Oleum Juniperi. - Wacholderbeerbl. - Essence de Genievre.
Origin and Production. Juniperus communis, L, the common juniper, is distributed throughout Europe. It occurs more abundantly in the northern portions where it prefers heaths and pine forests. It also occurs in the mountains of central and southern Germany, in the Alps, the Apennines and Pyrenees to an altitude of 1500 m. and more. It also occurs more abundantly in Hungary, between the Danube and the Theiss, more particularly in the Waag valley, the Little Carpathians, the Tatra mountains, the "Forest" Carpathians, also in the East Carpathians (Sieben-biirgen) and in Bosnia. The so-called juniper berries are the berry-like cones which are collected in the second year when they are ripe.
The distillation of juniper oil is conducted hand in hand with the production of juniper extract. After the crushed berries have been distilled with steam, the residue in the still is extracted with hot water. The aqueous extract is evaporated in vacuum to extract consistence and enters the trade as Succus1) or Roob Juniperi, Ger. Wacholderbeersaft. The yield of both oil and extract varies considerably in different years, as does the composition of the extract. In some years it is so rich in sugar that it congeals to a solid mass.
1) Report of Schimmel & Co. April 1889, 44.
2) Ibidem, October 1910, 144.
The average yield of oil is 1 to 1,5 p. c. for the Italian berries, 2 p. c. for the French and Bosnian, 1 to 1,2 p.c. for the Bavarian, and 0,8 p. c. to 1 p. c. for the Hungarian berries. The oil content of the berries from East Prussia, Poland, Thuringia and Franconia is less, viz. 0,6 to 0,9 p. c. A distillation of Swedish berries yielded only 0,5 p. c. of oil, Russian berries even less.
Juniper oil in not inconsiderable quantities enters the market from Trencsin. This Hungarian oil, as experience has shown, is of inferior quality and not normal. It is obtained as a by-product in the distillation of gin (Borowiczka). The annual production of juniper oil in Hungary is estimated at 30,000 kg. by A. Strocker2), an estimate that appears decidedly too high.
The oil of juniper berries is used principally in the production of gin (Wacholderbranntwein, Steinhager, genievre) and liquors, but is also used to a limited extent in medicine, more particularly in veterinary practice.
Properties. Oil of juniper berries is limpid and either colorless or slightly greenish in color. Old oil is viscid, reacts acid and has a more or less rancid odor. The fresh oil has a peculiar odor reminding of turpentine and a balsamic, burning, somewhat bitter taste. According to its origin and method of production, the oil reveals considerable variation as to its physical properties. The specific gravity lies between 0,865 and 0,882 and for normal oil varies mostly between 0,867 and 0,875 3). As a rule the oil is laevogyrate (up to - 11°) rarely, inactive and occasionally dextrogyrate1), nD20o 1,479 to 1,484; A. V. up to 3,0; E. V. 2 to 8; E. V. after acetylation 18 to 23. In alcohol, more particularly in in dilute alcohol, oil of juniper berries is but sparingly soluble. To dissolve 1 part of oil, 5 to 10 parts of 90 p. c. alcohol are required. With some oils, however, a clear solution cannot be effected with 90 p. c. alcohol. Freshly distilled oils yield, as a rule, a clear solution, older ones do not.
1) The extract thus obtained does not correspond to the Succus Juniperi of the German Pharmacopoeia. The method of preparation of the official extract is such that at least a small amount of oil remains in the extract.
2) Pharm. Post 38 (1905), 236.
3) Umney and Bennett record 0,870 to 0,900 as the specific gravity of the English oil. Chemist and Druggist 71 (1907), 171.
So-called extra strong oil of juniper berries, which is obtained either by fractional distillation or by shaking out with alcohol of varying strength, loses its original greater solubility within a short time.
Composition. Fraction 156 to 159° of juniper oil contains a-pinene 3) (m. p. of nitrosochloride 109 to 110°, of nitrolbenzyl-amine 123 to 124°)4), but no B-pinene5). In fraction 161° (d15o 0,8697; aD + 2°32') the presence of camphene6) was ascertained. The /soborneol obtained by hydration according to Bertram and Walbaum, although recrystallized repeatedly from petroleum ether, melted at 205 to 206°; [a]D - 6°28' in a 17,8 p. c. alcoholic solution. A more careful investigation revealed the fact that the product was a mixture of borneol and isoborneol. The amount of isoborneol was ascertained by converting it into the methyl ether and determining the methyl value. The amount of borneol was ascertained by Tschugaeff's nitric acid test1); also by means of Bertram and Walbaum's methyl ether reaction as modified by A.Hesse2).
