Reaktion #1954

Reaktionsgleichung

4-Chloro-5-fluoro-2-picoline-N-oxide

potassium carbonate

→

title compound

Ausbeute 142.1%

4-Chloro-5-fluoro-2-picoline

Ausbeute 142.1%

Lösungsmittel

acetic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeequiped with a mechanical stirrer, a condenser
2. 2
   Temperaturthe reaction mixture was carefully heated to 35°-40° C
3. 3
   Sonstigean exothermic reaction
4. 4
   Sonstigeto rise to 120° C.
5. 5
   SonstigeThe flask was transferred to a cold water bath
6. 6
   workup.ADDITIONThe reaction mixture was then poured over ice
7. 7
   workup.DISTILLATIONdistilled
8. 8
   workup.DISTILLATIONThe aqueous distillate collected at 92°-96° C.
9. 9
   Extraktionwas extracted with three portions of methylene chloride
10. 10
    ExtraktionThe combined organic extract
11. 11
    Trocknenwas dried over anhydrous sodium sulfate
12. 12
    Filtrationfiltered
13. 13
    workup.DISTILLATIONdistilled

Vorschrift

4-Chloro-5-fluoro-2-picoline-N-oxide (12.43 g, 76.93 mmol), from Step 7, was dissolved in 52 mL of glacial acetic acid in a 3-necked flask equiped with a mechanical stirrer, a condenser and a thermometer. Iron powder (6.45 g, 115.5 mmol) was added to the solution at ambient temperature and the reaction mixture was carefully heated to 35°-40° C. After 10 min at 30° C., an exothermic reaction took place which caused the reaction temperature to rise to 120° C. and the reaction mixture became a very dark brown-colored solution. The flask was transferred to a cold water bath and the temperature of the solution brought down to ambient. The reaction mixture was then poured over ice. The resultant aqueous mixture was adjusted to pH 9 with potassium carbonate and steam distilled. The aqueous distillate collected at 92°-96° C. was extracted with three portions of methylene chloride. The combined organic extract was dried over anhydrous sodium sulfate, filtered and distilled to afford 15.91 g (71% yield) of the title compound, b.p. 138°-140° C.; MS GC-MS M/Z: 146 (M+H)+ ; 1H NMR (CDCl3) d 2.53 (s, 3H), 7.23 (d, 1H, J=6.0 Hz), 8.37 (s, 1H).

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