Phosphorus oxychloride → Ethyl 4,6-dichloropicolinate
Reaktionsgleichung
[CH2:1]([O:3][C:4](=[O:13])[C:5]1[N+:6]([O-])=[CH:7][CH:8]=[C:9]([Cl:11])[CH:10]=1)[CH3:2].P(Cl)(Cl)([Cl:16])=O>>[CH2:1]([O:3][C:4](=[O:13])[C:5]1[CH:10]=[C:9]([Cl:11])[CH:8]=[C:7]([Cl:16])[N:6]=1)[CH3:2]Komponenten
3
Reaktionsbedingungen
- Temperatur
- 0 °C
Versuchsvorschrift
4-Chloropicolinic acid ethyl ester N-oxide (1.6 g, 8 mmol) was added to 4 mL of phosphorus oxychloride at 0° C. and stirred at 0° C. for one hour. The solution was then heated at 100° C. for four hours. Excess POCl3 was removed in vacuo, and the residue was dissolved in ethyl acetate, washed with cold sodium bicarbonate solution, and extracted with ethyl acetate. Removal of the solvent gave 4,6-dichloropicolinic acid ethyl ester (compound A) as an off-white solid (1.12 g, 64%). The methyl ester can be made by an analogous procedure.