Identification and Count of the Active Sites in Olefin Polymerization Catalysis by Oxygen Quench

摘要

A simple method for the counting and structural elucidation of the different active sites in an olefin polymerization catalyst system is introduced, based on a reaction quench by O_2 under controlled kinetics, followed by NMR analysis of the OH-labeled chain end-groups formed upon acidic work-up of the polymer. The method is successfully benchmarked using a molecular bis(phenoxyamino)Zr(IV)-based catalyst characterized by a comparatively long-lasting controlled kinetic transient at room temperature.