Previous studies concerning with ethylene and alpha-olefins homo- and copolymerization in the presence of MgCl2-supported Ti/Hf catalysts have shown that the kinetics and polymer properties can be affected by the addition of protic compounds. In order to gain more information about these effects and related modifications of active sites, an investigation was carried out by using optically active carboxylic acids and chiral monomers. The influence of the structure of optically active protic compounds on the preferential polymerization of one monomer enantiomer (stereoelective polymerization) has been related to selective molecular interactions of the different catalytic species present in the catalyst. The obtained results are discussed with reference to the role of different transition metals.
Characterization of active sites in Ti/Hf/MgCl2 catalysts by chiral reagents
ALTOMARE, ANGELINA;CIARDELLI, FRANCESCO;SOLARO, ROBERTO
1994-01-01
Abstract
Previous studies concerning with ethylene and alpha-olefins homo- and copolymerization in the presence of MgCl2-supported Ti/Hf catalysts have shown that the kinetics and polymer properties can be affected by the addition of protic compounds. In order to gain more information about these effects and related modifications of active sites, an investigation was carried out by using optically active carboxylic acids and chiral monomers. The influence of the structure of optically active protic compounds on the preferential polymerization of one monomer enantiomer (stereoelective polymerization) has been related to selective molecular interactions of the different catalytic species present in the catalyst. The obtained results are discussed with reference to the role of different transition metals.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
