Reacción #457933

Ecuación de reacción

2-Hydroxyacetophenone

potassium hydroxide

potassium hydroxide

glyoxylic acid

glyoxylic acid potassium hydroxide

hydrazine hydrate

sulphuric acid

→

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

Rendimiento 54.0%

Disolventes

water

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturacooled to 5°
2. 2
   workup.ADDITIONwas added slowly to
3. 3
   Temperaturawith external cooling
4. 4
   Temperaturato maintain the temperature below 25°
5. 5
   OtroAn inorganic sediment was removed by filtration
6. 6
   Extracciónthe filtrate was extracted with dichloromethane (3000 ml) and concentrated sulphuric acid (100 ml)
7. 7
   workup.ADDITIONwas added
8. 8
   Temperaturawith external cooling to the aqueous phase
9. 9
   Otroto give a mixture with pH 4.5
10. 10
    OtroA solid precipitated out during this process
11. 11
    workup.ADDITIONConcentrated aqueous ammonia (28% w/w) was added
12. 12
    Temperaturawith external cooling until the mixture
13. 13
    workup.DISSOLUTIONThe precipitate dissolved during this addition
14. 14
    Temperaturathe mixture was heated
15. 15
    Temperaturaunder reflux for 3 hours
16. 16
    FiltraciónThe solid was filtered off
17. 17
    Lavadowashed with water and 2-propanol
18. 18
    Otrodried

Procedimiento

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°.

Fuente