Question

Discuss the metal catalyzed polymerization of RCH=CH2 (alkenes or alpha olefins) using late metals. Show the catalytic cycle and discuss significant a difference between the well-known early metal metallocene catalysts. (5 marks)

Late metals include Pd, Rh, Ru etc...

Answer 1

Early metal metallocene catalyst is Zeiglar Natta catalysts which is a mixture of TiCl4 and AlEt3.This catalyst is used to polymerise ethene stereospecifically to give polyethylene.This catalyst has advantage to industry because it can be easily recovered by filteration.

The polymerisation reactions at the active sites of Zeiglar Natta catalysts are infuenced by the electronic and steric environment of the crystal lattice because the active metal centre occupies a position on the surface of the crystal.this is one of the drawback of these catalysts.