Bisabolene was first found by Tucholka2) in Bisabol myrrh oil. The same name was given later to sesquiterpenes which had originally been known by other designations, but which had been found to be identical with it.

In addition to its occurrence in Bisabol myrrh oil, it has been found in Siberian pine-needle oil, in the oil of Piper Volkensii, in camphor oil and in the oils of limette, lemon, bergamot and opopanax.

For the hydrocarbon fractionated from lemon oil, Gildemeister and Muller3) ascertained the following constants:

B. p. 110 to 112° (4 mm.); d15o0,8813; aD - 41°31'; nD20o 1,49015. For the inactive sesquiterpene regenerated from the tri-chlorhydrate by means of sodium acetate and glacial acetic acid, they ascertained the following constants:

B. p. 261 to 262° (751 mm.); aD + 0°; d15o0,8759; nD20o1,4901.

With hydrogen chloride, bisabolene yields a trichlorhydrate, C15H243HC1, which melts at 79 to 80° and which, according to Tucholka is optically active ([a]D(+ or - ?) 35°17' in chloroform solution), but which, according to Gildemeister and Miiller, is inactive. Neither a solid nitrosochloride, nor a nitrosite, nor a nitrosate could be obtained from bisabolene. It adds 6 atoms of bromine. Whether the hexabromide, obtained by Schmidt and Weilinger1) from the oil of Piper Volkensii, and melting at 154° is a derivative of bisabolene remains to be proven.

1) Report of Schimmel & Co. October 1899, 23.

2) Arch. der Pharm. 235 (1897), 292.

3) Wallach-Festschrift, Gottingen 1909, p. 448; Report of Schimmel $ Co. October 1909, 64.

For the characterization of bisabolene, the trichlorhydrate, obtained by passing gaseous hydrogen chloride into an ethereal solution of the sesquiterpene, is especially suited. Upon evaporation of the ether, it separates in handsome crystals, which can be further purified by recrystallization from alcohol.