C₁₈H₃₄O₂ + S = C₁₈H₃₄S.O₂.
C₁₈H₃₄S.O₂ + NaOH = C₁₈H₃₄SO₂Na + H₂O.
366. Detection of Cholesterin and Phytosterin in Glycerids.—Cholesterin is often found in animal glycerids and a corresponding body, phytosterin, is sometimes found in oils of a vegetable origin.[333] When one of these two bodies is present it may be useful in distinguishing between animal and vegetable glycerids. They are detected as follows: Fifty grams of the glycerids in each case are saponified with alcoholic alkali, preferably potash, in order to have a soft soap. After saponification is complete, the alcohol is evaporated and the residual soap dissolved in two liters of water. The mixture is shaken with ether and the ethereal solution evaporated to a small bulk. The residue, which may contain a small quantity of unsaponified fat, is again treated with alcoholic potash and subjected a second time to the action of ether, as indicated above, with the addition of a few drops of water and of alcohol if the emulsion separate slowly. The ethereal extract finally secured is allowed to evaporate slowly and the cholesterin (phytosterin) is obtained in a crystalline form. The melting point of the cholesterin crystals is 146° and that of the phytosterin 132°.
Cholesterin crystallizes in thin rhombic tables while phytosterin separates in stellar aggregates or in bundles of long needles.
When dissolved in chloroform the two products show different color reactions with sulfuric acid, cholesterin giving a cherry and phytosterin a blue-red tint. In a mixture of animal and vegetable glycerids the two products are obtained together and the melting point of the mixture may afford some idea of the relative quantities of each present. It is evident, however, that no reliable judgment can be formed from these data of the relative proportions of the two kinds of glycerids in the original sample.
367. Cholesterin and Paraffin in Ether Extracts.—In ethereal extracts of some bodies, especially of flowers of the chrysanthemum, paraffin is found combined with cholesterin. The two bodies may be separated as follows:[334]
The ether extract is treated with aqueous then with alcoholic potash several times; the residue soluble in ether is a solid body melting at from 70° to 100°.
If the ethereal solution be cooled in a mixture of snow and salt, a crystalline deposit is formed. This substance, purified by repeated precipitations, is obtained colorless in fine crystalline scales melting at 64°. It is very soluble in ether, benzene and chloroform, almost insoluble in cold alcohol, and somewhat soluble in hot.
Its percentage composition is:
| Per cent. | |
| Carbon | 85.00 |
| Hydrogen | 14.95 |
It is therefore a paraffin.