Living Polymerization of Propene with Alkyltitanium-Based Catalysts

Living polymerization of propene with alkyltitanium-based catalysts is described with emphasis on the role of the activators employed. (¹ : ³-tert-Butyl(dimethylfluorenylsilyl)amido)dimethyltitanium activated by tris(pentafluorophenyl)borane (B(C₆F₅)₃) catalyzes the living polymerization at -50 °C. The use of dried methylaluminoxane (MAO) in place of B(C₆F₅)₃ raises the living polymerization temperature to 0 °C and improves the syndiospecificity. A chelating diamide dimethyltitanium activated by dried modified MAO (MMAO) catalyzes the living polymerization at 0 °C to give a statistically atactic polymer. The heterogenization of the living systems is attempted by supporting MAO, MMAO and dried MMAO on SiO₂ as solid activators.