Volume 2

Recent advances in organic chemistry / by Alfred W. Stewart.

  • Stewart, Alfred W. (Alfred Walter), 1880-1947.
Date:
1927
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Recent advances in organic chemistry / by Alfred W. Stewart. Source: Wellcome Collection.

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    diterpene 1 a-camphorene, C20H32, which belongs to the group of tricyclic terpenes. The last compound with which it is necessary to deal in this chapter is /3-caryophyllene. Unlike the sesquiterpenes which have just been mentioned, it yields no benzenoid derivative when subjected to the Yesterberg reaction.2 This suggests that it contains a bridged-ring structure ; and Semmler and Mayer 3 put forward the view that /3-caryophyllene is a mixture of two compounds having the structures (I.) and (II.). ( ch3 ch3 -a H2cr I ^CH—CH:C(CH3)„ | CHg-^C—CH3|| HC<r C—CH3 chY H„C (I.) Caryophyllene. (II.) Now Wallach and Walker 4 found that caryophyllene forms caryophyllene alcohol, C15H25OH, when hydrated by means of sulphuric and acetic acids. This alcohol has recently been studied by Henderson, Robertson, and Kerr,5 with the following results. The alcohol behaves towards hydrogen peroxide, permanganate, and bromine as though it were a saturated com¬ pound. This indicates that it is a derivative of a tricyclic terpene; and this is confirmed by an examination of its refractive index. Since caryophyllene is a dicyclic terpene, it is clear that ring-closure must have occurred during the action of the hydrating reagents which produce the alcohol. This is supported by the fact that the alcohol is formed from caryophyllene through the agency of formic acid which, as has been seen above, is a reagent which induces ring-closure. By utilizing silver acetate in glacial acetic acid, Henderson, Robertson, and Kerr were successful in hjMrating caryophyllene without closing the ring, the result being an alcohol, C15H25OH, which is termed caryophyllol, which appears to be tertiary in type. In addition to this alcohol, a saturated glycol, 1 Ruzicka and Stoll, Ilelv. Chim. Acta, 1924, 7, 271. 2 Ruzicka and Stoll, Helv. Chim. Acta, 1923, 6, 854. 3 Semmler and Mayer, Ber., 1911, 44, 3657. 4 Wallach and Walker, Annalen, 1892, 271, 285. 5 Henderson, Robertson, and Kerr, J1926,129, 62. VOL. II. I