Reaktion #65635

Reaktionsgleichung

methanol

6-Hydroxynicotinic acid

methylene bromide

→

methyl 6-bromo-nicotinate

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGfurther stirred for 16 hours
2. 2
   TemperaturThe mixture was cooled to 10° C.
3. 3
   SonstigeThe cooling bath was removed
4. 4
   workup.STIRRINGstirring
5. 5
   workup.ADDITIONA solution of 76 g of K2CO3 in 610 mL of water was added
6. 6
   workup.STIRRINGstirred for a few minutes
7. 7
   SonstigeThe layers were separated
8. 8
   ExtraktionThe aqueous layer was extracted with methylene bromide
9. 9
   FiltrationThe combined organic phase was filtered through celite
10. 10
    Waschenwashed with water
11. 11
    workup.DISSOLUTIONThe residue was dissolved in 200 mL of ethanol on the steam bath
12. 12
    workup.ADDITIONTo this hot solution, 400 mL of water was added
13. 13
    Temperaturthe mixture was cooled in an ice bath
14. 14
    FiltrationThe precipitated solid was filtered
15. 15
    Waschenwashed with 20% ethanol in water
16. 16
    Sonstigeair-dried

Vorschrift

6-Hydroxynicotinic acid (31 g) and methylene bromide (300 mL) were added at 18° C. to 98.9 g of phosphorous pentabromide while stirring with a mechanical stirrer under an argon atmosphere. The mixture was warmed to 70° C. over 2 hours, and further stirred for 16 hours. The mixture was cooled to 10° C. and 300 mL of methanol (CAUTION: EXOTHERMIC) was added. The cooling bath was removed and stirring was continued for 1/2 hour more. A solution of 76 g of K2CO3 in 610 mL of water was added and stirred for a few minutes. The layers were separated. The aqueous layer was extracted with methylene bromide. The combined organic phase was filtered through celite, washed with water and stripped. The residue was dissolved in 200 mL of ethanol on the steam bath. To this hot solution, 400 mL of water was added and the mixture was cooled in an ice bath. The precipitated solid was filtered, washed with 20% ethanol in water and air-dried to give 38.3 g of methyl 6-bromo-nicotinate as a solid.

Quelle