Reaction #56384

Reaction equation

beclomethasone dipropionate

charcoal

→

beclomethasone dipropionate n-hexane

Solvents

methylene chloride

Conditions

Workup

1. 1
   Temperatureat reflux
2. 2
   workup.ADDITIONTreat with 15 g
3. 3
   Otherfor 15 minutes
4. 4
   Temperatureat reflux
5. 5
   Filtrationfilter while hot
6. 6
   ConcentrationConcentrate the filtered solution to a volume of 900 ml
7. 7
   Temperaturewhile maintaining
8. 8
   Temperaturereflux
9. 9
   workup.ADDITIONadd slowly 900 ml of n-hexane
10. 10
    FiltrationFilter the resultant precipitate
11. 11
    Washwash with n-hexane
12. 12
    OtherDry the precipitate in air at <50° C. until constant weight

Procedure

Dissolve 300 g of beclomethasone dipropionate in 2 liters of methylene chloride at reflux. Treat with 15 g activated charcoal for 15 minutes at reflux and filter while hot. Concentrate the filtered solution to a volume of 900 ml and while maintaining reflux add slowly 900 ml of n-hexane. Cool to 0-10° C. Filter the resultant precipitate and wash with n-hexane. Dry the precipitate in air at <50° C. until constant weight to afford beclomethasone dipropionate-n-hexane solvate having an [α]/D25 =+85.5±2° in dioxane and an ε1% (extinction coefficient) in 1% solution=275±10 at 239 mu. Analysis by gas chromatography shows an n-hexane content of 4.6%. The beclomethasone dipropionate content (determined by ultraviolet assay) is 94.5%.

Source