A solution of 59.6 g. (0.1 mole) of 3,12-diacetoxy-bisnor-cholanyldiphenylethylene (p. 237) in 60 ml. of chloroform is prepared by warming and poured into a 1-l. round-bottomed flask containing 300 ml. of glacial acetic acid at about 40°. The flask is provided with a stirrer, a thermometer dipping below the surface of the solution, and a dropping funnel, and is surrounded by a water bath through which cold water can be circulated. A solution of 37 g. of chromium trioxide in 30 ml. of water and 200 ml. of acetic acid is added from the dropping funnel at such a rate that the temperature is kept at about 50°; the mixture is stirred and cooled. This operation should require about 10 minutes. When the temperature starts to drop, the water bath is warmed and the temperature is maintained at about 50° for an additional 20 minutes. The solution is then cooled, and the excess chromic acid is destroyed by adding carefully about 30 ml. of methanol, the temperature being kept below 50° (Note 1).

The reaction mixture is concentrated by distillation under reduced pressure. At first the solvent may be distilled rapidly, but, after the mixture becomes syrupy, the distillation should be carried out below 30° until the residue is almost solid. At a pressure of 10 mm. the concentration requires about 2 hours. The residue is diluted with 500 ml. of cold water, which should be added in several portions with thorough shaking to break up all the lumps. The product is collected on a filter and washed with dilute hydrochloric acid until the filtrate comes through colorless.

The solid crystalline cake (Note 2) is dissolved in about 400 ml. of ether and extracted with 500 ml. of 2.5% potassium hydroxide solution (Note 3). The alkaline solution is immediately acidified with 200 ml. of 10% hydrochloric acid, and the crude 3,12-diacetoxy-nor-cholanic acid (Note 4) is collected on a filter.

The crude diacetate is hydrolyzed by dissolving it in 350 ml. of 10% aqueous potassium hydroxide and refluxing the solution for 2 hours. The alkaline solution is diluted to about 700 ml., cooled, and filtered. The filtrate is poured into 300 ml. of 10% hydrochloric acid, and the nor-desoxycholic acid is separated by filtration and dried. The crude product is dissolved in about 600 ml. of acetone and filtered, while hot, to remove small amounts of salt. On cooling, 25–30 g. (57–68%) of white crystals which melt at 209–211° is obtained in two crops (Note 5). This material contains 1 molecule of acetone of crystallization. The fully purified substance softens at about 160° (loss of acetone) and melts at 213.5–214.5°.