Isoprene is the repeating unit in natural rubber. The structure of isoprene is

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 around 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 rhe configuration around the carbon-carbon double bonds.

CH3 CH-=C-CH-CH- CH3 CH-CH2T CH2-C-CH-CH2