Reaktion #2665

Reaktionsgleichung

5-chloro vanillin

boron tribromide

→

expected product

Ausbeute 77.3%

3-chloro-4,5-dihydroxy benzaldehyde

Ausbeute 77.3%

Lösungsmittel

dichloromethane

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITthe mixture stood for one night at ambient temperature
2. 2
   EinengenIt was concentrated
3. 3
   Temperaturcooled again to 0° C.
4. 4
   SonstigeThe crystallized product was separated
5. 5
   Waschenwashed with water
6. 6
   Sonstigedried
7. 7
   Sonstigecrystallized from an isopropanol- water mixture (1-2 by volume)

Vorschrift

37.2 g of commercial 5-chloro vanillin and 800 ml of dichloromethane were mixed together under nitrogen and cooled to 0° C. 300 ml of a molar solution of boron tribromide in dichloromethane are added and the mixture stood for one night at ambient temperature. It was concentrated, cooled again to 0° C. and acidified. The crystallized product was separated, washed with water, dried and crystallized from an isopropanol- water mixture (1-2 by volume) to obtain 26.6 g of the expected product melting at >260° C.

Quelle