Q.29. - Organic Chemistry

Question

Question: 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.

Step-by-Step Solution

Answer

Answer

Step 1: Head-to-tail in an isoprene unit

In the isoprene unit, a head is located near the branch point of the isoprene unit, and a tail is located at the other end, farthest from the branch point. Isoprene units are joined to one another in a head-to-tail fashion, where the tail is connected to the head of the other isoprene unit.

Step 2: Head-to-tail fashion in lycopene

In lycopene, the head is located near the branch point and the tail at the farthest point from the branch point of the isoprene unit. It is shown below:

Head-to-tail fashion in lycopene

Step 3: Head-to-tail fashion in squalene

In squalene, the head is located near the branch point and the tail at the farthest point from the branch point of the isoprene unit. It is shown below:

Head-to-tail fashion in squalene