Dihydrocarveol, C10H18O, has only recently been found in caraway oil.1) Artificially prepared it has been known for a longer period. Thus it has been prepared from carvone by reduction with sodium and alcohol; also by the reduction of carv-oxime to carvylamine which, upon treatment with nitrous acid, yields dihydrocarveol.
Dihydrocarveol is a liquid which possesses the following properties:
B. p. 224°; d22o 0,935; nD 1,48506 (for dihydrocarveol from dihydrocarvylamine).2)
B. p. 112° (14 mm.), 224 to 225° (under ord. pressure); d20o 0,927; nD 1,48168 (for dihydrocarveol from carvone).3)
In the laboratory of Schimmel & Co. the following constants were observed in connection with a dihydrocarveol isolated from caraway oil:
B. p. 100 to 102° (7 to 8 mm.); d15o.0,9368; aD - 6° 14'; nD20o1,48364.4)
Dihydrocarveol deviates the ray of polarized light in the same direction as does the carvone used for its preparation.
1) Report of Schimmel & Co. April 1905, 20.
2) Wallach, Berl. Berichte 24 (1891), 3990.
3) Wallach, Liebig's Annalen 275 (1893), 111.
4) Report of Schimmel & Co. April 1905, 20.
When oxidized with chromic acid in glacial acetic acid,1) dihydrocarvone results (b. p. 221 to 222°; d19o 0,928; nD 1,47174). The dihydrocarvone from d-dihydrocarveol is laevogyrate, that from /-dihydrocarveol is dextrogyrate. The corresponding active di-hydrocarvoxime melts at 88 to 89°, the inactive modification at 115 to 116°. This oxidation can be utilized for the identification of di-hydrocarveol. For this purpose the phenylurethane is also serviceable. The active modifications melt at 87°, the inactive one at 930.2)