While investigating the highest boiling fractions of celery seed oil, Ciamician and Silber3) found a sesquiterpene which, however, they did not further characterize. When this sesquiterpene was later on examined in the laboratory of Schim-mel & Co. it was ascertained that it was not identical with any of the known sesquiterpenes and was named selinene.

1) Deussen, Liebig's Annalen 356 (1907), 1; 359 (1908), 245.

2) Wallach, Liebig's Annalen 271 (1892), 288.

3) Berl. Berichte 30 (1897), 492, 501.

Selinene constitutes about 20°/o of celery seed oil and can be obtained from fraction 265 to 273°. After repeated fractionation over sodium, it possessed the following properties:

B. p. 120 to 121° (6 mm.); d17.5o 0,9197; aD+35°11'; nD21o 1,49863.

Regenerated from its dichlorhydrate, it possessed the following properties:

B. p. 268 to 272°; d15o 0,9232; d20o0,9196; aD+49°30'; nD20O 1,50483; mol. refr. 65,82, corresponding to C16H24 /= 66,15.

The dichlorhydrate referred to is obtained by passing gaseous hydrogen chloride into an etheral solution of the sesquiterpene. It crystallizes in fine needles, which when pure melt at 72 to 74°; [a]D + 18° (in 4,07°/o chloroform solution). Selinene dichlorhydrate differs from the caryophyllene dichlorhydrate though both have simular melting points. Upon splitting off hydrogen chloride, selinene is regenerated, whereas caryophyllene dichlorhydrate, when submitted to like treatment, yields a new hydrocarbon.

With nitrosylchloride or oxides of nitrogen, no solid derivatives could be obtained.

Judging from its molecular refraction, selinene belongs to the bicyclic group of sesquiterpenes.