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

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.

1. additionis subsequently added dropwise within 1 hour at 80° to 83° C., with vigorous stirring
2. customThe mixture obtained
3. extractionis afterwards extracted twice with 100 ml of ether each time
4. washthe combined ether extracts are washed with 70 ml of water
5. dry with materialdried over sodium sulfate
6. customThe ether is evaporated off

ORD record

ord-2e1301ed09604ca492893cf268b68d5f

Source dataset

uspto-grants-1981_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04259495