OLIGOMERIZATION OF ETHYLENE

The addition of one olefin molecule to a second and to a third, etc. to form a dimer, a trimer, etc. is termed oligomerization. The reaction is normally acid-catalyzed. When propene or butenes are used, the formed compounds are branched because an intermediate carbocation is formed.

These compounds were used as alkylating agents for producing benzene alkylates, but the products were nonbiodegradable. Oligomerization of ethylene using a Ziegler catalyst produces unbranched alpha olefins in the C₁₂-C₁₆ range by an insertion mechanism.

A similar reaction using triethylaluminum produces linear alcohols for the production of biodegradable detergents.

Dimerization of ethylene to butene-l has been developed recently by using a selective titanium-based catalyst. Butene-l is finding new markets as a comonomer with ethylene in the manufacture of linear lowdensity polyethylene (LLDPE).