Reacción #360851

Ecuación de reacción

HBr

4-(4-chlorophenoxy)anisole

4-methoxyphenol

KOH

1-chloro-4-iodobenzene

→

4-(4-chlorophenoxy)phenol

Disolventes

acetic acid

p-xylene

ethanol

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroThe 4-(4-chlorophenoxy)phenol precurser was prepared
2. 2
   OtroA 1 L 3-necked flask equipped with a mechanical stirrer
3. 3
   Temperaturathe mixture was heated
4. 4
   Temperaturaat reflux for 1 hour
5. 5
   Otrothus removing
6. 6
   Otrothe water of reaction azeotropically
7. 7
   TemperaturaThe mixture was cooled
8. 8
   Temperaturathe mixture was heated
9. 9
   Temperaturaat reflux for 20 hours
10. 10
    workup.ADDITIONof diluting the cooled mixture
11. 11
    Filtraciónwith Et2O (200 mL), filtration through a medium-fritted funnel
12. 12
    Otroconcentration of the filtrate to leave a deep dark oily residue
13. 13
    Temperaturathe mixture was heated
14. 14
    Temperaturaat reflux for 24 hours
15. 15
    Otroof partitioning the mixture between H2O (1.2 L) and CH2Cl2 (0.5 L)
16. 16
    Lavadowashing the organic phase
17. 17
    Concentraciónwith H2O (0.5 L), and concentration
18. 18
    Otroto leave a deep dark oil residue
19. 19
    workup.ADDITIONtreated with activated carbon (Norit; 50 g)
20. 20
    FiltraciónFiltration through celite, and concentration of the filtrate

Procedimiento

The 4-(4-chlorophenoxy)phenol precurser was prepared as follows. A 1 L 3-necked flask equipped with a mechanical stirrer, a Dean-Stark trap carrying a reflux condenser, and a heating mantle, was charged with 4-methoxyphenol (35.9 g, 0.29 mol), 85 percent KOH (19.1 g, 0.29 mol) and p-xylene (350 mL), and the mixture was heated at reflux for 1 hour, thus removing the water of reaction azeotropically. The mixture was cooled, and 1-chloro-4-iodobenzene (69 g, 0.29 mol), copper powder (2.9 g, 46 mmol), and cuprous chloride (2.9 g, 29 mmol) were added and the mixture was heated at reflux for 20 hours. The reaction was monitored periodically by HPLC. Workup consisted of diluting the cooled mixture with Et2O (200 mL), filtration through a medium-fritted funnel, and concentration of the filtrate to leave a deep dark oily residue. This crude material, consisting primarily of 4-(4-chlorophenoxy)anisole, was treated with glacial acetic acid (275 mL) and 48 percent HBr (105 mL), and the mixture was heated at reflux for 24 hours. Workup consisted of partitioning the mixture between H2O (1.2 L) and CH2Cl2 (0.5 L), washing the organic phase with H2O (0.5 L), and concentration to leave a deep dark oil residue. This residue was taken up in ethanol (0.5 L) and treated with activated carbon (Norit; 50 g). Filtration through celite, and concentration of the filtrate gave the crude 4-(4-chlorophenoxy)phenol as a thick, red oil. Further purification of the product was achieved by chromatography on a column packed with flash-grade silica gel (6"×2" i.d.), eluting with CH2Cl2, to give after concentration a pinkish solid, which was subsequently recrystallized from hexane-EtOAc to give 31.4 g (49% yield) of the pure product as off-white prisms m.p. 85-86° C.

Fuente