Study of the interaction of diethyl 2,3-diisobutyl succinate (DIBS) with magnesium dichloride and the stereoisomeric configuration of DIBS within titanium-magnesium catalysts of propylene polymerization

It was found by chromatography and 13C NMR spectroscopy that diethyl 2,3-diisobutyl succinate (DIBS), which is used as a stereoregulating electron donor in titanium–magnesium catalysts, exists as rac and meso stereoisomers. Their molecular structure was calculated using the DFT method. It was ascertained that mainly rac-DIBS is anchored to the surface of MgCl2. Subsequent interaction between the MgCl2/DIBS sample and TiCl4 leads to further removal of meso-DIBS. Titanium–magnesium catalysts of composition MgCl2/DIBS/TiCl4 prepared by different procedures contain 85–91% rac-DIBS. The IR spectroscopy data on the stereoisomeric configuration of DIBS in MgCl2/DIBS samples and titanium–magnesium catalysts MgCl2/DIBS/TiCl4 prepared by different procedures and the data on propylene polymerization over these catalysts are presented. [Display omitted] •Titanium-magnesium catalysts with diethyl 2,3-diisobutyl succinate have been studied•Mainly rac-stereoisomer (85–91%) is anchored to the surface of MgCl2 in catalysts•Succinate is anchored preferentially to pentacoordinated Mg ions on MgCl2 surface