The hydrogen atoms of the Me group in tetrafluoro-4-methylpyridine (I) are much less acidic than those of 4-picoline because of the Iπ effect of the fluorine atoms in positions 3 and 5. Free radical halogenation of the side chain of I occurs less readily than for 4-picoline and the resulting di- and trichloromethyl-tetrafluoropyridines can be hydrolysed to the corresponding aldehyde and acid.