The Role of Professor G. Natta

An excellent account into the detailed role of Professor Natta and coworkers in the development of Ti-based catalysts was published in Boor s book [6,7]. A brief summary of these events is important to put the work of Ziegler and Natta (working with Ti-based catalysts) and Hogan and Banks (both of Phillips Petroleum and working with Cr-based catalysts) into historical perspective. 

Professor Karl Ziegler was at the Max Planck Institute for Coal Research during this period working primarily with ethylene (Aufbau process) and much of his research that followed the initial discovery of the Miilheim catalyst (TiCl + AlEt ) dealt with ethylene homopolymerization and eth-ylene/propylene copolymerization. Before Ziegler disclosed his discovery in a technical publication, he disclosed his results to two industrial companies Montecatini of Italy and Goodrich-Gulf of the United States. 

Chain transfer with hydrogen to ethylene coordinated to the active site produces a saturated polymer end group and a Ti-Et bond (or a Ti-H bond if chain transfer proceeds without an ethylene molecule coordinated to the active site) that is able to initiate the growth of another polymer molecule. 

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