Polyterpenes gutta

Caoutchouc elastic, high molecular mass polyter-penes, which can be converted into rubber by vulcanization. Natural C. is a mixture of polyisoprenoids with varying molecular masses, ranging from 300,000 to 700,000. According to X-ray and IR data, the double bonds are cis oriented, whereas in the C.-like polyterpenes, gutta and balata, they are trans. Hundreds of species of plants contain C in their latex, but it can only be obtained on a large scale from a... 

A class of hydrocarbons occurring in many essential oils of plants. They can be regarded as low-molecular weight polymers of isoprene (C5I I8)n. Dipentene is a terpene, while natural rubber, gutta percha and balata have been termed polyterpenes. 

Balata tree, Mimusops Balata, have achieved economic importance or are considered as resources for natural mbber as a renewable polymer. Chemically, natural rubbers are polyterpenes consisting of 1,4-c -(mbber) or 1,4-frans-(gutta-percha, balata) polyisoprene, generated by enzymatically catalyzed biosynthetic polymerization of isoprene, and stabilized by phospholipids. 

Polyterpenes (polyterpenoids). Natural products made up of n C lo units (= 2 n isoprene building blocks) with n>4, the biogenesis of which generally obeys the isoprene rule. The most important P. are the tetra-terpenes (n=4) including carotinoids, ficaprenols, natural rubber, balata, and gutta-percha. The name is also used for hydrocarbon resins (terpene resins) prepared synthetically by polymerization of monoter-penes. 

Chromenes, Benzofurans, Benzopyrans, and Precocenes Polyterpenes Biosynthesis Biological Activity Natural Rubber Hevea brasiliensis Guayule Gutta Percha Chicle... 

Gutta a rubber-like polyterpene of about 100 iso-prene units in which the double bonds are in the trans configuration (see Polyterpenes, Rg.)- G. is produced on the Malayan peninsula and the Indonesian islands from the latex of Palaguium gutta. G. is less elastic than rubber, but since it is more resistant to chemicals and environmental influences it serves well as an insulating material. Depending on its source, G. occurs... 

Isopentenyl pyrophosphate Hemiterpenes (isoprene). Monoterpenes (iridoid components of volatile oils). Sesquiterpenes (bitter principles, components of volatile oils). Diterpenes (components of resins, gibberellins, phytol). THterpenes (squalene, sterols, etc.). Tetraterpenes (carotenoids, xanthophylls). Polyterpenes (caoutchouc, gutta percha). 

Let us consider further the consequences of head-tail additions. If an additional molecule of IPP is added head-to-tail to farnesyl pyrophosphate geranylgeranyl pyrophosphate, a diterpene, is obtained. The series of events outlined above can now be repeated at a higher level of complexity geranylgeranyl pyrophosphate can either be converted to other diter-penes or two molecules of geranylgeranyl pyrophosphate can be joined tail-to-tail to give 40 C bodies. In this way tetraterpenes, i.e. carotenoids, are obtained. Further head-to-tail additions of IPP lead, finally, to the polyterpenes rubber, gutta-percha, and balata. 

Of the polyterpenes rubber, gutta-percha, and balata, our discussion will be restricted to the technically most important product, rubber. About 2,000 species of higher plants produce rubber but only a few of them, mainly from the families Apocynaceae, Asclepiadaceae, Compositae, Euphorbiaceae, and Moraceae, do so in sufficient quantity as to make its extraction technically worthwhile. A few of the more important species are listed in Table 5. The main source of rubber is the rubber tree Hevea brasiliensis. Achras sapota, the chicle of which provides the basic ingredient of chewing gum, is also included in the list. 

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