Perfluoroalkylations and perfluorooxaalkylations .4. Conversion of aryl perfluoroalkanes to aryl perfluoroalkyl ketones

The hydrolysis of benzylic fluorines with hydrobromic acid in glacial acetic acid has been utilized to convert some substituted phenyl perfluoroalkanes to the corresponding ketones. Electron-donating substituents such as -OMe, -OH or -NH2 on the benzene ring, ortho or para to the perfluoroalkyl group, were essential for the conversion to occur under the experimental conditions used. With an electron-donating substituent at the position meta to the perflurooalkyl substituent, only bromination of the aromatic ring was observed. In unsubstituted phenyl perfluoroalkanes or those with electron-withdrawing substituents on the aromatic ring, no hydrolysis of the benzylic fluorines occurred under the same conditions.