Reacción #4203

Ecuación de reacción

2-(hydroxymethyl)-5-(phenylmethoxy)-4H-pyran-4-one

acetone

Jones reagent

→

product

Rendimiento 5.0%

4-Oxo-5-(phenylmethoxy)-4H-pyran-2-carboxylic acid

Rendimiento 5.0%

Disolventes

water

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaThe clear solution was cooled to +5° C. by means of an ice bath
2. 2
   TemperaturaWhile maintaining the temperature at +5° C. to 10° C.
3. 3
   workup.STIRRINGStirring
4. 4
   Temperaturawithout cooling
5. 5
   FiltraciónThe reaction mixture was filtered through a glass frit
6. 6
   Lavadothe dark green residue washed with 500 ml of acetone
7. 7
   OtroThe filtrate was then evaporated until all of the acetone
8. 8
   Otrowas removed
9. 9
   workup.ADDITIONTo the aqueous, partly crystalline product was added 1.2 l of methanol
10. 10
    Temperaturathis mixture was then heated to its boiling point
11. 11
    OtroThe resulting clear dark green solution was placed in an ice bath
12. 12
    Otroto crystallize
13. 13
    FiltraciónThe crystalline product was filtered
14. 14
    Lavadowashed with 500 ml of a cold solvent mixture
15. 15
    Otrofinally dried

Procedimiento

232 g (1 mol) of 2-(hydroxymethyl)-5-(phenylmethoxy)-4H-pyran-4-one was put into a 10 l stirring flask containing 6.6 l of acetone and 400 ml of water. The clear solution was cooled to +5° C. by means of an ice bath. While maintaining the temperature at +5° C. to 10° C., 640 ml of Jones reagent (202 g CrO3, 600 ml water, 174 ml H2SO4) was added dropwise over a period of 1 hour. Stirring was continued for 2 hours without cooling. The reaction mixture was filtered through a glass frit and the dark green residue washed with 500 ml of acetone. The filtrate was then evaporated until all of the acetone was removed. To the aqueous, partly crystalline product was added 1.2 l of methanol, and this mixture was then heated to its boiling point. The resulting clear dark green solution was placed in an ice bath and the product allowed to crystallize. The crystalline product was filtered and washed with 500 ml of a cold solvent mixture consisting of 250 ml of methanol +250 ml of water and finally dried. Yield: 195 g. From the mother liquor, a further 5% of the product could be isolated.

Fuente