Perfluorination of Allene Derivatives by Direct Fluorination
Perfluoropropane was prepared from allene with elemental fluorine in the presence of sodium fluoride in 84percent yield for the first time.The reaction of allene with elemental fluorine afforded 2,2-difluoropropane in the absence of sodium fluoride.Methoxyallene and cyanoallene were perfluorinated with elemental fluorine in the presence of sodium fluoride to give heptafluoropropyl trifluoromethyl ether and heptafluoropropyl cyanide in good yields respectively.In addition, the direct fluorination of cyanoallene in the presence of cesium fluoride afforded N,N-difluorononafluorobutylamine in 95percent yield.
The monofluorination of hydrofluorocarbons over cobalt trifluoride
Hydrofluorocarbons (HFCs) have been fluorinated via the high-valency metal fluorides CoF3, MnF3 and KCoF4.The fluorinating powers of these reagents for the monofluorination of 2,2-difluoropropane are in the order CoF3>MnF3>KCoF4.The fluorinations of fluorinated ethanes with CoF3 have been examined in detail.The effects of temperature and the distribution products are described.Furthermore, regioselective monofluorination of gem-difluoro compounds (C3-C5) with CoF3 was achieved at the methylene position adjacent to the gem-difluoro group.The trifluoro compounds were obtained in good yield at low reaction temperatures.
19F nuclear magnetic resonance studies of halogenated propanes
The relationship between 19F chemical shifts in halogenated propanes and their structures are elucidated using MNDO calculations to determine the population of rotamers.The pairs of atom gauche to a fluorine atom and van der Waals interaction between the two terminal substituents are responsible for the 19F chemical shifts.The differences among chemical shifts in diastereomers are also discussed in terms of the conformation of molecule.
Tanuma, T.,Ohnishi, K.,Okamoto, H.,Miyajima, T.,Morikawa, S.
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(2007/10/02)
REACTION OF HYDROXY AND CARBONYL COMPOUNDS WITH SULFUR TETRAFLUORIDE. XIII. REACTIONS OF ALIPHATIC HYDROXY KETONES WITH SULFUR TETRAFLUORIDE
Aliphatic α-hydroxy ketones react with sulfur tetrafluoride to form trifluoroalkanes and difluoroalkyl fluorosulfinates.The action of sulfur tetrafluoride on 4-hydroxy-2-pentanone gives 2,2,4-trifluoropentane and 3-penten-2-one.