Nerolidol, C15H260, has been found in the high-boiling fractions of orange blossom oil.
B. p. 276 to 277°, 128 to 129° (6 mm.); d0,880; aD + 13°32/.1)
While it itself possesses but a faint odor, it has the capacity to fix other perfumes.
B. p. 160° (10 mm.); d18o 0,885; nD 1,488.2) B. p. 149° (4 mm.); d15o 0,894; aD + 0°.3)
Its odor is faint, reminding of that of cedarwood. Upon oxidation it yields the aldehyde farnesal, C13H240, the semi-carbazone of which melts at 133 to 135°.3)
More important than the aliphatic are the cyclic sesquiterpene alcohols. As a rule the amount in which they occur in the oils is smaller than that of the sesquiterpenes; though there are oils, like the East Indian sandalwood oil, that consist almost entirely of sesquiterpene alcohols. Many of them are characterized by a marked capacity to crystallize. This is particularly true of the tertiary compounds. Hence they occasionally separate from the oils in crystalline form upon standing. Formerly such separations were designated as "camphor", hence some of the conventional names are still in use.
For the crystalline sesquiterpene alcohols, the melting point serves as a characteristic constant. Their isolation from the volatile oils seldom affords difficulties since they can be separated by crystallization. In order to isolate the liquid sesquiterpene alcohols, fractional distillation has to be resorted to. Under ordinary pressure they distill at about 300°.
Chemically, a distinction is made between primary, secondary, and tertiary sesquiterpene alcohols. From another point of view they can be classified into dicyclic and tricyclic compounds. In addition, there are compounds of the formulas C15H240 and C15H220 which stand in very close relation to the sesquiterpene alcohols. But very little is known concerning the constitution of these as of the sesquiterpene alcohols. Herewith there follows a compilation of the representatives of this group that have thus far been found in volatile oils.
1) Hesse and Zeitschel, Journ. f. prakt. Chem. II. 66 (1902), 504.
2) Haarmann & Reimer, G. I. P. 149 603; Chem. Zentralbl. 1904, I. 975.
3) v. Soden and Treff, Berl. Berichte 37 (1904), 1095.