Group I fluorides

F exchange between F2CO and Group I fluorides (LiF—CsF) has been studied to ascertain the effect of dipolar aprotic solvents.160 Exchange varies in the order Cs>Rb K>Na, Li at 423 K (Cs>Rb K, Na, Li at 323 K), and is enhanced in the presence of acetonitrile or diglyme but not benzene or ether. 

The synthesis of POF3 and P2O3F4 from phosphorus pentafluoride, oxygen, and magnesium at 300 °C has been described. There is an instantaneous reaction between phosphoryl fluoride and nitrosyl fluoride at room temperature to give PF as the only fluorine species present. Reaction with the Group I fluorides is similar but slower and is represented by the equation ... 

Table 2 F Exchange after 1 h between labelled CFj COF and Group I fluorides...

The system CFs COF + M+F 5 CF, CFsO M+(M = Li—Cs inclusive) has been subjected to radiotracer investigation. (Comparison between the CFs-COF-Cs F and (CFa)jCO-Cs F systems (see Table 1) indicates that only the fluorocarbonyl F atom exchanges readily under the conditions used and, at 50—150 °C, the degree of F exchange between CFj-CO F and Group I fluorides varies in the order Cs > Rb > K > Na > Li (see Table 2). These results are in keeping with preparative experience. ... 

From the tables it is clear that elements in Groups I-IV can display a valency equal to the group number. In Groups V-VII. however, a group valency equal to the group number (x) can be shown in the oxides and fluorides (except chlorine) but a lower valency (8 — x) is displayed in the hydrides. This lower valency (8 — x) is also found in compounds of the head elements of Groups V-VII. 

Similar chain structures are well known of other compounds and seem to be preferred by ternary scdts, the A-ions of which are between the chains and hold them together. Binary fluorides on the other hand seem to prefer the forming of closed, finite groups, i. e. low rather than high polymer molecules. In the a-modification of UFj, however, such a chain stmcture is also found (343). But by the arrangement of chains further ligands in a second sphere are added to those of the primary octahedral coordination of the uranium. 

In another study by the same group, [ F]-fluoride-PET/CT was compared with [ F]-fluoride-PET, bone scintigraphy and SPECT in 44 patients with high-risk prostate cancer [195]. For detection of skeletal metastatic spread [ F]-fluoride-PET/CT revealed to be significantly more sensitive and specific than bone scintigraphy (p < 0.05) and SPECT (p < 0.05), and significantly more specific than [i F]-fluoride-PET (p < 0.001). 

Not only was this result a great achievement in its own right,9 but it also stands as the primeval example11 of a most important route to many types of organic fluorides, i.e. displacement of a nucleofugal group by fluoride ion. 

Exchange of the chlorines of 2,5-bis(trichloromethyl)thiophenes for fluorine with silver(I) fluoride has been attempted however, only the chlorines which are attached to methyl groups, are substituted by fluorine, e. g. formation of 4.36... 

In perfluoro a-diketone 7, which lacks a trifluoromethyl group /i to the carbonyl in the 2-position. it is the carbonyl in the 3-position that participates in the cyclization to form per-fluoro(2-acctyltetrahydrofuran) (8), when 7 is heated at 150 C in the presence of antimony(V) fluoride.5 Perfluoro(2-methyltetrahydropyran-3-one) also rearranges to furan derivative 8 in high yield when heated at 100 C in the presence of antimony(V) fluoride for 20 hours.5... 

The trends are similar to those found in halides of the Group I and Group II metals and are explained on an ionic packing model more anions can be packed round the large lanthanide ions early in the series than around the smaller, later ones similarly, more of the small fluoride ions can be packed round a given lanthanide ion than is the case with the much larger iodide anion. 

The addition of fluorine and a hydroxy group, i.e. formation of a 8-fluoro alcohol 1, can be carried out using oxygen difluoridc, as 1.430 hypofluorous acid, chromyl fluoride,... 

Potassium fluoride is the most frequently used metal fluoride for the substitution of inorganic ester groups by fluorine. Cesium fluoride in combination with crown ethers is preferable in difficult cases, while silver(I) fluoride is seldom used. 

In some of the first studies connected with the discovery of the general phenomenon of cocatalysis, f-butanol was found to play such a role in the polymerisation of isobutene by boron fluoride There is an apparent contradiction between this observation and tire fact that polyisobutene chains bearing hydroxyl end groups , i.e. the same structure as f-butanol, do not exhibit a cocatalytic function (see all the evidence of limited yields due to water consumption by termination with counterion to give those end groups). The likely explanation of this dichotomy is that the OH groups on the polymer molecules are embedded in the macromolecular cofls and therefore much less reactive towards the Lewis acid-moncaner complex. 

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