isoprene or 2-methyl-1,3-butadiene (Īˈsəprēn, byōˌtədĪˈēn) [key], colorless liquid organic compound. It is a hydrocarbon, and is insoluble in water but soluble in many organic solvents; it boils at 34°C. The isoprene molecule contains two double bonds. It is readily polymerized by the use of special catalysts; large numbers of isoprene molecules join together to form a single large, threadlike polyisoprene molecule. Isoprene polymers also occur naturally. The natural rubber caoutchouc is cis -1,4-polyisoprene, and trans -1,4-polyisoprene is present in the natural rubbers balata and gutta-percha. (The cis and trans polyisoprenes are structural isomers.)
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