THE ROLES OF OXIDATION-STATE, LEWIS-ACID COCATALYST AND SOLVENT POLARITY IN ACTIVATING TITANIUM COMPOUNDS FOR OLEFIN POLYMERIZATION

The polymerization activity of the following three catalyst systems to wards ethylene has been investigated and compared: 1) methyltitanocene chloride-Me(2)AlCl; 2) eta(3)-allyltitanocene-Me(2)AlCl and 3) titani um dichloride tetrahydrofuranate-Me(2)AlCl. The first two catalysts fo rmed homogeneous phases and produced linear polymer; the last catalyst functioned in a heterogeneous medium and formed crosslinked polymer. The titanium(IV) catalyst was about 30 times more active than the tita nium(III) system and the titanium(II) catalyst on MgCl2 could be made 8 times more active than the titanium(IV) system. A novel mechanism is proposed to explain the behavior and activity of the titanium(II) sys tem.