Oleum foliorum Betle. - Betelol. - Essence de Betel.
Origin. The custom of betel chewing, which is common throughout India, the entire Malay archipelago, also in Southern China, consists in chewing a betel leaf (Sirih) from Piper Betle, L. (Chavica Betle, Miq.) together with lime, some gambier (from Uncaria Gambir, Roxb.), and a piece of areca or pinang nut (from Areca Catechu, L.)1). The betel leaves owe their spicy, burning taste to a volatile oil which has been distilled repeatedly, but which has found no practical application thus far2).
Properties. Betel oil is a light yellow to dark brown liquid of an aromatic, somewhat creosote-like odor that also reminds one of tea, and has a sharp, burning taste. The specific gravity varies between 0,958 and 1,057, the oils from fresh leaves being less dense and lighter in color than those obtained from dry material.
The optical rotation has been determined for only six oils, four of which were laevogyrate (aD up to - 1°55') and two dextrogyrate (aD up to +2° 53').
The alcoholic solution of betel oil yields a green to blue-green color with ferric chloride.
Origin, yield, physical properties and composition of the betel oils examined thus far are specified in the following table (p. 310).
Composition. Of the two phenols which have so far been found in betel oil, viz., betelphenol and chavicol, the first only is contained in all oils and may therefore be regarded as the characteristic constituent of the oil. Chavicol, which has been found only in the Java oil, does not occur in Manila or Siam betel oil.
Betelphenol3) (Chavibetol) C10H12O, (comp. vol. I, p. 480) is isomeric with eugenol and contains the same side-chains, but in different position.
1) The details of the practice of betel chewing, also the several ingredients of the "betel box", which well-nigh every Malay family possesses, have been described by A. Tschirch in his ,,Indische Heil- und Nutzpflanzen" (Berlin 1892) p. 138.
2) As to the cultivation of the betel plant see H. Gilbert, Journ. d'Agri-culture tropicale 11 (1911), 227; Report of Schimmel & Co. October 1911, 22.
3) Bertram and Gildemeister, loc. cit.
Origin, material distilled and yield
Siam1). Leaves dried on hot plates. Yield 0,6 °/o.
1,024 at 15°
Siaml). Leaves dried by exposure to sun. Yield 0,9%.
1,020 at 15°
Manila2). Fresh leaves. Yield 0,127 °/o.
1,044 at 15°
Java3). Fresh leaves.
0,959 at 27°
Chavicol, betelphenol, sesquiterpene.
Java*). (Probably fresh leaves)
0,958 at 15°
Bombay5). Fresh leaves.
0,9404 at 28°
1,0566 at 15°
55°/o phenols; sol. in 3 vol. 70p.c. ale.
1,0551 at 15°, nd20° 1,52146
52°/o phenols; sol. in 1,7 vol. 70 p.c. alcohol.
1,0325 at 15°
1) J. Bertram and E. Gildemeister, Journ. f. prakt. Chem. II. 39 (1889), 349. - Schimmel's Bericht April 1888, 8; April 1889, 6; Report of Schimmel & Co. October 1889, 6; April 1890, 6; October 1891, 8.
2) Report of Schimmel & Co. April 1891, 14 and October 1891, 8.
3) J. F. Eykman, Berl. Berichte 22 (1889), 2736.
4) Report of Schimmel & Co., October 1893, 49.
5) D. S. Kemp, Pharmaceutical Journ. III. 20 (1890), 749. ") Report of Schimmel & Co. October 1907, 16.
It is a strongly refractive liquid of peculiar, not unpleasant, persistent betel odor, which differs materially from that of the closely related eugenol. When pure, betelphenol boils without appreciable decomposition at 254 to 255° (131 to 132° under 12 to 13 mm., 107 to 109° under 4 mm. pressure); d15o 1,067 to 1,069; nD20o 1,54134. In alcoholic, but not in aqueous, solution it yields an intensely blue-green color with ferric chloride.
For the identification of betelphenol the preparation of its benzoyl compound, crystallizing in laminae and melting at 49 to 50°, is resorted to. Acetylbetelphenol boils at 275 to 277°, melts at - 5°, and upon oxidation with permanganate is oxidized to acetisovanillic acid, which melts at 207°.
Chavicol1), also a phenol, the presence of which in the Java betel oil has been definitely established by Eykman, is p-hydroxyallyl benzene (comp. Vol. I, p. 475). It boils at 237°; sp.gr. 1,041 at 13°. Its aqueous solution is colored intensely blue by ferric chloride, the alcoholic solution becomes but faintly blue.
An oil, distilled in Java by de Vrij and examined in the laboratory Of Schimmel & Co.2), was found to contain a second phenol which is probably identical with chavicol. Its benzoyl compound crystallized in long needles, and melted at 72 to 73°.
Another oil, distilled in Manila from fresh leaves and examined in the laboratory of Schimmel & Co.3), contained no phenol other than betelphenol. The phenol separated from the sodium hydroxide solution, boiled uniformly between 128 and 129° (11 mm.) and yielded exclusively the benzoyl derivative of betelphenol crystallizing in laminae and melting at 50°.
An additional constituent is cadinene C15tH24 By means of its dihydrochloride melting at 118°, it was identified in the Siam betel oil4) only.
Java oils, distilled from fresh leaves, contain an appreciable amount of lower boiling constituents, the composition of which has not yet been ascertained. From fraction 173 to 190 l) Eykman, Ioc. cit.
2) Report of Schimmel & Co. April 1890, 7.
3) Ibidem October 1891, 8.
*) Bertram and Gildemeister, Ioc. cit.
Eykmanl) failed to isolate a pure terpene of constant boiling point and to identify it with one of the known terpenes. Presumably several terpenes are present, but no pinene. Fraction 173 to 175 (d16o0,848; aD - 5° 20') yielded neither a solid bromide nor a crystalline chlorhydrate. Fraction 190 to 220° contains a substance with mint-like odor (menthone or menthol?).
An oil distilled from dried Siam leaves was totally devoid of these lower fractions, only a few drops passing over below 200°. On the one hand, the absence of terpenes in this oil may be regarded as being explained satisfactorily by the character of the material from which it was distilled. On the other hand, the cause of the absence of chavicol in Siam and Manila oils, and its occurrence in Java oils may possibly be accounted for by the varying conditions of climate and soil of the countries of origin.
A new phenol which had not been found so far in any oil, was observed by Schimmel & Co.2) in the Java betel oil marked IX on p. 310. During fractionation of the phenols, separated by means of their sodium compounds, a substance distilled over between 137 to 139° (4 mm.), which congealed when cooled and consisted of allylpyrocatechol (elementary analysis; m.p. 48 to 49°). For its properties and derivatives see Vol. I, p. 480.
The same oil also contained a laevogyrate terpene, which boiled between 155 and 162°, but which was not further characterized, cineol (m.p. of iodol compound 112°), eugenolmethylether (m.p. of veratric acid 179°), and caryophyllene (m.p. of nitrosate 158°). A fraction with the properties of cadinene was not observed in this oil.