Diethyl Ether → 5-Chloro-2,3-difluoropyridine

Participants

Reaction Conditions

Reaction Steps

64.6 g (1.11 mol) of potassium fluoride and 11.25 g (0.074 mol) of caesium fluoride are suspended in 240 ml of sulfolane and the suspension is heated to 140° C. 50 mol of sulfolane are distilled off by decreasing the pressure and then 61.4 g (0.37 mol) of 2,5-dichloro-3-fluoropyridine and 1.45 g (0.0055 mol) of 18-crown-6 in 20 ml of sulfolane are added to the suspension. This reaction mixture is stirred for 35 hours at 140° C. and then taken up in ice water. The product is isolated from the aqueous mixture either by extraction with ether or by steam distillation, affording 48.7 g (88% of theory) of 5-chloro-2,3-difluoropyridine, b.p. 65°-66° C. at 133 mbar.

Provenance & Evidence