Org. Synth. 1937, 17, 43
DOI: 10.15227/orgsyn.017.0043
Submitted by William F. Bruce
Checked by Louis F. Fieser and R. P. Jacobsen.
1. Procedure
A solution of 50 g. (0.13 mole) of dihydrocholesterol (Note 1) in 500 cc. of benzene is added slowly with cooling (Note 2) to a solution of 68 g. (0.23 mole) of crystalline sodium dichromate, 50 cc. of glacial acetic acid, and 90 cc. of concentrated sulfuric acid in 300 cc. of water in a 3-l. flask. The mixture is agitated thoroughly in a shaking device or by efficient stirring (Note 3) for six hours at 25–30° (Note 4).
The benzene solution is separated and washed twice with 100 cc. of water, once with 200 cc. of 5 per cent potassium hydroxide, and twice with water. If the solution is not colorless it is clarified with 1 g. of Norite. The benzene is removed by distillation, and the resulting syrup is dissolved in 300 cc. of alcohol by heating. The solution on cooling deposits cholestanone as well-formed needles. The yield of collected, washed, and air-dried material, m.p. 129–130°, is 41.5–42 g. (83–84 per cent of the theoretical amount). The addition of 80 cc. of water to the filtrate gives about 2 g. of material melting at 125–126°.
2. Notes
1. Material melting at 140–141° (p. 191) is satisfactory. The presence of a trace of cholesterol is not objectionable since this is converted into acidic products which are removed in the course of the purification.
2. When the solutions are mixed without cooling the temperature rises to about 60° and the yield is somewhat less.
3. The checkers employed a Hershberg stirrer (p. 117).
4. The agitation may be continued twice as long without appreciable difference in yield. Six hours is regarded as the minimum time for the quantity specified.
3. Discussion
Cholestanone has been prepared by the oxidation of dihydrocholesterol with chromic anhydride in acetic acid solution.1 The yield is sometimes diminished as a result of the partial acetylation of the sterol.

References and Notes
  1. Diels and Abderhalden, Ber. 39, 884 (1906); Willstätter and Mayer, ibid. 41, 2199 (1908); Vavon and Jakubowicz, Bull. soc. chim. (4) 53, 584 (1933).

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

alcohol (64-17-5)

sulfuric acid (7664-93-9)

acetic acid (64-19-7)

Benzene (71-43-2)

Norite (7782-42-5)

potassium hydroxide (1310-58-3)

sodium dichromate (7789-12-0)

chromic anhydride

Cholestanone (566-88-1)

Dihydrocholesterol (80-97-7)

Cholesterol (57-88-5)