In additions of halogen fluorides

Additions of halogen fluorides to the more electrophilic perfluonnated olefins generally require different conditions Reactions of iodine fluoride, generated in situ from iodine and iodine pentafluoride [62 102 103, /05] or iodine, hydrogen fluoride, and parapeiiodic aud [104], with fluormated olefins (equations 8-10) are especially well studied because the perfluoroalkyl iodide products are useful precursors of surfactants and other fluorochemicals Somewhat higher temperatures are required compared with reactions with hydrocarbon olefins Additions of bromine fluoride, from bromine and bromine trifluonde, to perfluonnated olefins are also known [lOti]... 

More general procedures for additions of halogen fluorides to highly fluori-nated olefins involve reactions with a source of nucleophilic fluoride ion, such as an alkali metal fluoride, in the presence of aposttive halogen donor [62 107, lOff, 109, 110, 111] (equations 11 and 12) These processes are likely to occur by the generation and capture of perfluorocarbamonic intermediates Tertiary fluormated carbanions can be isolated as cesium [112], silver [113], or tns(dimethylamino)sul-... 

The addition of halogen fluorides to C = C bonds in steroids is affected by steric crowding to a greater extent than by electronic factors so that the products may be of the anti-Mar-kovnikov type. In several instances the orientation of the bromine monofluoride addition was shown to depend on reaction conditions resulting cither in 6/ -bromo-5a-fluoro- or 5a-bromo-6/i-fluorosteroids.33... 

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

In 1959 Bowers and Robinson and co-workers independently reported the addition of halogen fluorides to double bonds in steroids. The addition of bromine fluoride leads to C6, CTl, and C16 fluorinated steroids. Further publications describe many examples of the addition of bromine fluoride to 5,6-unsaturated... 

In 1959 Bowers176 and Robinson and co-workers 177 independently reported the addition of halogen fluorides to double bonds in steroids.316 The addition of bromine fluoride leads to C6, Cll, and C16 fluorinated steroids.173 Further publications describe many examples of the addition of bromine fluoride to 5,6-unsaturated steroids178 200,212 262,265 270 284-287-309 314 and to 9.11 -, 6,7- or 11,12-unsaturated steroids.209 210 281,695 An example is the bromofluorination of 3/ -acetoxyandrost-5-en-17-one (15) with aqueous hydrogen fluoride and A-bromosuc-cinimide.262 In addition to the main product, the 5a-bromo-6/I-fluoro derivative (58%), three... 

Catalysis. Catalytic properties of the activated carbon surface are useful in both inorganic and organic synthesis. For example, the fumigant sulfuryl fluoride is made by reaction of sulfur dioxide with hydrogen fluoride and fluorine over activated carbon (114). Activated carbon also catalyzes the addition of halogens across a carbon—carbon double bond in the production of a variety of organic haUdes (85) and is used in the production of phosgene... 

Tetrasubstituted phosphonium halides are just as effective as their ammonium counterparts. A combination of tetraphenylphosphonium bromide and either 18-crown-6 or polyethylene glycol dimethyl ether with spray-dried potassium fluoride converts 4-chlorobenzaldehyde to 4-fluorobenzaldehyde in 74% yield [67] In addition, the halogen of a primary alkyl chloride or bromide is easily displaced by fluorine in aqueous saturated potassium fluoride and a catalytic amount of hexadecyltributylphosphonium bromide [68] (Table 7 Procedure 4, p 194)... 

The stoichiometric equivalents of halogen fluorides, i.e. chlorine monofluoride, bromine monofluoride and iodine monofluoride, have found a wide application in addition reactions to double bonds. The equivalents are obtained by reacting A -haloamides or free halogens in combination with hydrogen fluoride or its salts as the source of fluoride ions. The reactions proceed under mild conditions at — 80 to 20 "C in anhydrous hydrofluoric acid or diethyl ether, tetrahydro-furan, dichloromethane or chloroform mainly by electrophilic addition with Markovnikov-type regioselectivity (anti addition).26-28... 

Treatment of perhalogenated and highly halogenated alkenes with sulfur tetrafluoride in the presence of lead(IV) oxide, which is most likely converted in situ into lead(IV) fluoride, results in addition of fluorine to the C = C bond of the alkenes. The addition proceeds at 100 C to afford per- and polyhalogenated alkanes 5 in yields ranging from a few percent to almost quantitative.190 Representative examples are given. 

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