Fractionation Studies on Provitamin

In previous studies we found that a commercial cholesterol preparation obtained from the Wilson Laboratories had a high concentration of antirachitic provitamin. In the present studies we undertook to concentrate the provitamin fraction in cholesterol and to study its properties. 175 gm. of the commercial product, Cholesterol W, were dissolved in 1200 cc. of 10 per cent solution of sodium hydroxide in alcohol and boiled under a reflux condenser for 1 hour. After chilling the solution to 38”, the mass of crystals was drained free from liquid by suction and washed with cold alcohol. The alkaline alcoholic filtrate was evaporated to dryness and extracted with boiling acetone. After evaporation of the acetone, the brown, semicrystalline mass was taken up in ether, the ether solution washed repeatedly with water and finally evaporated to dryness. The residue was still light brown and somewhat waxy in consistency. This was Fraction lc. The large mass of crystals separated from the alkaline alcohol above was dissolved in ether and this ether solution washed by shaking with water until the wash water was only faintly alkaline. A deep emulsion layer ‘containing cholesterol always formed between the water and ether layers. This was separated, the cholesterol filtered off, dried, and kept as Fraction II. 157 gm. of cholesterol obtained from the original ether solution were recrystallized twice from acetone. 113 gm. were recovered. This was Cholesterol B. 50 gm. of Cholesterol B were recrystallized from acetone three additional times with a final recovery of