Chlorine → 2,6-Dichloropyridin-3-ol

Temperature

20 °C

100 g (0.77 mole) of 2-chloro-3-pyridinol (I) was dissolved in 350 ml of dimethylformamide. 70 ml of chlorine (measured at -80°; 0.93 mole) was introduced in the course of 1.5 hours into the stirred solution at 0°. The reaction mixture was then stirred for 1.5 hours at 20° C. and subsequently concentrated in a rotary evaporator (bath: 50°; 10 torr). 400 ml of water and 100 ml of ether were added to the residue; the two phases were separated and the aqueous phase was extracted 5 times with 100 ml of ether each time. The combined ether phases were washed with water and dried. The solvent was removed in vacuo; the semisolid residue was stirred with 1.6 liters of water, and the resulting suspension was adjusted to pH 3. The suspension was heated to boiling, and after a few minutes the solution was decanted from an oily residue. The solution was purified with active charcoal, and the yellow product obtained on cooling was recrystallised from water; m.p. 136°-138° C.; yield 42 g.

1. concentrationsubsequently concentrated in a rotary evaporator (bath: 50°; 10 torr)
2. addition400 ml of water and 100 ml of ether were added to the residue
3. customthe two phases were separated
4. extractionthe aqueous phase was extracted 5 times with 100 ml of ether each time
5. washThe combined ether phases were washed with water
6. customdried
7. customThe solvent was removed in vacuo
8. stirringthe semisolid residue was stirred with 1.6 liters of water
9. temperatureThe suspension was heated
10. customafter a few minutes the solution was decanted from an oily residue
11. customThe solution was purified with active charcoal
12. customthe yellow product obtained
13. temperatureon cooling
14. customwas recrystallised from water

ORD record

ord-30f7b868d54e43b385871de2902e988d

Source dataset

uspto-grants-1983_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04404020