Chlorine → 2,6-Dichloropyridin-3-ol

Temperature

20 °C

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

1. concentrationafterwards concentrated in a rotary evaporator (bath: 50°; 10 torr)
2. additionTo the residue are added 400 ml of water and 100 ml of ether
3. customThe two phases are separated
4. extractionthe aqueous phase is extracted 5 times with 100 ml of ether each time
5. washThe combined ether phases are washed with water
6. customdried
7. customThe solvent is removed in vacuo
8. stirringthe semisolid residue is stirred with 1.6 liters of water
9. temperatureThe suspension is heated
10. customafter a few minutes the solution is decanted from an oily residue
11. customThe solution is purified with active charcoal
12. customthe yellow product, obtained
13. temperatureon cooling
14. customis recrystallised from water

ORD record

ord-f19df750125a4912b7de39ae688d0715

Source dataset

uspto-grants-1978_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04067725