Oleum Chenopodii anthelmintic!. - Amerikanisches Wurmsamenol. - Essence de semen-contra d'Amerique; Essence d'Anserine vermifuge.
Origin. In the neighborhood of Baltimore the oil is distilled from the entire wild or cultivated-) plant of Chenopodium ambrosioides, L. var. anthelminticum, Gray (American worm-seed), family Chenopodiaceae3).
Production. Westminster in Maryland is the centre of this industry. On account of the unstable nature of the ascaridol, the principal constituent of the oil, its distillation is coupled with difficulties. Several years ago the quality of the commercial oil suffered a marked depreciation: the oils became less dense, the solubility in 70 p. c. alcohol decreased, whereas at the same time the ascaridol content diminished. An investigation undertaken by Schimmel & Co.4) revealed the causes of these changes. It was ascertained that when ascaridol is heated with water for long periods, decomposition sets in with the formation of sub-stances that are specifically lighter and at the same time more difficultly soluble in 70 p.c. alcohol. The constants of a normal oil before and after boiling with water were as follows: normal oil: after boiling for two hours with water: d15o 0,9878 0,9632 aD - 4° 28' - 5° 44 soluble in 3 vol. of 70 p.c. alcohol. not soluble in 70 p.c. alcohol.
1) Chem. Ztg. 25 (1901), 1055.
2) Statements concerning the cultivation of this plant may be found under: Cultivation and Collection of Medicinal Plants, The Chemists' and Druggists' Diary 1908, 234.
3) Americ. Journ. Pharm. 22 (1850), 304 and 20 (1854), 503. 4) Report of Schimmel & Co. April 190S, 110.
Taking these changes into consideration, the mode of distillation was changed repeatedly. It was found that a normal oil could be obtained by reducing the length of distillation as much as possible and by using stills of moderate size; that, in order to secure a better separation of oil and water, it is necessary to allow the condenser to run warm, even hot. The aqueous distillate thus obtained contains little oil and is best thrown away. If it is used for the next distillation, the ascaridol contained therein is partly decomposed by heat and hence contributes to the deterioration of the subsequent oil, the density of which it diminishes. Moreover, it is advantageous to use large receivers in order to give the oil as much time as possible to separate from the water.
As becomes evident from the above statement, the yield will vary materially according to the kind of still used and the method of distillation. Under favorable conditions, the seeds yield 0,6 to 1 p.c. of oil, the leaves up to 0,35 p.c.
Properties. The odor of the colorless or yellowish oil is camphor-like, very penetrating and disagreeable. The taste is bitter and burning. The sp. gr. of good, commercial oils lies between 0,965 and 0,990 and above; aD - 4 to - 8°50'. Soluble in 3 to 10 vol. of 70 p.c. alcohol1).
Inferior oils have d15o 0,932) to 0,965 and do not yield a clear solution with 70 p.c. alcohol. At times, however, adulteration with turpentine oil is the cause of the poor solubility and the low specific gravity. Its detection can be brought about by fractional distillation, since turpentine oil will pass over below 170°, whereas pure oils yield no fractions below 170°. If the oil be heated with acetic acid anhydride and sodium acetate, the product yields a comparatively high ester value (about 280). This, however, cannot be regarded as an analytical constant, since radical changes are produced during the acetylation of the oil1).
1) The oils mentioned by Schimmel & Co. in their Report April 1894, 56 (seed oil, d15o 0,900; aD-18°55'; leaf oil, d18° 0,879; aD - 32°55'; both insoluble in 70 p.c. alcohol) appear to have been distilled under the unfavorable circumstances enumerated above, hence cannot be regarded as normal distillates.
2) E. Kremers, Pharm. Review 25 (1907), 155.
Fig. 33. Distillation of American Wormseed oil in Maryland.
Composition. An investigation made in 18542) contributed but little to our knowledge of the composition of the oil. It was not until 1908 when an investigation, undertaken by Schimmel & Co.3), revealed the presence of several known substances in the oil and also the composition of the principal constituent thereof, the ascaridol C10H16O2 dation to acetone with chromic acid (m. p. of dibenzylidene acetone 111 to 112°). At temperatures below 35° the reaction runs smoothly and without decomposition. Under these conditions ascaridol adds the elements of a molecule of water and is converted into a glycol C10H18O3 which, when benzoylated according to Schotten-Baumann, yielded a solid benzoate melting at 136 to 137°. Regenerated from this ester by saponification, this glycol is obtained as a colorless and odorless, sticky oil that boils at 271 to 272° and which upon prolonged standing in vacuum separates crystals that melt at 62,5 to 64°. The glycol has the following constants: d20o1,0981; aD + 0; nD20o 1,4796; mol. refr. 48,63 (computed 48,65). That the substance C10H18O3 contains a second OH group is proved by the formation of a dibenzoate which results when the glycol is heated with benzoic acid anhydride to 150° for two hours. From alcohol the ester crystallizes in needles that melt at 116,5 to 117,5°.
The lowest fractions which begin to boil at 172° consist of p-cymene (p-hydroxyisopropyl benzoic acid; m.p. of p-propenyl-benzoic acid 159 to 160°), with which are admixed small amounts of a terpene, presumably sylvestrene (sylvestrene reaction). In the middle fraction traces of d-camphor were found (m.p. of semicarbazone 236°; of oxime 118°).