1) Two oils from Russia deviated +7° 17' and +7°50'; an oil distilled from needles and berries, likewise Russian, deviated +8° 46' (Report of Schimmel & Co., April 1907, 60). The conclusion may be drawn that the first two oils were also partly distillates from needles and that presumably dextrogyration is always attributable to leaf oil. At least the Russian source of the berries does not appear to be the cause of the dextrorotation, for a distillate from Russian berries (yield 0,48 p.c.) had the following properties: d15o 0,8818; aD - 0°32'; nD20° 1,48112; A.V. 1,8; E.V. 5,6; soluble in 6 vols, of 90 p. c. alcohol, the solution being slightly turbid.
2) In connection with individual oils an even higher angle of rotation, up to - 21° 20', has been observed. According to the statement of the purveyor, these oils had been distilled from Bosnian berries. The subsequent distillation of berries from Bosnia yielded a slightly laevogyrate oil (aD - 0°35'). Hence the suspicion that the oils in question had been adulterated was not removed.
3) Wallach, Liebig's Annalen 227 (1885), 288.
4) Report of Schimmel & Co. October 1910, 72.
5) Comp. H. Haesel, Chem. Zentralbl. 1908, II. 1437. 6) Report of Schimmel & Co. October 1910, 72.
Another examination, likewise conducted in the laboratory of Schimmel & Co.3) revealed that a large portion of the oxygenated constituents consists of terpinenol. In order to secure the oxygenated constituents, the oil was repeatedly shaken with 70 p. c. alcohol. From the alcoholic solution the solvent was removed by distillation. Thus an oil was obtained which possessed a pleasant juniper-like odor and the following constants: d15o 0,9300; aD - 3°44'; E. V. 21,8; E. V. after acetylation 136 corresponding to 41,65 p. c. alcohol C10H17 OH. Diluted with xylene, the alcohol content was found to be 56,2 p. c. C10H17OH. When fractionated under 8 mm. pressure, 70 p.c. came over between 86 and 110°, and 30 p.c. between 110 and 155°. Repeated fractionation of the principal fraction resulted in the separation of a portion that consisted essentially of terpinenol-4 and possessed the following properties: b. p. 93 to 95° (8 mm.); 215 to 220° (750 mm.); d15o 0,9400; aD-+- 13°6 When oxidized with dilute permanganate solution while keeping the reaction mixture cool, 1,2,4-trihydroxy terpane, m. p. 114 to 116°, resulted, a glycerol which Wallach4) had obtained from terpinenol-4. This glycerol was further identified by its conversion into car-venone (m. p. of semicarbazone 202°. Comp. vol. I, p. 383).
In addition to terpinenol, but in much smaller amount, oil of juniper berries contains another alcohol with the following properties: b.p. 105 to 110° (8 mm.); 218 to 226° (ordinary pressure); d16o 0,9476; aD - 4° 30'; nD22o1,48248. It combines readily with phthalic acid anhydride5) and was separated from fraction 95 to 130° in the form of the acid phthalic ester. Its odor reminds of geraniol and borneol and it is probable that the substance is not a definite chemical compound but a mixture of several alcohols. Finally the oil contains a small amount of a substance of a particularly characteristic odor which is met with in fraction 12 to 88° (8 mm.).
1) Chem. Ztg. 26 (1902), 1224.
-) Berl. Berichte 39 (1906), 1141.
3) Report of Schimmel & Co. October 1909, 71.
4) Liebig's Annalen 362 (1908), 278.
5) As has been pointed out by H. Haensel the higher boiling fractions contain traces of a primary alcohol C10H18O that can be removed with phthalic acid anhydride (Chem. Zentralbl. 190S, II. 1437).
Cadinene1) is a constituent the presence of which in this oil has been known for some time. It is found in fraction 260 to 275° (m. p. of dihydrochloride 118°).
In the tailings of a juniper berry oil that had stood in a cool place for a long period, a separation was observed. After repeated crystallizations from alcohol, fine needle-shaped crystals melting at 165 to 166° were obtained 2). Similar crystal formations have been observed repeatedly and have been described in the older literature3) as juniper camphor, juniper stearoptene and juniper berry hydrate4).