| Abstract: | An IR/UV study of the interaction between ethyl benzoate and Al(C2H5)3 in dilute heptane solution at 25–75°C demonstrated that the ester is readily reduced under these conditions with the formation of two aluminum dialkyl alkoxides, Al(C2H5)2 and Al(C2H5)2OC(C2H5)2C6H5, as major products. Rate constants of the reduction of the initial AI(C2H5)3 · ester complex by free AI(C2H5)3 are 2.9 (26°C), 14.4 (50°C), and 59.6 (75°C) L/mol min; Eact = 52.0 kj/mol. Study of propylene polymerization with this catalytic system at 50°C showed that preliminary aging of the AI(C2H5)4–ethyl benzoate mixtures at 25°C for 24 h and at 50°C for 2 h does not adversely affect catalyst performance. These data suggest that the possible actual modifier in this catalytic system is aluminum alkoxide with a highly branched tertiary alkoxy group. |
