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Two-electron Process (two-electron + process)

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Chemistry100%

Selected Abstracts

Electrochemical Reduction of 4,4,-(2,2,2-Trichloroethane-1,1-diyl)- bis(chlorobenzene) (DDT) and 4,4,-(2,2-Dichloroethane-1,1-diyl)- bis(chlorobenzene) (DDD) at Carbon Cathodes in Dimethylformamide

ELECTROANALYSIS, Issue 4 2006
Mohammad
Abstract In dimethylformamide containing tetramethylammonium tetrafluoroborate, cyclic voltammograms for reduction of 4,4,-(2,2,2-trichloroethane-1,1-diyl)bis(chlorobenzene) (DDT) at a glassy carbon cathode exhibit five waves, whereas three waves are observed for the reduction of 4,4,-(2,2-dichloroethane-1,1-diyl)bis(chlorobenzene) (DDD). Bulk electrolyses of DDT and DDD afford 4,4,-(ethene-1,1-diyl)bis(chlorobenzene) (DDNU) as principal product (67,94%), together with 4,4,-(2-chloroethene-1,1-diyl)bis(chlorobenzene) (DDMU), 1-chloro-4-styrylbenzene, and traces of both 1,1-diphenylethane and 4,4,-(ethane-1,1-diyl)bis(chlorobenzene) (DDO). For electrolyses of DDT and DDD, the coulometric n values are essentially 4 and 2, respectively. When DDT is reduced in the presence of a large excess of D2O, the resulting DDNU and DDMU are almost fully deuterated, indicating that reductive cleavage of the carbon,chlorine bonds of DDT is a two-electron process that involves carbanion intermediates. A mechanistic scheme is proposed to account for the formation of the various products. [source]

Synthesis and Electrochemical Properties of Tetrasubstituted Tetraphenylethenes

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2006
Alina Schreivogel
Abstract Tetrakis(4-acetoxyphenyl and 4-benzoyloxyphenyl)ethenes 1f and 1g were obtained by acylation of tetrakis(4-hydroxyphenyl)ethene 1b. Ullmann etherification of 4,4,-dihydroxybenzophenone 2b and subsequent McMurry coupling yielded tetrakis(phenoxyphenyl)ethene 1i. The tetrakis(acetamidophenyl)ethene 1h was prepared in three steps from tetraphenylethene 1c by nitration, Raney-Ni reduction and subsequent acetylation. Alternatively, trifluoroacetamide 1j, 2-methylhexanamide 1k and 2,4-dimethylbenzamide 1l, with less tendency to form 2D hydrogen bonding networks and thus increased solubility as compared to 1h, were prepared by acylation of 4,4,-diaminobenzophenone 2a and subsequent McMurry coupling. Compounds 1f,l were investigated by cyclic voltammetry. While the phenyl ether derivative 1i displays single-electron processes during oxidation, a two-electron process was discovered for trifluoroacetamide 1j as was also supposed for the esters 1f and 1g. In addition, comproportionation constants were shown to be dependent on the solvent. In situ IR spectroelectrochemistry provided evidence for quinoidal type substructures in the dioxidized forms of tetraphenylethenes 1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Synthesis and Properties of DNA Complexes Containing 2,2,6,6-Tetramethyl-1-piperidinoxy (TEMPO) Moieties as Organic Radical Battery Materials

CHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2008
Jinqing Qu Dr.
Abstract We report here the first example of organic radical battery with DNA. Though there is a growing interest in DNA/cationic-lipid complexes as promising gene delivery vehicles, few efforts have been focused on the use of such complexes as advanced materials for organic optoelectronic applications. The present article describes how substitution of the sodium counter cation of DNA with cationic amphiphilic lipid(1,4) provided novel DNA,lipid complexes that contain TEMPO radicals, in which the actual mole ratio of phosphate to lipid was 1:0.84 to 1:0.16. All the TEMPO-containing DNA,lipid complexes displayed reversible two-stage charge/discharge processes, the discharge capacities of which were 40.5,60.0,A,h,kg,1. In particular, the capacity of a DNA,lipid(3)-based cell reached 60.0,A,h,kg,1, which corresponds to 192,% relative to its theoretical value for the single-electron one-stage process, indicating a two-electron process. [source]

Influence of pH on the Photochemical and Electrochemical Reduction of the Dinuclear Ruthenium Complex, [(phen)2Ru(tatpp)Ru(phen)2]Cl4, in Water: Proton-Coupled Sequential and Concerted Multi-Electron Reduction

CHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2005
Norma R. de Tacconi Prof.
Abstract The dinuclear ruthenium complex [(phen)2Ru(tatpp)Ru(phen)2]4+ (P; in which phen is 1,10-phenanthroline and tatpp is 9,11,20,22-tetraaza tetrapyrido[3,2-a:2,3,-c:3,,,2,,-l:2,,,,3,,,]-pentacene) undergoes a photodriven two-electron reduction in aqueous solution, thus storing light energy as chemical potential within its structure. The mechanism of this reduction is strongly influenced by the pH, in that basic conditions favor a sequential process involving two one-electron reductions and neutral or slightly acidic conditions favor a proton-coupled, bielectronic process. In this complex, the central tatpp ligand is the site of electron storage and protonation of the central aza nitrogen atoms in the reduced products is observed as a function of the solution pH. The reduction mechanism and characterization of the rich array of products were determined by using a combination of cyclic and AC voltammetry along with UV-visible reflectance spectroelectrochemistry experiments. Both the reduction and protonation state of P could be followed as a function of pH and potential. From these data, estimates of the various reduced species' pKa values were obtained and the mechanism to form the doubly reduced, doubly protonated complex, [(phen)2Ru(H2tatpp)Ru(phen)2]4+ (H2P) at low pH (,7) could be shown to be a two-proton, two-electron process. Importantly, H2P is also formed in the photochemical reaction with sacrificial reducing agents, albeit at reduced yields relative to those at higher pH. [source]