Addition of hydrogen fluoride to double

Boron trifluoride-diethyl ether complex is used as catalyst in addition reactions of hydrogen fluoride to double bonds. If the alkene is halogenated on the C = C bond, fluorine adds to the carbon that bears the halogen.51... 

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... 

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... 

These compounds are usually prepared by addition of hydrogen fluoride to a double bond or by the replacement of chlorine by fluorine in the presence of a metal fluoride catalyst.146 The trick is finding the catalyst and conditions that will give the desired selectively in high yield. An outstanding example is (3.1) ... 

Exercise 10-25 Calculate the AH° values for initiation and chain-propagation steps of radical addition of hydrogen fluoride, hydrogen chloride, and hydrogen iodide to an alkene. Would you expect these reagents to add easily to double bonds by such a mechanism ... 

Oxidation and hydrolysis of nitroso compound 5, readily available from the addition of nitrosyl fluoride to perfluoro(2-methylprop-2-enoyl) fluoride, leads to the corresponding alcohol 6.7 Alternatively, double bonds arc hydroborated and subsequently treated w ith hydrogen peroxide to yield the alcohol, c. g. conversion of compound 7 into Ihc two-product 8 (exoiendo 86 14).8... 

When chlorine is added to olefinic double bonds in the presence of hydrogen fluoride and aluminum trifluoride as catalyst addition, substitution and isomerization occurs17-25-26. Detailed investigations have been undertaken to elucidate the reaction pathways and the influence of the catalyst system on the prod uct distribution in the case of tetrachloroethene and chlorine.17... 

Terminal alkenes with at least three fluorine atoms attached to the double bond react with ammonia to yield carbonitriles. This proceeds via addition of ammonia and subsequent elimination of two equivalents of hydrogen fluoride. In the case of trifluoroethene or halotri-fluoroethencs the resulting monofluoroacctonitriles trimerize to give the respective... 

For this reason, electrophilic additions such as addition of hydrogen halides are very difficult, as can be seen in Explanations 13, 14, and 15. But because of the low overall electron density, the double bonds in perfluoroalkenes are easily attacked by nucleophiles such as fluoride ion. If perfluoropropene is treated with dry potassium fluoride in a proton-donor solvent such as formamide, the fluoride anion joins the less negative carbon of the double bond and forms a negatively charged intermediate that readily reacts with the proton of formamide to give 2 H-perfluo-ropropane [5/]. Such a nucleophilic addition takes place with other fluorides such as cesium fluoride, tetraethylammonium fluoride, and sil-... 

The electron-deficient double bond in lH-pentafluoropropene reacts easily with nucleophiles such as azide anion to form primarily an addition product l-azido-l,2,3,3,3-pentafluoropropane. In the basic medium, unsaturated l-azido-2,3,3,3-tetrafluoropropene is also formed, either by elimination of hydrogen fluoride from the addition product, or by direct displacement of fluorine by SN2 mechanism [90]. 

Treatment of 2 with 3 equiv of 3-phenyl-2-propenal in refluxing toluene-cfe while the reaction progress was monitored by H NMR spectroscopy resulted in the disappearance of the aldehyde hydrogen peak (5 1.56). The IR spectrum of 4 shows a new absorption due to a vC-o stretch at 1448 cm 1. The mass spectrum of the product shows a molecular ion at m/z 538. To our surprise, an X-ray study of 4 showed it to be the insertion product of the two carbonyl ligands into the C-Si bond in 2. The reaction has the potential for developing a new method for double C-C bond formation between the carboranyl unit and carbonyl compounds. Such an insertion of the carbonyl functionality into the o-carborane has been observed in Yamamoto s work on the chemoselective addition of o-carborane to the aldehyde groups by a palladium-catalyzed9 or a fluoride-promoted reaction.10... 

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