Word Finder - terpenes

definition

A very large class of naturally occurring and synthetic organic compounds formally derived from the hydrocarbon isoprene; they include many volatile compounds used in perfume and food flavours, turpentine, the steroids, the carotene pigments and rubber.

Benzo-ortho-diazines exist in two structural forms, cinnolin and phthalazine; benzo-meta-diazines are known as quinazolines; benzo-para-diazines are termed quinoxalines; the dibenzo-compounds are named phenazines, this last group including many valuable dyestuffs - indulines, safranines, &c. In addition to the types of compounds enumerated above we may also notice purin, tropine and the terpenes.

It thus possesses the same composition as the hydrocarbon of gutta-percha and as that of oil of turpentine and other terpenes which are the chief components of essential oils.

The exact chemical nature of caoutchouc is, however, not determined, and recent researches point to the view that its molecular structure may even be somewhat different from that of the terpenes.

This work led naturally to the synthesis of many terpenes and members of the camphor group; also to the investigation of various alkaloids and natural colouring matters.

They are closely related to the terpenes, with which they occur in plants and of which they are oxidation products.

Derivatives of the cyclo-pentane group are met with in the breaking-down products of the terpenes.

Hexahydrocymene (methyl-i-isopropyl-4-cyclo-hexane), C10H20, is important since it is the parent substance of many terpenes (q.v.).

In addition to these, a series of open-chain olefine terpenes is known.

The chief sources of the terpenes and their derivatives are the essential oils obtained by the distillation or extraction by pressure of various plants, chiefly of the Coniferae and different species of Citrus.

The terpenes all possess a characteristic odour and are fairly stable to alkalis, but are easily decomposed by acids or by heating to a sufficiently high temperature.

Chemically, oil of turpentine is a more or less complex mixture of hydrocarbons generically named terpenes.

Heussler (translated by Pond), The Chemistry of the Terpenes (London, 1904).

The resin contains aromatic chemicals called terpenes, which make it volatile and flammable.

The patterns of sensitivity to different terpenes can be expected to vary according to the exposure.

Berzelius immediately appreciated the importance of this discovery, notwithstanding 1 The reader is specially referred to the articles Alizarin; Indigo; Purin and Terpenes for illustrations of the manner in which chemists have artificially prepared important animal and vegetable products.

Citronellal, rhodinal and geranial are also unsaturated aldehydes (see Terpenes).

Many cyclic ketones are known, and in most respects they resemble the ordinary aliphatic ketones (see Polymethylenes; Terpenes).