Hydrochloric Acid → 2,3,5,6-Tetrachloropyridine

Participants

Reaction Steps

1.7 g (0.027 gram atom) of zinc dust is introduced into a solution, heated to 80° C., of 5.1 g (0.02 mol) of pentachloropyridine in 35 ml of trimethylphosphate, and there is subsequently added dropwise within 1 hour at 80° to 83° C., with vigorous stirring, a solution of 2.84 g (0.055 mol) of ammonium chloride in 10 ml of water. The reaction mixture is then poured into 250 ml of ice water; 5 ml of concentrated hydrochloric acid is added and stirring is continued for 10 minutes. The mixture obtained is afterwards extracted twice with 100 ml of ether each time; the combined ether extracts are washed with 70 ml of water and dried over sodium sulfate. The ether is evaporated off to leave 4.1 g (93.2% of theory) of crude 2,3,5,6-tetrachloropyridine, m.p. 86° to 88° C., which contains, according to gas-chromatographical analysis, 94.1% of 2,3,5,6-tetrachloropyridine, 2.0% of 2,3,5-trichloropyridine, 2.0% of 2,3,6-trichloropyridine and 2.8% of pentachloropyridine.

Provenance & Evidence