Fluorinations with complex metal fluorides. Part 7. Fluorinations of the methyl pyridines with caesium tetrafluorocobaltate

4-Methylpyridine passed over caesium tetrafluorocobaltate at 330 – 340° gave tridecafluoro(1,3-dimethylpyrrolidine) (1) and its 3-difluoromethyl analogue (2), together with a range of polyfluoro-4-picolines (4 – 10) with ?CF₃, ?CHF₂ or ?CH₂F groups in the 4-position. 3-Methylpyridine similarly gave 1 and its 1,2-isomer (11) together with several polyfluoro-3-picolines (14 – 18). 2-Methylpyridine at 270° gave tridecafluoro(1-ethylpyrrolidine) (13), a trace of 11 and 2-trifluoromethyl- (22), 2-difluoromethyl- (23) and 2-fluoromethyl-tetrafluoropyridine (24); there were also products arising by loss of methyl. Other unidentified fluoroalkylpyridines besides those isolated were present in each case.