Terpenes empirical formulas

Chlorinated Terpenes. A group of incompletely characterized insecticidal compounds has been produced by the chlorination of the naturally occurring terpenes. Toxaphene [8001-35-2] is prepared by the chlorination of the bicycHc terpene, camphene [79-92-5] to contain 67—69% chlorine and has the empirical formula C QH QClg. The technical product is a yellowish, semicrystalline gum (mp 65—90°C, d 1.64) and is a mixture of 175 polychloro... 

Prior to the discovery of the vulcanization or cross-linking of hevea rubber with sulfur by Goodyear in 1838, Faraday has shown that the empirical formula of this elastomer is CsHg making it a member of the terpene family. The product obtained by pyrolysis of rubber was named isoprene by Williams in 1860 and converted to a solid (polymerized) by Bouchardat in 1879. 

The term terpenes originally was applied to cyclic hydrocarbon structures with the empirical formula or to their derivatives which occur in the essential... 

The first few Type B (derivatives of dimethylcyclohexane) terpene monocyclic hydrocarbons that were discovered had the empirical formula and were... 

Turpentine is a volatile oil consisting primarily of terpene hydrocarbons, having the empirical formula C10H,6. These 26 atoms can have many different arrangements, only six of which are present in appreciable amounts in commercial turpentines a-pinene (b.p. 156°C), /3-pinene (b.p. 164°C), camphene (b.p. 159°C), A3-carene (b.p. 170°C), dipentene (b.p. 176°C), and ter-pinoline (b.p. 188°C). The molecular configurations of some of these are shown in Fig. 28.20. 

Historically, carbohydrates were defined as substances with the empirical formula Cn(H20)ni. The common sugars such as glucose and fructose (n = m = 6), or sucrose (n=12, m=ll) fit this formula, but nowadays the convention is to regard as a carbohydrate a polyhydroxyaldehyde or polyhydroxy ketone with the classical formula, a molecule closely related to it, or oligomers or polymers of such molecules. Their study evolved as a separate sub-discipline within organic chemistry for practical reasons - they are water-soluble and difficult to crystallise - so that their manipulation demanded different sets of skills from classical natural products such as terpenes, steroids, alkaloids, etc. 

Scheme 3.8 shows how the isoprene units and the original backbone can be traced out in a number of terpenes that are important in perfumery. Sometimes skeletal rearrangements occur which make this process more difficult and fragmentation or degradation reactions can reduce the number of carbon atoms so that the empirical formula does not contain a simple multiple of five carbons. Nonetheless, the natural product chemist quickly recognizes the characteristic terpene framework of the structure. 

Early studies indicated that terpenes were composed of five carbon units. By 1860, isoprene, a compound with the empirical formula C5H8, could be derived by pyrolysis of turpentine and rubber. Further, isoprene could be transformed into a C10H16 compound that subsequently decomposed back to the original five-carbon unit. Wallach recognized that terpenes could be subdivided into several groups hemiterpenes, true terpenes, sesquiterpenes, and diterpenes. In 1887, he proposed that monoterpenes (true terpenes) as well as other terpenoids were composed of isoprene units, a concept that became known as the isoprene rule (Wallach, 1887). The structure of isoprene was not solved until much later (Spurgeon and Porter, 1981). 

Terpene tor- pen [ISV terp- (fir. Gr Terpen-tin turpentine, fir. ML terhentina) + -ene] (1873) n. A class of unsaturated organic compounds having the empirical formula C10H16 occurring in most essential oils and oleoresinous plants. Structurally, the unimportant terpenes and their derivatives are classified as monocyclic (dipentene), bicyclic (pinene), and acyclic (myrcene). 

---