Vanadium oxide fluorides

Vanadium oxide fluoride/trifluoroacetic anhydride VOFJ(CFfiO)fi... 

Vanadium oxide fluoride trifluoroacetic acid Nonphenolic oxidative coupling s. 29,910... 

Vanadium oxide fluoride trifiuoroacetic acid fiuorosulfonic acid Nonphenolic oxidative coupling... 

The fluorination of polyfluorocyclohexenes with antimony(V) fluoride proceeds under much more severe temperature conditions ( 150 C) than with vanadium(V) fluoride (see Section 12.4.2). In these reactions antimony(V) fluoride effects both the oxidative addition of fluorine and the substitution of vinyl chlorine atoms by fluorine.48... 

Great differences in product structures and product distributions are obtained by lead(IV) oxide or acetate oxidation of perfluorophenol in different solvents and media. The reaction with the former agent gives a quinoid ether in 22% yield (Table 10).173 The oxidation with lead(IV) acetate has been optimized to such a level as to give perfluoro cyclohexa-2,5-dienone (4) in 65 % yield.174 Treating the phenol with vanadium(V) fluoride or vanadium(III) fluoride as well as xenon difluoride gives a mixture of products,175 therefore, the reactions are only of minor preparative importance. 

Recognizing the applicability of XRD to occupational health chemistry, Lennox and Leroux (1) suggested a number of chemical species which would be suitable for XRD analysis arsenic trioxide, beryllium oxide, mica, vanadium oxides, calcium fluoride in ceramic materials, as well as a number of organics such as DDT, lindane and chlordane. Unfortunately, the general application of XRD to the quantitation of industrial hygiene samples has not been realized and the majority of these analyses are restricted to free silica and to a lesser extent asbestos and talc. 

In addition to the antimony fluorides, silver, mercury, thallium, aluminium, zinc, zirconium, chromium and other fluorides [7] such as mercury(II) fluoride, vanadium pentafluoride [24] and various transition metal oxide fluorides [25] have been used in exchange processes, although much less widely. 

Gin s electrolytic method for ferrovanadium1 uses vanadic acid dissolved in a bath of fused iron fluoride and calcium carbide. The anode is a mixture of vanadic acid and retort carbon, and the cathode is fused steel. (2) A French process uses vanadic acid dissolved in calcium fluovanadate, and a current of 0.7 ampere per square centimeter of anode surface. (3) An American process electrolyzes a solution of vanadic acid in molten ferrosilicon. (4) Another American process passes an electric current through a charge made up of vanadium oxide and the calculated amounts of iron and carbon. 

Pure anhydrous vanadium(III) fluoride is more conveniently prepared by the thermal decomposition, in an inert atmosphere, of ammonium hexafluorovanadate(III), the latter being formed by the fusion of ammonium hydrogen fluoride with vanadium (III) oxide. Long and Wilhelm were unsuccessful in their efforts to prepare vanadium(III) fluoride by these reactions their product became oxidized since it was not protected by an inert atmosphere. Also, there is evidence that these investigators started with impure vanadium (III) oxide. The procedure described below employs an inert atmosphere for the decomposition of the hexafluorovanadate. 

Previously, ammonium hexafluorovanadate (III) has been obtained only from aqueous solution. Its preparation in molten ammonium hydrogen fluoride has the advantage that it yields a product which is anhydrous. Aqueous preparations of ammonium hexafluorovanadate (III) tend to have sorbed moisture, which, during the decomposition, could through hydrolysis contaminate the vanadium(III) fluoride with oxide. 

In a related study, Kupchan and his group utilized vanadium oxytri-fluoride in trifluoroacetic acid to oxidize monophenolic phenethyltetrahydro-isoquinoline trifluoroacetamides 8 and 9, and the analogous tertiary bases 14 and 15 (see Schemes 29.1 and 29.2, respectively). ... 

Finally, the 6-hydroxy analog 16 was oxidized with vanadium oxytri-fluoride in trifluoroacetic acid to supply the homoneoproaporphine 17 in an impressive yield. ... 

Some properties of selected vanadium compounds are Hsted in Table 1. Detailed solubiUty data are available (3), as are physical constants of other vanadium compounds (4). Included are the lattice energy of several metavanadates and the magnetic susceptibiUty of vanadium bromides, chlorides, fluorides, oxides, and sulfides (5). 

Calcium metal is an excellent reducing agent for production of the less common metals because of the large free energy of formation of its oxides and hahdes. The following metals have been prepared by the reduction of their oxides or fluorides with calcium hafnium (22), plutonium (23), scandium (24), thorium (25), tungsten (26), uranium (27,28), vanadium (29), yttrium (30), zirconium (22,31), and most of the rare-earth metals (32). 

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