Hydrogen replacement fluonne

Lead tetrafluoride, generated in situ from lead dioxide and hydrogen fluonde, can replace benzylic hydrogen by fluonne [3] Under sirmlar conditions phenol is simultaneously oxidized to 4,4-difluoro-2,5-cyclohexadienone [4 (equations 3 and 4)... 

Vanadium pentafluoride replaces benzylic hydrogen by fluonne but also adds fluonne to the aromatic system, giving fluonnated cyclohexadienes and cyclohexenes [5] (equation 5)... 

Anhydrous hydrogen fluonde, potassium fluonde, and sodium fluonde have all been used to promote the chlorine-fluonne exchangein tetmchloropyrukizine All three fliionne sources replace the chlonne in position 3 first Both sodium and potassium... 

Photochemically induced reduction of alkyl perfluoro carboxylates in hexa-methylphosphoramide (FfMPA) can replace one, two, or (in the case of tn-fluoroacetate) three a-fluonne atoms with hydrogen [7, S] (equation 5) Chlorine-containing fluorocarboxylates preferentially lose a-chlorme and may even lose P-chlorinc in preference to a fluonne [9] (equation 6) Cyclic a-fluoroketones are also defluonnated photochemically [10] (equation 7)... 

The reactivity of tetraphenylphosphonium hydrogen difluoride is comparable with more conventional chlonne-fluonne exchange reagents It can be used and regenerated as illustrated in equation 18 and its preparation is outlined in Procedure 3, p 193 The rate of reaction of tetraphenylphosphonium hydrogen difluonde with benzyl bromide using a fluoride concentration of 0 12 M in acetomtnle (f1/2=25 min at 52 °C) can be compared with that achieved by replacing it with potassium fluoride- 18-crown-6 (tm = 11 5 h at 82 °C) [28] The... 

---