241154-09-6Relevant articles and documents
Hydrodefluorination of functionalized fluoroaromatics with triethylphosphine: A theoretical and experimental study
Facundo, Aldo A.,Arévalo, Alma,Fundora-Galano, Gabriela,Flores-álamo, Marcos,Orgaz, Emilio,García, Juventino J.
, p. 6897 - 6908 (2019/05/17)
Recently we reported the metal free hydrodefluorination of selected fluoroaromatics using triethylphosphine as the sole defluorinating agent. That prompted us to evaluate the mechanistic proposal and in the light of these results, along with new experimental evidence, we have now modified the initial proposal. The new mechanism avoids the highly energetic β-elimination step of roughly 71 kcal mol-1 for hexafluorobenzene and pentafluoropyridine at 393.15 K, invoking the participation of water. The use of D2O confirmed the role of water as the hydrogen source, yielding the corresponding deutero-defluorinated products; DFT calculations agree with this new proposed mechanism. We also report herein the use of this one-pot hydrodefluorination method applied to a broader number of fluoroaromatic derivatives; some of them allowed the collection of key mechanistic evidence.
Reductive dehalogenation of polyfluoroarenes by zinc in aqueous ammonia
Laev, Sergey S.,Shteingarts, Vitalii D.
, p. 175 - 185 (2007/10/03)
Aqueous ammonia has been found to be a good and versatile medium for the highly selective hydrodehalogenation of polyfluoroarenes by zinc under unprecedentedly mild conditions. The reduction of pentafluorobenzoic acid, 2,3,4,5,6-pentafluorobenzyl alcohol, pentafluorobenzamide, pentafluoropyridine, heptafluoro-2-naphthoic acid, 1,3,4,5,7,8-hexafluoro-2-naphthoic acid, octafluoronaphthalene, octafluorotoluene, decafluorobiphenyl, chloropentafluorobenzene and 4-chlorotetrafluorobenzoic acid give products derived from the removal of one or two halogen atoms. A reduction mechanism, proceeding through electron capture to give a radical anion and then fragmentation of the latter, has been suggested. The observed high selectivity of the process suggests a radical anion formed by direct electron transfer from zinc to substrate. The dehalogenation regioselectivity is basically in accordance with that expected for radical anion fragmentation.
Aromatic radical-anions. XII. A cyclic amperometric and ESR study of the transformations of polyfluorinated benzonitrile radical-anions
Efremova, N. V.,Starichenko, V. F.,Shteingarts, V. D.
, p. 47 - 56 (2007/10/02)
Cyclic voltamperometry and ESR spectrometry were used to study the chemical transformations of radical-anions of benzonitrile derivatives containing from two to five fluorine atoms.Two types of transformations were found to be characteristic for such species, namely, the elimination of a fluoride anion and subsequent formation of defluorination products and dimerization with the subsequent formation of fluorinated derivatives of 4,4'-dicyanodiphenyl.The facility of these processes depends significantly on the number and arrangement of the fluorine atoms in the benzene ring.The relationship between the electronic structure and reactivity of fluorinated benzonitrile radical-anions was examined.