Fenchyl alcohol, to which Semmler has assigned the above formula, has thus far been found but once in a volatile oil,8) namely in the oil obtained by steam distillation from the stumps of the yellow pine or Pinus palustris several years after the timber had been cut. Artificially it is obtained by the reduction of fenchone. According to Barbier and Grignard4) fenchyl alcohol results together with other alcohols when French turpentine oil is hydrated. These investigators assume that it is formed from the ,B-pinene present, an assumption that has not yet been proven.
1) Berl. Berichte 25 (1892), 3344.
2) Liebig's Annalen 272 (1893), 109.
3) Report of Schimmel & Co. April 1910, 107.
4) Bull. Soc. chim. IV. 5 (1909), 512, 519.
Fenchyl alcohol obtained by reduction of fenchone is optically active in an opposite direction from that of the ketone.
Wallach records the following properties:
B. p. 201°; d50o0,933; [a]D - 10,35o;1) m. p. 45°.2)
Bertram and Helle3) found:
M. p. 45°; b. p. 201 to 202°; [a]D - 10,9°.
The i-fenchyl alcohol isolated from yellow pine oil possessed the following constants:
M. p. 33 to 35°; b. p. 202 to 203°; [a]D + 0°.
An inactive product obtained by Wallach by mixing d- and /-fenchyl alcohol had the same melting point.
When oxidized, fenchyl alcohol yields fenchone, when dehydrated, fenchene.
For the identification of active fenchyl alcohol, the acid fenchyl-phthalic acid ester, which melts at 145 to 145,5°, and the phenyl-urethane, which melts at 82 to 82,5°, are used. Of the inactive derivatives the acid phthalic ester melts lower (at 143°) and the phenyl urethane higher (at about 88°) than the corresponding active derivatives. The oxidation to fenchone and the characteristic derivatives of this ketone may be used for identifying fenchyl alcohol.
Corresponding to the aliphatic sesquiterpenes there are oxygenated derivatives found in volatile oils which, judging from their properties, must be regarded as derivatives of this class of sesquiterpenes. While they have been observed but rarely and though but little is known as to their constitution, it is to be expected that a more thorough investigation will reveal their more frequent occurrence.
1) Liebig's Annalen 263 (1891), 145.
2) Ibidem 284 (1895), 331.
3) Journ. f. prakt. Chem. II. 61 (1900), 295.