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

Canadian Journal of Chemistry ◽

10.1139/v92-263 ◽

1992 ◽

Vol 70 (7) ◽

pp. 2076-2080 ◽

Cited By ~ 8

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.

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