Studies of the active complex of a soluble catalyst. I. Ti(O-n-Bu)4-AlEt3 system

The characterization of an active complex in a soluble Ti(O‐n‐Bu)4‐AlEt3 system is reported in connection with its polymerization activity for styrene. The catalytic activity strongly depends on the Al/Ti ratio in the catalytic system. The optimal Al/Ti ratio for polymerization reaction is estimated as 1,5. Active titanium species are present in trivalent state. Further reduction of titanium species to a valency of less than 3 results in no activity for styrene polymerization. Two types of active species are detected by the IR and ESR studies of the catalytic system. One is Ti(O‐n‐Bu)2Et, and the other is a complex formed by 1 mole of Ti(O‐n‐Bu)2Et and 2 moles of (n‐BuO)‐AlEt2. The differences in activity between these are now under investigation. IR and ESR studies of the Ti(O‐n‐Bu)3‐AlEt3 system are also reported.