Origin and Production. Up to the close of last century, cardamom oil of commerce was not distilled from the official cardamoms obtained from Elettaria Cardamomum, Maton, but from the long Ceylon cardamoms, a variety of the above-named species which Fluckiger2) has named Elettaria Cardamomum var. B. Formerly this was regarded as a separate species to which the name Elettaria major, Smith, had been given. These cardamoms grow wild in the woods of the southern and more central Provinces of Ceylon, but are also cultivated in the island.
For distillation the fruits are ground and yield from 4 to 6 p. c. of oil. An experimental distillation of the seeds and shells, separately, yielded 4 p.c. of oil for the former, and 0,2 p.c. for the latter.
Properties. The oil of the long cardamoms is light yellow in color, somewhat viscid, has a strong aromatic odor of cardamom and a pleasant, cooling taste. The specific gravity lies between 0,895 and 0,906; aD + 12 to +15°; S. V. 25 to 70. The oil forms a clear solution with 1 to 2 or more vol. of 80 p.c. alcohol; with 70 p. c. alcohol it gives turbid mixtures.
The seed oil referred to above had the following properties: d16o0,908; aD+13°14'; that of the shells d15o 0,908; aD + 9°48'.
1) Pharmaceutical Journ. 63 (1899), 105.
2) Pharmacographia, II. ed., p. 644.
3) Liebig's Annalen 238 (1887), 98.
According to Wallach1) the lowest boiling portions consist of a mixture of hydrocarbons from which a fraction 165 to 167° (d 0,846) could be obtained which, when treated with hydrogen chloride, yielded terpinene dihydrochloride melting at 52°. The terpene yielding this compound was sabinene, since upon oxidation it was converted into sabinic acid, melting at 56 to 57°.
When Weber passed hydrogen chloride into fraction 170 to 178°, there resulted terpinene dihydrochloride, C10H162Hc1, melting at 52°. The terpinene nitrosite, m. p. 155°, was obtained from fraction 178 to 182°.
By treating fraction 205 to 220° with hydrogen chloride, Weber obtained a hydrochloride melting at 52°, and by shaking it with concentrated hydriodic acid, a hydriodide melting at 76°. He, therefore, believed that he had found a-terpineol, the only one known at that time. In spite of repeated attempts he could not obtain dipentene tetrabromide nor the terpinyl phenylurethane. As was shown later by Wallach, cardamom oil does not contain the ordinary a-terpineol but its isomer, the terpinenol-4 (see Vol.1, p. 382). This he identified not only by the derivatives mentioned above but by the dihydrobromide melting at 59°, also by the glycerol C10H17(OH)3 (m. p. 128 to 129°) obtained by oxidation.
During the process of distillation Weber observed the splitting off of formic and acetic acids, which seem to indicate the presence of esters of terpinenol. That the amount of these esters is not inappreciable (8 to 24 p. c.) is indicated by the saponification values. (Comp. Properties.)
From the distillation residue a solid compound separated which, upon recrystallization from alcohol, yielded light laminae with a silvery lustre, melting at 60 to 61°.