2,6-Dichloropyridine → 1-Fluoro-2,6-dichloropyridinium Triflate

Participants

Reaction Conditions

Reaction Steps

A 100 ml (milliliters) 3-necked round bottom flask was equipped with a magnetic stirring bar, a fluorine-helium inlet tube, and a gas outlet tube connected to a granular alumina trap and then to a 5 percent aqueous caustic trap. A 1.0 g (gram) (6.8 mmol (millimole)) sample of 2,6-dichloropyridine, 1.03 g (6.0 mmol) of sodium trifluoromethanesulfonate, and 40 ml of anhydrous acetonitrile were added and the mixture cooled to -40° C. A 1:9 mixture of fluorine and helium then was passed into the mixture with stirring at the rate of 30 ml per minute until 15 mmol of fluorine had been added. The fluorine gas mixture was replaced with nitrogen gas and the mixture was allowed to warm to ambient temperature. The mixture was filtered and the filtrate was concentrated by evaporation under reduced pressure to obtain 0.75 g (40 percent of theory) of the title compound as a yellowish solid. The compound had 19F NMR absorptions (CD3CN, CFCl3 standard) at 31.6 ppm (s) N-F and -78 ppm (s) CF3 in a 1:3 ratio as required by the structure.

Provenance & Evidence