450 Mr. Gervaise Le Bas on the 



If we consider a typical sesquiterpene like Clovine Ci 5 H< 

 B.P. 262°, d 15 . 5 0-932, we find :— 



4^ = '541 and 1 + ^l - -460 x *45 = 1*207 ; 



_ 0-932 _ 

 "b.p. — 1-2070 



M.Y. C 15 H 24 (Clovine) ... ^1 = 264-0 

 2A.V. C 15 H 24 84x3-7 310-8 



Contraction for Rings —46*8 



= 3x -15-6 



We conclude that Clovine Ci 5 H 24 , and the more typical 

 sesquiterpenes contain three rings. 



Among tricyclic sesquiterpenes we find : — 



Clovine, Cedrene, Ledene, Patchoulene, and doubtless 

 others. 



We thus see that the typical sesquiterpenes contain three 

 rings and three molecules of isoprene. It follows that a stage 

 similar to the bridging of the ring must have occurred in 

 the formation of these compounds. After this, the deve- 

 lopment of the molecule is simple, for, given an olefin linking 

 as in camphene, the sesquiterpene would be formed by the 

 addition of a molecule of isoprene thus : — 



CH CH 2 = CH 



i * i 



CH CH 2 = C 

 I 



— 



— CH- 



i 



— CH- 



— CH 2 — CH 



ii 



— CH 2 — C 



i 



CH 3 







CH 3 



It should be mentioned that Semmler classes aromadendrene, 

 clovene, cedrene, ledene, and vitevene as tricyclic, and these 

 are typical sesquiterpenes. Our theory is thus in agreement 

 with this view. 



Some, on the other hand, apparently possess only two 

 rings and are bi-cyclic : zangiberine, cannabene, &c. These 

 show a contraction of about —30*0. 



