Halogen fluorides, reactions with

Fluorine forms very reactive halogen fluorides. Reaction of CI2 and F2 at elevated temperatures can produce GIF, CIF, or CIF 3 be obtained from the reaction of Br2 and F2. These halogen fluorides react with all nonmetals, except for the noble gases, N2, and O2 (5). Fluorine also forms a class of compounds known as hypofluorites, eg, CF OF (6). Fluorine peroxide [7783-44-0], O2F2, has also been reported (6). 

Halogen fluorides react with sulfur, selenium, teUurium, phosphoms, sHicon, and boron at room temperature to form the corresponding fluorides. Slight warming may be needed to initiate the reactions (4) which, once started, proceed rapidly to completion accompanied by heat and light. The lack of protective film formation aHows complete reaction. 

PHENE (71-43-2) Forms explosive mixture with air (flash point 12°F/— 11°C). Violent reaction with strong oxidizers, halogens. Explosive reaction with fluorine, chlorine. Reacts with ozone, forming the shock-sensitive material ozobenzene. Reacts, possibly violently, with other oxidizers such as permanganates, oxygen, perchlorates, peroxides, many fluorides. 

The halogen fluorides are binary compounds of bromine, chlorine, and iodine with fluorine. Of the eight known compounds, only bromine trifluoride, chlorine trifluoride, and iodine pentafluoride have been of commercial importance. Properties and appHcations have been reviewed (1 7) as have the reactions with organic compounds (8). Reviews covering the methods of preparation, properties, and analytical chemistry of the halogen fluorides are also available (9). 

The halogen fluorides are best prepared by the reaction of fluorine with the corresponding halogen. These compounds are powerful oxidising agents chlorine trifluoride approaches the reactivity of fluorine. In descending order of reactivity the halogen fluorides are chlorine pentafluoride [13637-63-3] 1 5 chlorine trifluoride [7790-91-2] 3 bromine pentafluoride [7789-30-2], BrF iodine heptafluoride [16921 -96-3], chlorine... 

Reactions With Metals. AH metals react to some extent with the halogen fluorides, although several react only superficiaHy to form an adherent fluoride film of low permeabHity that serves as protection against further reaction. This protective capacity is lost at elevated temperatures, however. Hence, each metal has a temperature above which it continues to react. Mild steel reacts rapidly above 250°C. Copper and nickel lose the abHity to resist reaction above 400 and 750°C, respectively. 

The rapid reaction of CIF and BrF with metals is the basis of the commercial use in cutting pipe in deep oil weUs (64—68). In this appHcation, the pipe is cut by the high temperature reaction of the halogen fluoride and the metal. 

Another use of hydrogen fluoride, although not in halogen exchange, is the reaction with ethylenes or acetylenes to form the addition products, 1,1-difluoroethane [75-37-6] and vinyl fluoride [75-02-5]-. 

Krypton difluoride cannot be synthesized by the standard high pressure-high temperature means used to prepare xenon fluorides because of the low thermal stabitity of KrF. There are three low temperature methods which have proven practical for the preparation of gram and greater amounts of KrF (141—143). Radon fluoride is most conveniently prepared by reaction of radon gas with a tiquid halogen fluoride (CIE, CIE, CIE, BrE, or lE ) at room temperature (144,145). 

Fused basic salts and basic oxides react with vitreous siUca at elevated temperatures. Reaction with alkaline-earth oxides takes place at approximately 900°C. Hahdes tend to dissolve vitreous siUca at high temperatures fluorides are the most reactive (95). Dry halogen gases do not react with vitreous siUca below 300°C. Hydrogen fluoride, however, readily attacks vitreous siUca. 

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