Fluorinating agent, preparation

Siher I) fluoride, AgF, is prepared by evaporation of a solution of excess Ag20 in HF after filtration or by heating anhydrous AgBF. The anhydrous salt is yellow hydrates are known, It is very soluble in water and in many organic solvents. Used as a mild fluorinating agent. On treatment of a solution with Ag a sub-fluoride, Ag2F, is formed. 

The tetrafluorides of the elements can be prepared. They are all less stable than the corresponding hexafluorides and are hydrolysed readily by water. They can all be used as fluorinating agents and sulphur tetrafluoride is extensively used for this purpose, for example the fluorination of organic carbonyl groups ... 

Fluorine in the free state is too reactive to be of a direct practical value, but it may be used to prepare other compounds of fluorine, which are then used as fluorinating agents, for example chlorine... 

The only important compound is the paramagnetic silver(II) fluoride, AgFj, prepared by fluorination of the metal it is used as a convenient fluorinating agent. 

Uses. Agp2 is a powerful fluorinating agent and is used for substitution of hydrogen by fluorine in hydrohalocarbons (21), preparation of... 

Stable noble-gas compounds have no industrial uses as of this writing but are frequently utilized in laboratories as fluorinating and oxidizing agents. Xenon difluoride and xenon tetrafluoride are relatively mild oxidative fluorinating agents and have been used for the preparation of phosphoms, sulfur, tellurium. 

Iron(III) fluoride [7783-50-8] prepared from FeCl and anhydrous HF or other fluorinating agents ia a flow system at elevated temperature. 

The perchloryl fluoride [7616-94-6] FCIO, the acyl fluoride of perchloric acid, is a stable compound. Normally a gas having a melting poiat of —147.7° C and a boiling poiat of —46.7°C, it can be prepared by electrolysis of a saturated solution of sodium perchlorate ia anhydrous hydrofluoric acid. Some of its uses are as an effective fluorinating agent, as an oxidant ia rocket fuels, and as a gaseous dielectric for transformers (69). 

Bromine monofluoride [13863-59-7], BrF, can be prepared by the direct reaction of Br2 and F2, but because it readily disproportionates it has never been prepared in pure form (57). However, BrF can be prepared in situ by the reaction of Br2 with AgF in benzene (58) or by the reaction of A/-bromoacetamide and HF in ether (59). BrF adds to simple alkenes at room temperature to give products of trans-addition. Bromine trifluoride [7787-71-5], BrF, can be formed from gaseous fluorine and Hquid bromine (60). Bromine pentafluoride [7789-30-2], BrF, is formed from the reaction of BrF vapor with gaseous fluorine at 200°C (60). The tri- and pentafluorides are commercially available. As strong fluorinating agents they are useful in... 

Reeently, new fluorinating agents, tetrabutylphosphonium fluoride and its mono- and dihydrofluoride, were used for preparation of fluorohydrins from epoxides [14] (equation 13). 

Mixtures of anhydrous hydrogen fluoride and tetrahydrofuran are successfully used as fluorinating agents to convert 1,1,2-trifluoro-l-allcen-3-ols, easily prepared from bromotrifluoroethene via lithiation followed by the reaction with aldehydes or ketones, to 1,1,1,2-tetrafluoro-2-alkenes The yields are optimal with a 5 1 ratio of hydrogen fluoride to tetrahydrofuran The fluorination reaction involves a fluonde lon-induced rearrangement (Sf,j2 mechanism) of allylic alcohols [65] (equation 40)... 

Sulfur tetrafluoride, SF4, though extremely reactive (and valuable) as a selective fluorinating agent, is much more stable than the lower fluorides. It is formed, together with SFg, when a cooled film of sulfur is reacted with F2, but is best prepared by fluorinating SCI2 with NaF in warm acetonitrile solution ... 

Ti, Zr, Hf, Th, U and the pentafluorides of Nb and Ta). However, many higher fluorides require the use of a more aggressive fluorinating agent or even F2 itself. Typical of the fluorides prepared by oxidative fluorination with F2 are ... 

In addition to its use as a straight fluorinating agent, BrF3 has been extensively investigated and exploited as a preparative nonaqueous ionizing solvent. The appreciable electrical conductivity of the pure liquid (p. 828) can be interpreted in terms of the dissociative equilibrium... 

Xep4 is best prepared by heating a 1 5 volume mixture of Xe and Fi to 400°C under 6 atm pressure in a nickel vessel. It also is a white, crystalline, easily sublimed solid the molecular shape is square planar (Xe-F 195.2pm) and is essentially the same in both the solid and gaseous phases. Its properties are similar to those of XeFi except that it is a rather stronger fluorinating agent, as shown by the reactions ... 

For a review of the preparation of a-fluoro carbonyl compounds, see Rozen, S. Filler, R. Tetrahedron, 1985, 41, 1111. For a monograph, see German, L. Zemskov, S. New Fluorinating Agents in Organic Chemistry Springer NY, 1989. 

Dimethylamino)difluorophosphine has been prepared directly from phosphorus trifluoride and dimethylamine5,6 and also by the action of dimethylamine on (triehloromethyl)difluorophos-phine.13 The most convenient procedure yet reported4 appears to be the fluorination of C12PN(CH3)2 using ant mony trifluoride or sodium fluoride as a fluorinating agent. 

Many organic compounds sometimes react explosively with C1F3 and it is such a strong fluorinating agent that it can be used to prepare other interhalogens ... 

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