Chapter 31, Problem 31.29P

An isoprene unit can be thought of as having a head and a tail. The “head” of the isoprene unit is located at the end of the chain nearest the branch point, and the “tail” is located at the end of the carbon chain farthest from the branch point. Most isoprene units are connected together in a “head-to-tail” fashion, as illustrated. For both lycopene (Problem 31.26), and squalene (Figure 31.9), decide which isoprene units are connected in a head-to-tail fashion and which are not.

These two isoprene units are

connected in head-tail fashion.