Reaktion #457933

Reaktionsgleichung

2-Hydroxyacetophenone

potassium hydroxide

potassium hydroxide

glyoxylic acid

glyoxylic acid potassium hydroxide

hydrazine hydrate

sulphuric acid

→

6-(2-hydroxyphenyl)-3(2H)-pyridazinone

Ausbeute 54.0%

Lösungsmittel

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturcooled to 5°
2. 2
   workup.ADDITIONwas added slowly to
3. 3
   Temperaturwith external cooling
4. 4
   Temperaturto maintain the temperature below 25°
5. 5
   SonstigeAn inorganic sediment was removed by filtration
6. 6
   Extraktionthe filtrate was extracted with dichloromethane (3000 ml) and concentrated sulphuric acid (100 ml)
7. 7
   workup.ADDITIONwas added
8. 8
   Temperaturwith external cooling to the aqueous phase
9. 9
   Sonstigeto give a mixture with pH 4.5
10. 10
    SonstigeA solid precipitated out during this process
11. 11
    workup.ADDITIONConcentrated aqueous ammonia (28% w/w) was added
12. 12
    Temperaturwith external cooling until the mixture
13. 13
    workup.DISSOLUTIONThe precipitate dissolved during this addition
14. 14
    Temperaturthe mixture was heated
15. 15
    Temperaturunder reflux for 3 hours
16. 16
    FiltrationThe solid was filtered off
17. 17
    Waschenwashed with water and 2-propanol
18. 18
    Sonstigedried

Vorschrift

A 20% w/v solution of potassium hydroxide cooled to 5° was added slowly to a cooled (5°) 50% aqueous solution of glyoxylic acid (1184 g, 8 mol) until the mixture had pH 9, with external cooling to maintain the temperature below 25°. 2-Hydroxyacetophenone (1089 g, 8 mol) was poured into a solution of potassium hydroxide (783 g) in water (2580 ml), this mixture was added to the glyoxylic acid-potassium hydroxide solution and the resultant mixture was stirred at room temperature for 4 hours. The pH was adjusted to pH 8, with external cooling, by the addition of concentrated sulphuric acid (330 ml). An inorganic sediment was removed by filtration, the filtrate was extracted with dichloromethane (3000 ml) and concentrated sulphuric acid (100 ml) was added with external cooling to the aqueous phase to give a mixture with pH 4.5. A solid precipitated out during this process. Concentrated aqueous ammonia (28% w/w) was added with external cooling until the mixture had pH 8. The precipitate dissolved during this addition. Aqueous hydrazine hydrate (64% w/w, 402.4 g, 8 mol) was added, the mixture was heated under reflux for 3 hours and allowed to cool to room temperature. The solid was filtered off, washed with water and 2-propanol and dried to give 6-(2-hydroxyphenyl)-3(2H)-pyridazinone (811 g, 54%) m.p. 294°.

Quelle