- Mechanistic Studies on the Electrochemical Reductive Coupling of some Polyhalogenonitrobenzenes. A New Example of a Radical Anion Dimerization
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Coupling processes with loss of one halogen atom per ring are observed when heavily substituted polyhalogenonitrobenzenes (polyfluoro- and polychloro-) are electrochemically reduced in DMF.Product analyses and cyclic voltametry mechanistic studies suggest that in the particular case of pentafluoronitrobenzene, direct dimerization of the radical anions occurs prior to C-F bond fragmentation.On the contrary, reduction of the nitro group is the only observed process when less substituted polyhalogenonitrobenzenes are used in the same conditions.Nitro group reduction is also the main process for all the studied polyhalogenonitrobenzenes when the reactions are carried out in protic solvents. - Keywords: Reductive Coupling, Radical Anions, Fluoronitroaromatics, Dimerization
- Andrieux, Claude P.,Batlle, Anna,Espin, Martirio,Gallardo, Iluminada,Jiang, Ziqi,Marquet, Jorge
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- Selective mono-and diamination of polyfluorinated benzenes and pyridines with liquid ammonia
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Amination of pentafluoropyridine, 2,3,5,6-tetrafluoropyridine, 4-chlorotetrafluoropyridine, 3,5-dichlorotrifluoropyridine, octafluorotoluene, α,α,α,2,3,5,6-heptafluorotoluene, decafluoro-m-xylene, decafluorobiphenyl, hexafluorobenzene, and pentafluorobenzene with liquid ammonia was investigated. Bis-aminodefluorination temperatures for the majority of substrates were shown to exceed significantly the corresponding temperatures of monoaminodefluorination. The optimal conditions for selective preparation of mono-and diaminopolyfluoro(het)arenes were elucidated. An efficient method for isolation of particular polyfluorophenylenediamines from product mixtures formed in nonselective reactions of pentafluorobenzene and hexafluorobenzene with aqueous ammonia based on complexation with a crown ether is proposed.
- Vaganova,Kusov,Rodionov,Shundrina,Malykhin
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p. 2239 - 2246
(2008/09/20)
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