Reaktion #75910

Reaktionsgleichung

p-Fluorobenzaldehyde

propionic anhydride

sodium propionate

→

p-Fluoro-α-methylcinnamic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigehad been flushed with nitrogen
2. 2
   Temperaturthe flask is cooled to 100° C.
3. 3
   workup.ADDITIONpoured into 8 l of water
4. 4
   workup.DISSOLUTIONThe precipitate is dissolved
5. 5
   workup.ADDITIONby adding potassium hydroxide (302 g) in 2 l of water
6. 6
   ExtraktionThe aqueous solution is extracted with ether
7. 7
   Waschenthe ether extracts are washed with potassium hydroxide solution
8. 8
   FiltrationThe combined aqueous layers are filtered
9. 9
   Filtrationare filtered
10. 10
    WaschenThe collected solid, p-fluoro-α-methylcinnamic acid, is washed with water
11. 11
    Sonstigeis dried
12. 12
    Sonstigeas obtained

Vorschrift

p-Fluorobenzaldehyde (200 g, 1.61 mol), propionic anhydride (3.5 g, 2.42 mol) and sodium propionate (155 g, 1.61 mol) are mixed in a one liter three-necked flask which had been flushed with nitrogen. The flask is heated gradually in an oil-bath to 140° C. After 20 hours, the flask is cooled to 100° C. and poured into 8 l of water. The precipitate is dissolved by adding potassium hydroxide (302 g) in 2 l of water. The aqueous solution is extracted with ether, and the ether extracts are washed with potassium hydroxide solution. The combined aqueous layers are filtered, are acidified with concentrated HCl, and are filtered. The collected solid, p-fluoro-α-methylcinnamic acid, is washed with water, and is dried and used as obtained.

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