Nucleophilic displacement of halogen from fluorocarbon systems

Nucleophilic Displacement of Halogen from Fluorocarbon Systems 

It is the aim of this chapter to develop a model for the very broad spectrum of reactivity of fluorine-containing systems towards nucleophiles. Substiment effects of fluorine and fluorocarbon groups on the SnI process were considered earlier, in a more general discussion of carbocations (see Chapter 4, Section VI) effects on the Sn2 process will now be examined. Then the broader principles of displacement of fluorine, as fluoride ion, from carbon in different environments will be discussed to emphasise why, for example, nucleophilic displacement of fluoride ion from perfluoroalkenes occurs extremely rapidly while, in contrast, perfluoroalkanes are characterised by extreme inertness. 

Similarly, nucleophilic displacements from centres substituted with CF3 groups are retarded [3-5] in comparison with corresponding alkyl derivatives, due to steric hindrance and fluorine lone-pair repulsion of the incoming nucleophile, but preparatively useful 

A single-electron transfer process may be a competing mechanism in reactions between sterically demanding nucleophiles and CF3CH2I, since side products arising from radical coupling reactions are observed [9]. 

In contrast, fluorine or fluorocarbon groups directly attached to the reaction centre have a much more pronounced effect [4] for example, the hydrolytic displacement of chloride from PhCHFCl appears to be activated with respect to benzyl chloride [10], although the situation is complicated by concomitant SnI and Sn2 processes. 

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Nucleophilic Displacement of Halogen from Fluorocarbon Systems 123... 

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See also in sourсe #XX -- [ ]

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