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.

Like other alkenes, propylene trimer is used as an alkylating agent. A number of surfactants and lubricants are produced by alkylation of aromatic substrates.