Rubber, Borneo

An alternative chewing gum base is obtained from jelutong, a mixture of polyisoprene and resin obtained from latex of the Dyera costulata. This tree is found in many countries but Borneo is the principal commercial source. At one time jelutong was an important rubber substitute and 40000 tons were produeed in 1910. Production in recent years has been of the order of 5000 tons per annum, mainly for chewing gum. 

Gutta-percha (with or without the hyphen) is the hardened latex from a number of different trees found in Borneo, Sri Lanka, and Malaya. The name comes from the Malayan words for juice (gutta) and tree (percha). This viscous plant sap hardens quickly and, after vulcanization, looks and behaves like hard rubber. The term gutta percha has also been used to describe unvulcanized hard rubber, regardless of its origin. 

We begin with two trees, both cultivated on plantations in Southeast Asia. One, Hevea brasiliensis, is a source of natural rubber and was innported from Brazil in the nineteenth century. The other, Isonandra gutta, is native to Sumatra, Java, and Borneo and gives a latex from which gutta-percha is obtained. 

Two monomethyl ethers of m /o-inositol are known bornesitol 37), m.p. 199°, from Borneo rubber and opepe Sacrocephalus diderrichii) wood (S7a), and sequoyitol 11, 38), m.p. 234-235°, from California redwood. Sequoyitol, a meso compound, is 5-0-methyl-w2/o-inositol 39). Bornesitol is optically active. A dimethyl ether, dambonitol, m.p. 195°, is found in the latex of Gabon 40) and other rubbers and in the latex of the Dyera tree 41)- It has been shown to be 1,3-di-0-methyl-m2/o-inositol 41a)-... 

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