Solid‐State NMR characterization of a superactive supported ziegler–natta catalyst

摘要

AbstractThe formation of CH‐type catalysts has been investigated by high‐resolution and solid‐state NMR. These catalysts are prepared from a soluble MgCl2and 2‐ethyl‐1‐hexanol adduct (MgCl2·3EH) by reaction with phthalic anhydride (PA) to form dioctylphthalate (DOP) and then with TiCl4in the presence of di‐i‐butylphthalate (BP). In the model systems MgCl2·3EH/PA, MgCl2/BP, and MgCl2/TiCl4/BP, the ester is complexed with MgCl2and /or TiCl4in two or more states. Only single‐ester CO and OCH2resonances are seen in TiCl4/BP, probably due to exchange of ester coordinations. CH‐catalysts prepared by three different procedures exhibit a single mode of bonding for the ester. The chemical shift values are consistent for ester complexed with MgCl2. The most active and stereoselective catalyst has the most shielded chemical shift values for the CO and —OCH2— carbons, shortestTH1andTH1p, and longestTCHrelaxation times. These parameters change monotonically with the decrease of activity and stereoselectivity of the catalyst preparation