High-valency metal fluorides

The presence of carbocationic intermediates was inferred from the isolation of other perfluorinated isomers formed via rearrangement upon fluorination of n-hexane [75]. Similar arguments have been suggested for fluorinations of aromatics [74, 76, 77], ethers [78] and amines [79]. 

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Fluorination of organic compounds using high valency metallic fluorides (14) may be represented as follows ... 

For the past 20 years, four mam ways of replacement of hydrogen by fluorine have been used fluorination using elemental fluorine, electrochemical fluon nation, fluorination using high-valency metal fluorides, and selective electro philic fluorination... 

High-valency metal fluoride fluorination of pyridine [82JFC(21)171], quinoline [82JFC(21)413], and 2-methylfurans [91 JFC(51)179] has been reported. With 2-methylfuran a complex mixture of stereoisomers of partially fluorinated oxolans was obtained. These can be dehydrofluorinated to fluorooxolens and no furans have been observed. Conformation and structural group were found to influence the direction and readiness toward dehydrofluorination [91 JFC(52) 165]. 

The Exhaustive Fluorination of Organic Compounds by High Valency Metal Fluorides, M. Stacey and J. C. Tatlow, Adv. Fluorine Chem., 1 (1960) 166-198. 

Fluorofullerenes have been prepared by reaction with halogen fluorides, by direct fluorination with F2 or by fluorination with noble gas fluorides [7,8,14], The reaction with high valence metal fluorides is the most versatile route for the synthesis of CsoFnH. 

Fluorination of Q or C2 compounds by the high valency metallic fluoride. 

The most common method for the preparation of perfluorinated tetrahydrofurans is fluorination of tetrahydrofurans. Elemental fluorine or high-valency metal fluorides (AgF2, Mnp3, Hgp2, and Cop3) are usually used as fluorinating agents. ... 

Takubo, S. Sekiya, A. Monofluorination of fluorinated oxolanes with high-valency metal fluorides. J. Fluorine Chem. 1998, 87, 105-109. 

An interesting rationalization of the mechanistic pathways involved in the duorination of aromatic compounds by high-valency metal fluorides has been provided. The main features of the mechanism [outlined for the conversion of fluorobenzene into /)-difluorobenzene by cobalt(in) fluoride in Scheme 2] are oxidation of the aromatic system to a radical-cation (1) and its subsequent reaction with a fluorine atom from the metal fluoride to give the type of Wheland intermediate [or benzenium ion (c/. p. 362)] (2) which would be formed in a conventional electrophilic process. Such a scheme implies that the relative stabilities of Wheland intermediates might be used to rationalize orientation in this type of reaction in much the same way as for more traditional processes, and some examples of such applications have been provided. Alternative routes from the radical-cation (1) are discussed and possible... 

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