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Since cerotic acid may be obtained from montan wax only after a very tedious and laborious process, and since the cerotic acid of beeswax has been shown to be identical with that prepared from montan wax, beeswax was therefore used for the preparation of cerotic acid in large quantity.
The beeswax employed for the isolation of cerotic acid was New Zealand unbleached wax, which was obtained from a business firm dealing in large quantities of the natural product, and was guaranteed by them to be pure unadulterated New Zealand beeswax.
The beeswax was examined by Hübl's method, which consists in determinations — (1) the free-acid value, (2) the aaponification value, and the determination of the ratio of these two values.
The results are given in milligrams of caustic potash for 1 gram of beeswax. In each determination a blank experiment, using exactly the same quantities of alkali and alcohol, was performed simultaneously with that on the beeswax.
The following are the results of analysis:—
| Sample. | Melting-point. | Free-acid Value. | Ester Value. | Saponification Value. | Ratio. |
|---|---|---|---|---|---|
| I | 63° | 18·62 | 72·34 | 90·96 | 3·88 |
| II | 63° | 18·62 | 73·41 | 92·03 | 3·94 |
Lewkowitsch gives numerous estimations of European beeswax. In unbleached wax, he points out the following variations for normal beeswax:—
| Melting-point. | Acid Value. | Ester Value. | Saponification Value. | Ratio. |
|---|---|---|---|---|
| 63–64° | 19–21 | 72–74 | 91–95 | 3°5–3°78 |
These figures indicate that the beeswax used had rather a low saponification value, thus inferring the existence of much cerotin in the beeswax. This supposition was strengthened by the fact that on potash-lime fusion* of beeswax, and subsequent isolation and crystallization of the acids produced, a product was obtained melting near the temperature required for cerotic acid
Cerotic acid was prepared from this beeswax by Brodie's method—namely, extracting quantities of beeswax with successive volumes of ethyl alcohol until the free-acid value for 20 c.c. of the last extraction had been reduced to 2°90 c.c. N/10 KOH. Four extractions were necessary to do this.
[Footnote] * According to Gmelin, myricin contains varying quantities of cerotin and real myricin.
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The free acid was precipitated by adding alcoholic lead acetate to the boiling solution. The insoluble lead salts were filtered off, and then boiled out repeatedly with alcohol to remove impurities.
The purified lead salts were then decomposed by glacial acetic acid, and the free acid, after washing with water, was extracted with boiling methyl alcohol in which, according to Marie,* melissic acid is insoluble. The solution thus obtained was filtered while hot, and the cerotic acid, which separated on cooling, was then found to melt at 75°5°.
The acid was purified by recrystallization from ethyl alcohol, acetic acid, and motor spirit. An acid was thus obtained melting† at 77°5° (Brodie gives 78° for cerotic acid).
Attempts to improve the process of obtaining cerotic acid by complete saponification of the beeswax with alcoholic potash, followed by the precipitation of the acids with alcoholic calcium-chloride, thus retaining the non-acid substances in solution, were fruitless. It was found that the calcium salts in presence of a saturated solution of high-molecular-weight alcohols were easily soluble, and that the precipitated calcium salts always contained a considerable quantity of organic impurities. Attempts with the lead salts, using the same method, were also unsuccessful.
Cerotic acid has hitherto been stated to crystallize in microscopic needles.‡ Although this is the case when prepared by Brodie's method, yet a careful fractionation of the ester of the acid obtained by the above method gives on hydrolysis a pure acid which crystallizes in pearly plates from acetic acid.
A titration of the cerotic acid purified by fractionation of the ester gave a molecular weight of 392°7, corresponding to the formula§ C26H52O2, thus confirming the formula of Lewkowitsch∥ and Henriques.¶
[Footnote] * Journ. Chem. Soc., 1895, abs. I, 81.
[Footnote] † The melting-point of the purest cerotic acid obtained by the author was 78°. This was obtained by the conversion of the above acid into ester, and then by distillation under reduced pressure.
[Footnote] ‡ Beilstein, vol. 1, Supplement, p. 161.
[Footnote] § 1°5462 grams required 39°37 c.c. N/10 KOH.
[Footnote] ∥ Jahrb. f. Chemie, vol. 7, p. 369.
[Footnote] ¶ Zeit. f. Angew. Chem., 1897, p. 366.