Oleum Buccu foliorum. - Buccublatterol. - Essence de Feuilles de Bucco.
Origin. The genus Barosma (family Rutaceae) is represented in southern Africa by about 15 species2). The leaves known as bucco, buccu, buku or buchu, are used by the natives against insects and for medicinal purposes3).
In commerce a distinction is made between round and long buchu leaves. The former are the leaves of Barosma betulina, (Bartl.) and B. crenulata, (L.) Hook., the latter those of B. ser-ratifolia, Willd. The latter are occasionally adulterated with the leaves of Empleurum serrulatum, Ait.4) (see p. 644). The leaves of the other Barosma species are designated false buchu leaves. Moreover, foreign admixtures are not uncommon. Thus Holmes5) observed the admixture of the leaves of a species of Psoralea (Leguminosae), presumably P. obliqua, E. Mey. In a variety of samples.of buchu leaves W. Mansfield0) found up to 17 p.c. of the leaves of Diosma fragrans which are known as "clip-buchu".
Upon distillation the leaves of B. betulina yield 1,3 to 2,5 p.c. of oil, those of B. crenulata 1,7 and those of B. serratifolia 0,8 to 1 p.c.
1) Umney, Imperial Institute Journal 2 (1896), 302. - Pharmaceutical Journ. 57 (1896), 199.
2) Engler, Die naturlichen Pflanzenfamilien, Vol. Ill, Section IV, p. 149.
3) Chemist and Druggist 76 (1910), 358; 77 (1910), 17 and 622.
4) Fluckiger and Hanbury, Pharmacographia. Second Edit. 1879, p. 110 5) Pharmaceutical journ. 85 (1910), 69, 464. See also ibidem 73(1904), 893.
°) Chemist and Druggist 81 (1912), 546.
Properties. Buchu leaf oil is dark in color and has a strong, sweetish, mint-like unpleasant odor and a bitter, cooling taste.
The oil of B. betulina separates crystals of diosphenol even at ordinary temperature. The liquid portion separated from these crystals has the following properties: d18.o0,937 to 0,97; aD - 14 to - -48°'); nD20o 1,474 to 1,478; soluble in 3 to 5 vol. of 70 p. c. alcohol, but sometimes requiring 8 to 10 vol.; diosphenol content, determined by repeated shaking with 5 p.c. sodium hydroxide solution, 17 to 30 p.c.
An oil distilled from B. crenulata2) had the following properties: d16o0,9364; nD - 15°22'; nD20o1,48005; soluble in 2,5 vol. or more of 70 p. c. alcohol with the separation of paraffin. The original oil was colored green by copper. When this was removed the oil was brownish yellow. The odor was mint-like. The diosphenol content was minimal. When exposed to the temperature of a freezing mixture paraffin crystallized out.
But few observations are available concerning' the oil of B. serratifolia. d15o0,918 to 0,961; aD - 12 to -36°. The diosphenol content is so small that no crystals separate upon cooling.
For the purpose of removing the buchu camphor or diosphenol a single shaking with 5 p. c. sodium hydroxide solution does not suffice. In an experiment 15 p.c. were removed by the first shaking and 5 p. c. by the second. Upon the addition of acid to the alkaline phenol solution hydrogen sulphide is given off.
Composition. The separation of a crystalline substance from buchu leaf oil from B. betulina was first observed by Fluckiger3). This diosphenol or buchu camphor was first examined by him, later by P. Spica4), Y. Shimoyama5), N. Bialobrzeski6), J. Kon-dakow7) and N. Bachtschiew8). However, its constitution as cyclic reduced ketophenol was first interpreted by Semmler and Mc. Kenzie1) and proved by synthesis. The melting point of the diosphenol, after repeated recrystallization, was found to be 83 to 84°, the boiling point 109 to 110° (10 mm.). It is optically inactive, gradually soluble in caustic alkalis, reduces other substances while it itself is being oxidized. Alcoholic magenta solution, decolorized by sulphurous acid, is colored a rose red. Constitutional formula, synthesis, derivatives and degradation products of diosphenol are described in vol. I, p. 493.
1) Kondakow and Bachtschiew, Journ. f. prakt. Chem. II. 63 (1901), 50.
2) Report of Schimmel & Co. October 1911, 23.
3) Pharmaceutical Journ. III. 11 (1880), 174 and 219.
*) Gazz. chim. ital. 15 (1885), 195; Jahresber. d. Chem. 1885, 1821. 5) Arch, der Pharm. 226 (1888), 403. a) Pharm. Zeitschr. f. Russl. 35 (1896), 417, 433, 449. 7) Journ. f. prakt. Chem. II. 54 (1896), 433; Chem. Ztg. 30 (1906), 1090, 1100; 31 (1907), 90.
8) Journ. f. prakt. Chem. II. 63 (1901), 49.
Diosphenol occurs in the oil partly as such, partly as the ester of an acid melting at 94°.
Of terpenes buchu leaf oil contains d-limonene2) (m. p. of tetrabromide l04°) and a little dipentene (m.p. of tetrabromide 119°).
The constituent boiling above 200° was already observed by Fluckiger and was shown by Bialobrzeski to be a ketone. According to Kondakow2) it is identical with /-menthone. The fraction in question had the following properties: b. p. 86° (10 mm.); aD--51°. The menthone yields a liquid oxime, a hydrazone that melts at 80° and two semicarbazones melting at 180 and 123° respectively. From the former, when hydrolyzed with sulphuric acid, a strongly inverted ketone results: b. p. 85,5 to 86° (10 mm.); d19,5o 0,897; [a]D - 22,3°; nD 1,45169; mol.-refr. 46,28. According to Kondakow the oil of B. serratifolia contains more ketone than does the oil of B. betulina.