Heterogeneous Photoinduced Homolytic Aromatic Substitution of Electron-rich Arenes with Perfluoroalkyl Groups in Water and Aqueous Media. A Radical-ion Reaction

BARATA-VALLEJO SEBASTIAN; MARTÍN FLESIA MARINA; LANTAÑO BEATRIZ; ARGÜELLO, JUAN E; PEÑÉÑORY, ALICIA B.; POSTIGO AL

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2013 p. 998 - 1008

1434-193X

The photoinduced electron transfer (PET) substitution reaction of electron rich aromatic nuclei with perfluoroalkyl Rf groups was carried out in water or aqueous mixtures to render the substitution products resulting from replacement of aromatic H´s with the Rf moiety in good yields (57-88%). Some mechanistic aspects are discussed, supporting the notion of a PET reaction leading to a classical radical homolytic aromatic substitution (HAS) followed by an electron transfer (ET) and then a proton transfer (PT) sequence. A radical mechanism superimposed with a redox process is proposed to account for product formation. Evidence for the radical cation species (as an initiation event) generated from electron-rich arenes in the presence of perfluoroalkyl halides is provided by the UV-vis transient spectra obtained by Nanosecond Laser Flash Photolysis techniques.