The sesquiterpenes : a monograph / by Oswald Schreiner.

  • Schreiner, Oswald, 1875-
Date:
1904
Catalogue details

Licence: In copyright

Credit: The sesquiterpenes : a monograph / by Oswald Schreiner. Source: Wellcome Collection.

    12/140 (page 4)
    The characterization of several of the large number of known ses- quiterpenes has been accomplished. Like investigation of those not yet characterized will, no doubt, reduce materially the still consider- able number of supposedly different hydrocarbons. A system for their classification is also suggested in the body of this report. This system of classification does not only include the sesquiterpenes at present known and characterized, but being based broadly on the best principles of classification of hydrocarbons in general, it will in- clude all the numerous possible compounds of the formula C15H24. Only after the characterization of the numerous isomers is ac- complished will it be possible to study successfully the relation of one sesquiterpene to another, the relation of these hydrocarbons to their oxygenated derivatives, and the problem of their constitution. GENERAL PART. I. The Position of the Sesquiterpenes in the Various Systems of Classification of Terpenes at large (CrHs)x. Until quite recently the hydrocarbons of the formula (CsHsJx were identified and classified on the basis of their physical characteristics alone. Such a system inevitably had to lead to endless confusion. The hydrocarbon was usually named according to the plant from the volatile oil of which it had been isolated, or simply after the volatile oil itself. Thus, for instance, limonene was differently named, and also considered as a different compound, according to the source from which it was obtained. The limonene in lemon oil was considered as an isomer of that in orange oil, that in the oil of Citrus bigaradia as an isomer of that in the oil of Citrus lumia, and isomeric with all these was the limonene in caraway oil, the carvene. Thus we find in literature as many as ten synonyms for limonene, and as many as twenty synonyms for dipentene, the optically inactive modification of limonene. Pinene, as it occurs in the various turpentine oils; camphene; dipentene, obtained from dipentene dihydrochloride, the “camphre de citron;” caoutchene, etc., were also considered as iso- meric with these. This historical kind of quasi-isomerism, based on the source of the isolated hydrocarbons, might be termed genetic isomerism. This large group of supposedly different hydrocarbons was due to the fact that they are very often accompanied in the volatile oils by oxygenated constituents, which are not readily separated from the