Natural Rubber - Polymer of cis-isoprene

Natural rubber is a polymer of isoprene, which is a hydrocarbon molecule with the chemical formula C5H8. Isoprene exists in two different forms - cis and trans isomers. However, natural rubber is exclusively made up of cis-isoprene units.

Explanation:

1. Definition of Natural Rubber: Natural rubber is a polymer that is derived from the sap of rubber trees, mainly Hevea brasiliensis. It is an elastic material that is widely used in the manufacturing of various products, including tires, gloves, and conveyor belts.

2. Isoprene: Isoprene is a five-carbon hydrocarbon molecule that has two isomers - cis and trans. The difference between the two isomers lies in the orientation of the methyl groups attached to the central carbon-carbon double bond.

3. Polymerization: Polymerization is the process by which individual isoprene molecules are linked together to form a long chain polymer. In natural rubber, the polymerization occurs through the opening of the double bond in the isoprene molecule, which then links with another isoprene molecule to form a long chain.

4. Cis-Isoprene: In natural rubber, only the cis-isomer of isoprene is used in polymerization. The reason for this is that the cis-isomer has a more flexible structure that allows for greater intermolecular attraction and better elasticity in the resulting polymer.

5. Properties of Natural Rubber: Natural rubber has several unique properties that make it a valuable material in various industries. These properties include high elasticity, good tensile strength, and excellent resistance to wear and tear.

Conclusion:

In conclusion, natural rubber is a polymer of cis-isoprene units that are derived from the sap of rubber trees. The cis-isomer of isoprene is used exclusively in the polymerization process due to its more flexible structure and greater intermolecular attraction. Natural rubber has several useful properties that have made it a valuable material in various industries.