Addition of hydrogen fluoride

Vinyl Fluoride. Vinyl fluoride [75-02-5] C2H2F, the monomer for poly(vinyl fluoride), is manufactured by addition of hydrogen fluoride to acetylene (see Fluorine COMPOUNDS, ORGANIC, POLY(viNYL FLUORIDE)). 

Vinyl fluoride (fluoroethene), is manufactured from the cataly2ed addition of hydrogen fluoride to acetylene. It is used to prepare poly(vinyl fluoride) which has found use in highly weather-resistant films (Tedlar film, Du Pont). Poly(vinyhdene fluoride) also is used in weather-resistant coatings (see Eluorine compounds, organic). The monomer can be prepared from acetylene, hydrogen fluoride, and chlorine but other nonacetylenic routes are available. 

Poly(vinyl fluoride) was first introduced in the early 1960s, in film form, by Du Pont under the trade name Tedlar. Details of the commercial method of preparing the monomer have not been disclosed but it may be prepared by addition of hydrogen fluoride to acetylene at about 40°C. 

Alkyl fluorides have been prepared by reaction between elementary fluorine and the paraffins, by the addition of hydrogen fluoride to olefins, by the reaction of alkyl halides with mercurous fluoride, with mercuric fluoride, with silver fluoride, or with potassium fluoride under pressure. The procedure used is based on that of Hoffmann involving interaction at atmospheric pressure of anhydrous potassium fluoride with an alkyl halide in the presence of ethylene glycol as a solvent for the inorganic fluoride a small amount of olefin accompanies the alkyl fluoride produced and is readily removed by treatment with bromine-potassium bromide solution. Methods for the preparation of alkyl monofluorides have been reviewed. ... 

Table 1. Addition of Hydrogen Fluoride to Halogcnated Olefins...

The addition of hydrogen fluoride to acetylene has been widely investigated because the initial product, vinyl fluoride, is a commercially important monomer Acetylene reacts with hydrogen fluoride in the liquid phase in the absence of catalyst to give vinyl fluoride and 1,1 -ditluoroethane in modest yields [7 ], but better results are achieved by conducting the addition with various additives or catalysts... 

The addition of hydrogen fluoride to an aromatic isocyanide dichloride provides a route to the respective aryl-Af tnfluoromethyl amine [34] (equation 24)... 

Preparation ofKF-2HF. This is prepared by carefully adding hydrogen fluoride vapor mixed with nitrogen to solid potassium bifluoride.13 Potassium bifluoride is available in convenient quantities from some supply houses (Aldrich 23,928-3, for example). The addition of hydrogen fluoride vapor to potassium fluoride is extremely exothermic and is best not attempted. The addition of liquid hydrogen fluoride to potassium bifluoride is also extremely exothermic and is best not attempted. 

Halothane Halothane, 2-bromo-2-chloro-l,l,l-trifluorethane (1.1.2), is made by the addition of hydrogen fluoride to tricholoroethylene and simultaneous substitution of chlorine atoms in the presence of antimony(lll) chloride at 130 °C. The resulting 2-chloro-l,l,l-tri-fluorethane (1.1.1) undergoes further bromination at 450 °C to form halothane [1-3]. 

Tertiary polyfluoro alcohols, l,l,l,3,3,3-hexafluoro-2-methylpropan-2-ol, 1,1,1,3,3-penta-fluoro-2-methylpropan-2-ol and l,l,3,3-tetrafluoro-2-methylpropan-2-ol, on treatment with sulfur tetrafluoride undergo dehydration to give the respective alkenes 7, but not fluoroalkanes small amounts of byproducts resulting from the addition of hydrogen fluoride to the C = C bond of the resultant alkcncs are also formed.54... 

There are no reports of fluorination of acetophenone, but 2,2,2-trifluoro-t-phenylethanone and its homologs react with sulfur tetrafluoride at 100 150°C, even without addition of hydrogen fluoride, to give reasonable to good yields of fluoroalkylbenzcncs l.51... 

In reactions with benzophenone and aromatic vicinal polyketones, such as benzil, 1,3-diphenyl-propanc-l,2,3-trionc. and indane-l,2.3-trione monohydrate (ninhydrin). all the carbonyl oxygen atoms are replaced by fluorines to give the a,w-diphenylperfluoroalkanes 2 or 1,1.2,2,3,3-hexafluoroindane (3) in moderate yield. The yields increase upon the addition of hydrogen fluoride.41... 

Boron trifluoride has been applied as catalyst in addition of hydrogen fluoride to asymmetrically halogenated alkenes in the liquid phase.52... 

The addition of hydrogen fluoride to vinyl chloride (19) in the gas phase with activated carbon and boron trifluoride gives l-chforo-l-fluoroethane (90% yield).53... 

Potassium tetrafluoroborate is used as catalyst with fluorosulfonic acid in the addition of hydrogen fluoride to acetylene (4) in the liquid phase.67... 

The addition of hydrogen fluoride to the double bonds of chlorinated alkenes in the presence of an aluminum trifluoride catalyst is effective and has found broad synthetic application (Table 2). It proceeds so effectively that it is sometimes used to remove fluoroalkenes in crude product mixtures by adding hydrogen fluoride in this way.27 28... 

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