THEORETICAL INVESTIGATIONS ON ZIEGLER-NATTA CATALYSIS - ALKYLATION OFTHE TICL4 CATALYST

Theoretical ab initio methods have been used to study the alkylation r eaction of the MgCl2-supported TiCl4 catalyst. Investigation of the re action path indicated that the Al(CH3)(3) co-catalyst inserts into the coordination sphere of the titanium atom of the catalyst so that a me thyl group of Al(CH3)(3) interacts with the titanium. The methyl group migrates from Al(CH3)(3) to the vacant coordination site of the catal yst. When the catalyst loses one of its chlorine atoms to the co-catal yst during this reaction, the catalyst maintains its vacant site, but the position of the vacant site changes. The presence of the external electron donor coordinated to the co-catalyst makes the alkylation rea ction energetically more favourable.