Fluorine manufacturing methods

Another manufacturing method involves irradiation by UV light, in which acrylic-modified polyurethane resins are used. Reactive fluorinated oligomers are reviewed in Reference 36. 

The interest of pharmaceutical manufacturers in steroidal allenes containing fluorine continues. Methods for converting 17a-difluorocyclopro-penyl-5a-androstane-3p,17p-diol 3-acetate and the corresponding 17a-tri-fluoropropynyl diacetate into isomeric trifluoromethylallenes (132) and (133) have now appeared. The former precursor is treated with 2-chloro-l,I,2-trifluorotriethylamine in dry methylene chloride, giving a mixture in which the a-lsoraer (132) predominates, whereas the latter precursor is converted by zinc dust in diglyme into the isomeric compound (133). 

Considerable attention has been directed to the contamination of phosphates with fluorine owing to the possible manufacture of the phosphate from phosphatic rocks or bones contaminated with fluorine. Suitable methods are fully discussed on pp. 297 to 303. 

In addition, there are other methods of manufacture of cryoHte from low fluorine value sources, eg, the effluent gases from phosphate plants or from low grade fluorspar. In the former case, making use of the fluorosiHcic acid, the siHca is separated by precipitation with ammonia, and the ammonium fluoride solution is added to a solution of sodium sulfate and aluminum sulfate at 60—90°C to precipitate cryoHte (26,27) ... 

Manufacture. Boron trifluoride is prepared by the reaction of a boron-containing material and a fluorine-containing substance in the presence of an acid. The traditional method used borax, fluorspar, and sulfuric acid. 

Aromatic Ring Fluorination. The formation of an aryl diazonium fluoride salt, followed by decomposition, is a classical reaction (the Schiemaim reaction) for aryl fluoride preparation (21). This method has been adapted to the production-scale manufacture of fluorobenzene [462-06-6]... 

Manufacture. One commercial process features a three-stage saturation—rearomatization technique using benzene and fluorine gas as raw materials (73). Principal problems with this method are the complex nature of the process, its dependence on fluorine gas which is cosdy to produce, and the poor overall utilization of fluorine, because nearly one-half of the input fluorine is removed during the process. 

Almost all of the biomedical research done in the 25 years following the liquid-breathing work was conducted with commercially available fluorocarbons manufactured for various industnal uses by the electrochemical Simons process (fluonnation in a hydrofluoric acid solution) or the cobalt fluoride process (fluori-nation with this solid in a furnace at about 200 C) These processes tended to yield many by-products, partly because they were, to some extent, free radical reactions and partly because it was difficult to easily achieve complete fluonnation Aromatic hydrocarbons gave better products with the cobalt tnfluonde [73] method, whereas saturated hydrocarbons yielded better products with fluonnation using diluted or cooled gaseous fluorine (Lagow) Incompletely fluormated matenal was either... 

Modem processing of tantalum and niobium metals and their compounds is related to the treatment of fluoride compounds. Hence, successful technological improvements, the development of novel methods and the manufacturing of high-grade products depend on the application of technological achievements in the area of fluorine chemistry. 

It is clear that many new fluoropolymers can be synthesized by direct fluorination technology that cannot be obtained through other routes. The information in this chapter should serve as a strong indication that perhaps the best and ultimate synthetic method for fluoropolymers on both laboratory and manufacturing scales in the future will be direct fluorination reactions. 

Another argument in favor ofthe XeF2 method is the evidence that since 1995 it has been used by a manufacturing company that had no previous experience with direct fluorination or fluorine at all. 

Details of both these methods as used by us are given below in specimen analyses. With regard to the bomb method, the lead washer supplied by the manufacturers was useless the lead melted and disintegrated at the temperature of the reaction. Copper was also found to be attacked and was otherwise unsatisfactory. Gold, on the other hand, was found to be most suitable. It is soft, will withstand the required temperature without melting or disintegrating, and is not attacked by fluorine, fluoride or alkali. 

An industrial method for manufacturing fluorine gas is the electrolysis of liquid hydrogen fluoride. 

The market for fluoroaromatics, with fluorine atoms as ring substituents, has expanded considerably over the past 20 years, driven not only by the need for intermediates in pharmaceutical and crop protection products but also for the manufacture of monomers for high-performance aromatic polymers. Although a range of possible methods have been described for the introduction of fluorine into the aromatic ring, only three are currently established for... 

Attempts to manufacture anhydrous mercury(II) fluoride by methods more conventional than the action of elemental fluorine upon mercury(II) chloride (vide supra) showed that aqueous reagents invariably yielded a dihydratc salt which could not be converted into anhydrous mer-cury(II) fluoride, because it always eliminated hydrogen fluoride in preference to water. In an effort to circumvent this, mercury(II) fluoride generated in situ has been used as the reagent for the substitution of one or several halogens by fluorine in various types of compounds (see Houben-Weyl, Vol. 5/3, p202 for pre-1959 reports). 

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