Fluorinated silver catalysts

Puentes MA, MunozBK, Jacob K, etal. Functionalization ofnon-activated C-H bonds of alkanes an effective and recyclable catalytic system based on fluorinated silver catalysts and solvents. Chem EurJ. 2013 19 1327-1334. 

Following their investigations on nitrene, carbene, and oxo transfer reactions catalyzed by fluorinated silver tris(pyrazoyl)borate (see Chapter 6 on nitrene chemistry), Lovely et al. looked for a combined carbene transfer and [2,3]-sigmatropic rearrangement. On the basis of these mechanistic considerations, these authors showed that diazoacetates, indeed, reacted with allyl halides in the presence of this silver catalyst to give a-halo-y-unsaturated esters (Scheme 3.51).77... 

Later on, more fluorinated silver complexes (catalysts 5-7) were developed by Perez and coworkers [24]. Most of those complexes efficiently catalyzed carbene... 

There are two other examples from Buchmeiser [107] and Mingotaud [108] that describe catalyst modification at the X-type Hgand for use in aqueous media, although both of these are based on a micellar catalysis approach (see section MiceUar Catalysis Approaches ). Buchmeiser s system involved the use of an amphiphilic, poly(2-oxazoline)-based block copolymer that was functionalized and subsequently attached to the catalyst through a fluorinated silver carboxylate. 

Scheme 3-230. Fluorination of arylstannanes using T-TEDA-PFe in the presence or silver catalyst.

Rearrangement of fluorine with concomitant ring opening takes place in fluorinated epoxides Hexafluoroacetone can be prepared easily from perfluo-ropropylene oxide by isomerization with a fluorinated catalyst like alumina pre treated with hydrogen fluoride [26, 27, 28] In ring-opening reactions of epoxides, the distribution of products, ketone versus acyl fluoride, depends on the catalyst [29] (equation 7) When cesium, potassium, or silver fluoride are used as catalysts, dimenc products also are formed [29]... 

Thionyl tetrafluoride and pentafluorosulfur hypofluorite can be prepared by the fluorination of thionyl fluoride. The product distribution obtained upon fluorination appears to be dependent not only upon the reaction conditions, but on whether a source of fluoride ion is present. Fluorination of thionyl fluoride over a hot platinum gauze or in a Monel pressure reactor produces thionyl tetrafluoride, whereas fluorination in the presence of cesium fluoride or a silver fluoride catalyst jdelds pentafluorosulfur hypofluorite. The role of the fluoride ion in the fluorination has not been conclusively established however, the avail-... 

Use Etching glass, flux in silver solders, alkylation catalyst, electrolyte in fluorine production. 

The second generation of catalysts for this transformation was based on fully fluorinated trisindazolylborates, leading to highly electrophilic metal centers. A series of five new ligands were prepared (Scheme 13) and their silver complexes synthesized and tested as catalysts for the alkane functionalization reaction. In addition to excellent activities, they were employed in fluorous biphasic conditions, allowing a ready separation of products from the catalyst, and the subsequent recycling of the latter. 

Dimerization of alkanes can be brought about by the irradiation of zeolite-Y with added silver atoms and silver clusters lead to dimerization on irradiation at 220-300 nm104. Selective fluorination of di- and triphenyl methane in acetonitrile as solvent and TiC>2 as catalyst can be effected using AgF. Di- and triphenylacetic acid as well as alkenes can be fluorinated in the same way. A single electron transfer reaction is thought to be involved, followed by attack of fluoride105. It could be that the reaction is one that arises on the TiC>2 surface and that the Ag+, to which the electron transfer could take place, is not involved106. 

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