Ethanol → Colestolone

Participants

Reaction Conditions

Reaction Steps

A mixture of 120 g (0.238 mol) of 5, 3.0 liters of 95% ethanol, and 350 mL of water in a 5 liter round bottom flask is cooled to 5° C. in an ice bath for 30 minutes. Concentrated H2SO4 (650 mL) is added to this mixture over a period of 10 minutes in 50 mL portions. Any large chunks of suspended material are broken up mechanically. The mixture is heated under reflux for 20-24 hours. The brownish reaction mixture is cooled to 20° C. using an ice bath and then poured into 7 Kg of ice in a 12 liter carboy. The paste-like precipitate is collected on a Buchner funnel using either polypropylene filter cloth (Aldrich) or three layers of Whatman #1 filter paper, which is occasionally scratched to facilitate filtration. The pale-yellow cake is washed three times with 1 liter of cold water and dissolved in 1 liter of hot methanol, to which 1 liter of hexane and 50 mL of hot water are added. The resulting two-phase system is heated on a steam bath until all solid material is dissolved. This mixture is allowed to cool for 2-3 hours to 20° C.; at this point crystals begin to form at the solvent interface. The mixture is then cooled overnight at -15° C. to give a brown upper hexane phase, a lower light yellow aqueous phase, and white crystalline material. The crystals (roughly 90% pure by TLC) are collected by suction filtration and recrystallized again from methanol/hexane/water (2:2:1) as described above.

Provenance & Evidence