20 



Report of Schimmel § Co. April/October 1917. 



suspected the presence of olefinic and monocyclic sesquiterpene compounds in the 

 fractions with a higher boiling point, chemical compounds which have hitherto been 

 comparatively little examined. Oxygenated derivatives of the monocyclic sesquiterpene 

 series have only been described quite recently, so that the author found it necessary 

 to produce such compounds by synthetic means, to enable him by comparing their 

 properties with those compounds found in the oil of gum ammoniac to draw con- 

 clusions as to the composition of the latter. 



Semmler and Jonas 1 ) carried out the first syntheses in the sesquiterpene series. 

 For instance they obtained q/doisoprenemyrcene by heating myrcene and isoprene in 

 a sealed tube. This mode of procedure, however, by no means excludes the possibility 

 of molecular rearrangement; whereas Grignard's 2 ) reaction supplies a quite reliable 



H 3 C 

 H 2 C 



C 

 CH 



)H 2 H 3 C\ /CH 3 

 CH 



CH 



$ + 1 ^ - 



H 2 C 



H 3 C\ //CH 2 



C 

 __CH_ 



H 3 Cv /CH 3 



+ H 2 





HC^. /CO 

 C-CHs 



tn 2 



/ 

 JMg 



HC 



^C-CH 3 | ^CH 2 

 n 



CH 2 



Carvone + isoamylmagnesiumiodide. 





u 



\ 









MgJ 



H 2 C 



H 3 Cv 



^CH 2 



C 

 CH 



H 3 C\ 



CH 2 X 



/CH 3 

 CH H * C 



H 3 Cv >/CH 2 



C 

 __CH^ 



1 



H 3 C\ /CH 3 

 CH CH 



JOH + 











— H 2 -► 









HC 





"CH 3 • -_ CH 2 



CH 2 



HC 





r~^-^^^^ 



CH 2 



( 





C*CH 3 CH 2 







c 



Compound 



C 15 H 26 0. 







Zsoamyl-a-dehydrophellandrene. 





method for this synthesis. By the action of woamylmagnesiumiodide on d-carvone in 

 a solution of benzene, Roenisch obtained a compound Ci 5 H 26 which immediately split 

 off water and produced a sesquiterpene Ci 5 H 24> boiling between 130 and 132° (11 mm.) 

 and showing the following properties: d 22 o 0.8679; « D + 18°30'; n D20 o 1.49478. These 

 figures are quite in accord with the properties of the hitherto known monocyclic 

 sesquiterpenes, bisabolene (limene), zingiberene, and q/doisoprenemyrcene. Theory 

 demands that the synthetic hydrocarbon should contain a pair of conjugated double 

 bonds, besides that it contains a third double bond in the isopropylene group; 

 accordingly it can be characterized as an isoamyl-a-dehydrophellandrene, a dehydrated 

 a-phellandrene, in which the z'soamyl group takes the place of one hydrogen atom. 



Phellandrene with conjugated double bonds in the nucleus can by no means be 

 reduced by the action of sodium and ethyl alcohol, on the contrary with facility by 



») Berl.Berichte 46 (1913), 1569; 47 (1914), 2080; Report October 1913, 35; April 1915, 85. 

 M. Bruhnke, Inaug.-Dissert., Breslau 1915. 



2 ) Comp. 



