Spin-adduct of the P4 ·− radical anion during the electrochemical reduction of white phosphorus

The structure of fluorindine is established by nmr as the 5,14-dihydroquinoxalino[2,3-b]phenazine. The catalytic hydrogenation of 2,3-di(p-methoxyphenyl)pyrazino[2,3-b]phenazine 2a leads to the 6,11-dihydro derivative 4a. The electrochemical reduction in an hydroorganic medium furnishes 4a and then the 1,4,6,11-tetrahydro derivative 8a. In dry DMSO the voltammogram shows four monoelectronic reversible systems corresponding to the successive formation of a radical anion, dianion, radical trianion, and tetraanion. Thus 2a appears as a new example of the very restricted class of compounds leading to tetraanions upon electrochemical reduction. The catalytic hydrogenation of 2,7-diphenylpyrazino[2,3-g]quinoxaline 1a or the reaction of LiAlH4 with 1,2,7,8-tetramethylpyrazino[2,3-g]quinoxaline 1b leads to 1,2,3,4-tetrahydro compounds. The electrochemical reduction of 1a and 1b in hydroorganic medium leads successively to 1,4-dihydro and then to 1,4,6,9-tetrahydro compounds which undergo a further rearrangement. In dry DMSO 1a and 1b behave differently from 2a: one only observes two reversible monoelectronic systems.

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(2,3-Bis(methylen)bicycIo[2.2.2]octan)zirconocen: Synthese, Struktur und elektrochemische Reduktion/(2,3-Bis(methylene)bicyclo[2.2.2]octane)zirconocene: Synthesis, Structure, and Electrochemical Reduction

Zeitschrift für Naturforschung B ◽

10.1515/znb-1985-0203 ◽

1985 ◽

Vol 40 (2) ◽

pp. 150-157 ◽

Cited By ~ 5

Author(s):

Gerhard Erker ◽

Klaus Engel ◽

Carl Krüger ◽

Yi-Hung Tsay ◽

Edmond Samuel ◽

...

Keyword(s):

Electrochemical Reduction ◽

Structure Determination ◽

Radical Anion ◽

Nmr Spectra ◽

Activation Barrier ◽

Intramolecular Rearrangement ◽

Dynamic Nmr ◽

Space Group ◽

X Ray

Photolysis of diphenylzirconocene and 2,3-bis(methylene)bicyclo[2.2.2]octane in toluene at -25 °C yields biphenyl and (2,3-bis(methylene)bicyclo[2.2.2]octane)zirconocene (lg) (67.5% isolated yield).1g exhibits dynamic NMR spectra indicating rapid alternation of diene faces coordinated to zirconium (ring-flip mechanism). This degenerate intramolecular rearrangement is characterized by an extremely low activation barrier (⊿G≠-131°C = 7.1 ± 0.3 kcal/mol). 1g crystallizes in space group P1̄with a = 7.215(1) Å, b = 9.654(1) Å, c = 11.831(1) Å, α = 94.97(1)°, β = 91.81(1)°, and γ = 103.22(1)°. The X-ray structure determination reveals a pronounced metal alkyl character of the (diene)ZrCp2 moiety. Accordingly, 1g is easily reduced electrochemically to give a Zr(III) radical anion (7) observed by esr (g = 1.990; a(H) = 2.976 G; a(Zr) = 18.36 G).

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Dechlorination of PCBs by electrochemical reduction with aromatic radical anion as mediator

Chemosphere ◽

10.1016/j.chemosphere.2004.09.048 ◽

2005 ◽

Vol 58 (7) ◽

pp. 897-904 ◽

Cited By ~ 14

Author(s):

Atsushi Matsunaga ◽

Akio Yasuhara

Keyword(s):

Electrochemical Reduction ◽

Radical Anion ◽

Aromatic Radical

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Electrochemical Reduction of Cinnamonitrile in the Presence of Carbon Dioxide: Synthesis of Cyano- and Phenyl-Substituted Propionic Acids

Australian Journal of Chemistry ◽

10.1071/ch08092 ◽

2008 ◽

Vol 61 (7) ◽

pp. 526 ◽

Cited By ~ 6

Author(s):

Huan Wang ◽

Mei-Yu Lin ◽

Kai Zhang ◽

Su-Jiao Li ◽

Jia-Xing Lu

Keyword(s):

Carbon Dioxide ◽

Electrochemical Reduction ◽

Noble Metal ◽

Good Yield ◽

Radical Anion ◽

Competitive Reactions

Cyano- and phenyl-substituted propionic acids were synthesized simply and efficiently by electrocarboxylation of cinnamonitrile in undivided cells using the non-noble metal nickel as cathode and magnesium as the anode. The radical anion generated by the electroreduction of cinnamonitrile in the absence of CO2 is involved in several competitive reactions that lead to the formation of linear hydrodimers, cyclic hydrodimers, saturated dihydro products, and glutaronitrile derivatives. While under 101.325 kPa of CO2, the electrocarboxylation could easily be carried out in the absence of additional catalysts, and with good yield (84.8%). The influence of various synthetic parameters, such as the nature of the electrode, the working potential, the concentration, and the temperature, on the electrocarboxylation reaction was investigated.

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