- 83 - 
animals. This view, which had also been advocated already by other 
investigators, is supported by numerous examples and feeding -tests 
with the plants in question. For further particulars we must refer to 
the original work. 
Hydrocarbons. 
F. W. Semmler^) recommends sodium and alcohol as reducing 
agents for terpene derivatives, for the purpose of avoiding rearrange- 
ments in the molecule. The use of these agents has the desired 
effect not only in the case of aldehydes and ketones, but also in 
hydrocarbons which contain a conjugated system of double-linkings 
in the molecule 2). The absence of such linkings also explains, why 
limonene and terpinolene cannot be reduced by means of sodium 
and alcohol. With phellandrene, however, the reduction succeeds 
when the ethyl alcohol is substituted by amyl alcohol. The reduction - 
product, a dihydrophellandrene Qo-^iS' boils at 171° to 172°. Its 
physical constants are: d = 0,829, = ~1~ ^5°? = 1,4601. 
The oily glycol QoHgoOg formed by oxidation with permanganate 
is readily oxidised further into acetic acid and /S-isopropylglutaric acid 
(m. p. 100°). According to this, the following constitutional formula 
would belong to dihydrophellandrene: 
CH3\ xC * ^ 
)>CH.CH<( ^C-CHg. 
Starting from the hydrochloride of the hydrocarbon, a dihydro- 
limonene is obtained in the following manner: The hydrochloride ob- 
tained by the introduction of dry hydrochloric acid in a solution of 
I'imonene in carbon disulphide, is dissolved in alcohol in the cold; 
sodium is added, and care is taken, by cooling the solution in ice, 
that the temperature during the reaction does not rise to above -j- 10°. 
The resulting dihydrolimonene boils at 173° to 174°. d == 0,839, 
Hjy = 1,463, Qjy = -\- 40°. This reduction - method can be applied 
universally, and renders it possible to arrive from unsaturated com- 
pounds over their hydrohalogen addition-products to saturated hydro- 
carbons. In the same manner it is possible to produce from alcohols 
or aldehydes and ketones, the corresponding hydrocarbons by sub- 
stitution of the oxygen by halogens. In an analogous manner there 
is formed from tanacetyl alcohol, or from tanacetyl chloride, the di- 
hydrotanacetene Qo^is following constants: b. p. 164° to 166^, 
d = 0,810, nj) = 1,451. 
^) Berichte 36 {1903), 1033. 
2) Report April 1902, 88. 
6* 
