Sp2 hybridized C-H bonds

Fluorine also enhances the acidity of an sp2-hybridized C—H bond in aromatic and alkenyl hydrocarbons (Table 1.13). Pentafluorobenzene [18] and trifluoroethene [19] are much more acidic than the corresponding parent hydrocarbons (p Ka = 43 and 44 for benzene and ethene, respectively). 

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