Mechanism of formation of isotactic and syndiotactic PP with metallocene catalyst

In this paper we will discuss the mechanism of formation of isotactic propylene with the help of c1- symmetrized metallocene catalyst. Catalyst system used in the process is Me_2C(3-tert-butyl-C5H3)(C(13)H8)]ZrCl2/MAO(MAO = methylaluminoxane, C13H8 = fluorenylidene) As the temperature rises from 0 to 60*C the epimerization process begins which increases iso tacticity. Propylene microstructures can be obtained with Me2C(3-R-C5H3)(Oct)ZrCl2/MAO, where Oct = octa methyl octa hydro dibenzo fluorenyl idene and R = methyl, cyclohexyl, diphenyl methyl, and with Me2C(3-tert-butyl-4-Me-C5H2)(Oct)ZrCl2/MAO. In addition to above we also discuss the formation of highly stereoregular syndiotactic propylene. Catalyst system used in the formation of syndiotactic propylene is Ph2C(Oct)(C5H4)ZrCl2/MAO (8/MAO) (Oct = octamethyl octa hydro dibenzo fluorenyl; MAO = methyl aluminoxane) and Me2C(Oct)(C5H4)ZrCl2/MAO (12/MAO). The syndiotactic propylene obtained is free of all stereo errors.