4. Polyfluoroarenes. Part I. Pentafluorophenol

Abstract

Hexafluorobenzene, readily prepared by pyrolysis of tribromofluoromethane, has been converted into pentafluorophenol under mild conditions and in good yield; derivatives and properties of pentafluorophenol are described. Infrared spectroscopy reveals a characteristic ring vibration near 1520 cm.-l for pentafluorophenyl derivatives and suggests that appreciable aromatic character is associated with the ring. The decreased basicity of oxygen in pentafluorophenol causes less intermolecular hydrogen bonding than with phenol, and is reflected in its relatively low b. p. (143') ; the possibility of intramolecular hydrogen bonding to the ortho fluorine atoms is considered.ALTHOUGH many per-and poly-fluoroalkyl compounds are now known, very few compounds of type ArFX, where ArF is a perfluoroaryl group and X is a functional group, have been synthesised. Hexafluorobenzene was prepared by McBee et aZ.l but the route followed is unsatisfactory for synthesis on a larger scale. Earlier work by Dkirant, only recently published,2 provides the best method for the synthesis of hexafluorobenzene : 630-640"CFBr, -C6F, Pt tubeHexafluorobenzene has since been obtained by dehydrofluorination of a nonafluorocyclohexane, but the preparation of suitable pure precursors of this type is tedious.

Die Reduktion von CBr2F2 durch Blei - ein neuartiger Weg zum Difluorcarben / The Reduction of CBr2F2 by Lead -a Novel Pathway to Difluorocarbene

“…Das sehr reaktive und instabile Carbonylfluorid [6,7] [20] angegebenen Reaktionsführung erlaubte es, die Ausbeute auf nahezu 90% zu steigern [11].…”

Fluorinated esters : synthesis and identification

“…Even at 1:100,000 (30 seconds for reasons of safety) the compound was found to possess only a faint fruit like odor indistinguishable from that of many harmless esters not containing fluorine (17). The thermal stability of three fluorinated esters was studied by Shraydih et al (32), which resulted in the followings:…”

Structures of double-hydrogen-bonded adducts of 1,8-biphenylenediol and related compounds

“…For example, the O--O distance in the adduct of pentafluorophenol, whose acidity (pKa 5.53) (Birchall & Haszeldine, 1959) is comparable to that of (2) ~=~. …”