The formation of isotactic polypropylene under the influence of ziegler-natta catalysts

✍ Scribed by P. Cossee

• Publisher: Elsevier Science
• Year: 1960
• Tongue: French
• Weight: 209 KB
• Volume: 1
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)99341-4

✦ Synopsis

IN a previous publication 1 on the meohanism of the ethylene polymerization with heterogeneous 'Ziegler-Natta catalyst systems it was pointed out how an ethylene molecule is interposed between a Ti-ion and an alkyl group. The active center of the catalyst in the growth reaction was considered to be a Ti-ion in the surface layer of a-TiC13 of which one octahedral position is occupied by an alkyl group and another octahedral position is empty (chlorine vacancy). In this way a hole in the surface layer of the chlorine lattice is formed adJaoent to the alkyl group. A monomer molecule can be incorporated in this hole and by means of a n-bond it can be attached to the alkyl-bearing Ti-ion. Besides providing a better understanding of the driving force of the growth reaction and the possibility to explain the unique position of Ti and its neighbouring elements in producing the most active catalysts,the proposed ' P. Cossee, Tetrahedron Letters No. 17, 12 (1960).