Natural rubber is from the monomer isoprene (2-methyl-1,3-butadiene). Since isoprene has two double bonds, it still retains one of them after the polymerization reaction. Natural rubber has the cis configuration for the methyl groups.

Isoprene as the Monomer of Natural Rubber

Natural rubber is a polymer made from the monomer isoprene. Isoprene is a colorless liquid hydrocarbon that polymerizes to form natural rubber, which is an elastomer known for its flexibility and resilience. Here's a breakdown of why isoprene is the monomer of natural rubber:

Definition of Isoprene
- Isoprene is a naturally occurring unsaturated hydrocarbon with the molecular formula C5H8.
- It is commonly found in plants as a volatile compound emitted during photosynthesis.

Structure of Isoprene
- Isoprene has a branched molecular structure with two double bonds.
- The double bonds allow isoprene molecules to polymerize and form long chains of natural rubber.

Polymerization of Isoprene
- Isoprene molecules undergo polymerization in a process called vulcanization, where sulfur is added to the polymer chains to improve their strength and elasticity.
- The resulting polymer is known as natural rubber, which is widely used in various applications such as tires, seals, and adhesives.

Comparison with Other Polymers
- Bakelite is a synthetic polymer made from phenol and formaldehyde.
- PVC (polyvinyl chloride) is a synthetic polymer made from vinyl chloride monomers.
- Teflon is a synthetic polymer made from tetrafluoroethylene monomers.

In conclusion, isoprene is the monomer of natural rubber, making it distinct from other polymers like Bakelite, PVC, and Teflon. Its unique molecular structure and polymerization process contribute to the desirable properties of natural rubber, making it a versatile material in various industries.