Oligomerisation of 1-pentene with metallocene catalysts

Abstract

The homo-oligomerisation of 1-pentene in the presence of various bridged and non-bridged metallocenes and methylaluminoxane (MAO) at room temperature and at 60°C, respectively, has been studied. The use of the bridged catalysts rac-[C2H4(Ind)2]ZrCl2 (1) and [(CH3)2Si(Ind)2]ZrCl2 (2) leads to the formation of isotactic poly(1-pentene). The use of Cp2ZrCl2 (3), Cp2HfCl2 (4) and [(CH3)5C5]2ZrCl2 (5) leads to the formation of atactic poly(1-pentene). The stereoregularity of the isotactic poly(1-pentene) obtained with 1 was higher than that of the poly(1-pentene) synthesised with 2. The degree of polymerisation was highly dependent on the metallocene catalyst. Oligomers ranging from the dimer of 1-pentene to poly(1-pentene) with a number-average molar mass Mn = 5100 g mol–1 were formed. The 1H NMR spectra of the samples were analysed with regard to functional groups and these were attributed to different chain termination processes. A MALDI-TOF spectrum of low-molar-mass poly(1-pentene) could be recorded using dithranol as matrix and adding silver trifluoroacetate to promote ion formation.