Effect of Trichlorosilane Concentration

To investigate the effect of the R groups and of the solvents, the silsesquioxanes products were reacted with TifOPr1 and subsequently screened for catalytic activity in the epoxidation of 1-octene with TBHP. The reported activities are normalised to the activity of (c-C5H9)7Si70i2Ti0Pr1 (Fig. 9.3). 

For most of the trichlorosilane concentration tested, the order of activity is still cyclopentyl cyclohexyl phenyl. At low concentration the order between cyclohexyl and phenyl reverses but cyclopentyl still results in the best activity. This confirms the starting hypothesis that the R group is a more relevant factor than the concentration of the silane in influencing the hydrolytic condensation. The maximum activity corresponds to a different silane concentration for each of the three R groups. The maximum for cyclopentyl as R group - corresponding to a concentration of silane of 0.181 M - displays an activity that is 95% of that of pure Ti-(cyclopentyl silsesquioxane a7b3) this is a relevant improvement compared with the optimum obtained previously (87%) [39]. These results show that the experi- 

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