Isoprene is the repeating unit in natural rubber. The structure of isoprene is C=CC(C)=CC a. Give a systematic name for isoprene. b. When isoprene is polymerized, two polymers of the form are possible. In natural rubber, the cis configuration is found. The polymer with the trans configuration about the double bond is called gutta percha and was once used in the manufacture of golf balls. Draw the structure of natural rubber and gutta percha showing three repeating units and the configuration about the carbon-carbon double bonds.

To provide a systematic name for isoprene, we need to find the relevant functional groups and their positions. The isoprene chemical structure is: C=CC(C)=CC The first step is to identify the longest carbon chain containing the functional group, which is a double bond (=). In this case, the longest chain is only 4 carbons long. Next, we number the carbons in the chain, starting at the carbon with the double bond, and assign the appropriate suffix for the double bond (-ene). The systematic name for isoprene is 2-methyl-1,3-butadiene.

When isoprene is polymerized, it can form either natural rubber or gutta percha, depending on the configuration about the carbon-carbon double bonds. Natural rubber has the cis configuration, while gutta percha has the trans configuration. We will show three repeating units for both polymers. 1. Natural Rubber: The polymerization of isoprene can be represented using a single-bonded pair of carbon atoms with the cis configuration, connected to two single repeating units. Natural rubber with three repeating units can be drawn as follows: [\(CH_2C(CH_3)C(CH_2CH_3)=CCH_2{-}\) ]\(COO-\) _\( | )_ _\(-C_2H_5\) |\( -C_2H_5\) The above structure illustrates the cis configuration, with the ethyl and methyl groups on the same side of the double bond. 2. Gutta Percha: The polymerization of isoprene with the trans configuration about the carbon-carbon double bonds can be represented similarly, except the ethyl and methyl groups would be on the opposite sides of the double bond. Gutta percha with three repeating units can be drawn as follows: [ \(CH_2C(CH_3)C(CH_2CH_3)=CCH_2{-}\) ]\(|COO-\) _\( | )_|\(-C_2H_5\) |\( -C_2H_5\) The above structure illustrates the trans configuration, with the ethyl and methyl groups on opposite sides of the double bond.