Tripropylene
Tripropylene, also known as propylene trimer, is a mixture of organic compounds with the formula C9H18. This mixture is obtained by oligomerization of propene:
In this process, two double bonds are lost and one is retained as illustrated by the isomer shown in the figure. The reaction is catalyzed by acids, such as polyphosphoric acid. A variety of catalysts have been explored. The reaction proceeds via the formation of a carbocation ((CH3)2CH), which attacks another propylene unit, generating a new carbocation, etc. This kind of process affords mixtures (C3H6)n.